@misc{harmel_preisendanz_king_busch_birgand_sahoo_2023, title={A Review of Data Quality and Cost Considerations for Water Quality Monitoring at the Field Scale and in Small Watersheds}, volume={15}, ISSN={["2073-4441"]}, DOI={10.3390/w15173110}, abstractNote={Technological advances and resource constraints present scientists and engineers with renewed challenges in the design of methods to conduct water quality monitoring, and these decisions ultimately determine the degree of project success. Many professionals are exploring alternative lower-cost options because of cost constraints, and research and development is largely focused on in situ sensors that produce high temporal resolution data. While some guidance is available, contemporary information is needed to balance water quality monitoring decisions with financial and personnel constraints, while meeting data quality needs. This manuscript focuses on monitoring constituents, such as sediment, nutrients, and pathogens, at the field scale and in small watersheds. Specifically, the impacts on the costs and data quality of alternatives related to site selection, discharge measurement, and constituent concentration measurement, are explored. The present analysis showed that avoiding sites requiring extensive berm construction and the installation of electric power to reach distant sites greatly reduces the initial costs with little impact on data quality; however, other decisions directly impact data quality. For example, proper discharge measurement, high-frequency sampling, frequent site and equipment maintenance, and the purchase of backup power and monitoring equipment can be costly, but are important for high quality data collection. In contrast, other decisions such as the equipment type (mechanical samplers, electronic samplers, or in situ sensors) and whether to analyze discrete or composite samples greatly affect the costs, but have minimal impact on data quality. These decisions, therefore, can be based on other considerations (e.g., project goals, intended data uses, funding agency specifications, and agency protocols). We hope this guidance helps practitioners better design and implement water quality monitoring to satisfy resource constraints and data quality needs.}, number={17}, journal={WATER}, author={Harmel, Robert Daren and Preisendanz, Heather Elise and King, Kevin Wayne and Busch, Dennis and Birgand, Francois and Sahoo, Debabrata}, year={2023}, month={Sep} }
 @article{oliveira_dougherty_cooke_maxwell_helmers_birgand_pittelkow_christianson_christianson_2023, title={Aspect ratio and baffles impact hydraulic performance of full-size denitrifying bioreactors}, volume={189}, ISSN={["1872-6992"]}, DOI={10.1016/j.ecoleng.2023.106912}, abstractNote={Denitrifying woodchip bioreactors treating subsurface drainage in the US have high aspect ratios (i.e., length: width ratios; approximately 4:1) to encourage plug flow dynamics. Improved understanding of bioreactor hydraulics across aspect ratios would help assess possible increased flexibility for this practice to capture greater hydraulic loading or provide greater nitrate mass removal. The objective of this study was to assess the hydraulic impacts of aspect ratio and baffles using conservative tracer testing at full-scale denitrifying woodchip bioreactors. Fourteen tracer tests were performed at six bioreactors, spanning three design styles: (1) “conventional” bioreactors with high aspect ratios of ≥2.6:1; (2) a “wide” bioreactor with a low aspect ratio of 0.3:1; and (3) a relatively wide “advanced” bioreactor with baffles placed to route flow sinuously perpendicular (sideways) to the hydraulic gradient. The wide bioreactor had the most dispersion, the most short circuiting, and was the most well mixed based on the tanks-in-series model. The advanced design with baffles had higher volumetric efficiencies than the conventional and wide designs (2.9, 2.2, and 2.1, respectively) and trended toward the highest nitrate removals. The concept of baffles at relatively wide bioreactors merits additional field-scale assessment to increase hydraulic loading while maintaining hydraulic efficiency. The Morill Dispersion and Short Circuiting Indices were strongly and significantly correlated (Pearson's r: −0.88) across the fourteen tests as were the volumetric and hydraulic efficiency metrics (r: 0.87). While aspect ratio and baffles have been well studied in wetlands and other reactor types, this work is the first to establish these concepts using tracer testing at three woodchip bioreactor design styles.}, journal={ECOLOGICAL ENGINEERING}, author={Oliveira, Luciano Alves and Dougherty, Hannah and Cooke, Richard A. C. and Maxwell, Bryan M. and Helmers, Matthew J. and Birgand, Francois and Pittelkow, Cameron M. and Christianson, Reid D. and Christianson, Laura E.}, year={2023}, month={Apr} }
 @article{hammond_birgand_carey_bookout_breef-pilz_schreiber_2023, title={High-frequency sensor data capture short-term variability in Fe and Mn concentrations due to hypolimnetic oxygenation and seasonal dynamics in a drinking water reservoir}, volume={240}, ISSN={1879-2448}, url={https://doi.org/10.1016/j.watres.2023.120084}, DOI={10.1016/j.watres.2023.120084}, abstractNote={The biogeochemical cycles of iron (Fe) and manganese (Mn) in lakes and reservoirs have predictable seasonal trends, largely governed by stratification dynamics and redox conditions in the hypolimnion. However, short-term (i.e., sub-weekly) trends in Fe and Mn cycling are less well-understood, as most monitoring efforts focus on longer-term (i.e., monthly to yearly) time scales. The potential for elevated Fe and Mn to degrade water quality and impact ecosystem functioning, coupled with increasing evidence for high spatiotemporal variability in other biogeochemical cycles, necessitates a closer evaluation of the short-term Fe and Mn dynamics in lakes and reservoirs. We adapted a UV-visible spectrophotometer coupled with a multiplexor pumping system and partial least squares regression (PLSR) modeling to generate high spatiotemporal resolution predictions of Fe and Mn concentrations in a drinking water reservoir (Falling Creek Reservoir, Vinton, VA, USA) equipped with a hypolimnetic oxygenation (HOx) system. We quantified hourly Fe and Mn concentrations during two transitional periods: reservoir turnover (Fall 2020) and HOx initiation (Summer 2021). Our sensor system successfully predicted mean Fe and Mn concentrations and trends, ground-truthed by grab sampling and laboratory analysis. During fall turnover, hypolimnetic Fe and Mn concentrations began to decrease more than two weeks before complete mixing of the reservoir, with rapid equalization of epilimnetic and hypolimnetic Fe and Mn concentrations in less than 48 h after full water column mixing. During the initiation of HOx in Summer 2021, Fe and Mn displayed distinctly different responses to oxygenation, as indicated by the rapid oxidation of soluble Fe but not soluble Mn. This study demonstrates that Fe and Mn concentrations are sensitive to changes in redox conditions induced by stratification and oxygenation, although their responses to these changes differ. We also show that high spatio-temporal resolution predictions of Fe and Mn can improve drinking water monitoring programs and reservoir management practices.}, journal={WATER RESEARCH}, author={Hammond, Nicholas W. and Birgand, Francois and Carey, Cayelan C. and Bookout, Bethany and Breef-Pilz, Adrienne and Schreiber, Madeline E.}, year={2023}, month={Jul}, pages={120084} }
 @article{kamrath_burchell_birgand_aziz_2023, title={Quantification of Ammonium Release from an Aging Free Water Surface Constructed Wetland To Improve Treatment Performance}, url={https://doi.org/10.21428/f69f093e.db873c9f}, DOI={10.21428/f69f093e.db873c9f}, journal={Journal of Ecological Engineering Design}, author={Kamrath, Brock and Burchell, Michael and Birgand, François and Aziz, Tarek}, year={2023}, month={Dec} }
 @article{grande_seybold_tatariw_visser_braswell_arora_birgand_haskins_zimmer_2023, title={Seasonal and tidal variations in hydrologic inputs drive salt marsh porewater nitrate dynamics}, volume={37}, ISSN={["1099-1085"]}, DOI={10.1002/hyp.14951}, abstractNote={Abstract}, number={8}, journal={HYDROLOGICAL PROCESSES}, author={Grande, Emilio and Seybold, Erin C. and Tatariw, Corianne and Visser, Ate and Braswell, Anna and Arora, Bhavna and Birgand, Francois and Haskins, John and Zimmer, Margaret}, year={2023}, month={Aug} }
 @article{moin_hunt_birgand_ratzlaff_2022, title={Effect of Visibility on Maintenance Investment and Consequent Performance of Urban Stormwater Control Measures}, volume={8}, ISSN={["2379-6111"]}, DOI={10.1061/JSWBAY.0000975}, abstractNote={Studies on the performance of urban stormwater control measures (SCMs) mainly focus on hydrologic and biological factors. SCMs are located in an urban context and humans are part of this ecosystem, yet few studies have investigated the effect of human interaction on SCM performance. While SCM designs rarely encourage physical human interaction, their placement in the urban landscape does allow visual interaction. This study explores the impact of SCM visibility on the degree of maintenance received and, consequently, on the hydrologic performance of the system. Forty SCMs, including 20 bioretention cells and 20 wetlands or wet ponds, were assessed. Visibility was evaluated through SCM surveys to determine viewshed size, noticeability, and potential passerby traffic. Hydrologic performance was evaluated through (1) visual inspection, (2) surveying vegetation health, (3) measuring drawdown rates, and (4) soil tests of bioretention media. As the degree of maintenance varied for each SCM, previous maintenance records, including cost data for the preceding year, were obtained and compared to visibility scores and hydrologic performance metrics. The study findings concluded that (1) smaller practices (bioretention) were more expensive to maintain than larger practices (ponds and wetlands) on a per SCM-area basis; and (2) the communication between the design community and the maintenance crew is essential. As an example, because they are not aware that bioretention cells (BRCs) can drain too fast for effective nitrogen treatment, maintenance crews often assume a BRC with greater than recommended drawdown rate is functioning well. The authors believe that this misunderstanding impacted whether visibility could be a predictor of hydrologic performance. Ancillary results suggest that maintenance crews tend to prioritize more visible systems; however, based on the hydrologic performance, SCM priority did not significantly affect the quality of maintenance performed. Moreover, the SCMs examined tended to perform acceptably well. This finding is considered biased because of (1) generally informed and conscientious maintenance crews, as they hold an "SCM Inspection and Maintenance Certification"; and (2) routine SCM inspection and maintenance performed on a monthly basis, which is more frequent than those reported in other studies, and therefore not reflective of SCMs found elsewhere. Further research is needed, using a greater number of maintenance crews, and controlling for crews with appropriate training, utilizing the methodology presented herein.}, number={1}, journal={JOURNAL OF SUSTAINABLE WATER IN THE BUILT ENVIRONMENT}, author={Moin, Sheida and Hunt, William F. and Birgand, Francois and Ratzlaff, Steve}, year={2022}, month={Feb} }
 @article{birgand_chapman_hazra_gilmore_etheridge_staicu_2022, title={Field performance of the GaugeCam image-based water level measurement system}, url={https://doi.org/10.1371/journal.pwat.0000032}, DOI={10.1371/journal.pwat.0000032}, abstractNote={Image-based stage and discharge measuring systems are among the most promising new non-contact technologies available for long-term hydrological monitoring. This article evaluates and reports the long-term performance of the GaugeCam (www.gaugecam.org) image-based stage measuring system in situ. For this we installed and evaluated the system over several months in a tidal marsh to obtain a good stratification of the measured stages. Our evaluation shows that the GaugeCam system was able to measure within about ±5 mm for a 90% confidence interval over a range of about 1 m in a tidal creek in a remote location of North Carolina, USA. Our results show that the GaugeCam system nearly performed to the desired design of ±3 mm accuracy around 70% of the time. The system uses a dedicated target background for calibration and geometrical perspective correction of images, as well as auto-correction to compensate for camera movement. The correction systems performed well overall, although our results show a ‘croissant-shaped’ mean error (-1 to +4 mm,) varying with water stage. We attribute this to the small, yet present, ‘fish-eye’ effect embedded in images, for which our system did not entirely correct in the tested version, and which might affect all image-based water level measurement systems.}, journal={PLOS Water}, author={Birgand, François and Chapman, Ken and Hazra, Arnab and Gilmore, Troy and Etheridge, Randall and Staicu, Ana-Maria}, editor={Cheema, Muhammad Jehanzeb MasudEditor}, year={2022}, month={Jul} }
 @article{hammond_birgand_carey_bookout_breef-pilz_schreiber_2022, title={High-frequency sensor data capture short-term variability in Fe and Mn cycling due to hypolimnetic oxygenation and seasonal dynamics in a drinking water reservoir}, url={https://doi.org/10.1002/essoar.10512927.1}, DOI={10.1002/essoar.10512927.1}, abstractNote={The biogeochemical cycles of iron (Fe) and manganese (Mn) in lakes and reservoirs have predictable seasonal trends, largely governed by stratification dynamics and redox conditions in the hypolimnion.However, short-term (i.e., sub-weekly) trends in Fe and Mn cycling are less well-understood, as most monitoring efforts focus on longer-term (i.e., monthly to yearly) time scales.The potential for elevated Fe and Mn to degrade water quality and impact ecosystem functioning, coupled with increasing evidence for high spatiotemporal variability in other biogeochemical cycles, necessitates a closer evaluation of the short-term Fe and Mn cycling dynamics in lakes and reservoirs.We adapted a UV-visible spectrophotometer coupled with a multiplexor pumping system and PLSR modeling to generate high spatiotemporal resolution predictions of Fe and Mn concentrations in a drinking water reservoir (Falling Creek Reservoir, Vinton, VA, USA) equipped with a hypolimnetic oxygenation (HOx) system.We quantified hourly Fe and Mn concentrations during two distinct transitional periods: reservoir turnover (Fall 2020) and initiation of the HOx system (Summer 2021).Our sensor system was able to successfully predict mean Fe and Mn concentrations as well as capture sub-weekly variability, ground-truthed by traditional grab sampling and laboratory analysis.During fall turnover, hypolimnetic Fe and Mn concentrations began to decrease more than two weeks before complete mixing of the reservoir occurred, with rapid equalization of epilimnetic and hypolimnetic Fe and Mn concentrations in less than 48 hours after full water column mixing.During the initiation of hypolimnetic oxygenation in Summer 2021, we observed that Fe and Mn were similarly affected by physical mixing in the hypolimnion, but displayed distinctly different responses to oxygenation, as indicated by the rapid oxidation of soluble Fe but not soluble Mn.This study demonstrates that Fe and Mn concentrations are highly sensitive to shifting DO and stratification and that their dynamics can substantially change on hourly to daily time scales in response to these transitions.High-frequency sensor data capture short-term variability in Fe and Mn cycling due to hypolimnetic oxygenation and seasonal dynamics in a drinking water reservoir}, author={Hammond, Nicholas and Birgand, François and Carey, Cayelan C and Bookout, Bethany and Breef-Pilz, Adrienne and Schreiber, Madeline}, year={2022}, month={Nov} }
