@article{youssef_liu_chescheir_skaggs_negm_2021, title={DRAINMOD modeling framework for simulating controlled drainage effect on lateral seepage from artificially drained fields}, volume={254}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2021.106944}, abstractNote={We demonstrated a DRAINMOD modeling framework to predict controlled drainage (CD) effect on the fate of water in artificially drained agricultural fields, which is key for determining the water quality benefits of the practice. To demonstrate this modeling framework, DRAINMOD simulated the hydrology of a subsurface drained grass field in Eastern North Carolina, U.S. under both free drainage (FD) and CD. Three scenarios were simulated for each water management: no lateral seepage (LS) and LS with constant and dynamic hydraulic head (Hr). For each scenario, predicted water table depth (WTD) and subsurface drainage were compared to observed values using Mean Absolute Error, Nash-Sutcliffe Efficiency, and Normalized Percent Error. Predicted water balance components for different scenarios were also investigated. Results clearly showed that LS was a significant component of the water balance for CD. Model predictions showed that 96% of the reduction in subsurface drainage due to CD could be attributed to LS (33.5 cm yr−1). The large values of LS predicted by the model were attributed to the presence of a permeable sandy layer in the soil profile, the shallow management depth of the drain outlet, and the small size of the experimental field plots. Agreement between predicted and observed WTD and subsurface drainage ranged from acceptable to excellent for FD with and without considering LS. In contrast, DRAINMOD simulations for CD yielded acceptable predictions only for the scenario considering LS with dynamic Hr. This study demonstrated the power of process-based simulation models, such as DRAINMOD, for interpreting and explaining data of experimental studies and underscored the importance of using a proper model calibration strategy for yielding reliable predictions. This study highlights the need for well-coordinated experimental and modeling research to further investigate how seepage affect CD performance for reducing drainage flow and nitrogen losses from artificially drained agricultural fields.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Youssef, Mohamed A. and Liu, Yu and Chescheir, George M. and Skaggs, R. Wayne and Negm, Lamyaa M.}, year={2021}, month={Aug} }
 @article{askar_youssef_chescheir_negm_king_hesterberg_amoozegar_skaggs_2020, title={DRAINMOD Simulation of macropore flow at subsurface drained agricultural fields: Model modification and field testing}, volume={242}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2020.106401}, abstractNote={Macropores are critical pathways through which water and pollutants can bypass the soil matrix and be rapidly transported to subsurface drains and freshwater bodies. We modified the DRAINMOD model to simulate macropore flow using a simple approach as part of developing the DRAINMOD-P model to simulate phosphorus dynamics in artificially drained agricultural lands. The Hagen-Poiseuille's law was used to estimate the flow capacity of macropores. When ponding depths on the soil surface are greater than Kirkham's depth, water is assumed to flow through macropores directly to tile drains without interaction with the soil matrix. In the modified model, macropore size is adjusted based on wet or dry conditions while connectivity is altered by tillage. The model was tested using a 4-year data set from a subsurface drained field in northwest Ohio. The soils at the field are classified as very poorly drained and are prone to desiccation cracking. The modified model predicted the daily and monthly subsurface drainage with average Nash-Sutcliffe efficiency (NSE) values of 0.48 and 0.59, respectively. The cumulative drainage over the 4-year simulation period was under-predicted by 8%. The new macropore component was able to capture about 75% of 60 peak drainage flow events. However, surface runoff was over-predicted for the entire study period. Annual water budgets using measured data (precipitation, subsurface drainage, and surface runoff) and model predictions (evapotranspiration, vertical seepage, and change in storage) were not balanced with an average annual imbalance of 6.4 cm. The lack of closure in the water balance suggests that errors may have occurred in field measurements, particularly, surface runoff. Overall, incorporating macropore flow into DRAINMOD improved predictions of daily drainage peaks and enabled the model to predict subsurface drainage flux contributed by macropore flow, which is critical for expanding DRAINMOD to simulate phosphorus transport in subsurface drained agricultural land.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Askar, Manal H. and Youssef, Mohamed A. and Chescheir, George M. and Negm, Lamyaa M. and King, Kevin W. and Hesterberg, Dean L. and Amoozegar, Aziz and Skaggs, R. Wayne}, year={2020}, month={Dec} }
