@article{alghamdi_edwards_berglund_2024, title={Dynamic Pricing Framework for Water Demand Management Using Advanced Metering Infrastructure Data}, volume={60}, ISSN={["1944-7973"]}, DOI={10.1029/2023WR035246}, abstractNote={Abstract This research investigates dynamic pricing as a demand management tool to reduce cost and increase the lifespan of water distribution systems by reducing peak hour demand. Individual consumer responses to changes in hourly water price are simulated using advanced metering infrastructure (AMI) data. Demand profiles are used as input to a hydraulic simulation model to evaluate the effects of changing demands on flows and in‐network metrics. The framework is applied to Lakewood City, California, using a model of the pipe network and AMI data collected at nearly 20,000 accounts. Four dynamic pricing policies are applied to the model to show that reductions in morning peak demand ranging from 6% to 25% reduce peak energy demands up to 14%. These small changes in overall energy demand, up to a 1.7% reduction, lead to relatively larger overall reductions in energy cost, up to 5.5%. The results demonstrate the importance of dynamic pricing as a demand‐side strategy for infrastructure management and highlight the potential to accommodate demand growth without additional infrastructure investments.}, number={9}, journal={WATER RESOURCES RESEARCH}, author={Alghamdi, Faisal M. and Edwards, Eric C. and Berglund, Emily Z.}, year={2024}, month={Sep} }
 @article{giang_edwards_fletcher_frolick_gryba_mathias_cambron_anderies_berglund_carley_et al._2024, title={Equity and modeling in sustainability science: Examples and opportunities throughout the process}, volume={121}, ISSN={["1091-6490"]}, DOI={10.1073/pnas.2215688121}, abstractNote={Equity is core to sustainability, but current interventions to enhance sustainability often fall short in adequately addressing this linkage. Models are important tools for informing action, and their development and use present opportunities to center equity in process and outcomes. This Perspective highlights progress in integrating equity into systems modeling in sustainability science, as well as key challenges, tensions, and future directions. We present a conceptual framework for equity in systems modeling, focused on its distributional, procedural, and recognitional dimensions. We discuss examples of how modelers engage with these different dimensions throughout the modeling process and from across a range of modeling approaches and topics, including water resources, energy systems, air quality, and conservation. Synthesizing across these examples, we identify significant advances in enhancing procedural and recognitional equity by reframing models as tools to explore pluralism in worldviews and knowledge systems; enabling models to better represent distributional inequity through new computational techniques and data sources; investigating the dynamics that can drive inequities by linking different modeling approaches; and developing more nuanced metrics for assessing equity outcomes. We also identify important future directions, such as an increased focus on using models to identify pathways to transform underlying conditions that lead to inequities and move toward desired futures. By looking at examples across the diverse fields within sustainability science, we argue that there are valuable opportunities for mutual learning on how to use models more effectively as tools to support sustainable and equitable futures.}, number={13}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Giang, Amanda and Edwards, Morgan R. and Fletcher, Sarah M. and Frolick, Rivkah Gardner- and Gryba, Rowenna and Mathias, Jean-Denis and Cambron, Camille Venier- and Anderies, John M. and Berglund, Emily and Carley, Sanya and et al.}, year={2024}, month={Mar} }
 @article{koyama_fasaee_berglund_knappe_2024, title={Machine Learning Models to Predict Early Breakthrough of Recalcitrant Organic Micropollutants in Granular Activated Carbon Adsorbers}, volume={9}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.4c01316}, DOI={10.1021/acs.est.4c01316}, abstractNote={Granular activated carbon (GAC) adsorption is frequently used to remove recalcitrant organic micropollutants (MPs) from water. The overarching aim of this research was to develop machine learning (ML) models to predict GAC performance from adsorbent, adsorbate, and background water matrix properties. For model calibration, MP breakthrough curves were compiled and analyzed to determine the bed volumes of water that can be treated until MP breakthrough reaches ten percent of the influent MP concentration (BV10). Over 400 data points were split into training, validation, and testing sets. Seventeen variables describing MP, background water matrix, and GAC properties were explored in ML models to predict log}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Koyama, Yoko and Fasaee, Mohammad A. K. and Berglund, Emily Z. and Knappe, Detlef R. U.}, year={2024}, month={Sep} }
 @article{pesantez_vizanko_berglund_2024, title={Modeling a game to shift peak water demands: WaterTime leaderboard}, volume={470}, ISSN={["1879-1786"]}, url={https://doi.org/10.1016/j.jclepro.2024.143241}, DOI={10.1016/j.jclepro.2024.143241}, journal={JOURNAL OF CLEANER PRODUCTION}, author={Pesantez, Jorge E. and Vizanko, Brent and Berglund, Emily Z.}, year={2024}, month={Sep} }
 @article{vizanko_kadinski_cummings_ostfeld_berglund_2024, title={Modeling prevention behaviors during the COVID-19 pandemic using Bayesian belief networks and protection motivation theory}, volume={3}, ISSN={["1539-6924"]}, url={https://doi.org/10.1111/risa.14287}, DOI={10.1111/risa.14287}, abstractNote={AbstractPrevention behaviors are important in mitigating the transmission of COVID‐19. The protection motivation theory (PMT) links perceptions of risk and coping ability with the act of adopting prevention behaviors. The goal of this research is to test the application of the PMT in predicting adoption of prevention behaviors during the COVID‐19 pandemic. Two research objectives are achieved to explore motivating factors for adopting prevention behaviors. (1) The first objective is to identify variables that are strong predictors of prevention behavior adoption. A data‐driven approach is used to train Bayesian belief network (BBN) models using results of a survey of  participants reporting risk perceptions and prevention behaviors during the COVID‐19 pandemic. A large set of models are generated and analyzed to identify significant variables. (2) The second objective is to develop models based on the PMT to predict prevention behaviors. BBN models that predict prevention behaviors were developed using two approaches. In the first approach, a data‐driven methodology trains models using survey data alone. In the second approach, expert knowledge is used to develop the structure of the BBN using PMT constructs. Results demonstrate that trust and experience with COVID‐19 were important predictors for prevention measure adoption. Models that were developed using the PMT confirm relationships between coping appraisal, threat appraisal, and protective behaviors. Data‐driven and PMT‐based models perform similarly well, confirming the use of PMT in this context. Predicting adoption of social distancing behaviors provides insight for developing policies during pandemics.}, journal={RISK ANALYSIS}, author={Vizanko, Brent and Kadinski, Leonid and Cummings, Christopher and Ostfeld, Avi and Berglund, Emily Zechman}, year={2024}, month={Mar} }
 @article{armstrong_zhong_bhide_grant_birkland_berglund_2024, title={Simulating the emergence of institutions that reverse freshwater salinization: An agent-based modeling approach}, volume={25}, ISSN={["2589-9155"]}, url={http://dx.doi.org/10.1016/j.hydroa.2024.100188}, DOI={10.1016/j.hydroa.2024.100188}, journal={JOURNAL OF HYDROLOGY X}, author={Armstrong, Kingston and Zhong, Yinman and Bhide, Shantanu V and Grant, Stanley B. and Birkland, Thomas and Berglund, Emily Zechman}, year={2024}, month={Dec} }
 @article{vizanko_kadinski_ostfeld_berglund_2024, title={Social distancing, water demand changes, and quality of drinking water during the COVID-19 pandemic}, volume={102}, ISSN={["2210-6715"]}, url={https://doi.org/10.1016/j.scs.2024.105210}, DOI={10.1016/j.scs.2024.105210}, abstractNote={The COVID-19 pandemic changed daily routines for people around the globe due to the adoption of social distancing measures, such as working from home and restricted travel. Changes in daily routines created new water demand patterns, and the spatial redistribution of water demands in urban water distribution systems affected water quality. A range of factors can influence individual decisions to social distance, including demographics, risk perceptions, and prior experience with infectious disease. This research develops an agent-based modeling framework to simulate decisions to social distance, the effect of social distancing on water demands, and effects on the performance of water infrastructure and the quality of delivered drinking water. This framework couples a hydraulic model, a COVID-19 transmission model, and Bayesian belief network (BBN) driven decision-making models within an agent-based modeling framework. The model is applied for a virtual city, Micropolis, to explore the effects of social distancing decisions on water age. Results demonstrate an increase in average water age and changes to the expected flow directions in pipes under scenarios of increasing social distancing. Nodes near industrial areas experience higher degradation of water quality. This research provides a new framework to develop and evaluate water infrastructure management strategies during pandemics.}, journal={SUSTAINABLE CITIES AND SOCIETY}, author={Vizanko, Brent and Kadinski, Leonid and Ostfeld, Avi and Berglund, Emily Zechman}, year={2024}, month={Mar} }
 @article{berglund_skarbek_kanta_2023, title={A sociotechnical framework to characterize tipping points in water supply systems}, volume={97}, ISSN={["2210-6715"]}, DOI={10.1016/j.scs.2023.104739}, abstractNote={Population growth and a drying climate can push urban water supply across a tipping point into a new regime of water deficits. This research develops an analytical approach to characterize tipping points in water supply systems based on a loss of ecological resilience. A comprehensive sociotechnical modeling framework is developed to apply increasing stress gradients, representing climate change and population growth scenarios, to a water supply system and generate time series of deficits, which are analyzed to characterize tipping points. An agent-based modeling framework of water use, supply, and management simulates feedbacks and adaptations between human behavior and water infrastructure systems. Projections of climate change are generated using a stochastic reconstruction framework. A change point detection algorithm is applied to detect change points, and a tipping point rule selects a tipping point from a set of change points. The sociotechnical framework is applied for a case study to demonstrate tipping point analysis. A range of stress gradients are applied for a projected period, and tipping points are characterized for climate change scenarios and management strategies. The sociotechnical framework characterizes the resilience of water supply and can be applied to simulate, predict, and avert tipping points in water supply systems.}, journal={SUSTAINABLE CITIES AND SOCIETY}, author={Berglund, Emily Z. and Skarbek, Michael and Kanta, Lufthansa}, year={2023}, month={Oct} }
 @article{bolton_berglund_2023, title={Agent-based modeling to assess decentralized water systems: Micro-trading rainwater for aquifer recharge}, volume={618}, ISSN={["1879-2707"]}, DOI={10.1016/j.jhydrol.2023.129151}, abstractNote={Decentralized aquifer recharge programs are an alternative to centralized stormwater aquifer recharge systems and can improve groundwater tables in urban areas. In a decentralized aquifer recharge program, households and property-owners collect and store rainwater from rooftops and replenish aquifers through small gravity-fed recharge wells. This research presents a micro-trading rainwater for aquifer recharge (MRAR) system as a decentralized peer-to-peer water market that can recharge groundwater resources. Through a decentralized water market, households act as prosumers who collect and sell rainwater to consumer households and convey traded water via a shared aquifer. This research develops an agent-based modeling framework as an approach to evaluate the performance of a MRAR system to replenish groundwater resources and reduce energy required to pump water. Agents represent (1) prosumers that collect rainwater, sell rainwater to consumers, and replenish the groundwater system through dry wells, and (2) consumers that exert irrigation demands, buy rainwater from prosumers, and pump water from the groundwater system. The agent-based model is coupled with a groundwater flow model to evaluate the effects of micro-trading on groundwater resources. The agent-based modeling framework is applied for a virtual city to assess the performance of a MRAR system for scenarios that vary in the ratio of consumers to prosumers, location of prosumers and consumers, and aquifer properties. Model outcomes demonstrate the optimal ratio of consumers to prosumers based on the volume of traded water, improvements in groundwater head, and improvements in unit energy of water. Findings demonstrate that the optimal ratio of consumers to prosumers is consistent across different values for hydraulic conductivity. The location of prosumer and consumer households affects the unit energy of water and has a negligible effect on the groundwater table and total energy consumed to pump water. This manuscript proposes and demonstrates MRAR as a new decentralized water system and provides a modeling approach to assess the performance of a MRAR system to improve urban groundwater resources.}, journal={JOURNAL OF HYDROLOGY}, author={Bolton, Elizabeth Ramsey and Berglund, Emily Zechman}, year={2023}, month={Mar} }
 @article{dicarlo_berglund_kaza_grieshop_shealy_behr_2023, title={Customer complaint management and smart technology adoption by community water systems}, volume={80}, ISSN={["1878-4356"]}, DOI={10.1016/j.jup.2022.101465}, abstractNote={Community water systems (CWSs) supply safe drinking water through pipes and other conveyances to the same population year-round. Complaint management is an important activity for CWSs and can assist efforts to monitor water quality and improve public perceptions. This research explores how CWSs receive, store, and use customer complaints. A new dataset is constructed through the distribution of an online survey. Respondents represent more than 500 CWSs across the U.S. and vary in characteristics, including the population size served. This research gives new insight about the tools that CWSs need and are willing to adopt for analyzing and reporting water quality issues.}, journal={UTILITIES POLICY}, author={DiCarlo, Morgan and Berglund, Emily Zechman and Kaza, Nikhil and Grieshop, Andrew and Shealy, Luke and Behr, Adam}, year={2023}, month={Feb} }
 @article{berglund_shafiee_xing_wen_2023, title={Digital Twins for Water Distribution Systems}, volume={149}, ISSN={["1943-5452"]}, DOI={10.1061/JWRMD5.WRENG-5786}, abstractNote={Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.}, number={3}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, author={Berglund, Emily Zechman and Shafiee, M. Ehsan and Xing, Lu and Wen, Jason}, year={2023}, month={Mar} }
 @article{kadinski_salcedo_boccelli_berglund_ostfeld_2022, title={A Hybrid Data-Driven-Agent-Based Modelling Framework for Water Distribution Systems Contamination Response during COVID-19}, volume={14}, ISSN={["2073-4441"]}, DOI={10.3390/w14071088}, abstractNote={Contamination events in water distribution systems (WDSs) are highly dangerous events in very vulnerable infrastructure where a quick response by water utility managers is indispensable. Various studies have explored methods to respond to water events and a variety of models have been developed to simulate the consequences and the reactions of all stakeholders involved. This study proposes a novel contamination response and recovery methodology using machine learning and knowledge of the topology and hydraulics of a water network inside of an agent-based model (ABM). An artificial neural network (ANN) is trained to predict the possible source of the contamination in the network, and the knowledge of the WDS and the possible flow directions throughout a demand pattern is utilized to verify that prediction. The utility manager agent can place mobile sensor equipment to trace the contamination spread after identifying the source to identify endangered and safe places in the water network and communicate that information to the consumer agents through water advisories. The contamination status of the network is continuously updated, and the consumers reaction and decision making are determined by a fuzzy logic system considering their social background, recent stress factors based on findings throughout the COVID-19 pandemic and their location in the network. The results indicate that the ANN-based support tool, paired with knowledge of the network, provides a promising support tool for utility managers to identify the source of a possible water event. The optimization of the ANN and the methodology led to accuracies up to 80%, depending on the number of sensors and the prediction types. Furthermore, the specified water advisories according to the mobile sensor placement provide the consumer agents with information on the contamination spread and urges them to seek for help or support less.}, number={7}, journal={WATER}, author={Kadinski, Leonid and Salcedo, Camilo and Boccelli, Dominic L. and Berglund, Emily and Ostfeld, Avi}, year={2022}, month={Apr} }
 @article{daniel_pesantez_letzgus_fasaee_alghamdi_berglund_mahinthakumar_cominola_2022, title={A Sequential Pressure-Based Algorithm for Data-Driven Leakage Identification and Model-Based Localization in Water Distribution Networks}, volume={148}, ISSN={["1943-5452"]}, url={https://doi.org/10.1061/(ASCE)WR.1943-5452.0001535}, DOI={10.1061/(ASCE)WR.1943-5452.0001535}, abstractNote={: Leakages in water distribution networks (WDNs) are estimated to globally cost 39 billion USD = year and cause water and revenue losses, infrastructure degradation, and other cascading effects. Their impacts can be prevented and mitigated with prompt identification and accurate leak localization. In this work, we propose the leakage identification and localization algorithm (LILA), a pressure-based algorithm for data-driven leakage identification and model-based localization in WDNs. First, LILA identifies potential leakages via semisupervised linear regression of pairwise sensor pressure data and provides the location of their nearest sensors. Second, LILA locates leaky pipes relying on an initial set of candidate pipes and a simulation-based optimization framework with iterative linear and mixed-integer linear programming. LILA is tested on data from the L-Town network devised for the Battle of Leakage Detection and Isolation Methods. Results show that LILA can identify all leakages included in the data set and locate them within a maximum distance of 374 m from their real location. Abrupt leakages are identified immediately or within 2 h, while more time is required to raise alarms on incipient leakages. DOI: 10.1061/(ASCE) WR.1943-5452.0001535. © 2022 American Society of Civil Engineers.}, number={6}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, publisher={American Society of Civil Engineers (ASCE)}, author={Daniel, Ivo and Pesantez, Jorge and Letzgus, Simon and Fasaee, Mohammad Ali Khaksar and Alghamdi, Faisal and Berglund, Emily and Mahinthakumar, G. and Cominola, Andrea}, year={2022}, month={Jun} }
 @article{kadinski_berglund_ostfeld_2022, title={An Agent-Based Model for Contamination Response in Water Distribution Systems during the COVID-19 Pandemic}, volume={148}, ISSN={["1943-5452"]}, DOI={10.1061/(ASCE)WR.1943-5452.0001576}, abstractNote={Contamination events in water distribution systems (WDS) are emergencies that cause public health crises and require fast response by the responsible utility manager. Various models have been developed to explore the reactions of relevant stakeholders during a contamination event, including agent-based modeling. As the COVID-19 pandemic has changed the daily habits of communities around the globe, consumer water demands have changed dramatically. In this study, an agent-based modeling framework is developed to explore social dynamics and reactions of water consumers and a utility manager to a contamination event, while considering regular and pandemic demand scenarios. Utility manager agents use graph theory algorithms to place mobile sensor equipment and divide the network in sections that are endangered of being contaminated or cleared again for water consumption. The status of respective network nodes is communicated to consumer agents in real time, and consumer agents adjust their water demands accordingly. This sociotechnological framework is presented using the overview, design, and details protocol. The results comprise comparisons of reactions and demand adjustments of consumers to a water event during normal and pandemic times, while exploring new methods to predict the fate of a contaminant plume in the WDS.}, number={8}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, author={Kadinski, Leonid and Berglund, Emily and Ostfeld, Avi}, year={2022}, month={Aug} }
 @article{grant_rippy_birkland_schenk_rowles_misra_aminpour_kaushal_vikesland_berglund_et al._2022, title={Can Common Pool Resource Theory Catalyze Stakeholder-Driven Solutions to the Freshwater Salinization Syndrome?}, volume={9}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.2c01555}, DOI={10.1021/acs.est.2c01555}, abstractNote={Freshwater salinity is rising across many regions of the United States as well as globally, a phenomenon called the freshwater salinization syndrome (FSS). The FSS mobilizes organic carbon, nutrients, heavy metals, and other contaminants sequestered in soils and freshwater sediments, alters the structures and functions of soils, streams, and riparian ecosystems, threatens drinking water supplies, and undermines progress toward many of the United Nations Sustainable Development Goals. There is an urgent need to leverage the current understanding of salinization’s causes and consequences—in partnership with engineers, social scientists, policymakers, and other stakeholders—into locally tailored approaches for balancing our nation’s salt budget. In this feature, we propose that the FSS can be understood as a common pool resource problem and explore Nobel Laureate Elinor Ostrom’s social-ecological systems framework as an approach for identifying the conditions under which local actors may work collectively to manage the FSS in the absence of top-down regulatory controls. We adopt as a case study rising sodium concentrations in the Occoquan Reservoir, a critical water supply for up to one million residents in Northern Virginia (USA), to illustrate emerging impacts, underlying causes, possible solutions, and critical research needs.}, number={19}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Grant, Stanley B. and Rippy, Megan A. and Birkland, Thomas A. and Schenk, Todd and Rowles, Kristin and Misra, Shalini and Aminpour, Payam and Kaushal, Sujay and Vikesland, Peter and Berglund, Emily and et al.}, year={2022}, month={Sep} }
 @article{fasaee_pesantez_pieper_ling_benham_edwards_berglund_2022, title={Developing early warning systems to predict water lead levels in tap water for private systems}, volume={221}, ISSN={["1879-2448"]}, url={https://doi.org/10.1016/j.watres.2022.118787}, DOI={10.1016/j.watres.2022.118787}, abstractNote={Lead is a chemical contaminant that threatens public health, and high levels of lead have been identified in drinking water at locations across the globe. Under-served populations that use private systems for drinking water supplies may be at an elevated level of risk because utilities and governing agencies are not responsible for ensuring that lead levels meet the Lead and Copper Rule at these systems. Predictive models that can be used by residents to assess water quality threats in their households can create awareness of water lead levels (WLLs). This research explores and compares the use of statistical models (i.e., Bayesian Belief classifiers) and machine learning models (i.e., ensemble of decision trees) for predicting WLLs. Models are developed using a dataset collected by the Virginia Household Water Quality Program (VAHWQP) at approximately 8000 households in Virginia during 2012–2017. The dataset reports laboratory-tested water quality parameters at households, location information, and household and plumbing characteristics, including observations of water odor, taste, discoloration. Some water quality parameters, such as pH, iron, and copper, can be measured at low resolution by residents using at-home water test kits and can be used to predict risk of WLLs. The use of at-home water quality test kits was simulated through the discretization of water quality parameter measurements to match the resolution of at-home water quality test kits and the introduction of error in water quality readings. Using this approach, this research demonstrates that low-resolution data collected by residents can be used as input for models to estimate WLLs. Model predictability was explored for a set of at-home water quality test kits that observe a variety of water quality parameters and report parameters at a range of resolutions. The effects of the timing of water sampling (e.g., first-draw vs. flushed samples) and error in kits on model error were tested through simulations. The prediction models developed through this research provide a set of tools for private well users to assess the risk of lead contamination. Models can be implemented as early warning systems in citizen science and online platforms to improve awareness of drinking water threats.}, journal={WATER RESEARCH}, author={Fasaee, Mohammad Ali Khaksar and Pesantez, Jorge and Pieper, Kelsey J. and Ling, Erin and Benham, Brian and Edwards, Marc and Berglund, Emily}, year={2022}, month={Aug} }
 @article{behr_berglund_sciaudone_2022, title={Effectiveness of indicators for assessing the vulnerability of barrier island highways}, volume={105}, ISSN={["1879-2340"]}, DOI={10.1016/j.trd.2022.103234}, abstractNote={Highways along barrier islands are highly susceptible to storm impacts like overwash, erosion, and island breaching. The present research evaluates the effectiveness of 14 morphological indicators in predicting highway vulnerability to storm impacts from a data set of seven storms with documented roadway impacts. Multi-indicator functions were also developed and assessed. The research finds that distance from edge-of-pavement to dune toe, volume above mean high water between edge-of-pavement and ocean shoreline, distance from edge-of-pavement to ocean shoreline, and dune crest height above the road are the most skilled individual indicators of highway vulnerability. A multi-indicator function of dune toe elevation and distance from edge-of-pavement to dune toe is more skilled than any of the individual indicators that were evaluated. Some of these indicators can be projected to assess future vulnerability, as well. The results convey the value of geomorphology-based indicators and their potential in larger-scale coastal infrastructure vulnerability assessments.}, journal={TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT}, author={Behr, Adam and Berglund, Emily and Sciaudone, Elizabeth}, year={2022}, month={Apr} }
 @article{berglund_buchberger_cunha_faust_giacomoni_goharian_kleiner_lee_ostfeld_pasha_et al._2022, title={Effects of the COVID-19 Pandemic on Water Utility Operations and Vulnerability}, volume={148}, ISSN={["1943-5452"]}, DOI={10.1061/(ASCE)WR.1943-5452.0001560}, abstractNote={The COVID-19 pandemic affected the operation of water utilities across the world. In the context of utilities, new protocols were needed to ensure that employees can work safely, and that water service is not interrupted. This study reports on how the operations of 27 water utilities worldwide were affected by the COVID-19 pandemic. Interviews were conducted between June and October 2020;respondents represent utilities that varied in population size, location, and customer composition (e.g., residential, industrial, commercial, institutional, and university customers). Survey questions focused on the effects of the pandemic on water system operation, demand, revenues, system vulnerabilities, and the use and development of emergency response plans (ERPs). Responses indicate that significant changes in water system operations were implemented to ensure that water utility employees could continue working while maintaining safe social distancing or alternatively working from home. A total of 23 of 27 utilities reported small changes in demand volumes and patterns, which can lead to some changes in water infrastructure operations and water quality. Utilities experienced a range of impacts on finances, where most utilities discussed small decreases in revenues, with a few reporting more drastic impacts. The pandemic revealed new system vulnerabilities, including supply chain management, capacity of staff to perform certain functions remotely, and finances. Some utilities applied existing guidance developed through ERPs with slight modifications, other utilities developed new ERPs to specifically address unique conditions induced by the pandemic, and a few utilities did not use or reference their existing ERPs to change operations. Many utilities suggested that lessons learned would be used in future ERPs, such as personnel training on pandemic risk management or annual mock exercises for preparing employees to better respond to emergencies.}, number={6}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, author={Berglund, Emily Zechman and Buchberger, Steven and Cunha, Maria and Faust, Kasey M. and Giacomoni, Marcio and Goharian, Erfan and Kleiner, Yehuda and Lee, Juneseok and Ostfeld, Avi and Pasha, Fayzul and et al.}, year={2022}, month={Jun} }