 @article{liu_tian_youssef_birgand_chescheir_2022, title={Patterns of long-term variations of nitrate concentration - Stream discharge relationships for a drained agricultural watershed in Mid-western USA}, volume={614}, ISSN={["1879-2707"]}, DOI={10.1016/j.jhydrol.2022.128479}, abstractNote={Nitrate Concentration–discharge (C-Q) relationships have been used to infer nitrate sources, storage, reactions, and transport in watersheds, and to reveal key processes that control runoff chemistry. Yet, studies on long-term nitrate C-Q relationships are limited due to scarce high frequency (e.g., daily) concentration data. In this paper, using a long-term high-frequency dataset (1976–2019) comprising stream flow and nitrate concentrations, we quantitatively analyzed the long-term variations of event-scale hysteresis patterns (quantified by hysteresis index, HI, and flushing index, FI) to infer the leaching mechanisms of nitrate in an artificially drained agricultural watershed in Mid-western U.S. Our results revealed that most events exhibited anti-clockwise behaviors (HI < 0), regardless of whether nitrate was flushed or diluted during events. This means that water with high levels of nitrate-N reaches the stream network slower than water with lower nitrate concentrations. Long-term mean FI was close to zero but had strong seasonal patterns with dilution patterns observed during Winter and Summer, and flushing patterns during late Spring and Fall. The consistently negative HI values regardless of the FI value gave a strong indication of the preponderant role of the near-drain zone that usually exhibits accelerated leaching and less accumulation of nitrate in the soil profile in these drained agricultural watersheds. Both HI and FI depicted strong but opposite seasonality because of weather patterns and agricultural activities, particularly N fertilization. Overall, our findings suggest a little evidence of the role of deep groundwater and instead a strong evidence of the role of subsurface drainage as the primary pathway for nitrate transport in drained agricultural watersheds. Therefore, artificial drainage could dampen N legacy caused by the historically intensive N fertilization in drained agricultural landscapes.}, journal={JOURNAL OF HYDROLOGY}, author={Liu, Wenlong and Tian, Shiying and Youssef, Mohamed A. and Birgand, Francois P. and Chescheir, George M.}, year={2022}, month={Nov} }
 @article{chapman_gilmore_chapman_birgand_mittlestet_harner_mehrubeoglu_stranzl_2022, title={Technical Note: Open-Source Software for Water-Level Measurement in Images With a Calibration Target}, volume={58}, ISSN={["1944-7973"]}, DOI={10.1029/2022WR033203}, abstractNote={Abstract}, number={8}, journal={WATER RESOURCES RESEARCH}, author={Chapman, Kenneth W. and Gilmore, Troy E. and Chapman, Christian D. and Birgand, Francois and Mittlestet, Aaron R. and Harner, Mary J. and Mehrubeoglu, Mehrube and Stranzl, John E., Jr Jr}, year={2022}, month={Aug} }
 @article{shiau_burchell_krauss_broome_birgand_2021, title={Carbon storage potential in a recently created brackish marsh in eastern North Carolina, USA (vol 127, pg 579, 2019)}, volume={168}, ISSN={["1872-6992"]}, DOI={10.1016/j.ecoleng.2021.106276}, journal={ECOLOGICAL ENGINEERING}, author={Shiau, Yo-Jin and Burchell, Michael R. and Krauss, Ken W. and Broome, Stephen W. and Birgand, Francois}, year={2021}, month={Oct} }
 @misc{liu_birgand_tian_chen_2021, title={Event-scale hysteresis metrics to reveal processes and mechanisms controlling constituent export from watersheds: A review}, volume={200}, ISSN={["1879-2448"]}, DOI={10.1016/j.watres.2021.117254}, abstractNote={Due to the increased availability of high-frequency measurements of stream chemistry provided by in situ sensors, researchers have gained more access to relationships between stream discharge and constituent concentrations (C-Q relationships) at event-scales. Existing studies reveal that event-scale C-Q relationships are mostly non-linear and exhibit temporal lags between peaks (or troughs) of hydrographs and chemographs, resulting in apparent hysteresis effects. In this paper, we summarize and introduce tools and methods in hysteresis analysis, especially the history and progresses of metrics to quantify hysteresis patterns. In addition, this paper provides a typical workflow to conduct event-scale hysteresis analysis, such as how to obtain the access to high-frequency measurements, existing methods to delineate storm events, approaches to classify and quantify hysteresis patterns, possible features/properties controlling hysteresis patterns, statistical methods to identify features at play, and strategies to deliver the inferences from hysteresis analysis. Lastly, we discuss some potential limitations that arise in the workflow and possible future work to address the challenges, including the development of advanced quantitative hysteresis metrics, generalized and standardized tools to delineate events and the integration of hysteresis analysis with numerical modeling. This paper aims to provide a critical overview of technical approaches for hysteresis analysis for researchers and hopefully foster their interests to advance our understanding of complex mechanisms in event-scale hydro-biogeochemical processes.}, journal={WATER RESEARCH}, author={Liu, Wenlong and Birgand, Francois and Tian, Shiying and Chen, Cheng}, year={2021}, month={Jul} }
 @article{birgand_maxwell_thomas_schipper_williams_christianson_tian_helmers_chescheir_youssef_2020, title={Effects of drying and rewetting cycles on denitrification and greenhouse gas emissions in normally saturated organic substrate}, volume={3}, url={https://doi.org/10.5194/egusphere-egu2020-22205}, DOI={10.5194/egusphere-egu2020-22205}, abstractNote={
        <p>The effects of intermittent drying of normally saturated organic systems such as peatlands, swamps, or wetlands has not been reported quite as often as those of wetting and drying cycles of normally dry soils. We report here the effects of weekly drying and rewetting events on saturated woodchips used as denitrification bed. We used denitrification rates and gas effluxes as indicators of the response of normally saturated organic substrate to intermittent aerobic conditions. We used replicated eight upflow columns in the lab fed with nitrated water, and undergoing variable duration of intermittent aerobic conditions (none, 2, 8, and 24 hours) over a 400d experiment. &#160;We used high-frequency sensors to measure in- and outflow nitrate and DOC concentrations on a 2-hour basis, from which we calculated denitrification rates. We also measured the CO2 and N2O effluxes in the headspace on an hourly basis. The results show a burst of respiration activity during drying events and for several days after rewetting. Isotopic data suggest that respiration was bacterial denitrification. Intermittent aerobic conditions seem to provide the conditions conducive to the generation of more and better quality DOC, which microbes use during subsequent saturated conditions. Our results suggest that intermittent aerobic conditions may have lasting impacts on microbial respiration in wetlands.</p>
        }, publisher={Copernicus GmbH}, author={Birgand, François and Maxwell, Bryan and Thomas, Augustin and Schipper, Louis and Williams, David and Christianson, Laura and Tian, Shying and Helmers, Matthew and Chescheir, Chip and Youssef, Mohamed}, year={2020}, month={Mar} }
 @article{maxwell_winter_birgand_2020, title={Floating treatment wetland retrofit in a stormwater wet pond provides limited water quality improvements}, volume={149}, ISSN={["1872-6992"]}, DOI={10.1016/j.ecoleng.2020.105784}, abstractNote={Floating treatment wetlands (FTW) are an emerging management practice for improving water quality in stormwater wet ponds or other detention basins. Although there is substantial evidence of nutrient reductions by FTW in mesocosm-scale studies, findings from field-scale studies on the water quality benefits of FTW are less conclusive. A medium-sized stormwater wet pond (~0.8 ha) was partially divided using an impermeable liner and monitored for 280 d using a control and FTW treatment (~20–23% FTW coverage) to determine impact of FTW on concentrations of several water quality parameters at the field-scale. Discrete samples and high-frequency, multi-point monitoring were used to assess water quality differences. No significant differences between the two treatments were found for total nitrogen, total Kjeldahl nitrogen, or total phosphorus, based on discrete samples, and in situ monitoring showed dissolved oxygen was significantly lower in the FTW treatment by roughly 2.6 mg L−1. The FTW treatment had significantly higher nitrate concentrations in discrete samples, but this finding was not supported by the high-frequency data collected when considering the full monitoring period. The FTW had significantly lower total suspended solids, based on discrete and high-frequency sampling, and resulted in a 10–43% reduction in TSS (~25% mean reduction), relative to the control. Comparison of subsets of the high-frequency data to discrete sampling data demonstrated how limited discrete sampling can lead to partial information and potentially erroneous conclusions when assessing FTW treatment effect in stormwater, especially when differences in water quality chemistry are small.}, journal={ECOLOGICAL ENGINEERING}, author={Maxwell, Bryan and Winter, Danielle and Birgand, Francois}, year={2020}, month={Apr} }
 @article{maxwell_birgand_schipper_barkle_rivas_helmers_christianson_2020, title={High-frequency, in situ sampling of field woodchip bioreactors reveals sources of sampling error and hydraulic inefficiencies}, volume={272}, ISSN={["1095-8630"]}, DOI={10.1016/j.jenvman.2020.110996}, abstractNote={Woodchip bioreactors are a practical, low-cost technology for reducing nitrate (NO3) loads discharged from agriculture. Traditional methods of quantifying their performance in the field mostly rely on low-frequency, time-based (weekly to monthly sampling interval) or flow-weighted sample collection at the inlet and outlet, creating uncertainty in their performance and design by providing incomplete information on flow and water chemistry. To address this uncertainty, two field bioreactors were monitored in the US and New Zealand using high-frequency, multipoint sampling for in situ monitoring of NO3-N concentrations. High-frequency monitoring (sub hourly interval) at the inlet and outlet of both bioreactors revealed significant variability in volumetric removal rates and percent reduction, with percent reduction varying by up to 25 percentage points within a single flow event. Time series of inlet and outlet NO3 showed significant lag in peak concentrations of 1-3 days due to high hydraulic residence time, where calculations from instantaneous measurements produced erroneous estimates of performance and misleading relationships between residence time and removal. Internal porewater sampling wells showed differences in NO3 concentration between shallow and deep zones, and "hot spot" zones where peak NO3 removal co-occurred with dissolved oxygen depletion and dissolved organic carbon production. Tracking NO3 movement through the profile showed preferential flow occurring with slower flow in deeper woodchips, and slower flow further from the most direct flowpath from inlet to outlet. High-frequency, in situ data on inlet and outlet time series and internal porewater solute profiles of this initial work highlight several key areas for future research.}, journal={JOURNAL OF ENVIRONMENTAL MANAGEMENT}, author={Maxwell, Bryan M. and Birgand, Francois and Schipper, Louis A. and Barkle, Greg and Rivas, Aldrin A. and Helmers, Matthew J. and Christianson, Laura E.}, year={2020}, month={Oct} }
 @article{liu_youssef_birgand_chescheir_tian_maxwell_2020, title={Processes and mechanisms controlling nitrate dynamics in an artificially drained field: Insights from high-frequency water quality measurements}, volume={232}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2020.106032}, abstractNote={Intensive agricultural activities, especially in artificially drained agricultural landscapes, generate a considerable amount of nutrient export, which has been identified as a primary cause of water quality impairment. Several management practices have been developed and installed in agricultural watersheds to reduce nutrient export, e.g. nitrate-nitrogen (NO3-N). Although published research reported considerable water quality benefits of these practices, there exist many unanswered questions regarding the inherent processes and mechanisms that control nitrate fate and transport from drained agricultural landscape. To advance our understanding of processes and mechanisms, we deployed two high-frequency sampling systems in a drained agricultural field to investigate the relationship between agricultural drainage and nitrate concentrations (C-Q relationship). Results indicated that the high-frequency measuring system was able to capture the rapidly changing C-Q relationships at the experimental site, e.g. hysteresis patterns. The 22 identified storm events exhibited anti-clockwise behavior with high variability of flushing/dilution effects. In addition, high drainage flows contributed far more nitrate loading compared with lower flows. For instance, the top 10 % of drainage flow exported more than 50 % of the nitrate lost via subsurface drainage during the monitoring period. Additionally, we observed that animal waste application was the most influential practice to change the C-Q relationship by increasing the size of soil nitrogen pools. The insights obtained from the high-frequency water quality measurements could help provide practical suggestions regarding the design and management of conservation practices, such as controlled drainage, bioreactors, and saturated buffers, to improve their nitrogen removal efficiencies. This subsequently leads to better nutrient management in drained agricultural lands.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Liu, Wenlong and Youssef, Mohamed A. and Birgand, Francois P. and Chescheir, George M. and Tian, Shiying and Maxwell, Bryan M.}, year={2020}, month={Apr} }
 @article{muwamba_amatya_chescheir_nettles_appelboom_tollner_ssegane_youssef_birgand_callahan_2020, title={Response of Drainage Water Quality to Fertilizer Applications on a Switchgrass Intercropped Coastal Pine Forest}, volume={12}, ISSN={["2073-4441"]}, DOI={10.3390/w12051265}, abstractNote={The objectives of this study were (1) to test the hypothesis that fertilizer applications do not increase nutrient fluxes on a switchgrass/pine forest (IC) when compared to a mature pine forest (MP) and (2) to evaluate post-fertilization (post-fert, 2014–2016) fluxes of nitrogen (N) and phosphorus (P) on IC and compare them to those observed during switchgrass growth prior to fertilization (pre-fert, 2012–2014) and site preparation for switchgrass establishment (site prep, 2009–2012). Nitrogen and P were applied to IC, a paired pure switchgrass site (SG), and MP, each about 25 ha in size, in June 2014, and again in June 2015 for the IC and SG sites only. Nitrogen and P concentrations were measured biweekly and rainfall and drainage outflow were measured continuously. During post-fert, the mean N concentrations and total loads were lower (p < 0.05) in IC than in SG and MP. The mean NO3-N concentration and loads in IC were lower during post-fert than during site prep. The post-fert phosphate concentrations in IC were lower than they were during pre-fert and site prep. Frequent N and P applications in IC did not significantly (α = 0.05) increase N and P fluxes, likely due to plant uptake and sorption on the acidic site.}, number={5}, journal={WATER}, author={Muwamba, Augustine and Amatya, Devendra M. and Chescheir, George M. and Nettles, Jamie E. and Appelboom, Timothy and Tollner, Ernest W. and Ssegane, Hebert and Youssef, Mohamed A. and Birgand, Francois and Callahan, Timothy}, year={2020}, month={May} }