 @article{lisenbee_hathaway_negm_youssef_winston_2020, title={Enhanced bioretention cell modeling with DRAINMOD-Urban: Moving from water balances to hydrograph production}, volume={582}, ISSN={["1879-2707"]}, DOI={10.1016/j.jhydrol.2019.124491}, abstractNote={Bioretention systems have become a leading stormwater control measure for mitigating urban hydrology. Although these systems have performed well in many site-scale field studies, less investigation has been directed toward effectively modeling these systems. This is critical, as modeling of bioretention systems provides an avenue for evaluating their effectiveness prior to devoting time and resources into installation. Many hydrologic models capable of simulating bioretention consist of lumped parameters and simplifications that do not fully account for fundamental hydrologic processes such as soil-water interactions. DRAINMOD has shown promise for obtaining detailed daily water balances within bioretention systems under continuous simulations. One significant advantage of DRAINMOD is that it uses the soil-water characteristic curve to account for fluctuations in soil moisture instead of assuming saturation; however, the model historically only produces daily outputs. For this study, DRAINMOD was modified to develop DRAINMOD-Urban, which allows high temporal resolution inputs and outputs, more closely matching the residence time of runoff in urban systems. DRAINMOD-Urban simulations of a bioretention cell in Ohio, USA, revealed that DRAINMOD-Urban could effectively produce hydrographs with a cumulative Nash-Sutcliffe Efficiency (NSE) of 0.60 for the 12 events that produced drainage over a 7-month monitoring period. Overflow was also modeled by DRAINMOD-Urban, but additional overflow data are necessary to derive conclusions about model effectiveness in predicting this hydrologic component. Input parameters previously calibrated for the DRAINMOD model did not translate well to DRAINMOD-Urban with the top-down approach applied in this study (NSE = 0.31 for drainage and NSE = −1.83 for overflow), but the bottom-up approach showed that parameters calibrated with DRAINMOD-Urban (NSE = 0.60 for drainage and NSE = −0.1 for overflow) could be used in DRAINMOD to obtain reasonable drainage volumes (25.6% error compared to measured values). This study suggests DRAINMOD-Urban is an effective tool for modeling bioretention hydrographs and demonstrates the importance of temporal scale in bioretention modeling by illustrating multiple model calibration approaches. Despite the promising results of this study, additional studies are recommended where validation of the model is performed at more sites, in particular for events with overflow. Further, sensitivity analysis of input parameters and comparison of DRAINMOD-Urban to other commonly used bioretention models would inform future modeling efforts.}, journal={JOURNAL OF HYDROLOGY}, author={Lisenbee, W. and Hathaway, Jon and Negm, L. and Youssef, M. and Winston, R.}, year={2020}, month={Mar} }
 @article{negm_youssef_jaynes_2020, title={Evaluation of DRAINMOD-DSSAT simulated effects of controlled drainage on crop yield, water balance, and water quality for a corn-soybean cropping system in central Iowa (vol 187, pg 57, 2017)}, volume={229}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2019.105810}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Negm, Lamyaa M. and Youssef, Mohamed A. and Jaynes, Dan B.}, year={2020}, month={Feb} }
 @article{singh_bhattarai_negm_youssef_pittelkow_2020, title={Evaluation of nitrogen loss reduction strategies using DRAINMOD-DSSAT in east-central Illinois}, volume={240}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2020.106322}, abstractNote={Agricultural system modeling has become an effective tool for analyzing and quantifying the effects of varying management practices and environmental conditions on crop production and nutrient export from croplands. The use of such modeling tools provides useful insights in identifying the most effective management practices for enhancing productivity, sustainability, and resiliency of agricultural systems. This study focuses on testing and application of an integrated field-scale process-based model, DRAINMOD-DSSAT, for simulating hydrology, nitrate-nitrogen (NO3-N) loss, and crop growth and yield responses in artificially drained croplands. The tested model was used to evaluate the effects of different N fertilizer application rates and timings in both conventional and controlled drainage conditions on crop yield and NO3-N losses