 @article{dicarlo_berglund_2022, title={Using advanced metering infrastructure data to evaluate consumer compliance with water advisories during a water service interruption}, volume={221}, ISSN={["1879-2448"]}, DOI={10.1016/j.watres.2022.118802}, abstractNote={Water main breaks disrupt services provided by utilities and result in Water Service Interruptions (WSIs). Water utilities can manage WSIs through water advisories, which request that consumers limit their water use. The performance of water advisories depends on consumer compliance and decisions to conserve water. This research explores customer compliance with water advisories using water consumption data collected through Advanced Metering Infrastructure (AMI). AMI provides high temporal and spatial resolution of water consumption data, which is analyzed to identify changes in water use behaviors. This research explores water use changes during a major water main break in Orange County, North Carolina, that caused a significant WSI, limiting water supply for more than 80,000 people. Customers were asked to reduce water use to essential purposes only and to boil water over the course of two days in November 2018. This research analyzes hourly consumption data to evaluate water consumption trends during the WSI and in response to water advisories. Statistical analysis is used to estimate the number of consumers who complied with utility notifications and to evaluate the volume of water saved. Regression analysis is applied to explore compliance across different user segments. Results provide insight about the level and variation of water conservation that can be expected during a WSI.}, journal={WATER RESEARCH}, author={DiCarlo, Morgan Faye and Berglund, Emily Zechman}, year={2022}, month={Aug} }
 @article{fasaee_monghasemi_nikoo_shafiee_berglund_bakhtiari_2021, title={A K-Sensor correlation-based evolutionary optimization algorithm to cluster contamination events and place sensors in water distribution systems}, volume={319}, ISSN={["1879-1786"]}, DOI={10.1016/j.jclepro.2021.128763}, abstractNote={Contaminants that are introduced to drinking water systems can threaten large populations, and the potential for catastrophic consequences accentuates the need for efficient post-disaster strategies, including optimal hydrant flushing. Efficient hydrant flushing can significantly reduce impacts on public health, but performance relies on information about the propagation of a contaminant and the affected regions in a water network. While observations from water quality sensors are useful in timely detections of contaminants, little information on its source, propagation, and affected regions can be inferred. In the absence of such information, opening or closing hydrants might not help discharge contaminants but could accelerate propagation of a plume through the water network due to drops in pressure. To address this limitation of sensor layout optimization models, this research has developed a new model to identify the optimal location of sensors to effectively support hydrant flushing mechanisms. The model has been developed in three steps: (1) contamination events were simulated in a water network; (2) spatially similar propagating contamination events were identified; and (3) the layout of water quality sensors was optimized. In the first step, a representative number of potential contamination events were simulated using a hydraulic model. The second step clustered contamination events based on spatial similarity in their propagation regimes. Finally, the last step identified locations for placing water quality sensors within clusters (identified in the previous step) while minimizing detection time and maximizing probability of detection. This model ensures that when a sensor alarm is activated, contaminated region where hydrants should be opened or closed are spatially restricted. The approach developed in this research was applied to design a sensor network for a benchmark case study, Mesopolis. The layout of 10 water quality sensors was optimized over a set of 9161 contamination events, leading to 76% probability of detection with an average detection time of 8.2 h. The solution was compared with sensor layouts based on existing approaches, and it was found that the new approach could improve the mass of contaminant that was removed from the pipe network through hydrant flushing strategies. The new approach model improves the effectiveness of hydrant flushing strategies by restricting the area where hydrants are flushed to predefined zones based on the activation of sensors.}, journal={JOURNAL OF CLEANER PRODUCTION}, author={Fasaee, Mohammad Ali Khaksar and Monghasemi, Shahryar and Nikoo, Mohammad Reza and Shafiee, M. Ehsan and Berglund, Emily Zechman and Bakhtiari, Parnian Hashempour}, year={2021}, month={Oct} }
 @article{dicarlo_berglund_2021, title={Connected communities improve hazard response: An agent-based model of social media behaviors during hurricanes}, volume={69}, ISSN={["2210-6715"]}, DOI={10.1016/j.scs.2021.102836}, abstractNote={Social media platforms have a developing role in how people respond to hazards, providing a network to seek help and respond to help requests. Understanding the dynamics of behavior on social media networks can improve community-level hazard response efforts. People who experience damages may use social media to seek immediate help for debris removal, supplies delivery or emergency rescue, and peers connected on social media may respond by reposting the help request or providing help in person. This research develops an agent-based model (ABM) to simulate a community of individuals that use social media to seek help and respond to requests for help during a hurricane. Agents represent individuals that are in a community affected by a hurricane and share a social media network. Behavioral rules for seeking help and providing help are developed using the Theory of Planned Behavior and parametrized through analysis of a survey of social media use conducted in communities that were affected by 2018 Hurricanes Florence and Michael. The ABM simulates agents that post help requests, repost help requests, provide help in person, and receive help. A Design of Experiments approach is applied to assess how ABM parameters, including community size, connectivity of a network, damage rate, and propensity for using social media, influence the number of requests for help that are met through the social media network. Results demonstrate that high connectivity leads to rapid reposting and results in cascading responses to meet requests for help.}, journal={SUSTAINABLE CITIES AND SOCIETY}, author={DiCarlo, Morgan Faye and Berglund, Emily Zechman}, year={2021}, month={Jun} }
 @article{pesantez_alghamdi_sabu_mahinthakumar_berglund_2022, title={Using a digital twin to explore water infrastructure impacts during the COVID-19 pandemic}, volume={77}, ISSN={["2210-6715"]}, DOI={10.1016/j.scs.2021.103520}, abstractNote={During the coronavirus disease 2019 (COVID-19) pandemic, the daily pattern of activities changed dramatically for people across the globe, as they socially distanced and worked remotely. Changes in daily routines created changes in water consumption patterns. Significant changes in water demands can affect the operation of water distribution systems, resulting in new patterns of flow, with implications for water age, pressure, and energy consumption. This research develops a digital twin to couple Advanced Metering Infrastructure (AMI) data with a hydraulic model to assess impacts on infrastructure due to changes in water demands associated with the COVID-19 pandemic for a case study. Using 2019 and COVID-19 modeling scenarios, the hydraulic model was executed to evaluate changes to water quality based on water age, pressure across nodes in the network, and the energy required by the system to distribute potable water. A water supply interruption event was modeled as a water main break to assess network resiliency for 2019 and COVID-19 demands. A digital twin provides the capabilities to explore and visualize emerging consumption patterns and their effects on the functioning of water systems, providing valuable analyses for water utility managers and insight for optimizing infrastructure operations and planning for long-term impacts.}, journal={SUSTAINABLE CITIES AND SOCIETY}, author={Pesantez, Jorge E. and Alghamdi, Faisal and Sabu, Shreya and Mahinthakumar, G. and Berglund, Emily Zechman}, year={2022}, month={Feb} }
 @article{lee_taylor_berglund_2021, title={Water Use in the Landscape: A Comparison of Water Quality and Irrigation Technologies on Behavior}, volume={57}, ISSN={["1944-7973"]}, DOI={10.1029/2020WR028853}, abstractNote={AbstractReclaimed wastewater for outdoor irrigation purposes is an effective tool for conserving potable water sources and reducing effluent discharge from wastewater treatment facilities. Despite its “green” attributes, we find outdoor watering behavior that is consistent with households treating reclaimed water as a lower quality substitute to potable water for outdoor residential irrigation. Using unique microdata, we estimate the demand for outdoor water and find that after controlling for differences in irrigation water prices, households using reclaim water and households without automatic irrigation systems consume substantially less water in the landscape.}, number={10}, journal={WATER RESOURCES RESEARCH}, author={Lee, Jonathan M. and Taylor, Laura O. and Berglund, Emily Z.}, year={2021}, month={Oct} }
 @article{berglund_thelemaque_spearing_faust_kaminsky_sela_goharian_abokifa_lee_keck_et al._2021, title={Water and Wastewater Systems and Utilities: Challenges and Opportunities during the COVID-19 Pandemic}, volume={147}, ISSN={["1943-5452"]}, url={https://doi.org/10.1061/(ASCE)WR.1943-5452.0001373}, DOI={10.1061/(ASCE)WR.1943-5452.0001373}, abstractNote={Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal}, number={5}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, publisher={American Society of Civil Engineers (ASCE)}, author={Berglund, Emily Zechman and Thelemaque, Nathalie and Spearing, Lauryn and Faust, Kasey M. and Kaminsky, Jessica and Sela, Lina and Goharian, Erfan and Abokifa, Ahmed and Lee, Juneseok and Keck, Jonathan and et al.}, year={2021}, month={May} }
 @article{monroe_hansen_sorell_berglund_2020, title={Agent-Based Model of a Blockchain Enabled Peer-to-Peer Energy Market: Application for a Neighborhood Trial in Perth, Australia}, volume={3}, ISSN={["2624-6511"]}, DOI={10.3390/smartcities3030053}, abstractNote={The transfer of market power in electric generation from utilities to end-users spurred by the diffusion of distributed energy resources necessitates a new system of settlement in the electricity business that can better manage generation assets at the grid-edge. A new concept in facilitating distributed generation is peer-to-peer energy trading, where households exchange excess power with neighbors at a price they set themselves. However, little is known about the effects of peer-to-peer energy trading on the sociotechnical dynamics of electric power systems. Further, given the novelty of the concept, there are knowledge gaps regarding the impact of alternative electricity market structures and individual decision strategies on neighborhood exchanges and market outcomes. This study develops an empirical agent-based modeling (ABM) framework to simulate peer-to-peer electricity trades in a decentralized residential energy market. The framework is applied for a case study in Perth, Western Australia, where a blockchain-enabled energy trading platform was trialed among 18 households, which acted as prosumers or consumers. The ABM is applied for a set of alternative electricity market structures. Results assess the impact of solar generation forecasting approaches, battery energy storage, and ratio of prosumers to consumers on the dynamics of peer-to-peer energy trading systems. Designing an efficient, equitable, and sustainable future energy system hinges on the recognition of trade-offs on and across, social, technological, economic, and environmental levels. Results demonstrate that the ABM can be applied to manage emerging uncertainties by facilitating the testing and development of management strategies.}, number={3}, journal={SMART CITIES}, author={Monroe, Jacob G. and Hansen, Paula and Sorell, Matthew and Berglund, Emily Zechman}, year={2020}, month={Sep}, pages={1072–1099} }
 @article{fasaee_berglund_pieper_ling_benham_edwards_2021, title={Developing a framework for classifying water lead levels at private drinking water systems: A Bayesian Belief Network approach}, volume={189}, ISSN={["1879-2448"]}, DOI={10.1016/j.watres.2020.116641}, abstractNote={The presence of lead in drinking water creates a public health crisis, as lead causes neurological damage at low levels of exposure. The objective of this research is to explore modeling approaches to predict the risk of lead at private drinking water systems. This research uses Bayesian Network approaches to explore interactions among household characteristics, geological parameters, observations of tap water, and laboratory tests of water quality parameters. A knowledge discovery framework is developed by integrating methods for data discretization, feature selection, and Bayes classifiers. Forward selection and backward selection are explored for feature selection. Discretization approaches, including domain-knowledge, statistical, and information-based approaches, are tested to discretize continuous features. Bayes classifiers that are tested include General Bayesian Network, Naive Bayes, and Tree-Augmented Naive Bayes, which are applied to identify Directed Acyclic Graphs (DAGs). Bayesian inference is used to fit conditional probability tables for each DAG. The Bayesian framework is applied to fit models for a dataset collected by the Virginia Household Water Quality Program (VAHWQP), which collected water samples and conducted household surveys at 2,146 households that use private water systems, including wells and springs, in Virginia during 2012 and 2013. Relationships among laboratory-tested water quality parameters, observations of tap water, and household characteristics, including plumbing type, source water, household location, and on-site water treatment are explored to develop features for predicting water lead levels. Results demonstrate that Naive Bayes classifiers perform best based on recall and precision, when compared with other classifiers. Copper is the most significant predictor of lead, and other important predictors include county, pH, and on-site water treatment. Feature selection methods have a marginal effect on performance, and discretization methods can greatly affect model performance when paired with classifiers. Owners of private wells remain disadvantaged and may be at an elevated level of risk, because utilities and governing agencies are not responsible for ensuring that lead levels meet the Lead and Copper Rule for private wells. Insight gained from models can be used to identify water quality parameters, plumbing characteristics, and household variables that increase the likelihood of high water lead levels to inform decisions about lead testing and treatment.}, journal={WATER RESEARCH}, author={Fasaee, Mohammad Ali Khaksar and Berglund, Emily and Pieper, Kelsey J. and Ling, Erin and Benham, Brian and Edwards, Marc}, year={2021}, month={Feb} }
 @article{dicarlo_berglund_2020, title={Use of Social Media to Seek and Provide Help in Hurricanes Florence and Michael}, volume={3}, ISSN={["2624-6511"]}, DOI={10.3390/smartcities3040059}, abstractNote={During hazardous events, communities can use existing social media networks to share information in real time and initiate a local disaster response. This research conducted a web-based survey to explore two behaviors around the use of social media during hurricanes: seeking help and responding to help requests. Through the survey, we sampled 434 individuals across several counties affected by 2018 hurricanes Florence and Michael, which were both designated by the National Oceanic and Atmospheric Administration as billion-dollar weather disasters. The survey questions collected data about demographics, social media use habits, perceptions towards social media, hurricane damages, and actions taken during a hurricane to seek and provide help. The Theory of Planned Behavior (TPB) was used to conceptualize and frame parameters that affect intentions and behaviors regarding the use of social media during hurricanes to seek and provide help. Survey responses are analyzed using statistical regression to evaluate hypotheses about the influence of factors on seeking help and responding to help requests. Regression analyses indicate that attitude and perceived behavioral control predict intention to access social media during a hurricane, partially supporting the TPB. Intention and experiencing urgent damages predict help-seeking behaviors using social media. Posting frequency to social media under normal conditions and the number of help requests seen during the event predict help-responding behaviors. Linear regression equations governing intention and behavior were parameterized using survey results. The factors underlying social media behavior during hurricanes as identified in this research provide insight for understanding how smart information technologies, such as personal devices and social media networks, support community self-sufficiency and hazard resilience.}, number={4}, journal={SMART CITIES}, author={DiCarlo, Morgan Faye and Berglund, Emily Zechman}, year={2020}, month={Dec}, pages={1187–1218} }
 @article{pesantez_berglund_mahinthakumar_2019, title={Multiphase Procedure to Design District Metered Areas for Water Distribution Networks}, volume={145}, ISSN={["1943-5452"]}, url={https://doi.org/10.1061/(ASCE)WR.1943-5452.0001095}, DOI={10.1061/(ASCE)WR.1943-5452.0001095}, abstractNote={AbstractDividing a water distribution network into subsystems can improve the efficiency and ease of achieving management goals. Subsystems or district metered areas (DMAs) are isolated control zon...}, number={8}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, publisher={American Society of Civil Engineers (ASCE)}, author={Pesantez, Jorge E. and Berglund, Emily Zechman and Mahinthakumar, G.}, year={2019}, month={Aug} }
 @article{strickling_dicarlo_shafiee_berglund_2020, title={Simulation of containment and wireless emergency alerts within targeted pressure zones for water contamination management}, volume={52}, ISSN={2210-6707}, url={http://dx.doi.org/10.1016/j.scs.2019.101820}, DOI={10.1016/j.scs.2019.101820}, abstractNote={A sustainably managed city should implement strategies to mitigate water distribution contamination events and warn consumers. A modeling framework is developed to assess management strategies for issuing warnings via wireless emergency alerts (WEA) and isolating a contaminant by manipulating pumps and hydrants. A pressure zone-based paradigm divides a service area into sub-sections of similar pressures and is used to target WEA messages and contain and flush contaminant within affected zones. The framework couples a hydraulic model of a pipe network with an agent-based model of utility operators, who implement management strategies, and of consumers, who receive messages, comply with alerts, reduce water use, and communicate about the hazard. The framework is applied for a hypothetical city to test management strategies for two water contamination events. Targeted messages mitigate the loss of access to water supplies and perform similar to citywide messages in reducing the number of exposed consumers, when combined with containment operations. When warnings are used alone, citywide warnings protect more consumers compared with targeted broadcasts. Warnings may perform better than containment alone at times when critical social dynamics, such as ingestion of water and travel among pressure zones, coincide with the movement of a contaminant plume.}, journal={Sustainable Cities and Society}, publisher={Elsevier BV}, author={Strickling, Hayden and DiCarlo, Morgan Faye and Shafiee, M. Ehsan and Berglund, Emily}, year={2020}, month={Jan}, pages={101820} }
 @article{monroe_ramsey_berglund_2018, title={Allocating countermeasures to defend water distribution systems against terrorist attack}, volume={179}, ISSN={0951-8320}, url={http://dx.doi.org/10.1016/j.ress.2018.02.014}, DOI={10.1016/j.ress.2018.02.014}, abstractNote={Water distribution networks are critical infrastructure systems that are vulnerable to terrorist attack. Water utility management has the goal of protecting public health by allocating countermeasures, including security equipment and personnel, as a first line of defense. A malevolent actor may select an attack location, however, using a set of unknown priorities that include performance and susceptibility criteria. This research develops a multi-agent framework to simulate the attack and defense of a distribution system to analyze security resource allocation strategies for protecting against chemical contamination events. A single period attacker-defender game is simulated, in which an attacker seeks to contaminate a system node with high attack utility, and a group of defenders seeks to minimize the public health impact from intentional attack. Terrorist agent decisions are simulated using a multi-attribute utility function, and multiple cases are constructed to simulate alternative rankings of criteria. The water utility manager agent assigns security personnel and deterrent security equipment to nodes using one of three security resource allocation strategies. The agent-based modeling framework is applied to simulate attack and defense for a virtual municipality, D-town. Strategies are evaluated based on the number of consumers exposed to a critical dose when a contaminant is released.}, journal={Reliability Engineering & System Safety}, publisher={Elsevier BV}, author={Monroe, Jacob and Ramsey, Elizabeth and Berglund, Emily}, year={2018}, month={Nov}, pages={37–51} }
 @article{shafiee_berglund_lindell_2018, title={An Agent-based Modeling Framework for Assessing the Public Health Protection of Water Advisories}, volume={32}, ISSN={0920-4741 1573-1650}, url={http://dx.doi.org/10.1007/s11269-018-1916-6}, DOI={10.1007/s11269-018-1916-6}, number={6}, journal={Water Resources Management}, publisher={Springer Science and Business Media LLC}, author={Shafiee, M. Ehsan and Berglund, Emily Zechman and Lindell, Michael K.}, year={2018}, month={Feb}, pages={2033–2059} }
 @article{kandiah_berglund_binder_2019, title={An agent-based modeling approach to project adoption of water reuse and evaluate expansion plans within a sociotechnical water infrastructure system}, volume={46}, ISSN={2210-6707}, url={http://dx.doi.org/10.1016/j.scs.2018.12.040}, DOI={10.1016/j.scs.2018.12.040}, abstractNote={The introduction of water reuse infrastructure into an existing water supply system is a complex sociotechnical process. For a dual reticulation program, infrastructure designs affect adoption, as the expansion of infrastructure defines when a household can adopt and become active in communicating about water reuse. This research develops a coupled framework to capture the dynamics among consumer adoption and infrastructure expansion. An agent-based modeling approach is used to simulate opinion dynamics within a risk publics framework, which is based on the social amplification of risk and captures changes in perceptions about the risks and benefits of water reuse. The model is applied to simulate and project adoption of water reuse for the Town of Cary, North Carolina, using data about new water reclamation accounts and plans for infrastructure expansion. Performance of the agent-based model is compared with a cellular automata model for simulating historic data. Alternative infrastructure expansion schedules are simulated using the agent-based model to evaluate potable water savings and utilization of reclaimed water capacity, based on adoption projections. The framework provides a sociotechnical approach to evaluate development plans for infrastructure systems that rely on adoption of infrastructure-dependent technologies.}, journal={Sustainable Cities and Society}, publisher={Elsevier BV}, author={Kandiah, Venu K. and Berglund, Emily Z. and Binder, Andrew R.}, year={2019}, month={Apr}, pages={101412} }
 @article{garcia-cuerva_berglund_rivers_2018, title={An integrated approach to place Green Infrastructure strategies in marginalized communities and evaluate stormwater mitigation}, volume={559}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2018.02.066}, DOI={10.1016/j.jhydrol.2018.02.066}, abstractNote={Increasing urbanization augments impervious surface area, which results in increased run off volumes and peak flows. Green Infrastructure (GI) approaches are a decentralized alternative for sustainable urban stormwater and provide an array of ecosystem services and foster community building by enhancing neighborhood aesthetics, increasing property value, and providing shared green spaces. While projects involving sustainability concepts and environmental design are favored in privileged communities, marginalized communities have historically been located in areas that suffer from environmental degradation. Underprivileged communities typically do not receive as many social and environmental services as advantaged communities. This research explores GI-based management strategies that are evaluated at the watershed scale to improve hydrological performance by mitigating storm water run off volumes and peak flows. GI deployment strategies are developed to address environmental justice issues by prioritizing placement in communities that are underprivileged and locations with high outreach potential. A hydrologic/hydraulic stormwater model is developed using the Storm Water Management Model (SWMM 5.1) to simulate the impacts of alternative management strategies. Management scenarios include the implementation of rain water harvesting in private households, the decentralized implementation of bioretention cells in private households, the centralized implementation of bioretention cells in municipally owned vacant land, and combinations of those strategies. Realities of implementing GI on private and public lands are taken into account to simulate various levels of coverage and routing for bioretention cell scenarios. The effects of these strategies are measured by the volumetric reduction of run off and reduction in peak flow; social benefits are not evaluated. This approach is applied in an underprivileged community within the Walnut Creek Watershed in Raleigh, North Carolina.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Garcia-Cuerva, Laura and Berglund, Emily Zechman and Rivers, Louie, III}, year={2018}, month={Apr}, pages={648–660} }
 @article{al-amin_berglund_mahinthakumar_larson_2018, title={Assessing the effects of water restrictions on socio-hydrologic resilience for shared groundwater systems}, volume={566}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2018.08.045}, DOI={10.1016/j.jhydrol.2018.08.045}, abstractNote={Groundwater resources are shared across management boundaries. Multiple management units that differ in scale, constraints and objectives may manage a shared resource in a decentralized approach. The interactions among water managers, water users, and the water resource components influence the performance of management strategies and the resilience of community-level water supply and groundwater availability. This research develops an agent-based modeling (ABM) framework to capture the dynamic interactions among household-level consumers and policy makers to simulate water demands. The ABM is coupled with a groundwater model to evaluate effects on the groundwater table. The framework is applied to explore trade-offs between improvements in water supply sustainability for local resources and water table changes at the basin-level. A group of municipalities are simulated as agents who share access to a groundwater aquifer in Verde River Basin, Arizona. The framework provides a holistic approach to incorporate water user, municipal, and basin level objectives in evaluating water reduction strategies for long-term water resilience.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Al-Amin, Shams and Berglund, Emily Z. and Mahinthakumar, G. and Larson, Kelli L.}, year={2018}, month={Nov}, pages={872–885} }
 @article{monroe_ducoste_berglund_2019, title={Genetic Algorithm–Genetic Programming Approach to Identify Hierarchical Models for Ultraviolet Disinfection Reactors}, volume={145}, ISSN={0733-9372 1943-7870}, url={http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0001492}, DOI={10.1061/(ASCE)EE.1943-7870.0001492}, abstractNote={AbstractThe performance of ultraviolet (UV) disinfection reactors using experimental data poses major challenges to the water treatment industry, and a regression model has been developed in the wa...}, number={2}, journal={Journal of Environmental Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Monroe, Jacob G. and Ducoste, Joel and Berglund, Emily Z.}, year={2019}, month={Feb}, pages={04018139} }