 @article{muwamba_amatya_ssegane_chescheir_appelboom_nettles_tollner_youssef_walega_birgand_2020, title={Response of Nutrients and Sediment to Hydrologic Variables in Switchgrass Intercropped Pine Forest Ecosystems on Poorly Drained Soil}, volume={231}, ISSN={["1573-2932"]}, DOI={10.1007/s11270-020-04808-3}, number={9}, journal={WATER AIR AND SOIL POLLUTION}, author={Muwamba, Augustine and Amatya, Devendra M. and Ssegane, Herbert and Chescheir, George M. and Appelboom, Timothy and Nettles, Jamie E. and Tollner, Ernest W. and Youssef, Mohamed A. and Walega, Andrzej and Birgand, Francois}, year={2020}, month={Aug} }
 @article{maxwell_diaz-garcia_jose martinez-sanchez_birgand_alvarez-rogel_2020, title={Temperature sensitivity of nitrate removal in woodchip bioreactors increases with woodchip age and following drying-rewetting cycles}, volume={6}, ISBN={2053-1419}, DOI={10.1039/d0ew00507j}, abstractNote={Temperature sensitivity of nitrate removal in woodchip bioreactors changes according to short and long-term changes in carbon quality.}, number={10}, journal={ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY}, author={Maxwell, Bryan M. and Diaz-Garcia, Carolina and Jose Martinez-Sanchez, Juan and Birgand, Francois and Alvarez-Rogel, Jose}, year={2020}, pages={2752–2765} }
 @article{shiau_burchell_krauss_broome_birgand_2019, title={Carbon storage potential in a recently created brackish marsh in eastern North Carolina, USA}, volume={127}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2018.09.007}, DOI={10.1016/j.ecoleng.2018.09.007}, abstractNote={Carbon (C) sequestration through accumulated plant biomass and storage in soils can potentially make wetland ecosystems net C sinks. Here, we collected GHG flux, plant biomass, and litter decomposition data from three distinct vegetation zones (Spartina alterniflora, Juncus roemerianus and Spartina patens) on a 7-year-old created brackish marsh in North Carolina, USA, and integrate these data into an overall C mass balance budget. The marsh fixed an average of 1.85 g C m−2 day−1 through plant photosynthesis. About 41–46% of the fixed C remained in plants, while 18.4% of the C was decomposed and released back to the atmosphere as CO2 and CH4, and 8.6–13.2% of the decomposed C was stored as soil C. In all, this created marsh sequestered 28.7–44.7 Mg CO2 year−1 across the 14 ha marsh. Because the brackish marsh emitted only small amounts of CH4 and N2O, the CO2 equivalent emission of the marsh was −0.87 to −0.56 g CO2-eq m−2 day−1, indicating the marsh has a net effect in reducing GHGs to the atmosphere and contributes to cooling. However, resultant CO2 credit (through the increment of soil C) would be worth only $30.76–$47.90 USD per hectare annually, or $431–$671 per year for the project, which, coupled with other enhanced ecosystem services, could provide landowners with some additional economic incentive for future creation projects. Nevertheless, C mass balance determinations and radiative cooling metrics showed promise in demonstrating the potential of a young created brackish marsh to act as a net carbon sink.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Shiau, Yo-Jin and Burchell, Michael R. and Krauss, Ken W. and Broome, Stephen W. and Birgand, Francois}, year={2019}, month={Feb}, pages={579–588} }
 @article{frazar_gold_addy_moatar_birgand_schroth_kellogg_pradhanang_2019, title={Contrasting behavior of nitrate and phosphate flux from high flow events on small agricultural and urban watersheds}, volume={145}, ISSN={0168-2563 1573-515X}, url={http://dx.doi.org/10.1007/s10533-019-00596-z}, DOI={10.1007/s10533-019-00596-z}, number={1-2}, journal={Biogeochemistry}, publisher={Springer Science and Business Media LLC}, author={Frazar, Sarah and Gold, Arthur J. and Addy, Kelly and Moatar, Florentina and Birgand, François and Schroth, Andrew W. and Kellogg, D. Q. and Pradhanang, Soni M.}, year={2019}, month={Sep}, pages={141–160} }
 @article{messer_birgand_burchell_2019, title={Diel fluctuations of high level nitrate and dissolved organic carbon concentrations in constructed wetland mesocosms}, volume={133}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2019.04.027}, DOI={10.1016/j.ecoleng.2019.04.027}, abstractNote={Portable in situ ultraviolet-visual spectrometers, through high frequency water quality measurements, provide new insight into biogeochemical processes occurring within dynamic ecosystems. Nitrogen and carbon cycling were observed in two distinct wetland mesocosm environments during a two-year mesocosm study. Simulated drainage water was loaded into the mesocosms across seasons with target nitrate-N levels between 2.5 and 10 mg L−1. Nitrate-N and dissolved organic carbon concentrations in the water column were measured hourly with the spectrometer and calibrated with water quality grab samples. Prominent and unique diel cycles were observed in both nitrate-N and dissolved organic carbon readings from the spectrometer, which reveal biogeochemical processes in these systems are more complicated than typically considered in empirical models. Findings support the importance of utilizing high frequency monitoring to advance current knowledge of nitrogen and carbon processes occurring in treatment wetland ecosystems.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Messer, Tiffany L. and Birgand, François and Burchell, Michael R.}, year={2019}, month={Aug}, pages={76–87} }
 @article{maxwell_birgand_schipper_christianson_tian_helmers_williams_chescheir_youssef_2019, title={Drying–Rewetting Cycles Affect Nitrate Removal Rates in Woodchip Bioreactors}, volume={48}, ISSN={0047-2425}, url={http://dx.doi.org/10.2134/jeq2018.05.0199}, DOI={10.2134/jeq2018.05.0199}, abstractNote={Woodchip bioreactors are widely used to control nitrogen export from agriculture using denitrification. There is abundant evidence that drying–rewetting (DRW) cycles can promote enhanced metabolic rates in soils. A 287‐d experiment investigated the effects of weekly DRW cycles on nitrate (NO3) removal in woodchip columns in the laboratory receiving constant flow of nitrated water. Columns were exposed to continuous saturation (SAT) or to weekly, 8‐h drying‐rewetting (8 h of aerobiosis followed by saturation) cycles (DRW). Nitrate concentrations were measured at the column outlets every 2 h using novel multiplexed sampling methods coupled to spectrophotometric analysis. Drying–rewetting columns showed greater export of total and dissolved organic carbon and increased NO3 removal rates. Nitrate removal rates in DRW columns increased by up to 80%, relative to SAT columns, although DRW removal rates decreased quickly within 3 d after rewetting. Increased NO3 removal in DRW columns continued even after 39 DRW cycles, with ∼33% higher total NO3 mass removed over each weekly DRW cycle. Data collected in this experiment provide strong evidence that DRW cycles can dramatically improve NO3 removal in woodchip bioreactors, with carbon availability being a likely driver of improved efficiency. These results have implications for hydraulic management of woodchip bioreactors and other denitrification practices.}, number={1}, journal={Journal of Environment Quality}, publisher={American Society of Agronomy}, author={Maxwell, Bryan M. and Birgand, François and Schipper, Louis A. and Christianson, Laura E. and Tian, Shiying and Helmers, Matthew J. and Williams, David J. and Chescheir, George M. and Youssef, Mohamed A.}, year={2019}, pages={93} }
 @article{maxwell_birgand_schipper_christianson_tian_helmers_williams_chescheir_youssef_2019, title={Increased Duration of Drying–Rewetting Cycles Increases Nitrate Removal in Woodchip Bioreactors}, volume={4}, ISSN={2471-9625}, url={http://dx.doi.org/10.2134/ael2019.07.0028}, DOI={10.2134/ael2019.07.0028}, abstractNote={Core Ideas
Nitrate removal in woodchips increased linearly with drying–rewetting duration.
Nitrate removal increased up to 172% in the longest drying–rewetting duration.
Nitrate removal rates increased proportionally with dissolved organic C leaching.
}, number={1}, journal={Agricultural & Environmental Letters}, publisher={American Society of Agronomy}, author={Maxwell, Bryan M. and Birgand, François and Schipper, Louis A. and Christianson, Laura E. and Tian, Shiying and Helmers, Matthew J. and Williams, David J. and Chescheir, George M. and Youssef, Mohamed A.}, year={2019} }
 @article{park_batalla_birgand_esteves_gentile_harrington_navratil_lópez-tarazón_vericat_2019, title={Influences of Catchment and River Channel Characteristics on the Magnitude and Dynamics of Storage and Re-Suspension of Fine Sediments in River Beds}, volume={11}, ISSN={2073-4441}, url={https://www.mdpi.com/2073-4441/11/5/878}, DOI={10.3390/w11050878}, abstractNote={Fine particles or sediments are one of the important variables that should be considered for the proper management of water quality and aquatic ecosystems. In the present study, the effect of catchment characteristics on the performance of an already developed model for the estimation of fine sediments dynamics between the water column and sediment bed was tested, using 13 catchments distributed worldwide. The model was calibrated to determine two optimal model parameters. The first is the filtration parameter, which represents the filtration of fine sediments through pores of the stream bed during the recession period of a flood event. The second parameter is the bed erosion parameter that represents the active layer, directly related to the re-suspension of fine sediments during a flood event. A dependency of the filtration parameter with the catchment area was observed in catchments smaller than ~100 km2, whereas no particular relationship was observed for larger catchments (>100 km2). In contrast, the bed erosion parameter does not show a noticeable dependency with the area or other environmental characteristics. The model estimated the mass of fine sediments released from the sediment bed to the water column during flood events in the 13 catchments within ~23% bias.}, number={5}, journal={Water}, publisher={MDPI AG}, author={Park, Jungsu and Batalla, Ramon J. and Birgand, Francois and Esteves, Michel and Gentile, Francesco and Harrington, Joseph R. and Navratil, Oldrich and López-Tarazón, Jose Andres and Vericat, Damià}, year={2019}, month={Apr}, pages={878} }
 @article{cizek_johnson_birgand_hunt_mclaughlin_2019, title={Insights from using in-situ ultraviolet–visible spectroscopy to assess nitrogen treatment and subsurface dynamics in a regenerative stormwater conveyance (RSC) system}, volume={252}, ISSN={0301-4797}, url={http://dx.doi.org/10.1016/j.jenvman.2019.109656}, DOI={10.1016/j.jenvman.2019.109656}, abstractNote={Regenerative stormwater conveyance (RSC) is a recently developed stormwater control measure that marries the concepts of bioretention and stream restoration. RSC mitigates stormwater runoff by converting surface flow to subsurface seepage using a series of pools and riffles built over a sand media bed. Subsurface seepage flows through media and exits the RSC beneath the outlet weir. Previous studies on RSC pollutant mitigation have focused on surface flow discharges from the RSC. To date, no known research has been conducted on the potential pollutant contributions of RSC seepage, despite the fact that this water also enters receiving waters. This research used Multi-Point Sampling coupled with in-situ ultraviolet–visual spectroscopy to measure nitrogen in seepage during simulated storm events (n = 9) at a field-scale RSC in Raleigh, North Carolina. Calibrations between light absorbance and concentrations were acceptable (Nash-Sutcliffe coefficient > 0.65) for nitrate and total ammoniacal nitrogen (TAN) and very good (Nash-Sutcliffe coefficient > 0.90) for total Kjehdahl nitrogen (TKN). Early storm simulations revealed some initial nutrient flushing from the substrate, which subsided by the third simulation. Overall, subsurface seepage nitrate, TAN, and TKN concentrations were lower by 29%, 57%, and 4% relative to storm inflow concentrations, respectively. Computed subsurface nitrogen concentrations demonstrated temporal variability, highlighting dynamic transport and biogeochemical transformations in saturated and unsaturated conditions. Nitrogen concentrations were lower in seepage than in surface flow; however, due to the high volume of runoff converted to seepage, nitrogen loads discharged in seepage can be larger than those of surface flow. Further research is needed to examine subsurface pollutant reductions under varying hydrologic and seasonal conditions.}, journal={Journal of Environmental Management}, publisher={Elsevier BV}, author={Cizek, Adrienne R. and Johnson, Jeffrey P. and Birgand, François and Hunt, William F. and McLaughlin, Richard A.}, year={2019}, month={Dec}, pages={109656} }
 @article{liu_maxwell_birgand_youssef_chescheir_tian_2019, title={Multipoint High-Frequency Sampling System to Gain Deeper Insights on the Fate of Nitrate in Artificially Drained Fields}, volume={146}, ISSN={0733-9437 1943-4774}, url={http://dx.doi.org/10.1061/(ASCE)IR.1943-4774.0001438}, DOI={10.1061/(ASCE)IR.1943-4774.0001438}, abstractNote={AbstractThe application of high-frequency measurements could potentially enhance current understanding of the hydrology and biogeochemistry of artificially drained agricultural lands. In addition t...}, number={1}, journal={Journal of Irrigation and Drainage Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Liu, Wenlong and Maxwell, Bryan and Birgand, François and Youssef, Mohamed and Chescheir, George and Tian, Shiying}, year={2019}, month={Jan}, pages={06019012} }
 @article{maxwell_birgand_smith_aveni-deforge_2018, title={A small-volume multiplexed pumping system for automated, high-frequency water chemistry measurements in volume-limited applications}, volume={22}, ISSN={1607-7938}, url={http://dx.doi.org/10.5194/hess-22-5615-2018}, DOI={10.5194/hess-22-5615-2018}, abstractNote={Abstract. An automated multiplexed pumping system (MPS) for high-frequency water chemistry measurements at multiple locations previously showed the ability to increase spatial and temporal data resolution and improve understanding of biogeochemical processes in aquatic environments and at the land–water interface. The design of the previous system precludes its use in volume-limited applications in which highly frequent measurements requiring a large sample volume would significantly affect observed processes. A small-volume MPS was designed to minimize the sample volume while still providing high-frequency data. The system was tested for cross-contamination between multiple sources, and two applications of the technology are reported. Cross-contamination from multiple sources was shown to be negligible when using recommended procedures. Short-circuiting of flow in a bioreactor was directly observed using high-frequency porewater sampling in a well network, and the small-volume MPS showed high seasonal and spatial variability of nitrate removal in stream sediments, enhancing data collected from in situ mesocosms. The results show it is possible to obtain high-frequency data in volume-limited applications. The technology is most promising at the reach or transect scale for observing porewater solute dynamics over daily timescales, with data intervals  < 1 h for up to 12 locations.