in a poorly drained Drummer-Flanagan soil in east-central Illinois. The model was calibrated and validated for a corn [Zea Mays L.] – soybean [Glycine Max (L.)] rotation using 7 years (1992–1998) of field-measured tile drainage, crop yield, and NO3-N data. The graphical and statistical evaluations indicated very good model performance. Specifically, monthly tile drainage flow was predicted with modeling efficiency (NSE), index of agreement (d), and mean absolute error (MAE) of 0.85, 0.96, and 0.69 cm, respectively. Monthly NO3-N losses were predicted with NSE, d, and MAE of 0.82, 0.95, and 1.16 kg N ha−1, respectively. Corn and soybean yields were predicted with an absolute percent error (PE) of 1.84 and 12.07, respectively. The long-term model simulation results indicated that split N application of 50 % during spring-pre plant (S) and 50 % during side-dressing (SD) could increase crop yield and reduce N leaching losses compared to other tested N application methods: spring (S) only, fall-spring split (F-S), and fall-spring-side-dressing (F-S-SD). Further, applying 10 % and 20 % reduced N rates (194 kg N ha−1 and 174 kg N ha−1, respectively) in combination with S-SD split application in controlled drainage (CD) condition could reduce N leaching losses by 30 % and 33 %, respectively compared to the conventional application method. This study explored the effects of N fertilizer management on crop yield and nitrogen losses under two drainage conditions, and underscored the importance of N fertilizer application rates and timings for achieving yield goals while minimizing nitrogen export from drained agricultural fields. The results of the model simulations will be useful for stakeholders and policy makers while making decisions regarding promotion and adoption of best management practices for drained agricultural landscapes.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Singh, Shailendra and Bhattarai, Rabin and Negm, Lamyaa M. and Youssef, Mohamed A. and Pittelkow, Cameron M.}, year={2020}, month={Oct} }
 @article{negm_youssef_chescheir_skaggs_2019, title={DRAINMOD-based tools for quantifying reductions in annual drainage flow and nitrate losses resulting from drainage water management on croplands in eastern North Carolina (vol 166, pg 86, 2016)}, volume={226}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2019.105811}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Negm, L. M. and Youssef, M. A. and Chescheir, G. M. and Skaggs, R. W.}, year={2019}, month={Dec} }
 @article{youssef_abdelbaki_negm_skaggs_thorp_jaynes_2018, title={DRAINMOD-simulated performance of controlled drainage across the US Midwest}, volume={197}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2017.11.012}, abstractNote={Controlled drainage (CD) has recently been proposed as a best management practice for reducing nutrient export from drained cropland in the U.S. Midwest to the Mississippi River and the Gulf of Mexico. We conducted a 25-year simulation study using the hydrological model, DRAINMOD, and the carbon and nitrogen (N) model, DRAINMOD-NII, to evaluate the performance of CD at 48 locations across the U.S. Midwest. Hydrological and Nitrogen predictions of this simulation study were compared to RZWQM-DSSAT predictions by Thorp et al. (2008). Simulation results showed that CD reduced annual subsurface drainage by 86 mm (30%) and annual N drainage losses by 10.9 kg N ha−1 (32%), on average over the 48 sites. DRAINMOD predicted highest reductions in drain flow at the south and southeast locations and lowest reductions at the northwest locations. The large reductions in drain flow in the south and southeast locations resulted in a large increase in surface runoff, which could increase soil erosion and sediment transport to surface water. In the north and northwest locations, the smaller amount of water that did not pass through the drainage system because of CD was primarily lost as evapotranspiration. DRAINMOD-NII predictions of annual reductions in N drainage loss followed the same trend of annual reductions in drainage flow. DRAINMOD-NII predictions show that reductions in N drainage loss under CD were mainly attributed to increase in denitrification. The declining trend in predicted annual denitrification from the southern to the northern locations of the Midwest region is most likely attributed to the lower temperature and less precipitation at the northern locations. RZWQM-DSSAT predicted reductions in annual drainage and N loss under CD conditions showed a similar trend to DRAINMOD/DRAINMOD-NII predictions. RZWQM-DSSAT, however, predicted substantially higher reductions in both drain flow (regional average of 151 mm yr−1, 53%) and N drainage losses (regional average of 18.9 kg N ha−1 yr−1, 51%). The discrepancies between DRAINMOD/DRAINMOD-NII and RZWQM-DSSAT predictions of annual reductions in drain flow and N loss under CD conditions were caused by differences in model predictions of individual components of the water and nitrogen balances under both free drainage and controlled drainage scenarios. Overall, this simulation study showed that climate variation across the region has a substantial impact on CD efficacy for reducing N drainage loss.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Youssef, Mohamed A. and Abdelbaki, Ahmed M. and Negm, Lamyaa M. and Skaggs, R. Wayne and Thorp, Kelly R. and Jaynes, Dan B.}, year={2018}, month={Jan}, pages={54–66} }