 @article{raei_shafiee_nikoo_berglund_2018, title={Placing an ensemble of pressure sensors for leak detection in water distribution networks under measurement uncertainty}, volume={21}, ISSN={1464-7141 1465-1734}, url={http://dx.doi.org/10.2166/hydro.2018.032}, DOI={10.2166/hydro.2018.032}, abstractNote={AbstractLarge volumes of water are wasted through leakage in water distribution networks, and early detection of leakages is important to minimize lost water. Pressure sensors can be placed in a network to detect changes in pressure that indicate the presence of a new leak. This study presents a new approach for placing a set of pressure sensors by creating a list of candidate locations based on sensitivity to leaks that are simulated at all potential nodes in a network. The selection of a set of sensors is explored for two objectives, which are the minimization of the number of sensors and the time of detection. The non-dominated sorting genetic algorithm (NSGA-II) is used to explore trade-offs between these objectives. The effect of measurement uncertainty on the selection of sensor locations is explored by identifying alternative non-dominated fronts for different values for sensor error. The evolutionary algorithm-based approach is applied and demonstrated for the C-Town water network.}, number={2}, journal={Journal of Hydroinformatics}, publisher={IWA Publishing}, author={Raei, Ehsan and Shafiee, M. Ehsan and Nikoo, Mohammad Reza and Berglund, Emily}, year={2018}, month={Dec}, pages={223–239} }
 @article{al-amin_ajmeri_du_berglund_singh_2018, title={Toward effective adoption of secure software development practices}, volume={85}, ISSN={["1878-1462"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85045638469&partnerID=MN8TOARS}, DOI={10.1016/j.simpat.2018.03.006}, abstractNote={Security tools, including static and dynamic analysis tools, can guide software developers to identify and fix potential vulnerabilities in their code. However, the use of security tools is not common among developers. The goal of this research is to develop a framework for modeling the adoption of security practices in software development and to explore sanctioning mechanisms that may promote greater adoption of these practices among developers. We propose a multiagent simulation framework that incorporates developers and manager roles, where developers maximize task completion and compliance with security policies, and the manager enforces sanctions based on functionality and security of the project. The adoption of security practices emerges through the interaction of manager and developer agents in time-critical projects. Using the framework, we evaluate the adoption of security practices for developers with different preferences and strategies under individual and group sanctions. We use a real case study for demonstrating the model and initialize the occurrence of bugs using a 13 year database of bug reports for the Eclipse Java Development Tools. Results indicate that adoption of security practices are significantly dictated by the preferences of the developers. We also observed that repetitive sanctions may cause lower retention of developers and an overall decrease in security practices. The model provides comparison of security adoption in developers with different preferences and provides guidance for managers to identify appropriate sanctioning mechanism for increasing the adoption of security tools in software development.}, journal={SIMULATION MODELLING PRACTICE AND THEORY}, publisher={Elsevier BV}, author={Al-Amin, Shams and Ajmeri, Nirav and Du, Hongying and Berglund, Emily Z. and Singh, Munindar P.}, year={2018}, month={Jun}, pages={33–46} }
 @article{shafiee_berglund_2017, title={Agent-based modelling approach to evaluate the effect of collaboration among scientists in scientific workflows}, volume={13}, ISSN={1747-7778 1747-7786}, url={http://dx.doi.org/10.1080/17477778.2017.1387333}, DOI={10.1080/17477778.2017.1387333}, abstractNote={Abstract Automation in science is increasingly marked by the use of workflow systems (eg, Matlab) to facilitate the scientific discovery. The sharing of workflows through publication mechanisms supports the reproducibility and extensibility of computational experiments. However, the subsequent scientific discovery from a workflow relates to the level of collaboration among scientists. An agent-based model (ABM) is developed by coupling a scientific workflow with a model of scientist agents. The scientist agents are able to collaborate using a simplified small-world network. After a query is submitted to scientist agents, each scientist agent is able to extract data from data-sets, which are widely available online, using automated workflows to prepare a scientific report for a query. After data are collected from a workflow, data can be shared among scientists using one of the four collaboration scenarios, which simulate alternative level of data availability. Each scientist uses the data, which is collected from the database or through a shared environment, to deduce a scientific discovery. The ABM is demonstrated and evaluated for application within ecological science. Scientist agents collaborate and use the workflow tool, Kepler, to develop a linear regression model that captures the relationship between zooplankton populations and codfish population in the Norwegian Sea.}, number={1}, journal={Journal of Simulation}, publisher={Informa UK Limited}, author={Shafiee, M. Ehsan and Berglund, Emily Zechman}, year={2017}, month={Oct}, pages={1–13} }
 @article{kandiah_binder_berglund_2017, title={An Empirical Agent-Based Model to Simulate the Adoption of Water Reuse Using the Social Amplification of Risk Framework}, volume={37}, ISSN={0272-4332}, url={http://dx.doi.org/10.1111/risa.12760}, DOI={10.1111/risa.12760}, abstractNote={AbstractWater reuse can serve as a sustainable alternative water source for urban areas. However, the successful implementation of large‐scale water reuse projects depends on community acceptance. Because of the negative perceptions that are traditionally associated with reclaimed water, water reuse is often not considered in the development of urban water management plans. This study develops a simulation model for understanding community opinion dynamics surrounding the issue of water reuse, and how individual perceptions evolve within that context, which can help in the planning and decision‐making process. Based on the social amplification of risk framework, our agent‐based model simulates consumer perceptions, discussion patterns, and their adoption or rejection of water reuse. The model is based on the “risk publics” model, an empirical approach that uses the concept of belief clusters to explain the adoption of new technology. Each household is represented as an agent, and parameters that define their behavior and attributes are defined from survey data. Community‐level parameters—including social groups, relationships, and communication variables, also from survey data—are encoded to simulate the social processes that influence community opinion. The model demonstrates its capabilities to simulate opinion dynamics and consumer adoption of water reuse. In addition, based on empirical data, the model is applied to investigate water reuse behavior in different regions of the United States. Importantly, our results reveal that public opinion dynamics emerge differently based on membership in opinion clusters, frequency of discussion, and the structure of social networks.}, number={10}, journal={Risk Analysis}, publisher={Wiley}, author={Kandiah, Venu and Binder, Andrew R. and Berglund, Emily Z.}, year={2017}, month={Jan}, pages={2005–2022} }
 @article{shafiee_berglund_2017, title={Complex Adaptive Systems Framework to Simulate the Performance of Hydrant Flushing Rules and Broadcasts during a Water Distribution System Contamination Event}, volume={143}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000744}, DOI={10.1061/(asce)wr.1943-5452.0000744}, abstractNote={AbstractIn the event that a contaminant is introduced to a water distribution system, utility managers must respond quickly to protect public health. Mitigation strategies specify response actions,...}, number={4}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Shafiee, M. Ehsan and Berglund, Emily Zechman}, year={2017}, month={Apr}, pages={04017001} }
 @inproceedings{al-amin_berglund_2017, title={Optimization framework to identify demand reduction strategies for shared groundwater resources}, DOI={10.1061/9780784480601.056}, abstractNote={Groundwater management strategies should be designed to ensure efficient and sustainable management of groundwater. Optimization models and algorithms can be applied to identify groundwater withdrawals that will satisfy both hydrologic goals and water demands. In groundwater basins where urbanization increases demand and places stress on the supply-demand balance, safe yield based demand restrictions are used to reduce demands. Due to restrictions for water consumers, safe yield-based demand management strategies may result in unintended consequences, such as welfare loss, which is represented as a measure of consumer willingness to pay to avoid water service interruptions. This paper couples an agent-based modeling (ABM) framework and a groundwater model to quantify the improvement in water resources and corresponding welfare losses through mandatory restriction programs and to optimize the permitted yield for applying restrictions. The framework is applied to identify permitted yield as a trigger that should be used to implement restrictions under climate and population uncertainties for a long term planning period for cities in a shared groundwater basin in the Verde River Basin, Arizona. Results indicate trade-offs between groundwater table improvements and welfare losses for changing safe yields. The framework provides a comparison of hydrologic and economic consequences of mandatory restrictions for and reactive management with varying supply-demand balances. The research will guide water restriction policies and improve understanding of the hydrologic and economic consequences of water restriction policies at a basin scale.}, booktitle={World Environmental and Water Resources Congress 2017: Watershed Management, Irrigation and Drainage, and Water Resources Planning and Management}, author={Al-Amin, S. and Berglund, E. Z.}, year={2017}, pages={669–676} }
 @article{sankarasubramanian_sabo_larson_seo_sinha_bhowmik_vidal_kunkel_mahinthakumar_berglund_et al._2017, title={Synthesis of public water supply use in the United States: Spatio‐temporal patterns and socio‐economic controls}, volume={5}, ISSN={2328-4277 2328-4277}, url={http://dx.doi.org/10.1002/2016EF000511}, DOI={10.1002/2016ef000511}, abstractNote={AbstractRecent U.S. Geological Survey water‐use report suggests that increasing water‐use efficiency could mitigate the supply‐and‐demand imbalance arising from changing climate and growing population. However, this rich data have neither analyzed to understand the underlying patterns, nor have been investigated to identify the factors contributing to this increased efficiency. A national‐scale synthesis of public supply withdrawals (“withdrawals”) reveals a strong North–south gradient in public supply water use with the increasing population in the South contributing to increased withdrawal. Contrastingly, a reverse South–north gradient exists in per capita withdrawals (“efficiency”), with northern states consistently improving the efficiency, while the southern states' efficiency declined. Our analyses of spatial patterns of per capita withdrawals further demonstrate that urban counties exhibit improved efficiency over rural counties. Improved efficiency is also demonstrated over high‐income and well‐educated counties. Given the potential implications of the findings in developing long‐term water conservation measures (i.e., increasing block rates), we argue the need for frequent updates, perhaps monthly to annual, of water‐use data for identifying effective strategies that control the water‐use efficiency in various geographic settings under a changing climate.}, number={7}, journal={Earth's Future}, publisher={American Geophysical Union (AGU)}, author={Sankarasubramanian, A. and Sabo, J. L. and Larson, K. L. and Seo, S. B. and Sinha, T. and Bhowmik, R. and Vidal, A. Ruhi and Kunkel, K. and Mahinthakumar, G. and Berglund, E. Z. and et al.}, year={2017}, month={Jul}, pages={771–788} }
 @article{ramsey_berglund_goyal_2017, title={The Impact of Demographic Factors, Beliefs, and Social Influences on Residential Water Consumption and Implications for Non-Price Policies in Urban India}, volume={9}, ISSN={2073-4441}, url={http://dx.doi.org/10.3390/w9110844}, DOI={10.3390/w9110844}, abstractNote={In rapidly growing urban areas in India and the developing world, water demands typically exceed supply. While local governments may implement management programs to reduce demand for freshwater, water savings are dependent on the conservation behaviors of individuals. A household survey is presented here to examine residential water end uses and conservation behaviors in Jaipur, India. The survey explores end uses, engagement in conservation behaviors, and the influence of demographic factors, water sources, beliefs about water, and social pressures on these behaviors are tested. The survey was conducted at 248 households, including 29 households in the slums. Our study finds that while the majority of participants recognize the importance of water conservation, they do not necessarily conserve water themselves. Households report engaging most frequently in water-conservation behaviors that require little effort or financial investment. Multivariate analysis of variance (MANOVA) results and subsequent pairwise comparisons indicate higher incomes, longer water-supply durations, and the belief that droughts are preventable are positively correlated with overall amenability to adoption of water-conservation behaviors and technology. Binomial logistic regression analysis indicates that being in the age group 26–35, having higher income, and giving a neutral response about the responsibility of the government to provide relief during a drought were all predictors of the installation of dual-flush (DF) toilets. Education levels and water awareness were found to have no correlation with conservation behaviors or amenability to conservation technology adoption. Results are applied to examine their possible implications from a demand-management perspective and provide suggestions for further research and policy decisions.}, number={11}, journal={Water}, publisher={MDPI AG}, author={Ramsey, Elizabeth and Berglund, Emily and Goyal, Rohit}, year={2017}, month={Nov}, pages={844} }
 @article{shafiee_berglund_2016, title={Agent-based modeling and evolutionary computation for disseminating public advisories about hazardous material emergencies}, volume={57}, ISSN={["1873-7587"]}, DOI={10.1016/j.compenvurbsys.2016.01.001}, abstractNote={In the event of a large-scale disaster, an important aspect of humanitarian logistics is the distribution of information or warnings to the affected population. This research develops the problem formulation and solution approach for a specific routing for relief problem, in which warnings should be disseminated to an affected community, using public announcement systems mounted on emergency vehicles. The problem statement is formulated to maximize the number of individuals of a community who are protected. An evolutionary algorithm framework is developed by coupling an agent-based model with a variable-length genetic algorithm to route emergency vehicles. The dynamics of interactions among consumers, emergency vehicles, and the spatiotemporal trajectory of the hazard are simulated using an agent-based modeling approach, and a variable-length genetic algorithm approach selects routes to warn a maximum number of consumers before they are affected by the emergency. The example that is explored in this research is contamination of a water distribution network. A fleet of emergency vehicles is equipped with public address systems and is deployed to warn consumers to stop using contaminated water. The framework is demonstrated for an illustrative virtual city, Mesopolis. The results of the evolutionary algorithm framework are compared with two conventional routing optimization approaches, including a covering tour problem approach and a manual routing approach, for four contamination scenarios. The evolutionary algorithm can be applied to route emergency service vehicles to broadcast information for other emergencies, such as flash flooding, hazardous materials incidents, and severe weather.}, journal={COMPUTERS ENVIRONMENT AND URBAN SYSTEMS}, author={Shafiee, M. Ehsan and Berglund, Emily Zechman}, year={2016}, month={May}, pages={12–25} }
 @article{ali_shafiee_berglund_2017, title={Agent-based modeling to simulate the dynamics of urban water supply: Climate, population growth, and water shortages}, volume={28}, DOI={10.1016/j.scs.2016.10.001}, abstractNote={The sustainability of water resources depends on the dynamic interactions among the environmental, technological, and social characteristics of the water system and local population. These interactions can cause supply-demand imbalances at diverse temporal scales, and the response of consumers to water use regulations impacts future water availability. This research develops a dynamic modeling approach to simulate supply-demand dynamics using an agent-based modeling framework that couple models of consumers and utility managers with water system models. Households are represented as agents, and their water use behaviors are represented as rules. A water utility manager agent enacts water use restrictions, based on fluctuations in the reservoir water storage. Water balance in a reservoir is simulated, and multiple climate scenarios are used to test the sensitivity of water availability to changes in streamflow, precipitation, and temperature. The framework is applied to the water supply system in Raleigh, North Carolina to assess sustainability of drought management plans. Model accuracy is assessed using statistical metrics, and sustainability is calculated for a projected period as the satisfaction or deficit of meeting municipal demands. Multiple climate change scenarios are created by perturbing average monthly values of historical inflow, precipitation, and evapotranspiration data. Results demonstrate the use of the agent-based modeling approach to project the effectiveness of management policies and recommend drought policies for improving the sustainability of urban water resources.}, journal={Sustainable Cities and Society}, author={Ali, A. M. and Shafiee, M. E. and Berglund, E. Z.}, year={2017}, pages={420–434} }
 @article{kandiah_berglund_binder_2016, title={Cellular Automata Modeling Framework for Urban Water Reuse Planning and Management}, volume={142}, ISSN={["1943-5452"]}, url={https://publons.com/publon/21063767/}, DOI={10.1061/(asce)wr.1943-5452.0000696}, abstractNote={AbstractWater reuse provides a sustainable approach to balance water supply and demand in urban areas, and reclaimed water can be used for nonpotable applications to reduce demands on freshwater sources. Construction of a secondary network is required to distribute reclaimed water. Implementing water reuse projects on a wider scale is challenged by the need for communitywide public acceptance and adoption, which may be a dynamic and adaptive process. The adoption of new water infrastructure can drive hydraulic conditions in both the reclaimed network and an existing drinking water network. This research develops a dynamic modeling framework using a cellular automata (CA) approach to simulate consumer adoption of reclaimed water. The framework couples the CA model of consumer adoption with water distribution system models of the drinking and reclaimed water systems. Emergent distribution system hydraulic conditions are simulated, and the capacity utilization and system performance are evaluated as consumer...}, number={12}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, author={Kandiah, Venu K. and Berglund, Emily Z. and Binder, Andrew R.}, year={2016}, month={Dec} }
 @inproceedings{al-amin_berglund_mahinthakumar_2016, title={Coupling agent-based and groundwater modeling to explore demand management strategies for shared resources}, DOI={10.1061/9780784479858.016}, abstractNote={Municipal water demands in growing population centers in the arid southwest U.S. are typically met through increased groundwater withdrawals. Hydro-climatic uncertainties attributed to climate change and land use conversions may also alter demands and impact the replenishment of groundwater supply. Groundwater aquifers are not necessarily confined within municipal and management boundaries, and multiple diverse agencies may manage a shared resource in a decentralized approach, based on individual concerns and resources. The interactions among water managers, consumers, and the environment influence the performance of local management strategies and regional groundwater resources. This research couples an agent-based modeling (ABM) framework and a groundwater model to analyze the effects of different management approaches on shared groundwater resources. The ABM captures the dynamic interactions between household-level consumers and policy makers to simulate water demands under climate change and population growth uncertainties. The groundwater model is used to analyze the relative effects of management approaches on reducing demands and replenishing groundwater resources. The framework is applied for municipalities located in the Verde River Basin, Arizona that withdraw groundwater from the Verde Formation-Basin Fill-Carbonate aquifer system. Insights gained through this simulation study can be used to guide groundwater policy-making under changing hydro-climatic scenarios for a long-term planning horizon.}, booktitle={World Environmental and Water Resources Congress 2016: Watershed Management, Irrigation and Drainage, and Water Resources Planning and Management}, author={Al-Amin, S. and Berglund, E. Z. and Mahinthakumar, K.}, year={2016}, pages={141–150} }
 @inproceedings{garcia-cuerva_berglund_rivers_2016, title={Exploring Strategies for LID Implementation in Marginalized Communities and Urbanizing Watersheds}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84976484562&partnerID=MN8TOARS}, DOI={10.1061/9780784479889.005}, abstractNote={Increasing urbanization augments impervious surface area which results in increased run off volumes and peak flows. Low impact development (LID) approaches present a decentralized alternative for sustainable urban stormwater and provide water conservation opportunities. They also provide a wide array of ecosystem services and foster community building by enhancing neighborhood aesthetics, increasing property value, and providing shared green spaces. While projects involving sustainability concepts and environmental design are favored in privileged communities, marginalized communities have historically been located in areas that suffer from environmental degradation. Underprivileged communities typically do not receive as many social and environmental services as advantaged communities. This research develops a participatory decision-making approach to address environmental justice for marginalized communities and explore LID strategies at the watershed scale for improving hydrological performance and mitigating flooding. Focus groups are designed and conducted to solicit input from community members, stakeholders, and community advocates about sustainable stormwater management alternatives. Input will be used to develop LID strategies that meet community goals, such as maximizing the provision of ecosystem services, providing water conservation opportunities, and fostering community building. A hydrologic/hydraulic stormwater modeling system will be developed using HEC-HMS and SWMM to simulate the stormwater impacts of rain water harvesting systems, green roofs, and bioretention cells. This approach will be implemented for a marginalized community within the Walnut Creek Watershed in Raleigh, North Carolina. On-going research will seek further feedback from the community about LID strategies that are developed using the hydrologic/hydraulic modeling system to assess preferences about LID decisions and tradeoffs among design goals.}, booktitle={World Environmental And Water Resources Congress 2016: Water, Wastewater, and Stormwater and Urban Watershed Symposium - Papers from Sessions of the Proceedings of the 2016 World Environmental and Water Resources Congress}, author={Garcia-Cuerva, L. and Berglund, E.Z. and Rivers, Louie}, year={2016}, pages={41–50} }
 @article{garcia-cuerva_berglund_binder_2016, title={Public perceptions of water shortages, conservation behaviors, and support for water reuse in the US}, volume={113}, ISSN={["1879-0658"]}, url={https://publons.com/publon/21063766/}, DOI={10.1016/j.resconrec.2016.06.006}, abstractNote={Reclaimed water programs treat wastewater to remove hazardous compounds, pathogens, and organic matter and provide reclaimed water for non-potable applications. Reusing water may significantly reduce demands on freshwater resources and provide sustainable water management strategies. Though production of reclaimed water is highly regulated, public acceptability has historically hindered the implementation of successful reclaimed water systems. The public generally opposes the use of reclaimed water due to the “yuck factor”, which is the instinctive disgust associated with the idea of recycling sewage and the fear that exposure to reclaimed water is unsafe. This paper reports the results of an extensive survey that was conducted to evaluate the potential acceptability of reclaimed water use. A total of 2800 respondents across the U.S. participated in the survey. Results demonstrate that a small percentage of the population is concerned about water shortages, the majority of the population practices some level of water conservation, and a substantial percentage of the population supports the use of reclaimed water. Climate, demographic variables, and financial incentives were tested for influence on attitudes and behaviors regarding water, including awareness, conservation, and support for water reuse. Sex, age, last monthly water bill, and location (as EPA region) showed no significant effect on the acceptance of water reuse, while ethnicity, education level, metro/non metro, and income showed significant effects. Drought conditions do not have a statistically significant effect on the number of reclaimed water supporters, but increase the number of respondents who are water concerned, the number of respondents who are the most active water conservers, and the number of respondents who limit their use of water for lawn and garden watering. Financial incentives influence the willingness of respondents to participate in water reuse programs, and a decrease in the monthly water bills increased the likelihood that respondents would participate in a reclaimed water program. Support for the use of reclaimed water for various applications ranked positively, on average, except for the application of water reuse for food crop irrigation and use of reclaimed water at respondents’ own residences. Results and conclusions of the survey can provide insight for implementing successful reclaimed water programs.}, journal={RESOURCES CONSERVATION AND RECYCLING}, author={Garcia-Cuerva, Laura and Berglund, Emily Z. and Binder, Andrew R.}, year={2016}, month={Oct}, pages={106–115} }
 @article{barker_stillwell_berglund_2016, title={Scenario Analysis of Energy and Water Trade-Offs in the Expansion of a Dual Water System}, volume={142}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000714}, DOI={10.1061/(asce)wr.1943-5452.0000714}, abstractNote={AbstractUsing treated wastewater effluent (reclaimed water) for beneficial purposes can be a sustainable practice that reduces demand on potable networks. However, implementing reclaimed water networks can have unintended effects, specifically unintended increases in energy consumption. This case study employs multiperiod scenario analysis to examine energy consumption associated with the potable and reclaimed water systems for the Town of Cary, North Carolina. Using hydraulic planning models of both systems provided by the design engineers, the conveyance and additional treatment energy is tabulated. This method considers uncertainty in reclaimed water demand by varying the expected demand for each build out of the reclaimed water network. Differential electricity consumption is calculated as the difference between the electricity consumed to deliver reclaimed water through a secondary network compared to the electricity consumed to deliver the same volume through the potable water network. Demand uncert...}, number={12}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Barker, Zachary A. and Stillwell, Ashlynn S. and Berglund, Emily Z.}, year={2016}, month={Dec}, pages={05016012} }
 @inproceedings{al-amin_berglund_larson_2015, title={Agent-Based Modeling to Simulate Demand Management Strategies for Shared Groundwater Resources}, ISBN={9780784479162}, url={http://dx.doi.org/10.1061/9780784479162.203}, DOI={10.1061/9780784479162.203}, abstractNote={Growing population centers in the arid southwest increase the demand for water, which is typically met through increased groundwater withdrawals. Hydro-climatic extremes due to climate change may also increase demands and decrease the replenishment of groundwater supply. Groundwater aquifers typically cross watershed, municipal, and management boundaries, and as a result, multiple diverse agencies manage a shared resource. Municipalities and management districts define individual demand management strategies that adapt water consumption to falling groundwater levels. The interactions among governing agencies, consumers, and the environment influence the performance of local management strategies and the availability of regional groundwater resources. This research develops an agent-based modeling (ABM) framework to analyze the dynamic interactions among changing water demands and limited groundwater resources under the stresses of population growth and climate change scenarios. Households are initialized as agents with properties and attributes to define indoor water use, outdoor water use, and water use reduction. Policy-maker agents are encoded to represent governing agencies that mandate or encourage water use restrictions. Demand management strategies are simulated as the response of a policy-maker agent to groundwater levels, safe yield, and climate variables. The framework is applied for municipalities located in the Verde River Basin, Arizona that withdraw groundwater from the Verde Formation-Basin Fill-Carbonate aquifer system. The effects of management strategies on water savings and basin-wide groundwater levels are explored, based on water use demands and reductions in different sectors of municipal water use. Insights gained through this simulation study can be used to guide groundwater policy-making under changing hydro-climatic scenarios for a long-term planning horizon.}, booktitle={World Environmental and Water Resources Congress 2015}, publisher={American Society of Civil Engineers}, author={Al-Amin, Shams and Berglund, Emily Z. and Larson, Kelli L.}, year={2015}, month={May} }