                    }, number={11}, journal={Hydrology and Earth System Sciences}, publisher={Copernicus GmbH}, author={Maxwell, Bryan M. and Birgand, François and Smith, Brad and Aveni-Deforge, Kyle}, year={2018}, month={Oct}, pages={5615–5628} }
 @article{vongvixay_grimaldi_dupas_fovet_birgand_gilliet_gascuel-odoux_2018, title={Contrasting suspended sediment export in two small agricultural catchments: Cross-influence of hydrological behaviour and landscape degradation or stream bank management}, volume={29}, ISSN={1085-3278}, url={http://dx.doi.org/10.1002/ldr.2940}, DOI={10.1002/ldr.2940}, abstractNote={Abstract}, number={5}, journal={Land Degradation & Development}, publisher={Wiley}, author={Vongvixay, Amphone and Grimaldi, Catherine and Dupas, Rémi and Fovet, Ophélie and Birgand, François and Gilliet, Nicolas and Gascuel-Odoux, Chantal}, year={2018}, month={Apr}, pages={1385–1396} }
 @article{harmel_king_busch_smith_birgand_haggard_2018, title={Measuring edge-of-field water quality: Where we have been and the path forward}, volume={73}, ISSN={0022-4561 1941-3300}, url={http://dx.doi.org/10.2489/jswc.73.1.86}, DOI={10.2489/jswc.73.1.86}, abstractNote={Heightened pressure to demonstrate the resource benefits of conservation practices and continued high-profile water quality impairments and concerns are increasing the need to quantify edge-of-field (EOF) water quality. With this in mind, this manuscript summarizes previous developments in EOF water quality sampling and presents current research and glimpses into the future. This manuscript focuses on constituent sampling at the field-scale or at the “edge-of-field;” however, many of the findings are also applicable for small stream or small watershed sampling. With development of programmable automated samplers and initiation of numerous automated sampling projects, it became readily apparent that neither equipment manufacturers nor researchers could provide guidance on design components (e.g., sample initiation, timing/intervals, and type). This was problematic as available monitoring resources are too limited and data needs too great for such projects to be designed solely based on field experience and without a scientific basis or with complete disregard for potential data quality implications. Thus practical, science-based guidance for EOF sampling was developed and fundamental understanding of the inherent uncertainty was established to assist researchers, municipalities, consulting firms, and regulatory agencies improve data quality and monitoring resource efficiency. Looking to the future, further improvements are needed related to lower cost systems, practical improvements, and enhanced in situ sampling, along with enhanced understanding and consideration of data uncertainty in modeling and decision making.}, number={1}, journal={Journal of Soil and Water Conservation}, publisher={Soil and Water Conservation Society}, author={Harmel, R.D. and King, K. and Busch, D. and Smith, D. and Birgand, F. and Haggard, B.}, year={2018}, pages={86–96} }
 @article{addy_gold_loffredo_schroth_inamdar_bowden_kellogg_birgand_2018, title={Stream response to an extreme drought-induced defoliation event}, volume={140}, ISSN={0168-2563 1573-515X}, url={http://dx.doi.org/10.1007/s10533-018-0485-3}, DOI={10.1007/s10533-018-0485-3}, number={2}, journal={Biogeochemistry}, publisher={Springer Science and Business Media LLC}, author={Addy, Kelly and Gold, Arthur J. and Loffredo, Joseph A. and Schroth, Andrew W. and Inamdar, Shreeram P. and Bowden, William B. and Kellogg, D. Q. and Birgand, François}, year={2018}, month={Aug}, pages={199–215} }
 @article{howden_birgand_burt_worrall_2018, title={The seven sources of variance in fluvial flux time series}, volume={32}, ISSN={0885-6087 1099-1085}, url={http://dx.doi.org/10.1002/hyp.13300}, DOI={10.1002/hyp.13300}, abstractNote={Nicholas J K Howden1,2 Francois Birgand1,3 Tim Burt1,4,5 Fred Worrall6 1Department of Civil Engineering, School of Civil, Mechanical and Aerospace Engineering, University of Bristol, Bristol, UK 2Cabot Institute, Royal Fort House, University of Bristol, Bristol, UK 3Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, North Carolina, 4Department of Geography, Durham University, Durham, UK 5School of Geographical Sciences, University of Bristol, Bristol, UK 6Department of Earth Science, Science Laboratories, Durham University, Durham, UK Correspondence Nicholas J K Howden, Department of Civil Engineering, School of Civil, Mechanical and Aerospace Engineering, Queen's Building, University Walk, Bristol, BS9 1TR, UK. Email: nicholas.howden@bristol.ac.uk}, number={26}, journal={Hydrological Processes}, publisher={Wiley}, author={Howden, Nicholas J K and Birgand, Francois and Burt, Tim and Worrall, Fred}, year={2018}, month={Oct}, pages={3996–3997} }
 @article{ssegane_amatya_muwamba_chescheir_appelboom_tollner_nettles_youssef_birgand_skaggs_et al._2017, title={Calibration of paired watersheds: Utility of moving sums in presence of externalities}, volume={31}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.11248}, DOI={10.1002/hyp.11248}, abstractNote={Abstract}, number={20}, journal={Hydrological Processes}, publisher={Wiley}, author={Ssegane, H. and Amatya, D. M. and Muwamba, A. and Chescheir, G. M. and Appelboom, T. and Tollner, E. W. and Nettles, J. E. and Youssef, M. A. and Birgand, François and Skaggs, R. W. and et al.}, year={2017}, month={Sep}, pages={3458–3471} }
 @article{etheridge_burchell_birgand_2017, title={Can created tidal marshes reduce nitrate export to downstream estuaries?}, volume={105}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2017.05.009}, DOI={10.1016/j.ecoleng.2017.05.009}, abstractNote={Constructed marshes have the potential to serve as a buffer between anthropogenic sources of nitrogen and nutrient sensitive estuaries. Yet, there is little information available on the reduction of nitrogen loads that created tidal marshes might provide. A 5.6 ha brackish marsh was constructed between row crop agricultural production and an estuary in North Carolina. Nitrate-N fluxes in and out of the marsh were monitored multiple times per hour for over a year to capture tidal and storm dynamics. Out of the five storms when most of the fluxes occurred, nitrate was retained in four (up to 42%), and released in the fifth, such that over the monitoring period the marsh retained 9% (40 kg) of the nitrate that entered. Nutrient addition tracer studies confirmed the potential nitrate retention (up to 45%) of the marsh. The residence time of water in the constructed brackish marsh was identified as the primary factor limiting nitrate retention through an examination of the factors that were related to percent nitrate retention. A retention model based on a mass transfer coefficient was applied during the storm events and tracer studies to further evaluate the marsh N retention capacity. The model adequately simulated the nitrate retention with calibrated mass transfer coefficients (0.1–0.56 m day−1) that fell within the range of those reported in literature for other systems. These results indicate that constructed tidal marshes can serve as substantial nitrate sinks and can be an integral part of overall plans to reduce the nutrient export to estuaries.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Etheridge, J. Randall and Burchell, Michael R., II and Birgand, François}, year={2017}, month={Aug}, pages={314–324} }
 @article{messer_burchell_bírgand_2017, title={Comparison of Four Nitrate Removal Kinetic Models in Two Distinct Wetland Restoration Mesocosm Systems}, volume={9}, ISSN={2073-4441}, url={http://dx.doi.org/10.3390/w9070517}, DOI={10.3390/w9070517}, abstractNote={The objective of the study was to determine the kinetic model that best fit observed nitrate removal rates at the mesocosm scale in order to determine ideal loading rates for two future wetland restorations slated to receive pulse flow agricultural drainage water. Four nitrate removal models were investigated: zero order, first order decay, efficiency loss, and Monod. Wetland mesocosms were constructed using the primary soil type (in triplicate) at each of the future wetland restoration sites. Eighteen mesocosm experiments were conducted over two years across seasons. Simulated drainage water was loaded into wetlands as batches, with target nitrate-N levels typically observed in agricultural drainage water (between 2.5 and 10 mg L−1). Nitrate-N removal observed during the experiments provided the basis for calibration and validation of the models. When the predictive strength of each of the four models was assessed, results indicated that the efficiency loss and first order decay models provided the strongest agreement between predicted and measured NO3-N removal rates, and the fit between the two models were comparable. Since the predictive power of these two models were similar, the less complicated first order decay model appeared to be the best choice in predicting appropriate loading rates for the future full-scale wetland restorations.}, number={7}, journal={Water}, publisher={MDPI AG}, author={Messer, Tiffany and Burchell, Michael and Bírgand, François}, year={2017}, month={Jul}, pages={517} }
 @article{vaughan_bowden_shanley_vermilyea_sleeper_gold_pradhanang_inamdar_levia_andres_et al._2017, title={High‐frequency dissolved organic carbon and nitrate measurements reveal differences in storm hysteresis and loading in relation to land cover and seasonality}, volume={53}, ISSN={0043-1397 1944-7973}, url={http://dx.doi.org/10.1002/2017WR020491}, DOI={10.1002/2017wr020491}, abstractNote={Abstract}, number={7}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={Vaughan, M. C. H. and Bowden, W. B. and Shanley, J. B. and Vermilyea, A. and Sleeper, R. and Gold, A. J. and Pradhanang, S. M. and Inamdar, S. P. and Levia, D. F. and Andres, A. S. and et al.}, year={2017}, month={Jul}, pages={5345–5363} }
 @article{messer_burchell_birgand_broome_chescheir_2017, title={Nitrate removal potential of restored wetlands loaded with agricultural drainage water: A mesocosm scale experimental approach}, volume={106}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2017.06.022}, DOI={10.1016/j.ecoleng.2017.06.022}, abstractNote={Wetland restoration is often conducted in Eastern U.S. coastal plain watersheds alongside agricultural lands that frequently export significant amounts of nitrogen in drainage water. Restoration plans that incorporate the addition of agricultural drainage water can simultaneously increase the success of achieving a target hydroperiod and reduce discharge of nitrogen to nearby surface water. The potential nitrogen removal effectiveness of two wetland restoration sites with such a restoration plan was evaluated in a two-year mesocosm study. Six large wetland mesocosms (3.5 m long × 0.9 m wide × 0.75 m deep) along with unplanted controls were used in this experiment. Three replicates of two soils that differed in organic matter and pH were planted with soft-stem bulrush (Schoenoplectus tabernaemontani) and allowed to develop in the two growing seasons prior to the study. Simulated drainage water was loaded into the mesocosms over eighteen batch studies across seasons with target nitrate-N levels between 2.5 to 10 mg L−1. Grab samples were collected from the water column and analyzed for nitrate-N, dissolved organic carbon, and chloride, along with other environmental parameters such as pH, water temperature, and soil redox. Seasonally, nitrogen and carbon within the wetland plants and soil were also measured. Multivariate statistical analyses were utilized to determine differences in nitrate-N reductions between treatments. Variables included carbon availability, temperature, antecedent moisture condition, nitrogen loading, and water pH. Contrary to the hypothesis that higher nitrate-N removal rates would be observed in the wetlands with higher organic matter, overall removal rates were higher in the wetland mesocosms containing Deloss soils (WET-Min) (maximum of 726 mg m−2 d−1) than those containing Scuppernong soil (WET-Org) (maximum of 496 mg m−2 d−1) and were dependent on daily NO3-N concentrations and season. Significant differences in NO3-N removal were found between seasons and soil types (α = 0.05), which helped to provide insight to the expected magnitude of nitrogen removal within these systems throughout the year, and potential mechanisms (i.e. denitrification vs. plant uptake) that will govern these removals.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Messer, Tiffany L. and Burchell, Michael R., II and Birgand, François and Broome, Stephen W. and Chescheir, George}, year={2017}, month={Sep}, pages={541–554} }
 @article{muwamba_amatya_chescheir_nettles_appelboom_ssegane_tollner_youssef_birgand_skaggs_et al._2017, title={Water Quality Effects of Switchgrass Intercropping on Pine Forest in Coastal North Carolina}, volume={60}, ISSN={2151-0040}, url={http://dx.doi.org/10.13031/trans.12181}, DOI={10.13031/trans.12181}, abstractNote={Abstract.}, number={5}, journal={Transactions of the ASABE}, publisher={American Society of Agricultural and Biological Engineers (ASABE)}, author={Muwamba, Augustine and Amatya, Devendra M. and Chescheir, George M. and Nettles, Jami E. and Appelboom, Timothy and Ssegane, Herbert and Tollner, Ernest E and Youssef, Mohamed A. and Birgand, Francois and Skaggs, R. Wayne and et al.}, year={2017}, pages={1607–1620} }
 @article{birgand_aveni-deforge_smith_maxwell_horstman_gerling_carey_2016, title={First report of a novel multiplexer pumping system coupled to a water quality probe to collect high temporal frequency in situ water chemistry measurements at multiple sites}, volume={14}, ISSN={1541-5856}, url={http://dx.doi.org/10.1002/lom3.10122}, DOI={10.1002/lom3.10122}, abstractNote={The increasing availability and use of high‐frequency water quality sensors has enabled unprecedented observations of temporal variability in water chemistry in aquatic ecosystems. However, we remain limited by the prohibitive costs of these probes to explore spatial variability in natural systems. To overcome this challenge, we have developed a novel auto‐sampler system that sequentially pumps water from up to 12 different sites located within a 12 m radius to a single water quality probe. This system is able to generate high temporal frequency in situ water chemistry data from multiple replicated units during experiments as well as multiple sites and depths within natural aquatic ecosystems. Thus, with one water quality probe, we are able to observe rapid changes in water chemistry concentrations over time and space. Here, we describe the coupled multiplexer‐probe system and its performance in two case studies: a mesocosm experiment examining the effects of water current velocity on nitrogen dynamics in constructed wetland sediment cores and a whole‐ecosystem manipulation of redox conditions in a reservoir. In both lotic and lentic case studies, we observed minute‐scale changes in nutrient concentrations, which provide new insight on the variability of biogeochemical processes. Moreover, in the reservoir, we were able to measure rapid changes in metal concentrations, in addition to those of nutrients, in response to changes in redox. Consequently, we believe that this coupled system holds great promise for measuring biogeochemical fluxes in a diverse suite of aquatic ecosystems and experiments.}, number={12}, journal={Limnology and Oceanography: Methods}, publisher={Wiley}, author={Birgand, François and Aveni-Deforge, Kyle and Smith, Brad and Maxwell, Bryan and Horstman, Marc and Gerling, Alexandra B. and Carey, Cayelan C.}, year={2016}, month={Jul}, pages={767–783} }