 @article{negm_youssef_jaynes_2017, title={Evaluation of DRAINMOD-DSSAT simulated effects of controlled drainage on crop yield, water balance, and water quality for a corn-soybean cropping system in central Iowa}, volume={187}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2017.03.010}, abstractNote={Controlled drainage (CD) has been identified as a sustainable management practice whereby more soil water can be conserved and less nutrients are leached; alongside its potential benefit of alleviating drought stress and increasing yield. More than 12 million hectare of cropland in the US Midwest are suitable for implementing CD; however, the effectiveness of the practice can vary across the region with the variation in environmental conditions and management practices. The main objective of this study is to evaluate the performance of the integrated agro-ecosystem model; DRAINMOD-DSSAT, for simulating the effects of CD on drainage flow, nitrogen losses via drainage water and crop yield. Herein, we utilized a 4-yr dataset (2006–2009) that was collected from a corn–soybean cropping system near Story City, Iowa. This site was artificially drained under free drainage (FD) and CD treatments. The model was calibrated using the data collected from the FD plots, and validated for the CD plots. DRAINMOD-DSSAT predictions of drainage flow and nitrate-nitrogen (NO3-N) losses were in good agreement with measured values under FD and CD, with the former treatment showed slightly better performance. The modeling efficiencies (NSE’s) for simulating monthly drainage flows were 0.81 and 0.60 for FD and CD, respectively. Monthly NO3–N mass losses were simulated with NSE’s of 0.76 and 0.66 for FD and CD, respectively. DRAINMOD-DSSAT well simulated CD-induced percent reductions in annual drainage flow (measured = 24.6%, simulated = 27.1%), and NO3-N losses (measured = 34.8%, simulated = 33.5%). Low percent error (PE) values were associated with the model predictions of corn yields (−1.3 ≤ PE ≤ 1.3) and soybean yields (−6.0 ≤ PE ≤ 12.6). Overall, results obtained from this relatively short-term modeling study demonstrated the potential use of DRAINMOD-DSSAT as a management design tool. Yet, further model testing CD effectiveness under different conditions is critically needed to establish a higher credibility in model predictions and to allow for further model improvement and expansion.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Negm, Lamyaa M. and Youssef, Mohamed A. and Jaynes, Dan B.}, year={2017}, month={Jun}, pages={57–68} }
 @article{negm_youssef_chescheir_skaggs_2016, title={DRAINMOD-based tools for quantifying reductions in annual drainage flow and nitrate losses resulting from drainage water management on croplands in eastern North Carolina}, volume={166}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2015.12.014}, abstractNote={Nitrogen (N) leachate of drained agriculture has continued to be pervasive in the U.S. water resources. Nitrogen credit exchange program is a trading market to facilitate pollutant reductions and protect the environment. A simple tool suitable for eastern North Carolina (NC) was developed to quantify drainage flow and N mass reductions resulting from drainage water management (DWM); an efficient and common conservation practice for drained agricultural lands. The tool comprises a set of regression equations estimating the performance of DWM as a function of local site conditions. DRAINMOD and DRAINMOD-NII models simulations were conducted for a wide range of soil types, weather conditions, and management practices for different locations in eastern NC. Simulation results were used with SAS 9.3 software to develop a set of multi-linear regression equations to estimate DWM-caused reductions in annual drainage flow and corresponding nitrate-N (NO3-N) losses for continuous corn (CC) and corn–wheat–soybean (CWS) cropping systems. The regression model estimations of annual drainage flow were highly correlated with DRAINMOD simulated values with an adjusted coefficient of multiple determination (R2adj) equal to 0.91 or higher for different management scenarios. Similarly, the regression