 @article{giacomoni_berglund_2015, title={Complex Adaptive Modeling Framework for Evaluating Adaptive Demand Management for Urban Water Resources Sustainability}, volume={141}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000543}, DOI={10.1061/(asce)wr.1943-5452.0000543}, abstractNote={AbstractNew water resources management methodologies are needed to address increasing demands and future uncertainty for urban water resources. Adaptive water demand management strategies provide an approach to improve the efficiency of water system operations and meet water demands by adapting flexibility to increasing stresses, such as droughts. This study simulates adaptive water demand management through the development of a complex adaptive system modeling framework, which couples cellular automata modeling, agent-based modeling, and hydrologic modeling to simulate land-use change, consumer behaviors, management decisions, the rainfall-runoff process, and reservoir storage. The model is applied to simulate the effect of demand management strategies on reductions in municipal water demands and on the sustained storage in a surface water supply reservoir. Historic and projected climate change hydroclimatic time series are used to assess the effectiveness of domestic water restrictions, including outdoo...}, number={11}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Giacomoni, M. H. and Berglund, E. Z.}, year={2015}, month={Nov}, pages={04015024} }
 @article{kanta_berglund_2015, title={Exploring Tradeoffs in Demand- Side and Supply- Side Management of Urban Water Resources Using Agent- Based Modeling and Evolutionary Computation}, volume={3}, ISSN={["2079-8954"]}, DOI={10.3390/systems3040287}, abstractNote={Urban water supply systems may be managed through supply-side and demand-side strategies, which focus on water source expansion and demand reductions, respectively. Supply-side strategies bear infrastructure and energy costs, while demand-side strategies bear costs of implementation and inconvenience to consumers. To evaluate the performance of demand-side strategies, the participation and water use adaptations of consumers should be simulated. In this study, a Complex Adaptive Systems (CAS) framework is developed to simulate consumer agents that change their consumption to affect the withdrawal from the water supply system, which, in turn influences operational policies and long-term resource planning. Agent-based models are encoded to represent consumers and a policy maker agent and are coupled with water resources system simulation models. The CAS framework is coupled with an evolutionary computation-based multi-objective methodology to explore tradeoffs in cost, inconvenience to consumers, and environmental impacts for both supply-side and demand-side strategies. Decisions are identified to specify storage levels in a reservoir that trigger: (1) increases in the volume of water pumped through inter-basin transfers from an external reservoir; and (2) drought stages, which restrict the volume of water that is allowed for residential outdoor uses. The proposed methodology is demonstrated for Arlington, Texas, water supply system to identify non-dominated strategies for an historic drought decade. Results demonstrate that pumping costs associated with maximizing environmental reliability exceed pumping costs associated with minimizing restrictions on consumer water use.}, number={4}, journal={SYSTEMS}, author={Kanta, Lufthansa and Berglund, Emily Zechman}, year={2015}, month={Dec}, pages={287–308} }
 @article{shafiee_berglund_berglund_brill_mahinthakumar_2016, title={Parallel Evolutionary Algorithm for Designing Water Distribution Networks to Minimize Background Leakage}, volume={142}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000601}, DOI={10.1061/(asce)wr.1943-5452.0000601}, abstractNote={AbstractLeaks in water distribution systems waste energy and water resources, increase damage to infrastructure, and may allow contamination of potable water. This research develops an evolutionary algorithm-based approach to minimize the cost of water loss, new infrastructure, and operations that reduce background leakage. A new design approach is introduced that minimizes capital and operational costs, including energy and water loss costs. Design decisions identify a combination of infrastructure improvements, including pipe replacement and valve installment, and operation rules for tanks and pumps. Solution approaches are developed to solve both a single-objective and multiobjective problem formulation. A genetic algorithm and a nondominated sorting genetic algorithm are implemented within a high-performance computing platform to select tank sizes, pump placement and operations, placement of pressure-reducing valves, and pipe diameters for replacing pipes. The evolutionary algorithm approaches identif...}, number={5}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Shafiee, M. Ehsan and Berglund, Andrew and Berglund, Emily Zechman and Brill, E. Downey, Jr. and Mahinthakumar, G.}, year={2016}, month={May} }
 @inproceedings{garcia-cuerva_schmidt_berglund_binder_2015, title={Results of a National Survey about the Public Acceptability of Reclaimed Water}, ISBN={9780784479162}, url={http://dx.doi.org/10.1061/9780784479162.121}, DOI={10.1061/9780784479162.121}, abstractNote={Reclaimed water programs treat wastewater to remove hazardous compounds, pathogens, and organic matter and provide reclaimed water for non-potable applications. Reusing water may significantly reduce demands on freshwater resources and provide sustainable water management strategies. Though guidelines for reclaimed water are highly regulated, public acceptability has historically hindered the implementation of successful reclaimed water systems. The public generally opposes the use of reclaimed water due to the “yuck factor”, which is the instinctive disgust associated with the idea of recycling sewage and the fear that exposure to reclaimed water is unsafe. Public acceptability has been shown to vary significantly for diverse reclaimed water applications, and support for reclaimed water applications may vary based on the level of contact that consumers have with the recycled water. Opposition towards using reclaimed water in personal residences may be a major barrier in distributing reclaimed water to residential consumers, and the adoption of reclaimed water technologies by consumers can affect network performance and potable water savings. This paper reports the results of an extensive survey that was conducted to evaluate the potential acceptability of reclaimed water use. A total of 2800 respondents across the U.S. participated in the survey, and survey results demonstrate the types of reclaimed water applications that are most acceptable. In addition, climate, economic, and demographic factors affect the perceived acceptability of reclaimed water. Results and conclusions of the survey can provide insight for implementing successful reclaimed water programs.}, booktitle={World Environmental and Water Resources Congress 2015}, publisher={American Society of Civil Engineers}, author={Garcia-Cuerva, Laura and Schmidt, Michelle and Berglund, Emily Z. and Binder, Andrew R.}, year={2015}, month={May} }
 @article{berglund_2015, title={Using Agent-Based Modeling for Water Resources Planning and Management}, volume={141}, ISSN={["1943-5452"]}, DOI={10.1061/(asce)wr.1943-5452.0000544}, abstractNote={AbstractAgent-based systems have been developed for many scientific applications and simulation studies to model a group of actors and their interactions based on behavioral rules. Agent-based models and multiagent systems simulate the emergence of system-level properties based on the actions of adaptive agents that interact with other agents, react to environmental signals, and optimize decisions to achieve individual goals. In water resources planning and management, agent-based modeling has been applied to explore, simulate, and predict the performance of infrastructure design and policy decisions as they are influenced by human decision making, behaviors, and adaptations. The goal of this paper is to provide a comprehensive introduction to agent-based modeling for water resources researchers, students, and practitioners, and to explore water resources systems as complex adaptive systems that can be studied using agent-based modeling. Agent-based modeling is defined, and the characteristics of complex ...}, number={11}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, author={Berglund, Emily Zechman}, year={2015}, month={Nov} }
 @inproceedings{ali_shafiee_berglund_arumugam_2014, title={An Agent-Based Modeling Approach to Simulate the Dynamics of Water Supply and Water Demand}, ISBN={9780784413548}, url={http://dx.doi.org/10.1061/9780784413548.179}, DOI={10.1061/9780784413548.179}, abstractNote={Water resources management requires an insightful balance between water demand and water supply. US water supply is at risk of shortage due to population growth, land use changes, climate change, and water use behaviors of customers. Long-term water supply planning is conventionally based on projections of population growth and demands; however, the sustainability of water resources depends on the dynamic interactions among the environmental, technological, and social characteristics of the water system and local population. This research develops a sociotechnical model to simulate the interactions among the social and engineering systems. An agent-based model (ABM) is used to simulate households and water-use behaviors and is coupled with a set of technical models, including climate change projections, a hydrological watershed model, and a water reservoir model. The ABM framework simulates population growth as an increase in the number of household agents, which affects the water supply and demand balance through increasing demands. Household agents increase irrigation demands due to climate change and decrease indoor demands as they adopt low-flow appliances. Agents also respond to drought restrictions by limiting their use of water for outdoor application. The effects of these actions on the reservoir storage are simulated using engineering models and data describing the climatological and hydrological conditions of the watershed. The ABM framework is developed and demonstrated for the Raleigh, NC, water supply system, which withdraws water from the Falls Lake Reservoir. The model is tested against historic data (1983-2013) and is used to explore the effectiveness of policies for the period 2013-2033. Conservation programs and drought restrictions are simulated and to evaluate the need to develop new water source in the future. The ABM framework facilitates simulations that generate new insight about the dynamics involved in the sustainability of water supply and demands. 1806 World Environmental and Water Resources Congress 2014: Water without Borders © ASCE 2014}, booktitle={World Environmental and Water Resources Congress 2014}, publisher={American Society of Civil Engineers}, author={Ali, Alireza Mashhadi and Shafiee, M. Ehsan and Berglund, Emily Zechman and Arumugam, Sankarasubramanian}, year={2014}, month={May} }
 @article{scott_politte_saathoff_collard_berglund_barbour_sprintson_2014, title={An evaluation of the Stormwater Footprint Calculator and the Hydrological Footprint Residence for communicating about sustainability in stormwater management}, volume={10}, ISSN={1548-7733}, url={http://dx.doi.org/10.1080/15487733.2014.11908129}, DOI={10.1080/15487733.2014.11908129}, abstractNote={Abstract Low-Impact Development (LID) can enhance sustainability in stormwater management by attenuating excess runoff. Relevant technologies are typically implemented at individual lots and require the engagement of homeowners and developers. A new educational tool, the Stormwater Footprint Calculator (SFC), was developed to improve knowledge and change attitudes and behavior regarding stormwater sustainability. Similar to online carbon-footprint calculators, the SFC synthesizes a participant’s answers about lot and neighborhood-level land use and calculates hypothetical effects on instream flows, using hydrologic simulation. Participants receive feedback about their storm-water footprint using a new metric, the Hydrologic Footprint Residence (HFR), which measures the effect of urbanization on stream flow based on the duration and extent of flooding. An experiment was fielded to test the SFC as a tool for communicating about sustainable stormwater management and to compare the HFR against an orthodox stormwater metric, peak flow. A convenience sample of undergraduate students (N= 510) participated in the experiment. The results indicate that completing the SFC improves knowledge about the causes of stormwater runoff and LID technologies (although not about the effects of stormwater, which was already high among the students), and it influences intention to support sustainable stormwater management. The results also indicate that HFR provides a viable alternative to conventional engineering metrics for communicating a stormwater footprint and shows the value of online calculators for communicating complex civil engineering concepts.}, number={2}, journal={Sustainability: Science, Practice and Policy}, publisher={Informa UK Limited}, author={Scott, Tommi Jo and Politte, Alyssa and Saathoff, Sean and Collard, Sam and Berglund, Emily and Barbour, Joshua and Sprintson, Alex}, year={2014}, month={Oct}, pages={14–27} }
 @inproceedings{al-amin_berglund_larson_2014, title={Complex Adaptive System Framework to Simulate Adaptations of Human-Environmental Systems to Climate Change and Urbanization: The Verde River Basin}, ISBN={9780784413548}, url={http://dx.doi.org/10.1061/9780784413548.181}, DOI={10.1061/9780784413548.181}, abstractNote={Water management in the arid western United States must address imminent increases in freshwater withdraws due to population growth and climate change. Stresses in the water supply system can be addressed through demand management, which restricts water uses or instates bans, incentivizes toilet retrofits or landscape conversions, and encourages conservation through outreach and education. These policies rely on the behaviors, compliance, and conservation of residential and agricultural users. This research develops a complex adaptive system (CAS) framework to analyze the dynamic interactions between changing water demands and limited water resources for population growth, land use conversion, and climate change scenarios. Water supply and demand for the arid Verde River Basin is explored through an agent-based model (ABM). Three types of agents are encoded, including policy makers (utility managers/planners) and agricultural and residential water users. Agents are initialized with business-as-usual behaviors, a set of signals, demand-reduction actions, and supply-augmentation actions. ABMs are coupled with water infrastructure models, which are in turn forced with hydro-climate and water demand projections to capture the feedbacks and simulate policy and consumer-level agents' roles in promoting balance between water demands and supplies. To determine the dynamics of societal responses to hydro-climatic extremes and the likelihood of water system adaptations to environmental change in the future, this research explores data about sociopolitical responses and actions by analyzing existing policies and management strategies. By synthesizing these data, a timeline of events and estimates for the relative probability of actions being taken are generated and used to encode policy-maker agents. The ABM framework provides important insights into the dynamic interaction of sociotechnical variables by simulating potential feedbacks of human-environmental and hydro-ecological systems that arise from adaptations to climate change and growth. Insight gained through this simulation study can be used to guide policy making under changing hydro-climatic scenarios over a long-term planning horizon.}, booktitle={World Environmental and Water Resources Congress 2014}, publisher={American Society of Civil Engineers}, author={Al-Amin, Shams and Berglund, Emily Z. and Larson, Kelli L.}, year={2014}, month={May} }
 @inproceedings{kandiah_berglund_binder_2014, title={Empirical Acceptance-Resistance Agent-Based Modeling Approach for Simulating the Adoption of Water Reuse}, ISBN={9780784413548}, url={http://dx.doi.org/10.1061/9780784413548.183}, DOI={10.1061/9780784413548.183}, abstractNote={Though water reuse provides a promising and sustainable alternative for urban water supply, wide-scale implementation of water reuse within an existing water infrastructure system is challenged by the need for community-wide public acceptance and adoption. The public has historically perceived recycled water negatively, and, as a consequence, water reuse is typically omitted in the development of municipal water management plans. Consumer’s base acceptance and rejection of new technologies on an intuitive analysis of their risks and benefits, and their perceptions may change over time, based on interactions with other consumers, decision makers, and engineering infrastructure systems. This research creates a modeling framework to simulate the changing perceptions of consumers and their adoption of water reuse. The modeling framework is used to develop understanding about the mechanisms that drive the dynamic evolution of perceptions, which can aid the planning and decision making process for the integration of water reuse within existing water systems. This research develops an acceptance-resistance agent-based model to simulate the adoption and rejection of water reuse based on a “risk publics” framework, which is a theoretical model of how different groups perceive new technologies. The risk publics framework uses the perception of risk and benefits to determine the potential of households to adopt or resist new technology. Consumers are represented as agents, and their behaviors and attributes are developed using survey data of the US population, which measures attitudes, knowledge, and behavioral intentions for recycled water. The data is analyzed to determine empirical relationships among individuals; the presence of social groups; and informational and communicative variables governing individual use of reclaimed water. The variables are encoded in the agent-based modeling framework to simulate the key social mechanisms that impact consumer acceptance of water reuse. The framework couples the acceptance-resistance agent-based model of consumers, an agent-based model of utility management, and water distribution system models of the drinking and reclaimed water systems. The framework will be used to explore the interactions}, booktitle={World Environmental and Water Resources Congress 2014}, publisher={American Society of Civil Engineers}, author={Kandiah, Venu K. and Berglund, Emily Z. and Binder, Andrew R.}, year={2014}, month={May} }
 @article{shafiee_berglund_berglund_brill_mahinthakumar_2014, title={Evolutionary Computation-based Decision-making Framework for Designing Water Networks to Minimize Background Leakage}, volume={89}, ISSN={1877-7058}, url={http://dx.doi.org/10.1016/J.PROENG.2014.11.167}, DOI={10.1016/J.PROENG.2014.11.167}, abstractNote={Abstract This research minimizes the impact of leaks on the operation of the system to reduce lost water while meeting typical management goals. A genetic algorithm approach is implemented within a high-performance computing platform to select tank sizes, pump placement and operations, placement of pressure control valves, and pipe diameters for replacing pipes. It identifies solutions that minimize water loss, operational costs, and capital costs, while maintaining pressure at nodes and operational feasibility for tanks. Multiple problem formulations are solved that use alternative objective functions and allow varying degrees of freedom in the decision space. The methodology is demonstrated to identify a water distribution system re-design for the C-Town case study.}, journal={Procedia Engineering}, publisher={Elsevier BV}, author={Shafiee, M.E. and Berglund, A. and Berglund, E. Zechman and Brill, E. Downey, Jr. and Mahinthakumar, G.}, year={2014}, pages={118–125} }
 @article{giacomoni_gomez_berglund_2014, title={Hydrologic Impact Assessment of Land Cover Change and Stormwater Management Using the Hydrologic Footprint Residence}, volume={50}, ISSN={1093-474X}, url={http://dx.doi.org/10.1111/jawr.12187}, DOI={10.1111/jawr.12187}, abstractNote={AbstractUrbanization impacts the stormwater regime through increased runoff volumes and velocities. Detention ponds and low impact development (LID) strategies may be implemented to control stormwater runoff. Typically, mitigation strategies are designed to maintain postdevelopment peak flows at predevelopment levels for a set of design storms. Peak flow does not capture the extent of changes to the hydrologic flow regime, and the hydrologic footprint residence (HFR) was developed to calculate the area and duration of inundated land during a storm. This study couples a cellular automata land cover change model with a hydrologic and hydraulic framework to generate spatial projections of future development on the fringe of a rapidly urbanizing metropolitan area. The hydrologic flow regime is characterized for existing and projected land cover patterns under detention pond and LID‐based control, using the HFR and peak flow values. Results demonstrate that for less intense and frequent rainfall events, LID solutions are better with respect to HFR; for larger storms, detention pond strategies perform better with respect to HFR and peak flow.}, number={5}, journal={JAWRA Journal of the American Water Resources Association}, publisher={Wiley}, author={Giacomoni, M.H. and Gomez, R. and Berglund, E.Z.}, year={2014}, month={Apr}, pages={1242–1256} }
 @inproceedings{ali_kandiah_berglund_2014, title={Multiobjective Optimization to Explore Tradeoffs in Rainwater Harvesting Strategies for Urban Water Sustainability}, ISBN={9780784413548}, url={http://dx.doi.org/10.1061/9780784413548.180}, DOI={10.1061/9780784413548.180}, abstractNote={Urban water systems are designed for centralized management, where water is collected at a central location, treated, and delivered to a population of users through a pipe network. Decentralized systems may generate water and energy savings beyond conventional approaches, as they reduce the demands on the potable drinking water system and the energy required for treatment and conveyance. For example, rainwater harvesting systems that are installed at individual lots can be used to capture and reuse rainwater to irrigate lawns. This research explores the tradeoffs among infrastructure costs, energy savings, and water savings as consumers adopt rainwater harvesting within an existing centralized water supply system. The presence of rainwater harvesting within a community of individual households is a sociotechnical process, as interactions among existing water supply infrastructure, utility managers, and consumers can influence the adoption of decentralized technologies and the performance of centralized infrastructure. The urban water supply system is simulated as a complex adaptive system to analyze the water use behavior of consumers and their influence on system-level sustainability. An agent-based model is constructed to simulate households as water-consumer agents and is coupled with a system dynamics simulation of a water reservoir to capture the feedbacks that drive the household-level adoption of rainwater harvesting. An evolutionary computation approach is coupled with the agent-based modeling framework to optimize multiple objectives and explore tradeoffs among energy requirements, water savings, and the cost of rainwater harvesting systems. The framework is demonstrated for a virtual case study to develop management strategies for sizing rainwater harvesting cisterns and achieving sustainability goals for a sociotechnical water supply system.}, booktitle={World Environmental and Water Resources Congress 2014}, publisher={American Society of Civil Engineers}, author={Ali, Alireza Mashhadi and Kandiah, Venu and Berglund, Emily Zechman}, year={2014}, month={May} }
 @article{shafiee_berglund_2015, title={Real-Time Guidance for Hydrant Flushing Using Sensor-Hydrant Decision Trees}, volume={141}, ISSN={["1943-5452"]}, DOI={10.1061/(asce)wr.1943-5452.0000475}, abstractNote={AbstractA utility may detect contaminant in a water distribution network through water quality sensor information, which indicates that a biological pathogen or chemical contaminant is present in the network. A utility manager should identify actions that can be taken to protect public health, and flushing a contaminant by opening a set of hydrants can be an effective response action. Hydrants should be selected and timed to flush the contaminant; however, accurately ascertaining the characteristics of the contaminant source may be impossible, which creates difficulties in developing a hydrant flushing strategy. This research develops a decision-making approach that is designed to select hydrant flushing strategies in response to sensor activations and does not require information about the characteristics of the contaminant source. A sensor-hydrant decision tree is introduced to provide a library of rules for opening and closing hydrants based on the order of activated sensors. Sensor-hydrant decision tr...}, number={6}, journal={JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT}, author={Shafiee, M. Ehsan and Berglund, Emily Zechman}, year={2015}, month={Jun} }
 @inproceedings{schmidt_berglund_binder_2014, title={Tradeoffs in Public Acceptance and Water Savings in Using Reclaimed Water for Irrigation Applications}, ISBN={9780784413548}, url={http://dx.doi.org/10.1061/9780784413548.051}, DOI={10.1061/9780784413548.051}, abstractNote={Water scarcity is a growing concern, due to stresses imposed by climate change, population growth, and urbanization. Reclaimed water is a reliable source that can be produced by treating wastewater and used to supplement non-potable demands. According to the U.S. Geological Survey, 128 billion gallons of water are used per day for agricultural irrigation, accounting for roughly 31% of total water usage in the U.S. Reclaimed water is a viable option for irrigation applications; however, the success of reclaimed water programs can be affected by public support. This research develops an approach for assessing water savings and acceptability for irrigation applications of reclaimed water. The potential for using reclaimed water in Wake County, North Carolina, is explored through the use of a modeling framework. Potential water savings are evaluated based on the volume of wastewater produced and irrigation demands. The perceptions of using reclaimed water are compared for diverse irrigation applications using results from a recently conducted national survey. Results demonstrate that acceptability for using reclaimed water to irrigate public parks, athletic fields, and residential lawns is higher than the acceptability of use for irrigating food crops. Tradeoffs between public acceptance and the potential reduction of water stress are explored to provide guidance for Wake County infrastructure planning. The modeling methodology is general and can be applied to determine water reclamation potential at the county-level across the U.S.}, booktitle={World Environmental and Water Resources Congress 2014}, publisher={American Society of Civil Engineers}, author={Schmidt, Michelle and Berglund, Emily Zechman and Binder, Andrew}, year={2014}, month={May} }