 @article{shiau_burchell_krauss_birgand_broome_2016, title={Greenhouse Gas Emissions from a Created Brackish Marsh in Eastern North Carolina}, volume={36}, ISSN={0277-5212 1943-6246}, url={http://dx.doi.org/10.1007/s13157-016-0815-y}, DOI={10.1007/s13157-016-0815-y}, number={6}, journal={Wetlands}, publisher={Springer Nature}, author={Shiau, Yo-Jin and Burchell, Michael R. and Krauss, Ken W. and Birgand, Francois and Broome, Stephen W.}, year={2016}, month={Sep}, pages={1009–1024} }
 @article{burnette_genereux_birgand_2016, title={In-situ falling-head test for hydraulic conductivity: Evaluation in layered sediments of an analysis derived for homogenous sediments}, volume={539}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2016.05.030}, DOI={10.1016/j.jhydrol.2016.05.030}, abstractNote={The hydraulic conductivity (K) of streambeds is a critical variable controlling interaction of groundwater and surface water. The Hvorslev analysis for estimating K from falling-head test data has been widely used since the 1950s, but its performance in layered sandy sediments common in streams and lakes has not previously been examined. Our numerical simulations and laboratory experiments show that the Hvorslev analysis yields accurate K values in both homogenous sediment (for which the analysis was originally derived) and layered deposits with low-K sand over high-K sand. K from the Hvorslev analysis deviated significantly from true K only when two conditions were present together: (1) high-K sand was present over low-K sand, and (2) the bottom of the permeameter in which K was measured was at or very near the interface between high-K and low-K. When this combination of conditions exists, simulation and laboratory sand tank results show that in-situ Hvorslev K underestimates the true K of the sediment within a permeameter, because the falling-head test is affected by low-K sediment outside of (below the bottom of) the permeameter. In simulation results, the maximum underestimation (occurring when the bottom of the permeameter was at the interface of high K over low K) was by a factor of 0.91, 0.59, and 0.12 when the high-K to low-K ratio was 2, 10, and 100, respectively. In laboratory sand tank experiments, the underestimation was by a factor of about 0.83 when the high-K to low-K ratio was 2.3. Also, this underestimation of K by the Hvorslev analysis was about the same whether the underlying low-K layer was 2 cm or 174 cm thick (1% or 87% of the domain thickness). Numerical model simulations were useful in the interpretation of in-situ field K profiles at streambed sites with layering; specifically, scaling the model results to the maximum measured K at the top of the field K profiles helped constrain the likely ratio of high K to low K at field locations with layered heterogeneity. Vertical K values are important in field studies of groundwater–surface water interaction, and the Hvorslev analysis can be a useful tool, even in layered media, when applied carefully.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Burnette, Matthew C. and Genereux, David P. and Birgand, François}, year={2016}, month={Aug}, pages={319–329} }
 @article{gilmore_genereux_solomon_solder_kimball_mitasova_birgand_2016, title={Quantifying the fate of agricultural nitrogen in an unconfined aquifer: Stream-based observations at three measurement scales}, volume={52}, ISSN={0043-1397}, url={http://dx.doi.org/10.1002/2015WR017599}, DOI={10.1002/2015wr017599}, abstractNote={Abstract}, number={3}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={Gilmore, Troy E. and Genereux, David P. and Solomon, D. Kip and Solder, John E. and Kimball, Briant A. and Mitasova, Helena and Birgand, François}, year={2016}, month={Mar}, pages={1961–1983} }
 @article{polizzotto_birgand_badruzzaman_ali_2015, title={Amending irrigation channels with jute-mesh structures to decrease arsenic loading to rice fields in Bangladesh}, volume={74}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2014.10.030}, DOI={10.1016/j.ecoleng.2014.10.030}, abstractNote={Abstract Extensive use of arsenic-contaminated well water for irrigation of rice fields in Bangladesh has led to elevated arsenic concentrations in rice plants, decreased rice yields, and increased human exposure to arsenic. The goal of this study was to investigate whether arsenic removal from irrigation water could be improved within distribution channels by amending them with physical structures that both induce water treatment and maintain water-conveyance capacities. Chemical and hydraulic effects of amending channels with jute-mesh structures were characterized within 27 m-long experimental channels at a Bangladesh field site. Removal of total arsenic, iron and phosphorus from solution was enhanced within amended channels over unamended channels, with 7% of total As removed in amended channels vs. 3% in unamended channels. Increased elemental removal in amended channels was largely due to increases in residence time and particle-trapping efficiency, but removal via oxidative particle formation did not appear to be substantially enhanced. Results suggest that in-channel structures could be a useful tool for decreasing arsenic loading to rice fields, particularly where constrained channel spatial geometries limit the ability to overcome hydrogeochemical thresholds for enhanced arsenic removal. To improve the practical utility of structure-amended channels, future work could optimize structure designs and establish the season-long sustainability of enhanced arsenic-removal strategies.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Polizzotto, Matthew L. and Birgand, François and Badruzzaman, A. Borhan M. and Ali, M. Ashraf}, year={2015}, month={Jan}, pages={101–106} }
 @article{de billy_tournebize_barnaud_benoît_birgand_garnier_lesaffre_lévêque_de marsily_muller_et al._2015, title={Compenser la destruction de zones humides. Retours d’expérience sur les méthodes et réflexions inspirées par le projet d’aéroport de Notre-Dame-des-Landes (France)}, volume={23}, ISSN={1240-1307 1765-2979}, url={http://dx.doi.org/10.1051/nss/2015008}, DOI={10.1051/nss/2015008}, abstractNote={Debut 2013, les auteurs de cet article ont ete conjointement sollicites par l’Etat pour donner un avis sur la methode de compensation des atteintes aux zones humides proposees pour le projet d’aeroport du Grand Ouest a Notre-Dame-des-Landes en Loire-Atlantique. Cet article fait etat des reflexions consecutives a ce travail qui, au-dela du cas aborde, portent sur les methodes a utiliser pour compenser les atteintes aux zones humides alterees, degradees ou detruites par un amenagement. Il presente tout d’abord le cadre juridique actuel de la compensation ; puis l’experience internationale acquise principalement aux Etats-Unis, peu de cas similaires existant en France. Enfin, il propose des recommandations sur les modalites d’evaluation du besoin et de la reponse de compensation des atteintes aux zones humides, en insistant notamment sur l’utilite d’y integrer le facteur temporel, le risque d’echec, l’ecologie du paysage et la valeur patrimoniale de ces milieux. En conclusion, l’attention est portee sur les questions que soulevent la disponibilite et l’usage des terres de compensation, l’incertitude associee aux methodes de genie ecologique et la difficulte de prevoir les trajectoires de ces ecosystemes restaures/recrees.}, number={1}, journal={Natures Sciences Sociétés}, publisher={EDP Sciences}, author={de Billy, Véronique and Tournebize, Julien and Barnaud, Geneviève and Benoît, Marc and Birgand, François and Garnier, Josette and Lesaffre, Benoît and Lévêque, Christian and de Marsily, Ghislain and Muller, Serge and et al.}, year={2015}, month={Jan}, pages={27–41} }
 @article{muwamba_amatya_ssegane_chescheir_appelboom_tollner_nettles_youssef_birgand_skaggs_et al._2015, title={Effects of Site Preparation for Pine Forest/Switchgrass Intercropping on Water Quality}, volume={44}, ISSN={0047-2425}, url={http://dx.doi.org/10.2134/jeq2014.11.0505}, DOI={10.2134/jeq2014.11.0505}, abstractNote={A study was initiated to investigate the sustainability effects of intercropping switchgrass ( L.) in a loblolly pine ( L.) plantation. This forest-based biofuel system could possibly provide biomass from the perennial energy grass while maintaining the economics and environmental benefits of a forest managed for sawtimber. Operations necessary for successful switchgrass establishment and growth, such as site preparation, planting, fertilizing, mowing and baling, may affect hydrology and nutrient runoff. The objectives of this study were (i) to characterize the temporal effects of management on nutrient concentrations and loadings and (ii) to use pretreatment data to predict those treatment effects. The study watersheds (∼25 ha each) in the North Carolina Atlantic Coastal Plain were a pine/switchgrass intercropped site (D1), a midrotation thinned pine site with natural understory (D2), and a switchgrass-only site (D3). Rainfall, drainage, water table elevation, nitrogen (total Kjedahl N, NH-N, and NO-N), and phosphate were monitored for the 2007-2008 pretreatment and the 2009-2012 treatment periods. From 2010 to 2011 in site D1, the average NO-N concentration effects decreased from 0.18 to -0.09 mg L, and loads effects decreased from 0.86 to 0.49 kg ha. During the same period in site D3, the average NO-N concentration effects increased from 0.03 to 0.09 mg L, and loads effects increased from -0.26 to 1.24 kg ha. This study shows the importance of considering water quality effects associated with intensive management operations required for switchgrass establishment or other novel forest-based biofuel systems.}, number={4}, journal={Journal of Environment Quality}, publisher={American Society of Agronomy}, author={Muwamba, A. and Amatya, D. M. and Ssegane, H. and Chescheir, G.M. and Appelboom, T. and Tollner, E.W. and Nettles, J. E. and Youssef, M. A. and Birgand, F. and Skaggs, R. W. and et al.}, year={2015}, pages={1263} }
 @article{etheridge_birgand_burchell_2015, title={Quantifying nutrient and suspended solids fluxes in a constructed tidal marsh following rainfall: The value of capturing the rapid changes in flow and concentrations}, volume={78}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2014.05.021}, DOI={10.1016/j.ecoleng.2014.05.021}, abstractNote={Coastal tidal wetlands are perceived to provide nutrient dissipation services and serve as the final buffer between excess nutrient loads coming from nearby upland watersheds and sensitive estuarine waters. The construction and restoration of tidal marshes has the potential to benefit coastal waters. However, the water quality services of tidal wetlands have yet to be established with any certainty. This is in part due to the difficulty of monitoring these systems where flow and concentrations vary widely with tidal ebb and flood along with rainfall events mobilizing nutrients in pulses from upstream watersheds. In this article, we show over a period of 10 days following a rainfall event, the value of high temporal resolution data to characterize the complex nutrient and flow dynamics and to reliably calculate material balances in a created coastal marsh in North Carolina. Ultraviolet–visible spectrometers were used to obtain 15-min concentration data for nitrate, total Kjeldahl nitrogen, dissolved organic carbon, total suspended solids, phosphate, and total phosphorus. Our results show that a pulse of nitrate moved through the marsh from upstream agricultural production following the rainfall event and 25% (13 kg of 53 kg) of the nitrate was retained in the marsh over a period of 10 days. No other material showed a clear pulse from the upstream agricultural production. The marsh acted as a sink for total suspended solids (40 kg) and had near neutral mass balances for dissolved organic carbon, total Kjeldahl nitrogen, total phosphorus, and phosphate. Subsequent simulations indicated that different and erroneous results would have been obtained from 2-, 6- or 12-h sampling intervals. These results demonstrate, even on a short term basis, why high-frequency data acquisition is necessary in these tidal marsh systems to truly quantify their impact on water quality ecosystem services.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Etheridge, J. Randall and Birgand, François and Burchell, Michael R., II}, year={2015}, month={May}, pages={41–52} }
 @article{osburn_mikan_etheridge_burchell_birgand_2015, title={Seasonal variation in the quality of dissolved and particulate organic matter exchanged between a salt marsh and its adjacent estuary}, volume={120}, ISSN={2169-8953}, url={http://dx.doi.org/10.1002/2014JG002897}, DOI={10.1002/2014jg002897}, abstractNote={Abstract}, number={7}, journal={Journal of Geophysical Research: Biogeosciences}, publisher={American Geophysical Union (AGU)}, author={Osburn, Christopher L. and Mikan, Molly P. and Etheridge, J. Randall and Burchell, Michael R. and Birgand, François}, year={2015}, month={Jul}, pages={1430–1449} }
 @article{etheridge_birgand_burchell ii_lepistö_rankinen_granlund_2014, title={Technical Note: Alternative in-stream denitrification equation for the INCA-N model}, volume={18}, ISSN={1607-7938}, url={http://dx.doi.org/10.5194/hess-18-1467-2014}, DOI={10.5194/hess-18-1467-2014}, abstractNote={Abstract. The Integrated Catchment model for Nitrogen (INCA-N) is a semi-distributed, process based model that has been used to model the impacts of land use, climate, and land management changes on hydrology and nitrogen loading. An observed problem with the INCA-N model is reproducing low nitrate–nitrogen concentrations during the summer growing season in some catchments. In this study, the current equation used to simulate the rate of in-stream denitrification was replaced with an alternate equation that uses a mass transfer coefficient and the stream bottom area. The results of simulating in-stream denitrification using the two different methods were compared for a one year simulation period of the Yläneenjoki catchment in Finland. The alternate equation (Nash–Sutcliffe efficiency = 0.61) simulated concentrations during the periods of the growing season with the lowest flow that were closer to the observed concentrations than the current equation (Nash–Sutcliffe efficiency = 0.60), but the results were mixed during other portions of the year. The results of the calibration and validation of the model using the two equations show that the alternate equation will simulate lower nitrate–nitrogen concentrations during the growing season when compared to the current equation, but promote investigation into other errors in the model that may be causing inaccuracies in the modeled concentrations.