model estimations of annual nitrate losses achieved an R2adj of 0.88 or higher for all management scenarios. The developed regression models were further compared on a year-by-year basis to the calibrated DRAINMOD and DRAINMOD-NII models for local conditions of an experimental site in eastern NC over 25 years. Estimated annual drainage flow and NO3-N losses were in good agreement with corresponding values simulated by DRAINMOD-based models for CC and CWS under free and controlled drainage modes. In terms of DWM-induced annual reductions in drainage flow and N losses, noticeable differences occurred in several years between predictions of DRAINMOD-NII and the regression models. A comparison based on the 5-year moving average of DWM-induced reductions smoothed out the extreme year-to-year variations and indicated very similar reduction trends provided by both methods. The results presented in this case study indicated that the simple regression method provides an adequate alternative to the processes based DRAINMOD suite of models for estimating annual reductions in drainage rates and N mass losses resulting from implementation of DWM. Similar tools can be developed for other regions in the US and abroad that initiate nitrogen trading markets involving DWM.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Negm, L. M. and Youssef, M. A. and Chescheir, G. M. and Skaggs, R. W.}, year={2016}, month={Mar}, pages={86–100} }
 @article{mcdaniel_skaggs_negm_2016, title={INJURY AND RECOVERY OF MAIZE ROOTS AFFECTED BY FLOODING}, volume={32}, ISSN={["1943-7838"]}, DOI={10.13031/aea.32.11633}, abstractNote={Proper soil environment for adequate root growth is crucial to maintain crop yields. Excessively wet soil conditions cause poor root growth and restrict plant water and nutrient uptake. The purpose of this study was to investigate corn root response to flooding and the root system ability to recover after saturation. Corn plants were grown in 1.3 m tall acrylic cylinders under controlled conditions. Plants were subjected to flooding for 1, 3, or 5 days at growth stages V4, V8, V12, and R1. Data were collected throughout the growing season on: root growth, root depth, and root mass. Root mortality was noted after the flooding treatment. Roots responded quickly to saturation (flooding) and all growth ceased within 24 h. Recovery to normal growth rates occurred within five days unless the saturation caused severe plant damage. One day of flooding did not affect root mass at any stage of growth. Root mass was not affected by three days of flooding during the V4 and V8 stages. A significant reduction of root mass was noted for more than 35 days following 3-day inundation during V12 and R1. Flooding for five days during stage V4, V12, and R1 caused a significant reduction in root mass. Plants flooded during V8 suffered no significant reduction in root mass. Assessment of root response to saturated soil conditions is necessary to improve groundwater table management practices in high water table soils, as well as to enhance the performance of simulation model that predict plant growth and yield on drained lands.}, number={5}, journal={APPLIED ENGINEERING IN AGRICULTURE}, author={McDaniel, V. and Skaggs, R. W. and Negm, L. M.}, year={2016}, pages={627–638} }
 @article{negm_youssef_skaggs_chescheir_kladivko_2014, title={DRAINMOD-DSSAT Simulation of the Hydrology, Nitrogen Dynamics, and Plant Growth of a Drained Corn Field in Indiana}, volume={140}, ISSN={["1943-4774"]}, DOI={10.1061/(asce)ir.1943-4774.0000738}, abstractNote={AbstractDRAINMOD-DSSAT is an integrated model recently developed to simulate the hydrology, water quality, and crop growth for artificially drained croplands. DRAINMOD-DSSAT is an advanced research tool that contributes to increasing productivity, reducing cost, and enhancing sustainability of crop production on high water table soils with artificial drainage. In this study, the performance of the model was evaluated using a six-year data set (1985–1990) collected from a subsurface drained agricultural research site in Indiana in the United States. Subsurface drains were installed at three different spacings (5, 10, and 20 m). During the simulation period, all treatments were planted to corn receiving high preplant N-fertilization rates. Rainfall patterns varied significantly among the years. DRAINMOD-DSSAT predictions of monthly and annual drainage flow, and nitrate losses, were in good agreement with measured values. Similarly, variations in corn yield patterns were well captured by the model across dif...}, number={8}, journal={JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING}, author={Negm, Lamyaa M. and Youssef, Mohamed A. and Skaggs, Richard W. and Chescheir, George M. and Kladivko, Eileen J.}, year={2014}, month={Aug} }