 @inproceedings{lord_zechman_arumugam_2013, title={A Complex Adaptive System Approach Assessing the Dynamics of Population Growth, Land Use, and Climate Change for Urban Water Resources Management}, ISBN={9780784412947}, url={http://dx.doi.org/10.1061/9780784412947.281}, DOI={10.1061/9780784412947.281}, abstractNote={Urban water resources management requires careful planning to balance water supply and demand. Under increasing population growth and land use change through urbanization, water shortages may become increasingly frequent, and climate change can alter the availability and timing of water from expected levels. While long-term water supply planning is conventionally based on projections of population growth, demands, and system capacity under a stationary climate, the sustainability of water resources depends on the dynamic interactions among the environmental, technological, and social characteristics of the water system and local population. The response of consumers to water use regulations will affect future water availability, and to address the challenges of water resources management and provide insight to system dynamics a new modeling approach is needed that goes beyond simple assumptions about water availability, population growth, and demand increases, to explicitly incorporate the feedbacks among these systems and their impacts on water availability. A dynamic modeling approach is developed to provide insight about the supply-demand dynamics and feedbacks arising from urban growth dynamics, consumer behaviors, and potential changes in climate and land use. This research couples engineering and hydro-climatology models with complex adaptive system modeling techniques to assess the influence of social dynamics on water resources availability. Land use change is simulated using cellular automata modeling. Consumer adaptations of water demands and policy decisions about water restrictions are simulated using agent-based modeling. Watershed and reservoir simulation are implemented using the Soil Water Assessment Tool (SWAT) and integrated within a complex adaptive system simulation framework. This framework is developed for the Falls Lake Reservoir near Raleigh, North Carolina, to simulate the performance of alternative water shortage response plan and supply-side management scenarios under increased population and climate change scenarios.}, booktitle={World Environmental and Water Resources Congress 2013}, publisher={American Society of Civil Engineers}, author={Lord, Benjamin and Zechman, Emily and Arumugam, Sankar}, year={2013}, month={May} }
 @inproceedings{kanta_zechman_2013, title={A Mechanistic-Stochastic Approach to Classify Water Consumers and Simulate Urban Water Demand}, ISBN={9780784412947}, url={http://dx.doi.org/10.1061/9780784412947.224}, DOI={10.1061/9780784412947.224}, abstractNote={Stochasticity in urban water demand arises due to the unpredictability and randomness of consumer behavior, which is influenced by population growth, climatic conditions, and conservation programs. Most urban water demand estimation methodologies are based on end-use models or stochastic models. End-use models describe the uses of water by households at the appliance level and require extensive and detailed data about water activities and water appliances. Stochastic models, however, predict water use using empirical relationships based on predictors, such as population size and water pricing. Integration of mechanistic end-use modeling with stochastic modeling can aid in better understanding of consumers' water use behavior and, therefore, can aid in better estimation of water availability in planning and management of urban water resources. A novel mechanistic-stochastic water demand model is developed here through the integration of an end-use model and a stochastic model. The model is developed using residential customer billing records from two water utilities. The historical water billing records are fitted to a gamma distribution based on the Akaike Information Criterion (AIC) values compared to exponential, extreme value, and log-normal distribution. Consumers are categorized into different groups from the distribution of water billing records and aggregated demand is estimated for the water system. To validate the modeled customer categories, housing survey data is collected and analyzed. Integration of mechanistic and stochastic modeling along with linkage of multiple data sources through this methodology can provide a powerful tool for efficient and sustainable water resources management.}, booktitle={World Environmental and Water Resources Congress 2013}, publisher={American Society of Civil Engineers}, author={Kanta, Lufthansa and Zechman, Emily M.}, year={2013}, month={May} }
 @inproceedings{kandiah_zechman_binder_2013, title={An Agent-based Modeling Approach to Simulate the Influence of Consumer Behavior on Infrastructure Performance for Urban Water Reclamation Management}, ISBN={9780784412947}, url={http://dx.doi.org/10.1061/9780784412947.226}, DOI={10.1061/9780784412947.226}, abstractNote={Water reuse introduces new interconnections among urban water infrastructure services. For both decentralized and centralized systems, water recycling influences the burden on the stormwater, wastewater, and drinking water systems. Reductions in drinking water demands, caused by an uptake in water reuse, can cause changes in system pressures and new hydraulic conditions in the network. The proposed research will explore the interconnections among urban water infrastructure for water reuse strategies and develop a new agent-based modeling framework to simulate the interactions among consumer behaviors, water reuse technologies, and existing water supply infrastructure. An agent-based model of consumers will be coupled with water infrastructure systems models, and both the water distribution system and water reclamation system infrastructure will be simulated using EPANET. Each agent, representing a household, will be associated with a node in the drinking water system where its demand is exerted. As agents adopt reclaimed water, demand inputs to the drinking water model and reclamation system model are updated accordingly. The framework will be used to simulate the emergence of the adoption of water reclamation and infrastructure performance based on metrics, including extreme pressures, changes in flows, and utilization of existing capacity.}, booktitle={World Environmental and Water Resources Congress 2013}, publisher={American Society of Civil Engineers}, author={Kandiah, V. K. and Zechman, E. M. and Binder, Andrew R.}, year={2013}, month={May} }
 @article{shafiee_zechman_2013, title={An agent-based modeling framework for sociotechnical simulation of water distribution contamination events}, volume={15}, ISSN={1464-7141 1465-1734}, url={http://dx.doi.org/10.2166/hydro.2013.158}, DOI={10.2166/hydro.2013.158}, abstractNote={In the event that a contaminant is introduced to a water distribution network, a large population of consumers may risk exposure. Selecting mitigation actions to protect public health may be difficult, as contamination is a poorly predictable dynamic event. Consumers who become aware of an event may select protective actions to change their water demands from typical demand patterns, and new hydraulic conditions can arise that differ from conditions that would be predicted when demands are considered as exogenous inputs. Consequently, the movement of the contaminant plume in the pipe network may shift from its expected trajectory. A sociotechnical model is developed here to integrate agent-based models of consumers with an engineering water distribution system model and capture the dynamics between consumer behaviors and the water distribution system for predicting contaminant transport and public exposure. Consumers are simulated as agents with behaviors, including movement, water consumption, exposure, reduction in demands, and communication with other agents. As consumers decrease their water use, the location of the contaminant plume is updated and the amount of contaminant consumed by each agent is calculated. The framework is tested through simulating realistic contamination scenarios for a virtual city and water distribution system.}, number={3}, journal={Journal of Hydroinformatics}, publisher={IWA Publishing}, author={Shafiee, M. Ehsan and Zechman, Emily M.}, year={2013}, month={Jul}, pages={862–880} }
 @article{zechman_giacomoni_shafiee_2013, title={An evolutionary algorithm approach to generate distinct sets of non-dominated solutions for wicked problems}, volume={26}, ISSN={0952-1976}, url={http://dx.doi.org/10.1016/j.engappai.2013.03.004}, DOI={10.1016/j.engappai.2013.03.004}, abstractNote={Many engineering design problems must optimize multiple objectives. While many objectives are explicit and can be mathematically modeled, some goals are subjective and cannot be included in a mathematical model of the optimization problem. A set of alternative non-dominated fronts that represent multiple optima for problem solution can be identified to provide insight about the decision space and to provide options and alternatives for decision-making. This paper presents a new algorithm, the Multi-objective Niching Co-evolutionary Algorithm (MNCA) that identifies distinct sets of non-dominated solutions which are maximally different in their decision vectors and are located in the same non-inferior regions of a Pareto front. MNCA is demonstrated to identify a set of non-dominated fronts with maximum difference in decision vectors for a set of real-valued problems.}, number={5-6}, journal={Engineering Applications of Artificial Intelligence}, publisher={Elsevier BV}, author={Zechman, Emily M. and Giacomoni, Marcio H. and Shafiee, M. Ehsan}, year={2013}, month={May}, pages={1442–1457} }
 @inproceedings{shafiee_kandiah_barrett_zechman_2013, title={Applying Multi-objective Niching Co-evolutionary Algorithm to Generate Insight for Water Resources Management Problems}, ISBN={9780784412947}, url={http://dx.doi.org/10.1061/9780784412947.228}, DOI={10.1061/9780784412947.228}, abstractNote={Real-world engineering problems typically involve multiple objectives that should be addressed simultaneously. A set of Pareto-optimal solutions that represents the trade-off among conflicting objectives can be identified to provide knowledge about the performance of alternative solutions for design and management problems. Many multi-objective evolutionary algorithms (MOEA) have been developed and designed to efficiently identify a set of nondominated solutions, and these algorithms have been successfully applied for realistic engineering problems. Realistic design problems may require more analysis and solution generation capabilities than provided by a typical MOEA. The fitness landscapes for realistic design problems are often nonlinear, complex, and multi-modal, and, in addition, water resources planning and management problems typically involve a diverse set of stakeholders with a set of preferences that are not represented mathematically and included in an optimization model. Identification of alternative sets of nondominated solutions that are similarly Pareto-optimal can address the problem of multi-modality in the decision space and provide additional insight to problem solution and options for implementation. The Multi-objective Niching Co-evolutionary Algorithm (MNCA) was designed to use a multi-population optimization search to evolve multiple nondominated solution sets. MNCA is demonstrated here for solution of two illustrative water resources management problems, including a water supply network design problem and a water quality management problem. Results are analyzed to demonstrate the use of MNCA to generate new insight and options for addressing difficult problems.}, booktitle={World Environmental and Water Resources Congress 2013}, publisher={American Society of Civil Engineers}, author={Shafiee, M. E. and Kandiah, V. K. and Barrett, E. and Zechman, E. M.}, year={2013}, month={May} }
 @article{marchi_salomons_ostfeld_kapelan_simpson_zecchin_maier_wu_elsayed_song_et al._2014, edition={+59 co-authors}, title={Battle of the Water Networks II}, volume={140}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000378}, DOI={10.1061/(ASCE)WR.1943-5452.0000378}, abstractNote={The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multiobjective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems. (C) 2014 American Society of Civil Engineers.}, number={7}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Marchi, Angela and Salomons, Elad and Ostfeld, Avi and Kapelan, Zoran and Simpson, Angus R. and Zecchin, Aaron C. and Maier, Holger R. and Wu, Zheng Yi and Elsayed, Samir M. and Song, Yuan and et al.}, year={2014}, month={Jul}, pages={04014009} }
 @article{giacomoni_kanta_zechman_2013, title={Complex Adaptive Systems Approach to Simulate the Sustainability of Water Resources and Urbanization}, volume={139}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000302}, DOI={10.1061/(asce)wr.1943-5452.0000302}, abstractNote={AbstractUrban water resources should be managed to meet conflicting demands for environmental health, economic prosperity, and social equity for present and future generations. While the sustainability of water resources can depend on dynamic interactions among natural, social, and infrastructure systems, typical water resource planning and management approaches are based on methodologies that ignore feedbacks and adaptations among these systems. This research develops and demonstrates a new complex adaptive systems approach to model the dynamic interactions among population growth, land-use change, the hydrologic cycle, residential water use, and interbasin transfers. Agent-based and cellular automaton models, representing consumers and policymakers who make land- and water-use decisions, are coupled with hydrologic models. The framework is applied for an illustrative case study to simulate urbanization and the water supply system over a long-term planning horizon. Results indicate that interactions amon...}, number={5}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Giacomoni, M. H. and Kanta, L. and Zechman, E. M.}, year={2013}, month={Sep}, pages={554–564} }
 @article{kanta_zechman_2014, title={Complex Adaptive Systems Framework to Assess Supply-Side and Demand-Side Management for Urban Water Resources}, volume={140}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000301}, DOI={10.1061/(asce)wr.1943-5452.0000301}, abstractNote={AbstractThe availability of water resources in many urbanizing areas is the emergent property of the adaptive interactions among consumers, policy, and the hydrologic cycle. As water availability becomes more stressed, public officials often implement restrictions on water use, such as bans on outdoor watering. Consumers are influenced by policy and the choices of other consumers to select water-conservation technologies and practices, which aggregate as the demand on available water resources. Policy and behavior choices affect the availability of water for future use as reservoirs are depleted or filled. This research posited urban water supply as a complex adaptive system (CAS) by coupling a stochastic consumer demand model and a water supply model within an agent-based modeling (ABM) framework. Public officials were simulated as agents to choose water conservation strategies and interbasin transfer strategies, and consumers were simulated as agents, influenced by various conservation-based programs to...}, number={1}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Kanta, Lufthansa and Zechman, Emily}, year={2014}, month={Jan}, pages={75–85} }
 @inproceedings{shafiee_zechman_2013, title={Integrating Genetic Programming and Agent-based Modeling to Identify Sensor-based Rules for Flushing Contaminated Water from a Pipe Network}, ISBN={9780784412947}, url={http://dx.doi.org/10.1061/9780784412947.075}, DOI={10.1061/9780784412947.075}, abstractNote={A utility manager may become aware of a threat of contamination to a water distribution network through water quality sensor information, which may indicate that a biological pathogen or chemical contaminant was introduced to the network. In response, a utility manager can select a set of hydrants to flush contaminant from the network. As an event unfolds, a decision-maker may not be able to ascertain source characteristics, creating additional difficulties in determining the set of hydrants that should be opened. The research presented here develops a Genetic Programming (GP)-based approach to identify a set of response actions that are based on sensor information, instead of source characteristics, for guiding selection of hydrants. GP is a method within the class of evolutionary computation, and a solution is represented as a combination of values and symbols to represent a computer program for executing computations, such as a mathematical equation. GP is developed in this research to program a list of rules for opening and closing hydrants that will effectively protect public health for an ensemble of contamination events. An ensemble of contamination events is developed based on a set of similar activated sensors. As the public health effects of a contamination event are influenced by a set of complex interactions among consumers, utility operators, and the pipe network, an agent-based modeling framework is used to predict the dynamic location of a contaminant plume during a contamination event and the number of exposed consumers. To identify optimal hydrant strategies to flush a contaminant while considering the complexity of interactions in the system, a simulation-optimization model couples agent-based modeling with GP. Multiple contamination scenarios are modeled to evaluate potential solutions, and the simulation-optimization framework is demonstrated for a virtual mid-sized municipality, Mesopolis.}, booktitle={World Environmental and Water Resources Congress 2013}, publisher={American Society of Civil Engineers}, author={Shafiee, M. Ehsan and Zechman, Emily M.}, year={2013}, month={May} }
 @article{zechman_2013, title={Integrating evolution strategies and genetic algorithms with agent-based modeling for flushing a contaminated water distribution system}, volume={15}, ISSN={1464-7141 1465-1734}, url={http://dx.doi.org/10.2166/hydro.2013.102}, DOI={10.2166/hydro.2013.102}, abstractNote={Water utilities can prepare for water distribution hazards, such as the presence of contaminants in the pipe network and failure of physical components. In contamination events, the complex interactions among managers' operational decisions, consumers' water consumption choices, and the hydraulics and contaminant transport in the water distribution system may influence the contaminant plume so that a typical engineering model may not properly predict public health consequences. A complex adaptive system (CAS) approach couples engineering models of a water distribution system with agent-based models of consumers and public officials. Development of threat management strategies, which prescribe a set of actions to mitigate public health consequences, is enabled through a simulation–optimization framework that couples evolutionary algorithms with the CAS model. Evolution strategies and genetic algorithm-based approaches are developed and compared for an illustrative case study to identify a flushing strategy for opening hydrants to minimize the number of exposed consumers and maintain acceptable levels of service in the network.}, number={3}, journal={Journal of Hydroinformatics}, publisher={IWA Publishing}, author={Zechman, Emily M.}, year={2013}, month={Jul}, pages={798–812} }
 @article{suresh_stoleru_zechman_shihada_2013, title={On Event Detection and Localization in Acyclic Flow Networks}, volume={43}, ISSN={2168-2216 2168-2232}, url={http://dx.doi.org/10.1109/tsmca.2012.2210411}, DOI={10.1109/tsmca.2012.2210411}, abstractNote={Acyclic flow networks, present in many infrastructures of national importance (e.g., oil and gas and water distribution systems), have been attracting immense research interest. Existing solutions for detecting and locating attacks against these infrastructures have been proven costly and imprecise, particularly when dealing with large-scale distribution systems. In this article, to the best of our knowledge, for the first time, we investigate how mobile sensor networks can be used for optimal event detection and localization in acyclic flow networks. We propose the idea of using sensors that move along the edges of the network and detect events (i.e., attacks). To localize the events, sensors detect proximity to beacons, which are devices with known placement in the network. We formulate the problem of minimizing the cost of monitoring infrastructure (i.e., minimizing the number of sensors and beacons deployed) in a predetermined zone of interest, while ensuring a degree of coverage by sensors and a required accuracy in locating events using beacons. We propose algorithms for solving the aforementioned problem and demonstrate their effectiveness with results obtained from a realistic flow network simulator.}, number={3}, journal={IEEE Transactions on Systems, Man, and Cybernetics: Systems}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Suresh, Mahima Agumbe and Stoleru, Radu and Zechman, Emily M. and Shihada, Basem}, year={2013}, month={May}, pages={708–723} }
 @article{rasekh_shafiee_zechman_brumbelow_2014, title={Sociotechnical risk assessment for water distribution system contamination threats}, volume={16}, ISSN={1464-7141 1465-1734}, url={http://dx.doi.org/10.2166/hydro.2013.023}, DOI={10.2166/hydro.2013.023}, abstractNote={Water distribution systems (WDS) are vulnerable to contaminants, and systematic risk assessment can provide valuable information for assisting threat management. Contamination events are sociotechnical systems, in which the interactions among consumers and water infrastructure may generate unpredicted public health consequences. This research develops a sociotechnical risk assessment framework that simulates the dynamics of a contamination event by coupling an agent-based modeling (ABM) framework with Monte Carlo simulation (MCS), genetic algorithm (GA) optimization, and a multi-objective GA. The ABM framework couples WDS simulation with agents to represent consumers in a virtual city. MCS is applied to estimate the uncertainty in human exposure, based on probabilistic models of event attributes. A GA approach is used to identify critical contamination events by maximizing risk, and a multi-objective approach explores the trade-off between consequence and occurrence probabilities. Results that are obtained using the sociotechnical approach are compared with results obtained using a conventional engineering model. The sociotechnical approach removes assumptions that have been used in engineering analysis about the static, homogeneous, and stationary behaviors of consumers, and results demonstrate new insight about the impacts of these actions and interactions on the public health consequences of contamination events.}, number={3}, journal={Journal of Hydroinformatics}, publisher={IWA Publishing}, author={Rasekh, Amin and Shafiee, M. Ehsan and Zechman, Emily and Brumbelow, Kelly}, year={2014}, month={May}, pages={531–549} }
 @inproceedings{kandiah_zechman_2012, title={Agent-Based Modeling for Simulating the Decentralization of Urban Water Infrastructure Systems}, ISBN={9780784412312}, url={http://dx.doi.org/10.1061/9780784412312.223}, DOI={10.1061/9780784412312.223}, abstractNote={Urban water infrastructure systems, including drinking water, wastewater, and stormwater, should be designed to efficiently use water and energy resources. Current design paradigms typically neglect the interconnection among these systems; water, wastewater, and stormwater are treated at centralized facilities, and water services are distributed within a municipality through pipe networks. Due to water shortages and limited budgets, water utilities may encourage individual households to adopt water reuse, water conservation, and lot-level stormwater treatment technologies, which may produce a decentralized water service system. Transitioning from a centralized to a decentralized approach within urban water infrastructure systems will change demands and affect the performance of the existing infrastructure and the use of energy and water resources. To enable exploration of the impacts of decentralization on the sustainability and resilience of urban water infrastructure systems, a Complex Adaptive Systems (CAS) approach is developed here. This modeling framework characterizes the various feedback loops, dynamic interactions, and emergent phenomena that result from the interactions of decentralized and centralized components of the water infrastructure systems. Specifically, rainwater harvesting is explored as a decentralization technology, which reduces stormwater service demands and drinking water demands on the centralized infrastructure systems. An agent-based modeling approach is used to simulate technology adoption of individual consumers in response to water shortages and is coupled with water and energy utilization models. The framework provides insight to the interconnections and interactions between the consumers, water supply and delivery system and the effect of these interactions on water and energy use and sustainability; infrastructure system design; and system resilience, as a system transitions from a centralized to a decentralized layout.}, booktitle={World Environmental and Water Resources Congress 2012}, publisher={American Society of Civil Engineers}, author={Kandiah, V. K. and Zechman, E. M.}, year={2012}, month={May} }
 @article{mirghani_zechman_ranjithan_mahinthakumar_2012, title={Enhanced Simulation-Optimization Approach Using Surrogate Modeling for Solving Inverse Problems}, volume={13}, ISSN={1527-5922 1527-5930}, url={http://dx.doi.org/10.1080/15275922.2012.702333}, DOI={10.1080/15275922.2012.702333}, abstractNote={This study investigates and discusses groundwater system characterization problem utilizing surrogate modeling. In this inverse problem, the contaminant signals at monitoring wells are recorded to recreate the pollution profiles. In this study, simulation-optimization approach is a technique utilized to solve inverse problems by formulating them as an optimization model, where evolutionary computation algorithms are used to perform the search. In this approach, the partial differential equations (PDE) groundwater transport simulation model is solved iteratively during the evolutionary search, which in general can be computationally expensive since thousands of simulation model evaluations will be evaluated. To overcome this limitation, the simulation model is replaced by a surrogate model, which is computationally much faster than the simulation model and yet is relatively accurate. Artificial neural networks (ANN) is used to construct surrogate models that provide acceptable accuracy performances. The ANN surrogate model, which replaces the PDE groundwater transport simulation model, is then coupled with a genetic algorithm (GA) search procedure to solve the source identification problem. The results will present the quality solution of the ANN surrogate model versus the groundwater simulation model, the solution of the inverse problem for different experiment scenarios and finally a timing study analysis conducted to measure the surrogate model performance.}, number={4}, journal={Environmental Forensics}, publisher={Informa UK Limited}, author={Mirghani, Baha Y. and Zechman, Emily M. and Ranjithan, Ranji S. and Mahinthakumar, G. (Kumar)}, year={2012}, month={Jan}, pages={348–363} }
 @inproceedings{kanta_zechman_2012, title={Exploring Adaptive Demand-Side and Supply-Side Management of Urban Water Resources Using a Multi-Objective Optimization Approach}, ISBN={9780784412312}, url={http://dx.doi.org/10.1061/9780784412312.232}, DOI={10.1061/9780784412312.232}, abstractNote={Urban water management specifies supply-side infrastructure and demand-side policies to balance water supply and demands for social and environmental systems. As the sustainability of water resources depends on the dynamic interactions among the environmental, technological, and social characteristics of the water system and local population, an adaptive water management approach can be used to update utility decisions based on the feedback among these systems and may enable a more efficient use of resources. Adaptive demand-side management strategies, such as regulating water for outdoor use, can be designed with increasing restrictions corresponding to the depletion of reservoirs. Adaptive supply-side strategies supplement supply by increasing the volume of water that is transferred among basins when reservoirs levels drop. Frequent water use restrictions, however, can have adverse effects on property values, due to prolonged periods without lawn watering, while pumping water from external basins carries a high cost due to energy requirements. A trade-off exists between the management costs to the water utility and the number of day when outdoor water use is restricted. In this study, a Complex Adaptive Systems (CAS) framework is used to simulate the adaptive behaviors of consumers, the adaptive decisions of the water utility, and an engineering model of the water supply infrastructure. The CAS framework is coupled with a multi-objective optimization methodology to evaluate a combination of supply-side and demand-side adaptive water management strategies in achieving the conflicting goals of minimizing management costs and minimizing the number of days with outdoor water use restrictions. An evolutionary computation-based methodology, Hypervolume Maximizing Multi-objective Evolutionary Algorithm (HM2EA), is applied to an illustrative case study of an urban water supply system to explore Pareto-optimal solution sets of adaptive water management strategies.}, booktitle={World Environmental and Water Resources Congress 2012}, publisher={American Society of Civil Engineers}, author={Kanta, Lufthansa and Zechman, Emily M.}, year={2012}, month={May} }
 @article{liu_zechman_mahinthakumar_ranji ranjithan_2012, title={Identifying contaminant sources for water distribution systems using a hybrid method}, volume={29}, ISSN={1028-6608 1029-0249}, url={http://dx.doi.org/10.1080/10286608.2012.663360}, DOI={10.1080/10286608.2012.663360}, abstractNote={The rapid discovery of the contaminant source in a water distribution system (WDS) is vital for generating an efficient control strategy during a contamination event. An inverse problem can be constructed, given sensor measurements in a WDS, to identify the contaminant source characteristics by integrating a WDS simulation model with an optimisation method. However, this approach requires numerous compute-intensive simulation runs to evaluate potential solutions. This paper reports the findings of an investigation by introducing a hybrid method for the real-time characterisation of a contaminant source. This new method integrates a simulation-optimisation approach with a logistic regression and a local improvement method to expedite the convergence and possibly solve the problem quickly. The results of numerical experiments on two example WDS networks demonstrate the efficiency of the proposed hybrid method for contaminant source characterisation. Effects of various hybrid strategies on the algorithm performance are discussed.}, number={2}, journal={Civil Engineering and Environmental Systems}, publisher={Informa UK Limited}, author={Liu, Li and Zechman, Emily M. and Mahinthakumar, G. and Ranji Ranjithan, S.}, year={2012}, month={Jun}, pages={123–136} }