                    }, number={4}, journal={Hydrology and Earth System Sciences}, publisher={Copernicus GmbH}, author={Etheridge, J. R. and Birgand, F. and Burchell II, M. R. and Lepistö, A. and Rankinen, K. and Granlund, K.}, year={2014}, month={Apr}, pages={1467–1473} }
 @article{etheridge_birgand_osborne_osburn_burchell_irving_2014, title={Using in situ ultraviolet-visual spectroscopy to measure nitrogen, carbon, phosphorus, and suspended solids concentrations at a high frequency in a brackish tidal marsh}, volume={12}, ISSN={1541-5856}, url={http://dx.doi.org/10.4319/lom.2014.12.10}, DOI={10.4319/lom.2014.12.10}, abstractNote={The collection of high frequency water quality data are key to making the next leap in hydrological and biogeochemical sciences. Commercially available in situ ultraviolet‐visual (UV‐Vis) spectrometers make possible the long‐term collection of absorption spectra multiple times per hour. This technology has proven useful for measuring nitrate, dissolved organic carbon, and total suspended solids in many environments, but has not been tested in tidal marsh conditions where upstream freshwater mixes with estuarine waters, resulting in rapid changes in concentrations and salinity. These three parameters encompass only a portion of the nutrients that are of interest in these systems. To test the potential of spectroscopy to measure these and other nutrient concentrations, spectrometers were installed in a constructed brackish tidal marsh and absorbance spectra were compared to lab analyses for coinciding discrete samples. Variable selection techniques, including partial least squares regression, lasso regression, and stepwise regression, were used to develop models with which nitrate, total kjeldahl nitrogen, dissolved organic carbon, phosphate, total phosphorus, total suspended solids, and salinity in brackish marsh waters can be predicted from UV‐Vis spectrometer measurements. Significant relationships between the absorption spectra and the laboratory measured concentrations were observed for all of the parameters. Phosphate and total phosphorus were the only nutrients which had R2 values less than 0.86 for their best calibrations. This study shows the potential to collect multiple water quality parameters at a high frequency in brackish waters using in situ spectrometers and gives the tools to replicate this analysis in all environments.}, number={1}, journal={Limnology and Oceanography: Methods}, publisher={Wiley}, author={Etheridge, J. Randall and Birgand, François and Osborne, Jason A. and Osburn, Christopher L. and Burchell, Michael R., II and Irving, Justin}, year={2014}, month={Jan}, pages={10–22} }
 @article{etheridge_birgand_burchell_smith_2013, title={Addressing the Fouling of In Situ Ultraviolet-Visual Spectrometers Used to Continuously Monitor Water Quality in Brackish Tidal Marsh Waters}, volume={42}, ISSN={0047-2425}, url={http://dx.doi.org/10.2134/jeq2013.02.0049}, DOI={10.2134/jeq2013.02.0049}, abstractNote={The introduction of portable in situ ultraviolet-visual spectrometers has made possible the collection of water quality parameters at a high frequency in dynamic systems such as tidal marshes. The usefulness of this technology is inhibited by fouling of the instrument's optics. In this study, a spectrometer fitted with manufacturer-recommended compressed air optical cleaning was installed in a brackish marsh to determine if fouling interfered with measurements between bi-weekly servicing. During a 2-wk period, the absorbance measured in air at 220 nm increased from 9 to 549 m, indicating major fouling. An antifouling system was developed that reduced the time of exposure of the optics to stream water and used a pressurized fresh water cleaning. After implementation of the system, the absorbance in air increased to at most 63 m after 2 wk of data collection. The dramatic reduction in fouling will allow quality long-term data to be collected using this technology.}, number={6}, journal={Journal of Environment Quality}, publisher={American Society of Agronomy}, author={Etheridge, J. Randall and Birgand, François and Burchell, Michael R. and Smith, Brad T.}, year={2013}, pages={1896} }
 @article{brown_birgand_hunt_2013, title={Analysis of Consecutive Events for Nutrient and Sediment Treatment in Field-Monitored Bioretention Cells}, volume={224}, ISSN={0049-6979 1573-2932}, url={http://dx.doi.org/10.1007/s11270-013-1581-6}, DOI={10.1007/s11270-013-1581-6}, number={6}, journal={Water, Air, & Soil Pollution}, publisher={Springer Science and Business Media LLC}, author={Brown, Robert A. and Birgand, Francois and Hunt, William F.}, year={2013}, month={May} }
 @article{billy_birgand_ansart_peschard_sebilo_tournebize_2013, title={Factors controlling nitrate concentrations in surface waters of an artificially drained agricultural watershed}, volume={28}, ISSN={0921-2973 1572-9761}, url={http://dx.doi.org/10.1007/s10980-013-9872-2}, DOI={10.1007/s10980-013-9872-2}, number={4}, journal={Landscape Ecology}, publisher={Springer Science and Business Media LLC}, author={Billy, Claire and Birgand, François and Ansart, Patrick and Peschard, Julien and Sebilo, Mathieu and Tournebize, Julien}, year={2013}, month={Mar}, pages={665–684} }
 @article{birgand_lellouche_appelboom_2013, title={Measuring flow in non-ideal conditions for short-term projects: Uncertainties associated with the use of stage-discharge rating curves}, volume={503}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2013.09.007}, DOI={10.1016/j.jhydrol.2013.09.007}, abstractNote={The vast majority of hydrological stations are set up such that discharge can be estimated from the sole measurement of water height or stage above a local datum. Hydraulics laws show that in the right conditions there may be a unique and stable relationship between stage and discharge, which can be described by a rating curve. For short-term projects where there may be little choice for station location and time to construct a detailed rating curve, conditions for the use of rating curves may be less than ideal, potentially yielding high uncertainties on hydrologic measurements. This article evaluates uncertainties induced on instantaneous flow rates and cumulative annual flow volumes by the use of one-segmented rating curves in small streams. Uncertainty distributions were obtained by simulating rating curves calculated from random sampling of reference flow and stage data obtained with Doppler flowmeters. Factors tested included the number of manual gauged points, the type of rating curve (power vs polynomial), the use or not of the observed stage-of-zero flow, the spread of gauged points along flow range, and the measurement errors during gauging. Results could vary widely depending on the scenarios tested and sometimes yielded very high uncertainties. The best scenario yielded significant uncertainties on annual cumulative flow volume included between −13% and +14% for the low gradient streams and between −5% and +7% for the higher gradient streams, and for 22 manual gauged points per year. Our results show that, even in the best scenario, very significant uncertainty can result from using one-segmented rating curve in non-ideal situations in the field.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Birgand, François and Lellouche, Guillaume and Appelboom, T.W.}, year={2013}, month={Oct}, pages={186–195} }
 @article{randall etheridge_lepistö_granlund_rankinen_birgand_burchell_2013, title={Reducing uncertainty in the calibration and validation of the INCA-N model by using soft data}, volume={45}, ISSN={0029-1277 2224-7955}, url={http://dx.doi.org/10.2166/nh.2013.039}, DOI={10.2166/nh.2013.039}, abstractNote={Process-based nutrient models are increasingly used to determine the impact of future changes in land use, agriculture production practices and climate on the quantity and timing of nutrients reaching surface waters. Calibration of catchment-scale models to observed conditions can be difficult due to parameter uncertainty and the heterogeneity of catchment processes. Soft data, i.e. knowledge of processes gained through experimentation, have been suggested as one method of reducing uncertainty and producing a more accurate model of the processes that occur in a catchment. In this work, the Integrated Catchment model for Nitrogen was calibrated and validated for the Yläneenjoki catchment in south-western Finland by incorporating soft data. The calibration for 2003–2008 produced an adequate model of the in-stream nitrate concentrations (R2 = 0.45, NS = 0.42). However, model validation using data from 1997–2002 showed that the simulated in-stream nitrate concentrations were above the observed concentrations throughout the entire period (R2 = 0.34, NS < 0). These results show that soft data can be used to constrain model parameters, resulting in a more accurate model of the catchment, but do not guarantee the best validation results as the simulated processes may not occur at the same time and rate as they did in the catchment.}, number={1}, journal={Hydrology Research}, publisher={IWA Publishing}, author={Randall Etheridge, J. and Lepistö, Ahti and Granlund, Kirsti and Rankinen, Katri and Birgand, François and Burchell, Michael R., II}, year={2013}, month={Jun}, pages={73–88} }
 @article{gilmore_birgand_chapman_2013, title={Source and magnitude of error in an inexpensive image-based water level measurement system}, volume={496}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2013.05.011}, DOI={10.1016/j.jhydrol.2013.05.011}, abstractNote={Recent technological advances have opened the possibility to use webcams and images as part of the environmental monitoring arsenal. The potential sources and magnitude of uncertainties inherent to an image-based water level measurement system are evaluated in an experimental design in the laboratory. Sources of error investigated include image resolution, lighting effects, perspective, lens distortion and water meniscus. Image resolution and meniscus were found to weigh the most in the overall uncertainty of this system. Image distortion, although largely taken into account by the software developed, may also significantly add to uncertainty. Results suggest that “flat” images with little distortion are preferable. After correction for the water meniscus, images captured with a camera (12 mm or 16 mm focal lengths) positioned 4–7 m from the water level edge have the potential to yield water level measurements within ±3 mm when using this technique.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Gilmore, Troy E. and Birgand, François and Chapman, Kenneth W.}, year={2013}, month={Jul}, pages={178–186} }
 @article{moatar_meybeck_raymond_birgand_curie_2012, title={River flux uncertainties predicted by hydrological variability and riverine material behaviour}, volume={27}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.9464}, DOI={10.1002/hyp.9464}, abstractNote={Abstract}, number={25}, journal={Hydrological Processes}, publisher={Wiley}, author={Moatar, Florentina and Meybeck, Michel and Raymond, Sébastien and Birgand, François and Curie, Florence}, year={2012}, month={Aug}, pages={3535–3546} }
 @article{birgand_appelboom_chescheir_skaggs_2011, title={Estimating Nitrogen, Phosphorus, and Carbon Fluxes in Forested and Mixed-Use Watersheds of the Lower Coastal Plain of North Carolina: Uncertainties Associated with Infrequent Sampling}, volume={54}, ISSN={2151-0040}, url={http://dx.doi.org/10.13031/2013.40668}, DOI={10.13031/2013.40668}, abstractNote={Assessing the impact of a land use change or the water quality improvement provided by a treatment system almost always involves computation of the difference in nutrient loads before and after implementation, or upstream and downstream of the system studied. Reporting meaningful values on mass balance or differences in nutrient loads implies that the uncertainty in the computed loads is several times smaller than the difference itself. This may imply very small uncertainties for the nutrient load measurements. The level of uncertainty induced by infrequent sampling on annual loads was investigated for a suite of nutrients in runoff from a forested watershed and a mixed land use watershed in the lower coastal plain of North Carolina. Reference data were used to simulate discrete sampling and to calculate new annual load estimators, which were then compared to the reference loads to calculate the level of uncertainty. Uncertainties depended on the watershed and the nutrients and other constituents, but their level was generally found to be high, around ±20% and ±40% or more for weekly and monthly sampling for most nutrients. This was generally attributed to the short periods of active flow in these watersheds and the flashiness of flow associated with subsurface drainage. The results suggest that to obtain uncertainties of ±2% or ±5% for nitrogen forms, 100 or more than 200 samples over six months of the year might be necessary in the forested and mixed-use watersheds of the lower coastal plain.}, number={6}, journal={Transactions of the ASABE}, publisher={American Society of Agricultural and Biological Engineers (ASABE)}, author={Birgand, F. and Appelboom, T. W. and Chescheir, G. M. and Skaggs, R. W.}, year={2011}, pages={2099–2110} }
 @article{billy_birgand_sebilo_billen_tournebize_kao_2011, title={Nitrate dynamics in artificially drained nested watersheds}, volume={36}, ISSN={1474-7065}, url={http://dx.doi.org/10.1016/j.pce.2008.09.007}, DOI={10.1016/j.pce.2008.09.007}, abstractNote={There is concern that subsurface drainage, by destroying or by-passing active denitrification areas, may prevent nitrate retention processes and enhance nitrate contamination of surface water by agriculture. To address this question, we studied the flow and concentration signatures of drainage waters and their transformations in a series of 5 nested watersheds, from 1 to 100 km2 area, in the Brie region near Paris (France). At all scales, nitrate concentrations are generally higher during the winter drainage season compared to the low flow periods (late spring to early fall). High nitrate concentrations characterizing drainage waters are visible at the 1st, 2nd and 3rd stream order but are “diluted” by surface runoff from forested zones and buffered by groundwater contributions. The analysis of nitrate chemographs and nitrate budgets established for the different nested watersheds show significant nitrogen retention. Isotopic measurements indicate that the nitrate pool is enriched in δ15N–NO3- as its concentration decreases. Direct estimation of benthic denitrification with benthic chambers allowed concluding that benthic denitrification is not the only retention mechanism and that “underground” denitrification, affecting nitrate on its way from the base of the root zone down to the limit of the river bed, may in fact dominate nitrogen retention processes even in this intensively drained watershed.}, number={12}, journal={Physics and Chemistry of the Earth, Parts A/B/C}, publisher={Elsevier BV}, author={Billy, C. and Birgand, F. and Sebilo, M. and Billen, G. and Tournebize, J. and Kao, C.}, year={2011}, month={Jan}, pages={506–514} }
 @article{birgand_faucheux_gruau_moatar_meybeck_2011, title={Uncertainties in Assessing Annual Nitrate Loads and Concentration Indicators: Part 2. Deriving Sampling Frequency Charts in Brittany, France}, volume={54}, ISSN={2151-0040}, url={http://dx.doi.org/10.13031/2013.36263}, DOI={10.13031/2013.36263}, abstractNote={In water quality monitoring programs, standard sampling frequency schemes tend to be applied throughout entire regions or states. Ideally, the common standard among monitoring stations ought not to be the sampling frequency but instead the level of uncertainty of the estimated water quality indicators. Until now, there was no obvious way of doing this. This article proposes, for the first time, guidelines to select appropriate sampling frequencies to harmonize the level of uncertainty in the case of yearly nitrate indicators for the regional river water quality monitoring network in Brittany, France. A database of 50 watershed-year datasets (nine watersheds of 4 to 252 km 2 in size) was used for which high temporal resolution data (hourly and daily) were available for flow and nitrate concentrations. For each dataset, the uncertainty levels were calculated by numerically simulating sampling intervals varying from 2 to 60 days. The precision limits of the uncertainties were successfully correlated to a hydrological reactivity index. The correlations were used to derive sampling frequency charts. These charts can be used by watershed managers to optimize the sampling frequency scheme for any watershed for a desired uncertainty level, provided that the dimensionless local hydrological reactivity can be calculated from previous records of continuous flow rates. The sampling frequency charts also suggest that, depending on the hydrological reactivity, expected uncertainties generated by monthly sampling range between ±6% and ±14% for the annual load and between-5% and +2.5% to +7.2% for the annual concentration average.}, number={1}, journal={Transactions of the ASABE}, publisher={American Society of Agricultural and Biological Engineers (ASABE)}, author={Birgand, F. and Faucheux, C. and Gruau, G. and Moatar, F. and Meybeck, M.}, year={2011}, pages={93–104} }
 @article{henine_nédélec_augeard_birgand_chaumont_ribstein_kao_2010, title={Effect of Pipe Pressurization on the Discharge of a Tile Drainage System}, volume={9}, ISSN={1539-1663}, url={http://dx.doi.org/10.2136/vzj2008.0152}, DOI={10.2136/vzj2008.0152}, abstractNote={Predicting the drainage impacts on downstream peak events is complex because it involves studying many physical processes at different interdependent scales: the individual field, the drainage network, and the catchment. This study focused on an experiment performed in a small subsurface‐drained catchment (130 ha), east of Paris, France. The main objective was to study the influence of the temporary pipe pressurization of the drainage network on the field drainage discharge during intense rainfall events. The flow rates at one buried pipe collector within the drainage network and at the catchment outlet were monitored concurrently with the pressure head in the pipe. Water levels were recorded in rows of piezometers aligned between drains connected to the studied collector so that water storage in the water table could be investigated during pipe pressurization. Two years of observations showed that when a pipe pressurization condition existed, the collector discharge was limited or reversed and the infiltrated water was temporarily stored within the field soil as the water table rose. Between the usual stages of normal subsurface drainage (peak flow and recession), two additional behaviors appeared to occur, similar to those resulting from implementing controlled drainage and subirrigation practices, and with noticeable consequences on the discharge hydrograph. No strong relationship could be established between the collector discharge limitation and the catchment hydrology, probably because pressurization affected only a small part of the drainage network.}, number={1}, journal={Vadose Zone Journal}, publisher={Soil Science Society of America}, author={Henine, H. and Nédélec, Y. and Augeard, B. and Birgand, F. and Chaumont, C. and Ribstein, P. and Kao, C.}, year={2010}, pages={36} }
 @article{billy_billen_sebilo_birgand_tournebize_2010, title={Nitrogen isotopic composition of leached nitrate and soil organic matter as an indicator of denitrification in a sloping drained agricultural plot and adjacent uncultivated riparian buffer strips}, volume={42}, ISSN={0038-0717}, url={http://dx.doi.org/10.1016/j.soilbio.2009.09.026}, DOI={10.1016/j.soilbio.2009.09.026}, abstractNote={In the small, agricultural, artificially drained Orgeval watershed δ15N values of leached nitrates and soil organic nitrogen were found to be significantly higher than the primary nitrogen (N) sources from which they are derived, namely, synthetic fertilizers, atmospheric deposition, and symbiotic or nonsymbiotic N2 fixation (all with δ15N close to zero). In vertical soil profiles, the δ15N of organic N increased with depth, reaching higher values (up to 8‰) particularly at stations that were frequently waterlogged as judged from ochre iron traces, such as downhill field sites or in riparian buffer strips. Nitrification, volatilization, and denitrification are the main fractionating processes able to modify the isotopic composition of soil N. Using a newly designed algorithm for calculating the equilibrium isotopic composition of all soil N species, resulting from the average annual balance of their transformations, we show that the observed trends can be explained by the action of denitrification. We suggest that the isotopic composition of soil organic N can be used as a semiquantitative indicator of the intensity of denitrification integrated over century-long periods.}, number={1}, journal={Soil Biology and Biochemistry}, publisher={Elsevier BV}, author={Billy, Claire and Billen, Gilles and Sebilo, Mathieu and Birgand, François and Tournebize, Julien}, year={2010}, month={Jan}, pages={108–117} }
 @article{appelboom_chescheir_birgand_skaggs_gilliam_amatya_2010, title={Temperature Coefficient for Modeling Denitrification in Surface Water Sediments Using the Mass Transfer Coefficient}, volume={53}, ISSN={2151-0040}, url={http://dx.doi.org/10.13031/2013.29578}, DOI={10.13031/2013.29578}, abstractNote={Watershed modeling has become an important tool for researchers. Modeling nitrate transport within drainage networks requires quantifying the denitrification within the sediments in canals and streams. In a previous study, several of the authors developed an equation using a term called a mass transfer coefficient to mathematically describe sediment denitrification. This equation takes into account the effect that water column nitrate concentration and flow depth have on denitrification in the sediments. Water column temperature also has a marked effect on the rate of denitrification in the sediments. In the present study, a relationship between denitrification rate and temperature was developed. This relationship was inserted into the original mathematical relationship to improve its ability to predict nitrate removal due to denitrification within drainage networks. The modified equation was tested by comparing predicted and measured nitrate concentrations over time in denitrification tanks at various temperatures. Results show that the modified equation increased the accuracy of predicting nitrate removal by denitrification in drainage canals. Overall Nash-Sutcliffe model efficiency values ranged from 0.72 to 0.76 for the original equation and from 0.90 to 0.97 for the equation developed in this study. The effective temperature range for the equation is 0°C to 40°C. The equation has also only been tested under stagnant/low-flow conditions.}, number={2}, journal={Transactions of the ASABE}, publisher={American Society of Agricultural and Biological Engineers (ASABE)}, author={Appelboom, T. W. and Chescheir, G. M. and Birgand, F. and Skaggs, R. W. and Gilliam, J. W. and Amatya, D.}, year={2010}, pages={465–474} }
 @article{birgand_faucheux_gruau_augeard_moatar_bordenave_2010, title={Uncertainties in Assessing Annual Nitrate Loads and Concentration Indicators: Part 1. Impact of Sampling Frequency and Load Estimation Algorithms}, volume={53}, ISSN={2151-0040}, url={http://dx.doi.org/10.13031/2013.29584}, DOI={10.13031/2013.29584}, abstractNote={The objectives of this study are to evaluate the uncertainty in annual nitrate loads and concentrations (such as annual average and median concentrations) as induced by infrequent sampling and by the algorithms used to compute fluxes. A total of 50 watershed-years of hourly to daily flow and concentration data gathered from nine watersheds (5 to 252 km²) in Brittany, France, were analyzed. Original (high frequency) nitrate concentration and flow data were numerically sampled to simulate common sampling frequencies. Annual fluxes and concentration indicators calculated from the simulated samples were compared to the reference values calculated from the high-frequency data. The uncertainties contributed by several algorithms used to calculate annual fluxes were also quantified. In all cases, uncertainty increased as sampling intervals increased. Results showed that all the tested algorithms that do not use continuous flow data to compute nitrate fluxes introduced considerable uncertainty. The flow-weighted average concentration ratio method was found to perform best across the 50 annual datasets. Analysis of the bias values suggests that the 90th and 95th percentiles and the maximum concentration values tend to be systematically underestimated in the long term, but the load estimates (using the chosen algorithm) and the average and median concentrations were relatively unbiased. Great variability in the precision of the load estimation algorithms was observed, both between watersheds of different sizes and between years for a particular watershed. This has prevented definitive uncertainty predictions for nitrate loads and concentrations in this preliminary work, but suggests that hydrologic factors, such as the watershed hydrological reactivity, could be a key factor in predicting uncertainty levels.}, number={2}, journal={Transactions of the ASABE}, publisher={American Society of Agricultural and Biological Engineers (ASABE)}, author={Birgand, F. and Faucheux, C. and Gruau, G. and Augeard, B. and Moatar, F. and Bordenave, P.}, year={2010}, pages={437–446} }
 @article{moatar_birgand_meybeck_faucheux_raymond_2009, title={Incertitudes sur les métriques de qualité des cours d'eau (médianes et quantiles de concentrations, flux, cas des nutriments) évaluées a partir de suivis discrets}, volume={6}, ISSN={0018-6368 1958-5551}, url={http://dx.doi.org/10.1051/lhb/2009029}, DOI={10.1051/lhb/2009029}, abstractNote={L'évaluation de la qualité des cours d'eau est réalisée à partir de deux principaux types d'indicateurs : les concentrations annuelles (moyennes arithmétiques (Cmoy), médianes (C50), quantiles supérieurs (C90), moyennes pondérées par les débits, (C*..) qui sont rapportées à une grille de qualité (SEQ-Eau) et les flux annuels ramenés généralement à la surface du bassin versant productrice. Ces indicateurs sont entachés d'une incertitude, rarement quantifiée, qui dépend d'abord de la variabilité des concentrations des différents constituents avec la saison et les débits, de la variabilité hydrologique et du nombre de mesures N/an. C'est la spécificité du programme VARIFLUX soutenu par le programme ECCO-ANR/INSU/CNRS dont les résultats sont présentés ici.}, number={3}, journal={La Houille Blanche}, publisher={EDP Sciences}, author={Moatar, Florentina and Birgand, François and Meybeck, Michel and Faucheux, C. and Raymond, S.}, year={2009}, month={Jun}, pages={68–76} }
 @article{birgand_faucheux_gruau_augeard_moatar_meybeck_bouédo_bordenave_2009, title={Une approche quantitative du rôle de la fréquence d’échantillonnage sur les incertitudes associées aux calculs des flux et des concentrations moyennes en nitrate en Bretagne}, volume={59-60}, journal={Ingénieries : eau agriculture territoires}, author={Birgand, F. and Faucheux, C. and Gruau, G. and Augeard, B. and Moatar, F. and Meybeck, M. and Bouédo, A. and Bordenave, P.}, year={2009}, pages={23–37} }