 @article{damodaram_zechman_2013, title={Simulation-Optimization Approach to Design Low Impact Development for Managing Peak Flow Alterations in Urbanizing Watersheds}, volume={139}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000251}, DOI={10.1061/(asce)wr.1943-5452.0000251}, abstractNote={AbstractThe process of urbanization transforms natural landscape into impervious land cover, affecting the ecosystem health of receiving water bodies and downstream communities by changing the timing and volumes of the natural flow regime. Best management practices (BMP) and low impact development (LID) are a set of mitigating measures that can be considered for watershed management to mitigate the hydrologic consequences of urbanization. This research develops a methodology to select sites for placing LID technologies, namely rainwater harvesting and permeable pavements, to reduce hydrologic impacts, measured as alterations to the peak flow while meeting a prespecified budget. A simulation-optimization methodology couples a genetic algorithm with a hydrologic model, a hydraulic model, and curve number-based models of LID technologies. The trade-off between costs and peak flow alteration is explored by optimizing LID placement under varying budget constraints. Strategies that combine a detention pond and ...}, number={3}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Damodaram, Chandana and Zechman, Emily M.}, year={2013}, month={May}, pages={290–298} }
 @inproceedings{shafiee_zechman_2012, title={Sociotechnical Simulation for Evaluating Adaptive Threat Response Actions for Water Distribution Contamination Events}, ISBN={9780784412312}, url={http://dx.doi.org/10.1061/9780784412312.330}, DOI={10.1061/9780784412312.330}, abstractNote={In the event that pathogens or toxins are introduced to a water distribution system, water utility managers should take the most effective actions to protect public health. As a contaminant propagates through the pipe network, a utility manager must select response actions based on available information, such as water quality sensing or complaints from consumers. Response plans are developed from a large set of options, including hydraulic responses that influence the mechanisms of system hydraulics and social responses that alter water consumption behaviors of the public through, for example, media broadcasts. The contaminant plume can shift from a previously expected direction due to public behaviors and altered system hydraulics during the event; in addition, new information will become available from water quality sensors and consumer complaints. Therefore, a manager should adapt to new conditions and information during the event to select the most effective responses. This research explores a new simulation framework to evaluate the efficiency of adaptive response rules for a water utility during a contamination event. A Complex Adaptive System (CAS)-based methodology is developed to couple the engineering model of a water distribution system with agent-based models of consumers and utility managers to simulate feedback among management decisions, system hydraulics, and the public behavior. A utility manager is represented as an agent, who responds to the event through a set of rules and equations, and consumers are represented as agents who update their water activities based on exposure to the contaminant and warnings from the utility agent. The proposed model is applied to an illustrative mid-sized virtual city to investigate the significance of interactions and identify sets of rules to effectively protect public health.}, booktitle={World Environmental and Water Resources Congress 2012}, publisher={American Society of Civil Engineers}, author={Shafiee, M. Ehsan and Zechman, Emily M.}, year={2012}, month={May} }
 @inbook{agumbe suresh_stoleru_denton_zechman_shihada_2012, place={Berlin Heidelberg}, series={Lecture Notes in Computer Science}, title={Towards Optimal Event Detection and Localization in Acyclic Flow Networks}, ISBN={9783642259586 9783642259593}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-25959-3_13}, DOI={10.1007/978-3-642-25959-3_13}, abstractNote={Acyclic flow networks, present in many infrastructures of national importance (e.g., oil & gas and water distribution systems), have been attracting immense research interest. Existing solutions for detecting and locating attacks against these infrastructures, have been proven costly and imprecise, especially when dealing with large scale distribution systems. In this paper, to the best of our knowledge for the first time, we investigate how mobile sensor networks can be used for optimal event detection and localization in acyclic flow networks. Sensor nodes move along the edges of the network and detect events (i.e., attacks) and proximity to beacon nodes with known placement in the network. We formulate the problem of minimizing the cost of monitoring infrastructure (i.e., minimizing the number of sensor and beacon nodes deployed), while ensuring a degree of sensing coverage in a zone of interest and a required accuracy in locating events. We propose algorithms for solving these problems and demonstrate their effectiveness with results obtained from a high fidelity simulator.}, booktitle={Distributed Computing and Networking: ICDCN 2012}, publisher={Springer}, author={Agumbe Suresh, Mahima and Stoleru, Radu and Denton, Ron and Zechman, Emily and Shihada, Basem}, editor={Bononi, L. and Datta, A.K. and Devismes, S. and Misra, A.Editors}, year={2012}, pages={179–196}, collection={Lecture Notes in Computer Science} }
 @inproceedings{drake_zechman_2012, title={Using Consumer Complaints to Characterize Contamination Events in a Water Distribution System}, ISBN={9780784412312}, url={http://dx.doi.org/10.1061/9780784412312.332}, DOI={10.1061/9780784412312.332}, abstractNote={Water distribution systems (WDS) are vulnerable to accidental contamination events and intentional attacks that may cause dire effects on public health. In the event of water contamination, consumers may complain about unusual color, smell, or taste of their drinking water to their local water utility. Utility managers use this information to implement response actions that address the water quality problem. To maximize the effect of the response actions, the location of the source of contamination should be known. Consumer complaints can be used to identify the source. Since consumers behave in a complex manner depending on their characteristics (i.e. age, gender, mobility, and water consumption habits), complexity is added to the existing dynamics and complexity of WDS modeling. An Agentbased Model (ABM) is used to simulate complex consumer actions within a WDS during a contamination event. ABM and a WDS simulation model are coupled with an evolutionary algorithm to solve for the contamination source characteristics. However, since consumer behavior is less predictable, the use of their complaints to identify the source of contamination may not always lead to one unique source. Nonuniqueness within a WDS makes it difficult for utility managers to implement optimal response actions. To address the problem of non-uniqueness, alternative sources of contamination are generated.}, booktitle={World Environmental and Water Resources Congress 2012}, publisher={American Society of Civil Engineers}, author={Drake, Kristen and Zechman, Emily M.}, year={2012}, month={May} }
 @inproceedings{kanta_zechman_2011, title={A Complex Adaptive Systems Approach to Develop Basin-Scale Optimal Management Strategies for Water Resources Systems}, ISBN={9780784411735}, url={http://dx.doi.org/10.1061/41173(414)296}, DOI={10.1061/41173(414)296}, abstractNote={Sustainable basin-scale management of water resources is challenged by the rapid increase in population and the expected changes in future climatic conditions. Population and economic growth has caused increases in water demands which, along with climate variability, may reduce the availability of water resources. Management strategies often employ supply-side management for water scarcity through the design and implementation of large infrastructure improvements. The stresses on water system could alternatively be reduced by conservation-based policy developments, including outdoor water use restrictions and household-level adoption of water smart technologies. An adaptive management approach may achieve high levels of water conservation most effectively. For example, policy officials may campaign for water conservation measures during drought conditions only, or inter-basin transfers may be implemented by anticipating the timing of inflows to the reservoirs. This research will explore adaptive basin-scale management strategies by modeling an urban water resources system as a Complex Adaptive System. Agent-based modeling is used to represent policy and consumer water use model, and are coupled with a reservoir system model. Policy officials can select pumping and inter-basin transfer operations and or water use restrictions, and consumers can select water use behaviors based on policy developments and pricing information. The proposed adaptive modeling framework will be applied to a case study, and optimal management strategies will be developed to minimize energy costs for different climatic conditions.}, booktitle={World Environmental and Water Resources Congress 2011}, publisher={American Society of Civil Engineers}, author={Kanta, Lufthansa and Zechman, Emily M.}, year={2011}, month={May} }
 @article{zechman_2011, title={Agent-Based Modeling to Simulate Contamination Events and Evaluate Threat Management Strategies in Water Distribution Systems}, volume={31}, ISSN={0272-4332}, url={http://dx.doi.org/10.1111/j.1539-6924.2010.01564.x}, DOI={10.1111/j.1539-6924.2010.01564.x}, abstractNote={In the event of contamination of a water distribution system, decisions must be made to mitigate the impact of the contamination and to protect public health. Making threat management decisions while a contaminant spreads through the network is a dynamic and interactive process. Response actions taken by the utility managers and water consumption choices made by the consumers will affect the hydraulics, and thus the spread of the contaminant plume, in the network. A modeling framework that allows the simulation of a contamination event under the effects of actions taken by utility managers and consumers will be a useful tool for the analysis of alternative threat mitigation and management strategies. This article presents a multiagent modeling framework that combines agent‐based, mechanistic, and dynamic methods. Agents select actions based on a set of rules that represent an individual's autonomy, goal‐based desires, and reaction to the environment and the actions of other agents. Consumer behaviors including ingestion, mobility, reduction of water demands, and word‐of‐mouth communication are simulated. Management strategies are evaluated, including opening hydrants to flush the contaminant and broadcasts. As actions taken by consumer agents and utility operators affect demands and flows in the system, the mechanistic model is updated. Management strategies are evaluated based on the exposure of the population to the contaminant. The framework is designed to consider the typical issues involved in water distribution threat management and provides valuable analysis of threat containment strategies for water distribution system contamination events.}, number={5}, journal={Risk Analysis}, publisher={Wiley}, author={Zechman, Emily M.}, year={2011}, month={Jan}, pages={758–772} }
 @inproceedings{shafiee_zechman_2011, title={An Agent-Based Modeling Approach to Evaluate Protective Action Strategies in a Water Distribution Contamination Event}, ISBN={9780784411735}, url={http://dx.doi.org/10.1061/41173(414)30}, DOI={10.1061/41173(414)30}, abstractNote={Water distribution systems are vulnerable to both intentional and accidental contamination, which endangers public health and erodes public trust in municipal services. Appropriate protective actions should be selected by public officials or utility managers as the contaminant propagates through the network to best protect public health. Response actions typically attempt to control hydraulics in the network or the water consumption of the public, and decision-makers may be made aware of a security threat through consumer complaints or public health services. Consumers can be influenced to reduce their water consumption through, for example, boil water orders and drinking water restrictions. The interactions and information exchange between the utility managers and consumers will dynamically influence the system hydraulics, increasing the complexity of the decision-making process for the utility managers. An agent-based modeling framework was developed to simulate the dynamic and adaptive actions and reactions in a contamination event. Utility managers and consumers are modeled as agents, and the agent-based model was coupled with a water distribution system simulator to predict the emergent public health for diverse protective action strategies. The modeling framework is applied to a virtual case study, Mesopolis, to investigate the significance of the interactions among consumers and utility managers in water distribution system threat management.}, booktitle={World Environmental and Water Resources Congress 2011}, publisher={American Society of Civil Engineers}, author={Shafiee, Mohammadmehdi and Zechman, Emily M.}, year={2011}, month={May} }
 @inproceedings{giacomoni_zechman_2011, title={Assessing Sustainability of Integrated Urban Water Resources Systems through a Complex Adaptive Systems Approach}, ISBN={9780784411735}, url={http://dx.doi.org/10.1061/41173(414)297}, DOI={10.1061/41173(414)297}, abstractNote={The sustainability of urban water resources is the emergent property of a set of interactions across diverse water sectors, consumers, and management strategies. The availability and quality of water resources are threatened by processes including increasing water consumption caused by population growth and hydrologic alterations due to land use change and climate change. As these processes involve interactions among the built, human, and natural environments, a novel modeling technique is developed here to capture the interactions among diverse systems and their impacts on the emergent sustainability of water resources. This research presents a Complex Adaptive Systems (CAS) approach, which simulates the interactions among population growth, construction of houses, land use change, domestic water use practices, and hydrologic processes, through the integration of a set of complex modeling paradigms, including agent based models and cellular automata with hydrologic models. A sustainability index is computed as the product of reliability, resilience and vulnerability of the system and is used to assess different management scenarios and adaptive strategies. The CAS framework is demonstrated for assessing the performance of adaptive land and water use strategies in the development of more sustainable water management strategies.}, booktitle={World Environmental and Water Resources Congress 2011}, publisher={American Society of Civil Engineers}, author={Giacomoni, M. H. and Zechman, E. M.}, year={2011}, month={May} }
 @article{putha_quadrifoglio_zechman_2012, title={Comparing Ant Colony Optimization and Genetic Algorithm Approaches for Solving Traffic Signal Coordination under Oversaturation Conditions}, volume={27}, ISSN={1093-9687}, url={http://dx.doi.org/10.1111/j.1467-8667.2010.00715.x}, DOI={10.1111/j.1467-8667.2010.00715.x}, abstractNote={Abstract:   This article proposes to solve the oversaturated network traffic signal coordination problem using the Ant Colony Optimization (ACO) algorithm. The traffic networks used are discrete time models which use green times at all the intersections throughout the considered period of oversaturation as the decision variables. The ACO algorithm finds intelligent timing plans which take care of dissipation of queues and removal of blockages as opposed to the sole cost minimization usually performed for undersaturation conditions. Two scenarios are considered and results are rigorously compared with solutions obtained using the genetic algorithm (GA), traditionally employed to solve oversaturated conditions. ACO is shown to be consistently more effective for a larger number of trials and to provide more reliable solutions. Further, as a master‐slave parallelism is possible for the nature of ACO algorithm, its implementation is suggested to reduce the overall execution time allowing the opportunity to solve real‐time signal control systems.}, number={1}, journal={Computer-Aided Civil and Infrastructure Engineering}, publisher={Wiley}, author={Putha, Rahul and Quadrifoglio, Luca and Zechman, Emily}, year={2012}, month={Jan}, pages={14–28} }
 @article{liu_zechman_mahinthakumar_ranji ranjithan_2012, title={Coupling of logistic regression analysis and local search methods for characterization of water distribution system contaminant source}, volume={25}, ISSN={0952-1976}, url={http://dx.doi.org/10.1016/j.engappai.2011.10.009}, DOI={10.1016/j.engappai.2011.10.009}, abstractNote={Accidental or intentional drinking water contamination has long been and remains a major threat to water security throughout the world. An inverse problem can be constructed, given sensor measurements in a water distribution system (WDS), to identify the contaminant source characteristics by integrating a WDS simulation model with an optimization method. However, this approach requires numerous compute-intensive simulation runs to evaluate potential solutions; thus, determining the best source characteristic within a reasonable computational time is challenging. In this paper, we describe the development of a WDS contamination characterization algorithm by coupling a statistical model with a heuristic search method. The statistical model is used to identify potential source locations of contamination and a local search aims at further refining contaminant source characteristics. Application of the proposed approach to two illustrative example water distribution networks demonstrates its capability of adaptively discovering contaminant source characteristics as well as evaluating the degree of non-uniqueness of solutions. The results also showed that the local search as an optimizer has better performance than a standard evolutionary algorithm (EA).}, number={2}, journal={Engineering Applications of Artificial Intelligence}, publisher={Elsevier BV}, author={Liu, Li and Zechman, Emily M. and Mahinthakumar, G. and Ranji Ranjithan, S.}, year={2012}, month={Mar}, pages={309–316} }
 @article{giacomoni_zechman_brumbelow_2012, title={Hydrologic Footprint Residence: Environmentally Friendly Criteria for Best Management Practices}, volume={17}, ISSN={1084-0699 1943-5584}, url={http://dx.doi.org/10.1061/(asce)he.1943-5584.0000407}, DOI={10.1061/(asce)he.1943-5584.0000407}, abstractNote={The natural hydrologic flow regime is altered by urbanization, which can be mitigated through best management practices (BMPs) or low impact development (LID). Typically, the effectiveness of different management scenarios is tested by comparing post- and predevelopment instantaneous peak flows. This approach, however, does not capture the extent of hydrologic change and the effect on downstream communities. A new hydrologic sustainability metric is presented here to quantify the impact of urbanization on downstream water bodies on the basis of the inundation dynamics of the flow regime. The hydrologic footprint residence (HFR) is designed to capture both temporal and spatial hydrological changes to an event-based flow regime by calculating the inundated areas and duration of a flood. The HFR is demonstrated for a hypothetical watershed and a watershed on the Texas A&M University Campus, located in College Station, Texas. For the campus watershed, three design storms (2-, 10-, and 100-year) and a set of h...}, number={1}, journal={Journal of Hydrologic Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Giacomoni, Marcio H. and Zechman, Emily M. and Brumbelow, Kelly}, year={2012}, month={Jan}, pages={99–108} }
 @article{kanta_zechman_brumbelow_2012, title={Multiobjective Evolutionary Computation Approach for Redesigning Water Distribution Systems to Provide Fire Flows}, volume={138}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000156}, DOI={10.1061/(asce)wr.1943-5452.0000156}, abstractNote={One of the critical public safety roles for water distribution systems (WDS) is suppression of urban fire events. Previous studies have investigated WDS rehabilitation with a major focus on improving reliability by pipe enlargement. However, pipe enlargement can cause water quality problems and place public health at risk during normal operational periods. Thus, a novel approach is required to effectively address the conflicting goals of the WDS: reliable delivery of water during normal and emergency conditions, meeting water quality standards, and finding cost-effective design and rehabilitation options. In this study an evolutionary computation-based multiobjective optimization-simulation framework is developed to design effective mitigation strategies for urban fire events for water distribution systems with three objectives: (1) minimizing potential fire damages, (2) minimizing water quality deficiencies, and (3) minimizing the cost of mitigation. An elitist nondominated sorting genetic algorithm (NSG...}, number={2}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Kanta, Lufthansa and Zechman, Emily and Brumbelow, Kelly}, year={2012}, month={Mar}, pages={144–152} }
 @article{manian_kaihatu_zechman_2012, title={Using Genetic Algorithms to Optimize Bathymetric Sampling for Predictive Model Input}, volume={29}, ISSN={0739-0572 1520-0426}, url={http://dx.doi.org/10.1175/jtech-d-11-00051.1}, DOI={10.1175/jtech-d-11-00051.1}, abstractNote={Abstract
               This paper describes the use of an optimization method to effectively reduce the required bathymetric sampling for forcing a numerical forecast model by using the model’s sensitivity to this input. A genetic algorithm is developed to gradually evolve the survey path for a ship, autonomous underwater vehicle (AUV), or other measurement platform to an optimum, with the resulting effect of the corresponding measured bathymetry on the model used as a metric. Starting from an initial simulated set of possible random or heuristic sampling paths over the given bathymetry using certain constraints like limited length of track, the algorithm can be used to arrive at the path that would provide the best possible input to the model under those constraints. This suitability is tested by a comparison of the model results obtained by using these new simulated observations, with the results obtained using the most recent and complete bathymetric data available. Two test study areas were considered, and the algorithm was found to consistently converge to a sampling pattern that best captured the bathymetric variability critical to the model prediction.}, number={3}, journal={Journal of Atmospheric and Oceanic Technology}, publisher={American Meteorological Society}, author={Manian, Dinesh and Kaihatu, James M. and Zechman, Emily M.}, year={2012}, month={Mar}, pages={464–477} }
 @inproceedings{drake_zechman_2011, title={Using Niched Co-Evolution Strategies to Address Non-Uniqueness in Characterizing Sources of Contamination in a Water Distribution System}, ISBN={9780784411735}, url={http://dx.doi.org/10.1061/41173(414)35}, DOI={10.1061/41173(414)35}, abstractNote={Threat management of water distribution systems is essential for protecting consumers. In a contamination event, different strategies may be implemented to protect public health, including flushing the system through opening hydrants or isolating the contaminant by manipulating valves. To select the most effective options for responding to a contamination threat, the location and loading profile of the source of the contaminant should be considered. These characteristics can be identified by utilizing water quality data from sensors that have been strategically placed in a water distribution system. A simulation-optimization approach is described here to solve the inverse problem of source characterization, by coupling an evolutionary computation-based search with a water distribution system model. The solution of this problem may reveal, however, that a set of non-unique sources exists, where sources with significantly different locations and loading patterns produce similar concentration profiles at sensors. The problem of non-uniqueness should be addressed to prevent the misidentification of a contaminant source and improve response planning. This paper aims to address the problem of non-uniqueness through the use of Niched Co-Evolution Strategies (NCES). NCES is an evolutionary algorithm designed to identify a specified number of alternative solutions that are maximally different in their decision vectors, which are source characteristics for the water distribution problem. NCES is applied to determine the extent of non-uniqueness in source characterization for a virtual city, Mesopolis, with a population of approximately 150,000 residents. Results indicate that NCES successfully identifies non-uniqueness in source characterization and provides alternative sources of contamination events.}, booktitle={World Environmental and Water Resources Congress 2011}, publisher={American Society of Civil Engineers}, author={Drake, Kristen and Zechman, Emily}, year={2011}, month={May} }
 @inproceedings{scott_white_politte_damodaram_baltensperger_collard_saathoff_zechman_barbour_sprintson_2011, title={Using the Hydrologic Footprint Residence for Raising Awareness of Stormwater Sustainability}, ISBN={9780784411735}, url={http://dx.doi.org/10.1061/41173(414)336}, DOI={10.1061/41173(414)336}, abstractNote={The urbanization of watersheds leads to the degradation of watershed health, as increased areas of imperviousness produce alterations in the flow regime of receiving water bodies. While large infrastructure improvements, such as detention ponds, are typically implemented to manage excess runoff, a more decentralized approach that utilizes Low Impact Development (LID) design principles may better preserve the pre-development flow regime. Decentralized approaches, however, are more difficult to regulate, and homeowners and developers may be hesitant to adopt expensive technologies for stormwater control. A new stormwater sustainability metric, the hydrologic footprint residence (HFR), was recently introduced to measure more holistically the impacts of urbanization on the downstream residence. HFR measures changes to the flow regime as the area of land inundated for one unit of time in response to one rainfall event. It is the hypothesis of this work that HFR can be used to communicate the impacts of urbanization on watershed health more effectively than traditional stormwater metrics, such as peak flow. This paper describes a set of online interactive quizzes that were designed for educating about issues of stormwater sustainability and LID options, such as permeable pavements, rainwater harvesting, and cluster development. A survey was fielded to evaluate and compare the use of HFR and peak flow within the quiz for communicating to the general public about stormwater sustainability.}, booktitle={World Environmental and Water Resources Congress 2011}, publisher={American Society of Civil Engineers}, author={Scott, Tommi Jo and White, Avery and Politte, Alyssa and Damodaram, Chandana and Baltensperger, April and Collard, Sam and Saathoff, Sean and Zechman, Emily M. and Barbour, Joshua and Sprintson, Alex}, year={2011}, month={May} }
 @inproceedings{giacomoni_zechman_2010, title={A Complex Adaptive Systems Approach to Simulate Urban Water Resources Sustainability}, ISBN={9780784411148}, url={http://dx.doi.org/10.1061/41114(371)262}, DOI={10.1061/41114(371)262}, abstractNote={Urban growth impacts the sustainability of water resources due to conversion of natural to impervious cover and increased withdraws for human consumption. These processes increase runoff, change the timing of in-stream flows and storage, and deplete available water resources. The quality and availability of urban water resources, therefore, is the aggregated result of landand water-use choices of citizens in a municipality. For example, land owners define the amount of imperviousness in lots through the adoption of Low Impact Development (LID), and consumers choose water conservation techniques and practices. Consumer decision-making is a dynamic process, however, as it is driven by water resources policies, which is, in turn, based on the current quality and availability of water resources. This research simulates a watershed as a Complex Adaptive System (CAS), which is characterized by interacting actors who influence and are influenced by the environment and the choices of other actors through dynamic feedback processes. A CAS can be simulated through the use of Agent Based Models (ABMs), which represents the interaction of multiple actors within an environment. A CAS framework is developed for an illustrative case study to simulate landowners and households as ABMs, coupled with a hydrologic and reservoir model. Agents make decisions to choose land use types, implement LID, and adopt water conservation practices. The CAS framework presents a more comprehensive view of the urban water system and the dynamic interactions between stormwater management and water supply for facilitating the water resources planning process.}, booktitle={World Environmental and Water Resources Congress 2010}, publisher={American Society of Civil Engineers}, author={Giacomoni, M. H. and Zechman, E. M.}, year={2010}, month={May} }