 @inbook{augeard_kao_chaumont_ansart_nédélec_birgand_2008, place={Wallingford, UK}, title={Effect of a nonlinear runoff response on flood statistical properties: the case of a tile-drained watershed}, ISBN={978-1-901502-59-6}, number={321}, booktitle={Groundwater-surface water interaction : process understanding, conceptualization and modeling}, publisher={IAHS Press}, author={Augeard, B. and Kao, C. and Chaumont, C. and Ansart, P. and Nédélec, Y. and Birgand, F.}, editor={Abesser, Corinna and Wagener, Thorsten and Nuetzmann, GunnarEditors}, year={2008}, pages={124–133} }
 @article{tournebize_arlot_billy_birgand_gillet_dutertre_2008, title={Quantification et maîtrise des flux de nitrates : de la parcelle drainée au bassin versant}, journal={Ingénieries : eau agriculture territoires - Numéro Spécial Azote, Phosphore et pesticides}, author={Tournebize, J. and Arlot, M. and Billy, C. and Birgand, F. and Gillet, J. and Dutertre, A.}, year={2008}, pages={5–25} }
 @article{turlan_birgand_marmonier_2007, title={Comparative use of field and laboratory mesocosms for in-stream nitrate uptake measurement}, volume={43}, ISSN={0003-4088}, url={http://dx.doi.org/10.1051/limn/2007026}, DOI={10.1051/limn/2007026}, abstractNote={Recent publications suggest that in large watersheds a large proportion (20 to 70%) of the net nitrogen input to the aquatic environment may be removed during water’s downstream path towards the outlet. In small watersheds there are few to no evaluations of the importance of in-stream processes in the overall nitrogen budget due in part to the lack of simple and robust methods for measuring in-stream nitrate uptake. We propose a comparative study for laboratory and field measurements on open mesocosms, 30 cm in diameter. Nitrate uptake was evaluated from the kinetics of disappearance of nitrate in water overlying undisturbed sediment cores, both in the laboratory and in-situ. Using both laboratory and in-situ mesocosms was an effort to determine whether the methods were comparable and applicable on a routine basis. Nitrate disappearance kinetics in the laboratory yielded expected results, which are that nitrate uptake rates are linearly correlated to nitrate concentration in the water column. In such conditions, our results show that the potential for nitrate uptake in streams can be calculated from the mass transfer coefficient. Our comparative study shows that incubations conducted in the laboratory intrinsically limit hyporheic exchanges, associated with small water level fluctuations, which may in fact prevail in the field as the in-situ incubations have shown. In-situ experiments yielded unexpected results, such as the succession of disappearance and gain of nitrate in the mesocosms through time. This was attributed to hyporheic exchanges, both natural and artificially induced by the design of the mesocosms. Both methods should be considered for future nitrate uptake studies as they yield complementary results, provided that some simple changes are made in the design of in-situ mesocosms.}, number={1}, journal={Annales de Limnologie - International Journal of Limnology}, publisher={EDP Sciences}, author={Turlan, T. and Birgand, F. and Marmonier, P.}, year={2007}, pages={41–51} }
 @article{peu_birgand_martinez_2007, title={Long term fate of slurry derived nitrogen in soil: A case study with a macro-lysimeter experiment having received high loads of pig slurry (Solepur)}, volume={98}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2006.07.019}, DOI={10.1016/j.biortech.2006.07.019}, abstractNote={In intensive livestock production areas, land application remains the traditional management of manure and slurries for nutrient recycling. For sustainable agriculture there is fear, however, that this practice may have detrimental effects, particularly on the depletion of Soil Organic Matter associated with pig slurry applications. We investigated the long-term fate of nitrogen in a reconstituted soil having received high doses of pig slurry during 5 years (1991-1995). After 5 years of intensive application rates (nearly 1000 m(3)yr(-1)), the N and C content of the soil profile (0-20 cm) had increased by about 60% and 50%, respectively. These results confirm previous findings although it seems that the particularly high rates of application may explain, in part, the relatively important N incorporation in soil. Pig slurry applications ceased in 1995 and nitrogen content in soil and drainage water have been monitored. Apparent mineralization rates were calculated from the decrease in N content of the soil. This analysis indicated that more than 50% of the added N stored in the soil at the end of the applications would eventually be mineralized, leaving nearly 50% of the stored N to be immobilized in the soil. These results are the first published of their kinds, as most reports never examine the fate of applied pig slurry N after halting applications. In addition the few reports on long-term experiments suggest that Soil Organic Matter following pig slurry applications may be unstable. Our analysis tends to show the contrary. However, this conclusion must be tempered because data on nitrate leachate patterns suggest that soil management such as ploughing and sowing may actually trigger mineralization that could eventually deplete nitrogen stored following applications.}, number={17}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Peu, P. and Birgand, F. and Martinez, J.}, year={2007}, month={Dec}, pages={3228–3234} }
 @article{birgand_skaggs_chescheir_gilliam_2007, title={Nitrogen Removal in Streams of Agricultural Catchments—A Literature Review}, volume={37}, ISSN={1064-3389 1547-6537}, url={http://dx.doi.org/10.1080/10643380600966426}, DOI={10.1080/10643380600966426}, abstractNote={Excess nutrient loads have been recognized to be the major cause of serious water quality problems recently encountered in many estuaries and coastal waters of the world. Agriculture has been recognized in many regions of the world to be the largest single source of nitrogen emissions to the aquatic environments, and best management practices have been proposed to reduce nutrient losses at the field edge. As a result, there is growing awareness that nutrient management must be handled at the watershed scale. However, the key to nutrient management at the watershed scale is the understanding and quantification of the fate of nutrients both at the field scale and after they enter the aquatic environment. There has been widespread evidence since the late 1970s that nitrogen can be removed from water during its downstream transport in watersheds or basins. Although this information is becoming crucial, no overview has been proposed, so far, to qualitatively as well as quantitatively summarize available information in the literature. For this reason, we propose a review on the biogeochemical processes involved in nitrogen removal in streams, the rates of removal reported, and the factors influencing those rates. Nitrogen removal rates in agricultural streams should be expected to vary between 350 and 1250 mg N m−2 day−1. Mass transfer coefficients (coefficient evaluating intrinsic ability of a stream to remove nitrogen) values in agricultural streams may vary between 0.07 and 0.25 m day−1, although these values correspond to values obtained from reach scale studies. Reviewing values obtained from different measurement scales has revealed that results from incubations or experiments performed in the laboratory clearly underestimate mass transfer coefficients compared to those reported at the reach scale, from severalfold to more than one order of magnitude. Nitrogen removal rates and efficiency in streams are the highest in the summer, and this is critical for receiving ecosystems, which are most sensitive to external inputs at this period of the year. Removal efficiency is the lowest in winter in temperate climates due to high flow and loading combined with lowest removal rates. In-stream processes, on an annual basis, may remove at the watershed scale as much as 10 to 70% of the total N load to the drainage network.}, number={5}, journal={Critical Reviews in Environmental Science and Technology}, publisher={Informa UK Limited}, author={Birgand, Françoisx and Skaggs, R. Wayne and Chescheir, George M. and Gilliam, J. Wendell}, year={2007}, month={Jun}, pages={381–487} }
 @article{turpin_bontems_rotillon_bärlund_kaljonen_tattari_feichtinger_strauss_haverkamp_garnier_et al._2005, title={AgriBMPWater: systems approach to environmentally acceptable farming}, volume={20}, ISSN={1364-8152}, url={http://dx.doi.org/10.1016/j.envsoft.2003.09.004}, DOI={10.1016/j.envsoft.2003.09.004}, abstractNote={To help local regulators mitigate non-point source agricultural pollution and implement environment-friendly agricultural practices, a comparison between different existing or simulated best management practices (BMPs) has been carried out within a pluridisciplinary project called AgriBMPWater (FP5 founded). The project has been imagined and built in a pluridisciplinary approach and framework. The approach developed corresponds to a cost/effectiveness assessment of several BMPs in several European watersheds, also including the study of their acceptability by farmers. Thanks to the integrated assessment of existing and potential BMPs, a selection grid contributes to provide assistance to regulators on how to conduct environmental, economic and sociological analyses for helping decision makers. Water quality problems encountered and dealt with in this project include nitrate, phosphorus, sediment, pesticide loads and acid water concerns. Thus, the developed framework allows for a large range of hydrological and economic models, depending on the environmental problem detected in each watershed.}, number={2}, journal={Environmental Modelling & Software}, publisher={Elsevier BV}, author={Turpin, Nadine and Bontems, Philippe and Rotillon, Gilles and Bärlund, Ilona and Kaljonen, Minna and Tattari, Sirkka and Feichtinger, Franz and Strauss, Peter and Haverkamp, Randel and Garnier, Monica and et al.}, year={2005}, month={Feb}, pages={187–196} }
 @article{birgand_benoist_novince_gilliet_saint-cast_saos_2005, title={Guide d’application de la technique du Doppler continu pour une section calibrée en bois}, volume={41}, journal={Ingénieries : eau agriculture territoires}, author={Birgand, F. and Benoist, J. and Novince, É. and Gilliet, N. and Saint-Cast, P. and Saos, É.Le}, year={2005}, pages={77–82} }
 @article{birgand_benoist_novince_gilliet_saint-cast_le saos_2005, title={Mesure des débits à l’aide de débitmètres ultrasoniques Doppler - Cas des petits cours d’eau ruraux}, volume={41}, journal={Ingénieries : eau agriculture territoires}, author={Birgand, F. and Benoist, J. and Novince, É. and Gilliet, N. and Saint-Cast, P. and Le Saos, É.}, year={2005}, pages={23–38} }
 @article{kenny_yamulki_blackwell_maltby_french_birgand_2005, title={The release of nitrous oxide from the intertidal zones of two European estuaries in response to increased ammonium and nitrate loading}, volume={4}, ISSN={1567-7230 1573-2940}, url={http://dx.doi.org/10.1007/s11267-005-3014-z}, DOI={10.1007/s11267-005-3014-z}, number={6}, journal={Water, Air, & Soil Pollution: Focus}, publisher={Springer Science and Business Media LLC}, author={Kenny, C. and Yamulki, S. and Blackwell, M. and Maltby, E. and French, P. and Birgand, F.}, year={2005}, month={Jan}, pages={61–66} }
 @article{birgand_lefrançois_grimaldi_novince_gilliet_gascuel-odoux_2004, title={Mesure des flux et échantillonnage des matières en suspension sur de petits cours d’eau}, volume={40}, journal={Ingénieries : eau agriculture territoires}, author={Birgand, F. and Lefrançois, J. and Grimaldi, C. and Novince, É. and Gilliet, N. and Gascuel-Odoux, C.}, year={2004}, month={Dec}, pages={21–35} }
 @article{kenny_yamulki_blackwell_maltby_french_birgand_2004, title={The Release of Nitrous Oxide from the Intertidal Zones of Two European Estuaries in Response to Increased Ammonium and Nitrate Loading}, volume={4}, ISSN={1567-7230 1573-2940}, url={http://dx.doi.org/10.1007/S11267-004-3014-4}, DOI={10.1007/S11267-004-3014-4}, number={6}, journal={Water, Air, & Soil Pollution: Focus}, publisher={Springer Science and Business Media LLC}, author={Kenny, C. and Yamulki, S. and Blackwell, M. and Maltby, E. and French, P. and Birgand, F.}, year={2004}, month={Dec}, pages={61–66} }
 @article{benoist_birgand_2002, title={Les dispositifs de mesure des débits dans les bassins versants agricoles}, volume={32}, journal={Ingénieries : eau agriculture territoires}, author={Benoist, J. and Birgand, F.}, year={2002}, pages={51–63} }
 @phdthesis{birgand_2000, place={Raleigh, NC, USA}, title={Quantification and modeling of in-stream processes in agricultural canals of the lower coastal plain}, school={North Carolina State University}, author={Birgand, F.}, year={2000} }
 @inproceedings{birgand_chescheir_skaggs_gilliam_1999, title={Quantification and effects of in-stream processes in the ditches and canals of the Lower Coastal Plain of North Carolina}, number={1999}, booktitle={Proceedings of the Mini-Conference, Advances in Water Quality Modeling}, publisher={St. Joseph, MI: ASAE}, author={Birgand, F. and Chescheir, G. M. and Skaggs, R. W. and Gilliam, J. W.}, year={1999}, pages={45–50} }
 @inproceedings{amatya_chescheir_skaggs_fernandez_birgand_1998, title={Evaluation of a DRAINMOD based watershed scale model}, booktitle={Drainage in the 21st century: Food production and the environment: Proceedings of the seventh International Drainage Symposium}, publisher={St. Joseph, Michigan: American Society of Agricultural Engineers}, author={Amatya, D. M. and Chescheir, G. M. and Skaggs, R. W. and Fernandez, G. and Birgand, F.}, year={1998}, pages={211–219} }
 @phdthesis{birgand_1994, place={Rennes, France}, title={Measurements and modeling of nitrogen budget in poorly drained soils.}, school={Ecole Nationale Supérieure Agronomique de Rennes}, author={Birgand, F.}, year={1994} }