 @inproceedings{shafiee_zechman_2010, title={An Agent-Based Modeling Approach for Simulating Contamination Events Applied to the Mesopolis Water Distribution System}, ISBN={9780784411148}, url={http://dx.doi.org/10.1061/41114(371)441}, DOI={10.1061/41114(371)441}, abstractNote={Water distribution system contamination is a realistic threat to public health, and both intentional and accidental contamination of water utilities can cause devastating consequences. The most effective responses to a contamination incident should be planned to manage the impact of contamination events and protect public health. Making threat management decisions while the contaminant is spreading through the network is a difficult process; however, due to uncertainty and lack of monitoring data, and the various interaction and responses of consumers, policy makers and media during an event make the problem more complex and dynamic. The behaviors of consumers cause diverse fluctuations in the hydraulics of the water system, changing the propagation of the contaminant plume in the network. Decision-makers may choose to mitigate the contaminant and change hydraulics in the network through flushing hydrants and closing valves. A modeling framework that allows the simulation of a contamination event under the effects of actions taken by utility managers and consumers allows in-depth analysis of alternative threat mitigation and management strategies. Agent Based Modeling is coupled with a water distribution network model to simulate the interaction among different agents in the system and evaluate the emergent properties of the contamination event, which would be difficult to predict by assessing individual agent behaviors alone. Individual consumers are simulated as agents, who, once exposed to a contaminant, will change their water usage and communicate with other consumers and decision-makers. In the model, as actions taken by agents affect demands and flows in the system, dynamic approaches will update the mechanistic model and the identification of the contaminant source to supply the utility manager agents with the latest information as it becomes available. This framework is applied for a virtual case study, Mesopolis. The results of the case study indicate the significance of considering the behavior of agents in threat management and response planning to better protect public health.}, booktitle={World Environmental and Water Resources Congress 2010}, publisher={American Society of Civil Engineers}, author={Shafiee, Mohammadmehdi and Zechman, Emily M.}, year={2010}, month={May} }
 @inproceedings{kanta_zechman_2010, title={An Agent-Based Modeling Approach to Evaluate the Impact of Conservation Practices on Water Resources Sustainability}, ISBN={9780784411148}, url={http://dx.doi.org/10.1061/41114(371)432}, DOI={10.1061/41114(371)432}, abstractNote={The availability of water resources in many urbanizing areas is the emergent property of the adaptive interactions among consumers, policy, and the hydrologic cycle. As water availability becomes more stressed, public officials often implement restrictions on water use, such as bans on outdoor watering. Consumers are influenced by policy and the choices of other consumers to select water conservation technologies and practices, which aggregate as the demand on available water resources. Policy and behavior choices impact the availability of water for future use as reservoirs are depleted or filled. This research posits urban water supply as a Complex Adaptive System (CAS) by coupling a consumer end use model and a water supply model within an agent-based modeling (ABM) framework. Public officials are simulated as agents to choose water pricing structures, and consumers are simulated as agents, influenced by water prices and the choices of other consumers, to select water conservation technologies and behaviors, and correspondingly update their individual end use models. A water supply reservoir is simulated to receive rainfall from the contributing watershed and supply the demands of consumer agents. The ABM framework is applied to an illustrative urban case study. A set of water pricing structures are developed to represent risky and risk-averse policies and are simulated for a long-term precipitation record to evaluate the sustainability of water conservation practices.}, booktitle={World Environmental and Water Resources Congress 2010}, publisher={American Society of Civil Engineers}, author={Kanta, Lufthansa and Zechman, Emily M.}, year={2010}, month={May} }
 @article{booker_sprintson_zechman_singh_guikema_2010, title={Efficient traffic loss evaluation for transport backbone networks}, volume={54}, ISSN={1389-1286}, url={http://dx.doi.org/10.1016/j.comnet.2010.01.008}, DOI={10.1016/j.comnet.2010.01.008}, abstractNote={The resilience and survivability of transport backbone networks are vital for the economy and security. Modern backbone networks use a mesh of fiber optic cables, which are, due to their ubiquitous deployment, prone to failures. The goal of this paper is to develop efficient computational methods for assessing the expected traffic loss in such networks. We present both analytical and simulation approaches for this problem. Our analytical approach is based on the cut set enumeration technique, while our simulation approach is based on Monte Carlo sampling techniques. To facilitate the computational process, we employ artificial intelligence methods based on genetic algorithms.}, number={10}, journal={Computer Networks}, publisher={Elsevier BV}, author={Booker, G. and Sprintson, A. and Zechman, E. and Singh, C. and Guikema, S.}, year={2010}, month={Jul}, pages={1683–1691} }
 @inproceedings{damodaram_zechman_2010, title={Optimizing the Placement of Low Impact Development in an Urban Watershed}, ISBN={9780784411148}, url={http://dx.doi.org/10.1061/41114(371)320}, DOI={10.1061/41114(371)320}, abstractNote={An increase in urbanization adversely impacts the health of watersheds and receiving water bodies, causing increased peak flows, runoff volumes, velocities and erosion along the banks of a stream. Low Impact Development (LID) methods are strategies which are used to mitigate the impacts of urbanization by reducing runoff at the source and restore the natural hydrologic flow regime. Rainwater harvesting systems, permeable pavements, and green roofs are common LID techniques used to mitigate runoff generated from rooftops and parking lots. As the effectiveness of a LID strategy is determined by both the infiltration capabilities of alternative technologies and their placement within the watershed, this study optimizes the allocation of LID in a watershed to minimize the impact on the natural hydrologic flow regime, subject to an allowable cost. The hydrologic impacts of LID strategies are simulated using hydrologic and hydraulic models and are evaluated based on the peak flow. A genetic algorithm is coupled with the simulation models and applied for an illustrative watershed, located on the Texas A&M University campus, to identify the tradeoff between hydrologic impacts and implement costs of LID strategies.}, booktitle={World Environmental and Water Resources Congress 2010}, publisher={American Society of Civil Engineers}, author={Damodaram, Chandana and Zechman, Emily M.}, year={2010}, month={May} }
 @article{damodaram_giacomoni_prakash khedun_holmes_ryan_saour_zechman_2010, title={Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management}, volume={46}, ISSN={1093-474X}, url={http://dx.doi.org/10.1111/j.1752-1688.2010.00462.x}, DOI={10.1111/j.1752-1688.2010.00462.x}, abstractNote={Damodaram, Chandana, Marcio H. Giacomoni, C. Prakash Khedun, Hillary Holmes, Andrea Ryan, William Saour, and Emily M. Zechman, 2010. Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management. Journal of the American Water Resources Association (JAWRA) 1‐12. DOI: 10.1111/j.1752‐1688.2010.00462.xAbstract:  Urbanization causes increased stormwater runoff volumes, leading to erosion, flooding, and the degradation of instream ecosystem health. Although Best Management Practices (BMPs) are used widely as a means for controlling flood runoff events, Low Impact Development (LID) options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID practices such as rainwater harvesting, green roofs, and permeable pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices in an existing hydrologic model to estimate the effects of LID choices on streamflow. The modeling approach has been applied to a watershed located on the campus of Texas A&M University in College Station, Texas, to predict the stormwater reductions resulting from retrofitting existing infrastructure with LID technologies. Results demonstrate that use of these LID practices yield significant stormwater control for small events and less control for flood events. A combined BMP‐LID approach is tested for runoff control for both flood and frequent rainfall events.}, number={5}, journal={JAWRA Journal of the American Water Resources Association}, publisher={Wiley}, author={Damodaram, Chandana and Giacomoni, Marcio H. and Prakash Khedun, C. and Holmes, Hillary and Ryan, Andrea and Saour, William and Zechman, Emily M.}, year={2010}, month={Oct}, pages={907–918} }
 @inproceedings{damodaram_giacomoni_zechman_2010, title={Using the Hydrologic Footprint Residence to Evaluate Low Impact Development in Urban Areas}, ISBN={9780784410998}, url={http://dx.doi.org/10.1061/41099(367)148}, DOI={10.1061/41099(367)148}, abstractNote={Urbanization adversely impacts the health of a watershed and the receiving water body, as increased runoff volumes, velocities, and peak flows cause erosion, flooding, and degradation of ecosystem habitats. Low Impact Development (LID) strategies are used to mitigate the impacts of urbanization by reducing the runoff at the source and restoring the natural hydrologic flow regime. Rainwater harvesting, permeable pavements and green roofs may be placed in urban areas to mitigate the runoff generated from rooftops and parking lots. This study simulates and evaluates the placement of these LID strategies for an urban watershed on the Texas A&M University campus. A conventional metric, the peak flow, is used to evaluate the hydrologic performance of LID, in addition to the Hydrologic Footprint Residence (HFR), which is a new metric that captures the inundated areas and duration of floods in downstream reaches. The results indicate that HFR can be used to evaluate the hydrologic performance of LID as it captures both changes in runoff volumes and the duration of flooding to represent the impacts of urbanization.}, booktitle={Low Impact Development 2010}, publisher={American Society of Civil Engineers}, author={Damodaram, Chandana and Giacomoni, Marcio H. and Zechman, Emily M.}, year={2010}, month={Apr} }
 @inproceedings{rasekh_brumbelow_zechman_2010, title={WDS Vulnerability Analysis: Focusing on Random Factors, Consumer Behavior, and System Dynamics in Contamination Events}, ISBN={9780784411148}, url={http://dx.doi.org/10.1061/41114(371)443}, DOI={10.1061/41114(371)443}, abstractNote={A contamination event in a water distribution system (WDS) occurs in a dynamic system where hydraulics, operations, and consumer demands can all change significantly during the course of the event. Past research has typically not included the role of consumer actions and responses during contamination events in changing WDS behavior. This paper will present ongoing work to address this deficiency in WDS emergency response planning. Vulnerability assessment is an initial phase in the overall emergency planning framework. However, standard vulnerability assessment methods do not generally focus on the role of dynamic system changes nor do they focus on the role of false positives. A novel method will be presented that combines traditional assessment techniques with attention to these issues. Moreover, meta- analysis of contamination case studies is used to determine probabilistic functions for important characteristics of contamination events. The goals of the vulnerability assessment are expanded beyond traditional ones to include identification of needed information on consumer behavior, utility operations response, and system dynamics. This work is preparatory to upcoming public surveys, agent-based modeling, and stochastic simulation-optimization analysis.}, booktitle={World Environmental and Water Resources Congress 2010}, publisher={American Society of Civil Engineers}, author={Rasekh, Amin and Brumbelow, Kelly and Zechman, Emily M.}, year={2010}, month={May} }
 @inproceedings{kanta_brumbelow_zechman_2009, title={A Multi-Objective Evolutionary Computation Approach to Hazards Mitigation Design for Water Distribution Systems}, ISBN={9780784410363}, url={http://dx.doi.org/10.1061/41036(342)43}, DOI={10.1061/41036(342)43}, abstractNote={One of the critical public safety roles for water distribution systems (WDS) is suppression of urban fire events. Previous studies have investigated WDS rehabilitation for mitigation of potential fire events with a major focus on improving fire flows by pipe enlargement. However, pipe enlargement can cause water quality problems and place public health at risk during normal operational periods. Thus a novel approach is required to effectively address the conflicting goals of the WDS: reliable delivery of water during normal as well as emergency conditions, meeting water quality standards, and finding cost-effective design and rehabilitation options. In this study an evolutionary computation-based multi-objective optimization-simulation framework is developed to design effective mitigation strategies for urban fire events for water distribution systems with three objectives: (1) minimizing fire damages, (2) minimizing water quality deficiencies, and (3) minimizing the cost of mitigation. An elitist non-dominated sorting genetic algorithm (NSGA-II) is modified by incorporating an evolution strategy (ES) to address difficulties for heuristic algorithms posed by WDS problems. Implementation of this methodology generates Pareto-optimal solution surfaces that express the trade-off relationship between fire damage, water quality, and least cost objectives. Thus, the method provides decision makers with the flexibility to choose a mitigation plan for urban fire events best suited for their circumstances. Each Paretooptimal solution comprises a set of pipes to be enlarged to achieve increased fire flow and the corresponding diameters of these pipes. The algorithm is illustrated with several test functions. The Micropolis virtual city is then used to demonstrate the application of the proposed methodology to a complex WDS.}, booktitle={World Environmental and Water Resources Congress 2009}, publisher={American Society of Civil Engineers}, author={Kanta, Lufthansa and Brumbelow, Kelly and Zechman, Emily}, year={2009}, month={May} }
 @article{mirghani_mahinthakumar_tryby_ranjithan_zechman_2009, title={A parallel evolutionary strategy based simulation–optimization approach for solving groundwater source identification problems}, volume={32}, ISSN={0309-1708}, url={http://dx.doi.org/10.1016/j.advwatres.2009.06.001}, DOI={10.1016/j.advwatres.2009.06.001}, abstractNote={Groundwater characterization involves the resolution of unknown system characteristics from observation data, and is often classified as an inverse problem. Inverse problems are difficult to solve due to natural ill-posedness and computational intractability. Here we adopt the use of a simulation–optimization approach that couples a numerical pollutant-transport simulation model with evolutionary search algorithms for solution of the inverse problem. In this approach, the numerical transport model is solved iteratively during the evolutionary search. This process can be computationally intensive since several hundreds to thousands of forward model evaluations are typically required for solution. Given the potential computational intractability of such a simulation–optimization approach, parallel computation is employed to ease and enable the solution of such problems. In this paper, several variations of a groundwater source identification problem is examined in terms of solution quality and computational performance. The computational experiments were performed on the TeraGrid cluster available at the National Center for Supercomputing Applications. The results demonstrate the performance of the parallel simulation–optimization approach in terms of solution quality and computational performance.}, number={9}, journal={Advances in Water Resources}, publisher={Elsevier BV}, author={Mirghani, Baha Y. and Mahinthakumar, Kumar G. and Tryby, Michael E. and Ranjithan, Ranji S. and Zechman, Emily M.}, year={2009}, month={Sep}, pages={1373–1385} }
 @article{zechman_ranjithan_2009, title={Evolutionary Computation-Based Methods for Characterizing Contaminant Sources in a Water Distribution System}, volume={135}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)0733-9496(2009)135:5(334)}, DOI={10.1061/(asce)0733-9496(2009)135:5(334)}, abstractNote={The area of systematic identification of contamination sources in water distribution systems is in its infancy and is rapidly growing. The real water distribution network problem poses many challenges that current methods usually assume away to facilitate manageable method development and testing. Current methods may not readily and efficiently address issues, such as multiple sources, unknown contamination types with different reaction kinetics, use of different types of sensors with varying degree of resolution, dynamically varying demand and sensor information, and uncertainty and errors in the data and measurements. With the aim of addressing these imminent challenges, this paper reports the findings of an ongoing research investigation that develops and tests an evolutionary algorithm-based flexible and generic procedure, which is structured within a simulation-optimization paradigm. This paper describes the specific implementation of the method using evolution strategies (ESs), a population-based he...}, number={5}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Zechman, Emily M. and Ranjithan, S. Ranji}, year={2009}, month={Sep}, pages={334–343} }
 @inproceedings{giacomoni_zechman_2009, title={Hydrologic Footprint Residence: A New Metric to Assess Hydrological Alterations Due to Urbanization}, ISBN={9780784410363}, url={http://dx.doi.org/10.1061/41036(342)119}, DOI={10.1061/41036(342)119}, abstractNote={Urbanization modifies hydrological processes in a watershed as surface alterations, such as the use of impervious cover, increase runoff volumes and modify the temporal patterns of the hydrograph. Higher peak flows and increased flood duration often lead to erosion and degradation of ecosystems. Typically, the peak flow for a design storm is used to assess the impact of land use change on the hydrological cycle. This approach, however, does not capture the extent of hydrologic change and impact on downstream communities. Floodplains have an important function in controlling downstream floods and sustaining sensitive ecosystems. This research proposes a new metric to quantify the effects of development based on the change in floodplain areas. The Hydrologic Footprint Residence (HFR) is proposed to evaluate the modification of floodplain areas and duration of a flood's residence. HFR can be used to analyze hydrological changes, gauge riparian ecosystem health, and develop watershed management plans. The use of HFR is demonstrated for a case study located on the Texas A&M University campus to evaluate the hydrologic impact of watershed development.}, booktitle={World Environmental and Water Resources Congress 2009}, publisher={American Society of Civil Engineers}, author={Giacomoni, M. H. and Zechman, E. M.}, year={2009}, month={May} }
 @inproceedings{khedun_damodaram_giacomoni_ryan_holmes_klein_saour_hollingsworth_berthold_davis_et al._2009, title={Improving Hydrologic Sustainability of Texas A&M University Campus}, ISBN={9780784410363}, url={http://dx.doi.org/10.1061/41036(342)122}, DOI={10.1061/41036(342)122}, abstractNote={This research investigates the hydrologic sustainability of urban development and stormwater management for a watershed on the Texas A&M campus. The main Texas A&M campus has become increasingly urbanized, resulting in areas of imperviousness that generate higher rates of runoff. This growth has proceeded unchecked, and significant growth and development are planned for the future. Both increased rates of runoff from previous development and the impact of anticipated development should be addressed through mitigation efforts. This research provides a means to assess watershed health through biological indicators, water quality indicators, riparian ecosystems, the floodplain footprint, and the long term flow regime. A modeling framework is implemented to couple hydrologic and hydraulics models to simulate a set of watershed management plans that employ alternative best management practices. Development plans will be evaluated based on a set of comprehensive metrics that synthesize ecological, hydrologic, and environmental aspects of watershed health. The selection of management plans based on these metrics will enhance the environmental sustainability of further campus development.}, booktitle={World Environmental and Water Resources Congress 2009}, publisher={American Society of Civil Engineers}, author={Khedun, Prakash and Damodaram, Chandana and Giacomoni, Marcio and Ryan, Andrea and Holmes, Hillary and Klein, Ross and Saour, William and Hollingsworth, Michelle and Berthold, Troy and Davis, Meg and et al.}, year={2009}, month={May} }
 @article{reichold_zechman_brill_holmes_2010, title={Simulation-Optimization Framework to Support Sustainable Watershed Development by Mimicking the Predevelopment Flow Regime}, volume={136}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000040}, DOI={10.1061/(asce)wr.1943-5452.0000040}, abstractNote={A new approach is presented to achieve a more aggressive sustainability objective for designing transportation infrastructure and land use planning: to design BMPs to continuously mimic the natural flow regime and ensure that ecosystems downstream of development would not be adversely affected. As the land uses are changed for development of urban areas and transportation infrastructure, ecosystems in receiving water bodies are significantly affected by the changes in duration, peak, and minimum flows. Though Best Management Practices (BMPs) are typically designed to not exceed some peak flow during a design storm and perhaps maintain a minimum flow at low-flow periods, downstream conditions are altered, potentially harming ecosystems. A new approach is presented to achieve a more aggressive sustainability objective: to design BMPs to continuously mimic the natural flow regime and ensure that ecosystems downstream of development would not be adversely affected. This objective may not be achievable through the implementation of a single detention pond at a watershed outlet; a system of BMPs strategically placed throughout the watershed may be required. Several BMPs exist as options for treatment, such as detention/retention ponds, constructed wetland systems, infiltration systems (i.e., porous pavement), and vegetative filtrations systems. As each system chosen for implementation must be specified by a set of design decisions and placement location, an efficient mechanism of optimization is needed to handle the large array of decisions. In addition, a comprehensive modeling framework is needed to simulate a collection of BMPs simultaneously. A quantitative analysis framework is described and illustrated for coupling BMP and watershed models with optimization techniques.}, number={3}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Reichold, Laurel and Zechman, Emily M. and Brill, E. Downey and Holmes, Hillary}, year={2010}, month={May}, pages={366–375} }
 @article{nicklow_reed_savic_dessalegne_harrell_chan-hilton_karamouz_minsker_ostfeld_singh_et al._2010, title={State of the Art for Genetic Algorithms and Beyond in Water Resources Planning and Management}, volume={136}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000053}, DOI={10.1061/(asce)wr.1943-5452.0000053}, abstractNote={During the last two decades, the water resources planning and management profession has seen a dramatic increase in the development and application of various types of evolutionary algorithms (EAs). This observation is especially true for application of genetic algorithms, arguably the most popular of the several types of EAs. Generally speaking, EAs repeatedly prove to be flexible and powerful tools in solving an array of complex water resources problems. This paper provides a comprehensive review of state-of-the-art methods and their applications in the field of water resources planning and management. A primary goal in this ASCE Task Committee effort is to identify in an organized fashion some of the seminal contributions of EAs in the areas of water distribution systems, urban drainage and sewer systems, water supply and wastewater treatment, hydrologic and fluvial modeling, groundwater systems, and parameter identification. The paper also identifies major challenges and opportunities for the future, ...}, number={4}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Nicklow, John and Reed, Patrick and Savic, Dragan and Dessalegne, Tibebe and Harrell, Laura and Chan-Hilton, Amy and Karamouz, Mohammad and Minsker, Barbara and Ostfeld, Avi and Singh, Abhishek and et al.}, year={2010}, month={Jul}, pages={412–432} }
 @article{jin_mahinthakumar_zechman_ranjithan_2009, title={A genetic algorithm-based procedure for 3D source identification at the Borden emplacement site}, volume={11}, ISSN={1464-7141 1465-1734}, url={http://dx.doi.org/10.2166/hydro.2009.002}, DOI={10.2166/hydro.2009.002}, abstractNote={Finding the location and concentration of groundwater contaminant sources typically requires the solution of an inverse problem. A parallel hybrid optimization framework that uses genetic algorithms (GA) coupled with local search approaches (GA-LS) has been developed previously to solve groundwater inverse problems. In this study, the identification of an emplaced source at the Borden site is carried out as a test problem using this optimization framework by using a Real Genetic Algorithm (RGA) as the GA approach and a Nelder–Mead simplex as the LS approach. The RGA results showed that the minimum objective function did not always correspond to the minimum solution error, indicating a possible non-uniqueness issue. To address this problem, a procedure to identify maximally different starting points for LS is introduced. When measurement or model errors are non-existent or minimal it is shown that one of these starting points leads to the true solution. When these errors are significant, this procedure leads to multiple possible solutions that could be used as a basis for further investigation. Metrics of mean and standard deviation of objective function values was adopted to evaluate the possible solutions. A new selection criterion based on these metrics is suggested to find the best alternative. This suggests that this alternative generation procedure could be used to address the non-uniqueness of similar inverse problems. A potential limitation of this approach is the application to a wide class of problems, as verification has not been performed with a large number of test cases or other inverse problems. This remains a topic for future work.}, number={1}, journal={Journal of Hydroinformatics}, publisher={IWA Publishing}, author={Jin, Xin and Mahinthakumar, G. (Kumar) and Zechman, Emily M. and Ranjithan, Ranji S.}, year={2009}, month={Jan}, pages={51–64} }
 @inproceedings{liu_zechman_brill, jr._mahinthakumar_ranjithan_uber_2008, title={Adaptive Contamination Source Identification in Water Distribution Systems Using an Evolutionary Algorithm-based Dynamic Optimization Procedure}, ISBN={9780784409411}, url={http://dx.doi.org/10.1061/40941(247)123}, DOI={10.1061/40941(247)123}, abstractNote={Accidental drinking water contamination has long been and remains a major threat to water security throughout the world. Consequently, contamination source identification is an important and difficult problem in the managing safety in water distribution systems. This problem involves the characterization of the contaminant source based on observations that are streaming from a set of sensors in the distribution network. Since contamination spread in a water distribution network is relatively quick and unpredictable, rapid identification of the source location and related characteristics is important to take contaminant control and containment actions. As the contaminant event unfolds, the streaming data could be processed over time to adaptively estimate the source characteristics. This provides an estimate of the source characteristics at any time after a contamination event is detected, and this estimate is continually updated as new observations become available. We pose and solve this problem using a dynamic optimization procedure that could potentially provide a real-time response. As time progresses, additional data is observed at a set of sensors, changing the vector of observations that should be predicted. Thus, the prediction error function is updated dynamically, changing the objective function in the optimization model. We investigate a new multi population-based search using an evolutionary algorithm (EA) that at any time represents the solution state that best matches the available observations. The set of populations migrates to represent updated solution states as new observations are added over time. At the initial detection period, non-uniqueness is inherent in the source-identification due to inadequate information, and, consequently, several solutions may predict similarly well. To address nonuniqueness at the initial stages of the search and prevent premature convergence of the EA to an incorrect solution, the multiple populations in the proposed methodology are designed to maintain a set of alternative solutions representing different non-unique solutions. As more observations are added, the EA solutions not only migrate to better solution states, but also reduce the number of solutions as the degree of non-uniqueness diminishes. This new dynamic optimization algorithm adaptively converges to the best solution(s) to match the observations available at any time. The new method will be demonstrated for a contamination source identification problem in an illustrative water distribution network.}, booktitle={Water Distribution Systems Analysis Symposium 2006}, publisher={American Society of Civil Engineers}, author={Liu, Li and Zechman, Emily M. and Brill, Jr., E. Downey and Mahinthakumar, G. and Ranjithan, S. and Uber, James}, year={2008}, month={Mar} }
 @inproceedings{zechman_brill, jr._mahinthakumar_ranjithan_uber_2008, title={Addressing Non-uniqueness in a Water Distribution Contaminant Source Identification Problem}, ISBN={9780784409411}, url={http://dx.doi.org/10.1061/40941(247)126}, DOI={10.1061/40941(247)126}, abstractNote={The source of contamination in a water distribution system may be identified through a simulation-optimization approach. The optimization method searches for the contaminant source characteristics by iteratively estimating the contaminant plume concentrations until they match observations at sensors. The amount of information available for characterizing the source depends on the number and spatial locations of the sensors, as well as on the temporally varying stream of sensed data. The accuracy of the source characterization depends on the amount of observations available. A major factor affecting this accuracy is the degree of non-uniqueness present in the problem, which may cause misidentification of the source characteristics. As more sensors are added to the network, the non-uniqueness may be reduced and a unique solution may be identified. Thus, a key consideration when solving these problems is to assess whether the solution identified is unique, and if not, what other possible solutions are present. A systematic search for a set of alternatives that are maximally different in solution characteristics can be used to address and quantify non-uniqueness. For example, if the most different set of solutions that are identified by a search procedure are very similar, then that solution will be considered as the unique solution with a higher degree of certainty. Alternatively, identification of a set of maximally different solutions that vary widely in solution characteristics will indicate that nonuniqueness is present in the problem, and the range of solutions can be used as a general representation of the amount of non-uniqueness. This paper investigates the use of evolutionary algorithm (EA)-based alternatives generation procedures to quantify and address non-uniqueness present in a contaminant source identification problem for a water distribution network. As additional sensors may decrease the amount of non-uniqueness, several sensor configurations will be tested to investigate and quantify the improvement in uniqueness as more information is used in the source characterization.}, booktitle={Water Distribution Systems Analysis Symposium 2006}, publisher={American Society of Civil Engineers}, author={Zechman, Emily M. and Brill, Jr., E. Downey and Mahinthakumar, G. and Ranjithan, S. and Uber, James}, year={2008}, month={Mar} }
 @inproceedings{zechman_2008, title={An Agent-Based Simulation-Optimization Approach to Identify Threat Management Strategies for Water Distribution Systems}, ISBN={9780784409763}, url={http://dx.doi.org/10.1061/40976(316)506}, DOI={10.1061/40976(316)506}, abstractNote={Threat management decisions in the event of contamination of a water distribution system must be tailored to protect public health, maintain fire-fighting flows and flows to critical care facilities, and avoid inciting panic due to false alarms. Threat management strategies may be composed as a set of rules for taking actions to mitigate the situation and protect public health, such as flushing the water distribution system by opening fire hydrants or inducing demands, isolating portions of the system using control valves, and broadcasting boil water orders. These strategies must be robust to control contamination events that vary in time of injection, duration, and mass flow profiles, as well as to avoid false alarms. The development of threat management strategies can be improved through the use of a simulation-optimization framework that simulates the complex interactions between managers' operation decisions, consumers' water consumption choices and the response of the hydraulics and contaminant transport in the water distribution system through mechanistic and dynamic methods enabled by agent-based models. Heuristic optimization methods are coupled within the dynamic system simulation framework to allow identification of efficient threat management strategies to achieve public health protection and maintain acceptable service. These methods will be explored for an illustrative case study to identify strategies to achieve these objectives.}, booktitle={World Environmental and Water Resources Congress 2008}, publisher={American Society of Civil Engineers}, author={Zechman, Emily M.}, year={2008}, month={May} }
 @inproceedings{zechman_2007, title={Agent-Based Modeling to Simulate Contamination Events and to Analyze Threat Management Strategies in Water Distribution Systems}, ISBN={9780784409275}, url={http://dx.doi.org/10.1061/40927(243)525}, DOI={10.1061/40927(243)525}, abstractNote={In the event of contamination of a water distribution system, decisions must be made to mitigate the impact of the contamination to protect public health. Making threat management decisions while the contaminant is spreading through the network is a difficult process due to uncertainty and lack of monitoring data. This is further complicated by the response actions taken by the utility managers and water consumption choices made by the consumers as they all will affect the hydraulics, thus the spread of the contaminant plume, in the network. A modeling framework that allows the simulation of a contamination event under the effects of actions taken by utility managers and consumers will be a useful tool for the analysis of alternative threat mitigation and management strategies. The complex interactions between the managers' network operation decisions and consumers' water consumption choices, and the response of the hydraulics and contaminant transport in the water distribution system will be simulated using an agent-based modeling approach. Agent-based models are simulated individuals that are formulated as interacting autonomous entities. Each agent selects actions based on a set of rules that represent an individual's autonomy, goal-based desires, and reaction to the environment and the actions of other agents. This paper presents a multi-agent modeling framework that will combine agent-based, mechanistic, and dynamic methods. As actions taken by agents affect demands and flows in the system, dynamic approaches will update the mechanistic model and the identification of the contaminant source to supply the "utility manager" agents with the latest information as it becomes available. The framework will be designed to consider the typical issues involved in water distribution threat management and will provide valuable analysis of threat containment strategies for water distribution system contamination events.}, booktitle={World Environmental and Water Resources Congress 2007}, publisher={American Society of Civil Engineers}, author={Zechman, Emily M.}, year={2007}, month={May} }
 @inproceedings{liu_brill, jr._mahinthakumar_uber_zechman_ranjithan_2007, title={Considering Demand Variability and Measurement Uncertainties in Adaptive Source Characterization in Water Distribution Networks}, ISBN={9780784409275}, url={http://dx.doi.org/10.1061/40927(243)502}, DOI={10.1061/40927(243)502}, abstractNote={Characterizing the sources of contamination in water distribution networks continues to be a challenging problem. Several methods have been reported to address this problem. The authors previously presented and continue to investigate an adaptive search procedure that attempts to solve this problem under dynamic conditions. Since demand variability and measurement errors contribute significantly to the quality of the solutions obtained as well as the time to solve the problem, we investigate these effects on the adaptive dynamic optimization procedure. First, the effects of these variabilities and uncertainties on the solutions obtained under deterministic conditions are evaluated. Second, we incorporate them such that the search for the source characterization is conducted under noisy conditions. This paper reports the results from these investigations based on an investigation conducted for an illustrative water distribution network.}, booktitle={World Environmental and Water Resources Congress 2007}, publisher={American Society of Civil Engineers}, author={Liu, Li and Brill, Jr., E. Downey and Mahinthakumar, G. and Uber, James and Zechman, Emily M. and Ranjithan, S.}, year={2007}, month={May} }
 @inbook{sreepathi_mahinthakumar_zechman_ranjithan_brill_ma_von laszewski_2007, place={Berlin Heidelberg}, series={Lecture Notes in Computer Science}, title={Cyberinfrastructure for Contamination Source Characterization in Water Distribution Systems}, ISBN={9783540725831 9783540725848}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-540-72584-8_139}, DOI={10.1007/978-3-540-72584-8_139}, abstractNote={This paper describes a preliminary cyberinfrastructure for contaminant characterization in water distribution systems and its deployment on the grid. The cyberinfrastructure consists of the application, middleware and hardware resources. The application core consists of various optimization modules and a simulation module. This paper focuses on the development of specific middleware components of the cyberinfrastructure that enables efficient seamless execution of the application core in a grid environment. The components developed in this research include: (i) a coarse-grained parallel wrapper for the simulation module that includes additional features for persistent execution, (ii) a seamless job submission interface, and (iii) a graphical real time application monitoring tool. The performance of the cyberinfrastructure is evaluated on a local cluster and the TeraGrid.}, booktitle={Computational Science – ICCS 2007}, publisher={Springer}, author={Sreepathi, Sarat and Mahinthakumar, Kumar and Zechman, Emily and Ranjithan, Ranji and Brill, Downey and Ma, Xiaosong and von Laszewski, Gregor}, editor={Shi, Y. and van Albada, G.D. and Dongarra, J. and Sloot, P.M.A.Editors}, year={2007}, pages={1058–1065}, collection={Lecture Notes in Computer Science} }
 @inproceedings{kumar_zechman_brill_mahinthakumar_ranjithan_uber_2007, title={Evaluation of Non-Uniqueness in Contaminant Source Characterization Based on Sensors with Event Detection Methods}, ISBN={9780784409275}, url={http://dx.doi.org/10.1061/40927(243)513}, DOI={10.1061/40927(243)513}, abstractNote={Due to the present state of sensor technology, during a water distribution contamination event, sensors may be able to detect only the presence of a contaminant and not necessarily the complete concentration profile. Some sensors trigger a detection based on a specified threshold concentration of observation, yielding a binary detection/no-detection signal. Event detection can also be based on observed concentrations of water quality parameters, such as pH and chlorine, which are routinely measured. These concentration observations are then processed through event detection algorithms to yield a detection/no-detection signal. These event detection techniques filter the measured concentrations at sensors to produce a discrete signal. When using this filtered information to characterize the contamination source, the certainty of identifying a unique solution is likely reduced, i.e., a set of widely different source characteristics may provide a match for the sensor observations. The authors previously presented an evolutionary algorithm-based procedure for source characterization and for assessing nonuniqueness by generating a set of maximally different alternatives. The procedure is extended here to characterize a contaminant source and any non-uniqueness arising by using sensor information processed through different event detection methods.}, booktitle={World Environmental and Water Resources Congress 2007}, publisher={American Society of Civil Engineers}, author={Kumar, Jitendra and Zechman, E. M. and Brill, E. D. and Mahinthakumar, G. and Ranjithan, S. and Uber, J.}, year={2007}, month={May} }
 @article{zechman_ranji ranjithan_2007, title={Evolutionary computation-based approach for model error correction and calibration}, volume={30}, ISSN={0309-1708}, url={http://dx.doi.org/10.1016/j.advwatres.2006.11.013}, DOI={10.1016/j.advwatres.2006.11.013}, abstractNote={Calibration is typically used for improving the predictability of mechanistic simulation models by adjusting a set of model parameters and fitting model predictions to observations. Calibration does not, however, account for or correct potential misspecifications in the model structure, limiting the accuracy of modeled predictions. This paper presents a new approach that addresses both parameter error and model structural error to improve the predictive capabilities of a model. The new approach simultaneously conducts a numeric search for model parameter estimation and a symbolic (regression) search to determine a function to correct misspecifications in model equations. It is based on an evolutionary computation approach that integrates genetic algorithm and genetic programming operators. While this new approach is designed generically and can be applied to a broad array of mechanistic models, it is demonstrated for an illustrative case study involving water quality modeling and prediction. Results based on extensive testing and evaluation, show that the new procedure performs consistently well in fitting a set of training data as well as predicting a set of validation data, and outperforms a calibration procedure and an empirical model fitting procedure.}, number={5}, journal={Advances in Water Resources}, publisher={Elsevier BV}, author={Zechman, Emily M. and Ranji Ranjithan, S.}, year={2007}, month={May}, pages={1360–1370} }
 @article{zechman_ranjithan_2007, title={Generating Alternatives Using Evolutionary Algorithms for Water Resources and Environmental Management Problems}, volume={133}, ISSN={0733-9496 1943-5452}, url={http://dx.doi.org/10.1061/(asce)0733-9496(2007)133:2(156)}, DOI={10.1061/(asce)0733-9496(2007)133:2(156)}, abstractNote={Contemporary heuristic search procedures [e.g., evolutionary algorithms (EAs)] continue to offer increased capabilities for systematic search for a range of water resources and environmental management problems. These problems are often riddled, however, with numerous unquantifiable issues that are important when making decisions, but escape being incorporated in the system model. The mathematically optimal solution to such an incompletely defined model may be found unrealistic or altogether incorrect for the real problem. Optimization procedures could still be made useful if they can be utilized effectively to generate, in addition to the optimal solution, a small number of different alternatives that are near optimal. Alternatives with maximal differences in the decision variable values are expected to perform differently with respect to the unmodeled issues, providing valuable choices when making decisions. Although successful alternative generation procedures have been reported for mathematical progra...}, number={2}, journal={Journal of Water Resources Planning and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Zechman, Emily M. and Ranjithan, Ranji S.}, year={2007}, month={Mar}, pages={156–165} }
 @article{raghavachar_mahinthakumar_worley_zechman_ranjithan_2007, title={Parallel Performance Modeling using a Genetic Programming-based Error Correction Procedure}, volume={83}, ISSN={0037-5497 1741-3133}, url={http://dx.doi.org/10.1177/0037549707084691}, DOI={10.1177/0037549707084691}, abstractNote={ Performance models of high performance computing (HPC) applications are important for several reasons. First, they provide insight to designers of HPC systems on the role of subsystems such as the processor or the network in determining application performance. Second, they allow HPC centers more accurately to target procurements to resource requirements. Third, they can be used to identify application performance bottlenecks and to provide insights about scalability issues. The suitability of a performance model, however, for a particular performance investigation is a function of both the accuracy and the cost of the model.  A semi-empirical model previously published by the authors for an astrophysics application was shown to be inaccurate when predicting communication cost for large numbers of processors. It is hypothesized that this deficiency is due to the inability of the model adequately to capture communication contention (threshold effects) as well as other unmodeled components such as noise and I/O contention. In this paper we present a new approach to capture these unknown features to improve the predictive capabilities of the model. This approach uses a systematic model error-correction procedure that uses evolutionary algorithms to find an error correction term to augment the eXisting model. Four variations of this procedure were investigated and all were shown to produce better results than the original model. Successful cross-platform application of this approach showed that it adequately captures machine dependent characteristics. This approach was then successfully demonstrated for a second application, further showing its versatility. }, number={7}, journal={SIMULATION}, publisher={SAGE Publications}, author={Raghavachar, Kavitha and Mahinthakumar, G. and Worley, Patrick and Zechman, Emily and Ranjithan, Ranji}, year={2007}, month={Jul}, pages={515–527} }
 @inbook{mahinthakumar_von laszewski_ranjithan_brill_uber_harrison_sreepathi_zechman_2006, place={Berlin Heidelberg}, series={Lecture Notes in Computer Science}, title={An Adaptive Cyberinfrastructure for Threat Management in Urban Water Distribution Systems}, volume={3993}, ISBN={9783540343837 9783540343844}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/11758532_54}, DOI={10.1007/11758532_54}, abstractNote={Threat management in drinking water distribution systems involves real-time characterization of any contaminant source and plume, design of control strategies, and design of incremental data sampling schedules. This requires dynamic integration of time-varying measurements along with analytical modules that include simulation models, adaptive sampling procedures, and optimization methods. These modules are compute-intensive, requiring multi-level parallel processing via computer clusters. Since real-time responses are critical, the computational needs must also be adaptively matched with available resources. This requires a software system to facilitate this integration via a high-performance computing architecture such that the measurement system, the analytical modules and the computing resources can mutually adapt and steer each other. This paper describes the development of such an adaptive cyberinfrastructure system facilitated by a dynamic workflow design.}, booktitle={Computational Science – ICCS 2006}, publisher={Springer}, author={Mahinthakumar, Kumar and von Laszewski, Gregor and Ranjithan, Ranji and Brill, Downey and Uber, Jim and Harrison, Ken and Sreepathi, Sarat and Zechman, Emily}, editor={Alexandrov, V.N. and Albada, G.D. and Sloot, P.M.A. and Dongarra, J.Editors}, year={2006}, pages={401–408}, collection={Lecture Notes in Computer Science} }
 @inproceedings{zechman_mirghani_clayton_mahinthakumar_ranji ranjithan_2006, title={Use of Surrogate Models for a Groundwater Pollutant Source Characterization Problem}, ISBN={9780784408568}, url={http://dx.doi.org/10.1061/40856(200)117}, DOI={10.1061/40856(200)117}, abstractNote={This paper investigates a groundwater source identification problem in which concentrations at observation wells are used to reconstruct the pollution loading scenario. This inverse problem is solved using a simulation-optimization approach using evolutionary algorithms to conduct the search. Varying levels of complexity may be modeled, leading to different levels of accuracy in predictions of source location, size, and concentration. More complex models will increase the computational effort needed to model pollutant transport as part of a search procedure. In addition, the amount of non-uniqueness will typically increase as the complexity of the problem increases. This paper describes an investigation of surrogate modeling procedures and methods to generate very different solutions to characterize groundwater pollutant source under varying degrees of problem complexity.}, booktitle={World Environmental and Water Resource Congress 2006}, publisher={American Society of Civil Engineers}, author={Zechman, Emily M. and Mirghani, Baha and Clayton, Matthew and Mahinthakumar, G. and Ranji Ranjithan, S.}, year={2006}, month={May} }
 @inproceedings{zechman_mirghani_mahinthakumar_ranjithan_2005, title={A Genetic Programming-Based Surrogate Model Development and Its Application to a Groundwater Source Identification Problem}, ISBN={9780784407929}, url={http://dx.doi.org/10.1061/40792(173)341}, DOI={10.1061/40792(173)341}, abstractNote={This paper investigates a groundwater source identification problem in which chemical signals at observation wells are used to reconstruct the pollution loading scenario. This inverse problem is solved using a simulation-optimization approach that uses a genetic algorithm to conduct the search. As the numerical pollution-transport model is solved iteratively during the heuristic search, the evolutionary search can be in general computationally intensive. This is addressed by constructing a surrogate modeling approach that is able to predict quickly the concentration profiles at the observation wells. A genetic program is used in the development of the surrogate models that provides an acceptable prediction performance. The surrogate model, which replaces the numerical simulation model, is then coupled with the evolutionary search procedure to solve the inverse problem. The results will illustrate 1) the performance of the surrogate model in predicting the concentration compared with the predictions using the original numerical model, and 2) the quality of the solution to the inverse problem obtained using the surrogate model to that obtained using the numerical model.}, booktitle={Impacts of Global Climate Change}, publisher={American Society of Civil Engineers}, author={Zechman, Emily and Mirghani, Baha and Mahinthakumar, G. and Ranjithan, S. Ranji}, year={2005}, month={Jul} }
 @inproceedings{zechman_mahinthakumar_ranjithan_2005, title={Investigation and Demonstration of an Evolutionary Computation-Based Model Correction Procedure for a Numerical Simulation Model}, ISBN={9780784407929}, url={http://dx.doi.org/10.1061/40792(173)346}, DOI={10.1061/40792(173)346}, abstractNote={Traditional model calibration attempts to correct a model so that the model output will match a set of system observations by tweaking a set of model parameters. Potential model structural error limits, however, the effectiveness and accuracy of calibration, undermining the predictive capabilities of the calibrated model. An evolutionary computation-based model error correction procedure that couples an evolutionary algorithm and a genetic program was previously developed and tested for two analytical models. Due to nonuniqueness in the solution space, numerous forms of correction terms that similarly fit the observation data were found. This procedure is further investigated to explore and identify alternative correction terms that not only provide a good fit but also results in good prediction performance. This approach is then demonstrated using a numerical groundwater contaminant transport simulation model.}, booktitle={Impacts of Global Climate Change}, publisher={American Society of Civil Engineers}, author={Zechman, Emily and Mahinthakumar, G. and Ranjithan, S. Ranji}, year={2005}, month={Jul} }
 @inproceedings{zechman_ranjithan_2005, place={New York}, title={Multipopulation cooperative coevolutionary programming (MCCP) to enhance design innovation}, ISBN={1595930108}, url={http://dx.doi.org/10.1145/1068009.1068286}, DOI={10.1145/1068009.1068286}, abstractNote={This paper describes the development of an evolutionary algorithm called Multipopulation Cooperative Coevolutionary Programming (MCCP) that extends Genetic Programming (GP) to search for a set of maximally different solutions for program induction problems. The GP search is structured to generate a set of alternatives that are similar in design performance, but are dissimilar from each other in the solution (or design parameter) space. This is expected to yield potentially more creative designs, thus enhancing design innovation. Application of MCCP is demonstrated through an illustrative example involving GP-based classification of genetic data to diagnose malignancy in cancer. Four different classifiers, based on highly dissimilar combinations of genes, but with similar prediction performances were generated. As these classifiers use a diverse set of genes, they are collectively more effective in screening cancer samples that may not all properly express every gene.}, booktitle={Genetic and Evolutionary Computation Conference : GECCO 2005, June 25-29, 2005 (Saturday-Wednesday) Washington, D.C., USA}, publisher={ACM Press}, author={Zechman, Emily M. and Ranjithan, S. Ranji}, editor={Beyer, H-GEditor}, year={2005} }
 @article{zechman_ranjithan_2004, title={An evolutionary algorithm to generate alternatives (EAGA) for engineering optimization problems}, volume={36}, ISSN={0305-215X 1029-0273}, url={http://dx.doi.org/10.1080/03052150410001704863}, DOI={10.1080/03052150410001704863}, abstractNote={Typically for a real optimization problem, the optimal solution to a mathematical model of that real problem may not always be the ‘best’ solution when considering unmodeled or unquantified objectives during decision-making. Formal approaches to explore efficiently for good but maximally different alternative solutions have been established in the operations research literature, and have been shown to be valuable in identifying solutions that perform expectedly well with respect to modeled and unmodeled objectives. While the use of evolutionary algorithms (EAs) to solve real engineering optimization problems is becoming increasingly common, systematic alternatives-generation capabilities are not fully extended for EAs. This paper presents a new EA-based approach to generate alternatives (EAGA), and illustrates its applicability via two test problems. A realistic airline route network design problem was also solved and analyzed successfully using EAGA. The EAGA promises to be a flexible procedure for exploring alternative solutions that could assist when making decisions for real engineering optimization problems riddled with unmodeled or unquantified issues.}, number={5}, journal={Engineering Optimization}, publisher={Informa UK Limited}, author={Zechman, Emily M. and Ranjithan, S. Ranji}, year={2004}, month={Oct}, pages={539–553} }
 @article{ormsbee_elshorbagy_zechman_2004, title={Methodology for pH Total Maximum Daily Loads: Application to Beech Creek Watershed}, volume={130}, ISSN={0733-9372 1943-7870}, url={http://dx.doi.org/10.1061/(asce)0733-9372(2004)130:2(167)}, DOI={10.1061/(asce)0733-9372(2004)130:2(167)}, abstractNote={This paper presents a methodology for developing total maximum daily loads ~TMDLs! for pH impaired streams that characterizes the pH impact in terms of an associated hydrogen ion load. Because pH and an equivalent ion load can be related as a function of discharge and ionic strength, a functional relationship can be developed between discharge and the associated ion loading for a given pH value. By specifying a minimum pH value ~e.g., 6.0! and an associated ion activity correction factor, an envelope of ion loads may be obtained as a function of discharge. By identifying a critical discharge for a given watershed, the hydrogen ion load and associated TMDL can be obtained. Determination of the associated ion load reduction can further be accomplished by developing functional relationships between measured discharges and measured ion loads for a given watershed. Finally, the required mass loading of an associated neutralizing agent ~e.g., CaCO3) can be determined by constructing a functional relationship between the neutralizing agent and the required hydrogen ion reduction. The proposed approach has been applied to several watersheds in the state of Kentucky and was recently approved by EPA Region IV as an acceptable protocol for pH TMDLs. An application of the methodology is presented for the Beech Creek watershed, which is located in Muhlenberg County, Kentucky.}, number={2}, journal={Journal of Environmental Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Ormsbee, Lindell and Elshorbagy, Amin and Zechman, Emily}, year={2004}, month={Feb}, pages={167–174} }