{"title":"Estimating Daily Nitrate Loads in Iowa Streams Using a Partial Least Squares Regression Framework","authors":"Patrick Dunn, Emily Elliott, Leanne M. Gilbertson","doi":"10.1111/1752-1688.70036","DOIUrl":"https://doi.org/10.1111/1752-1688.70036","url":null,"abstract":"<div>\u0000 \u0000 <p>Agricultural nitrate pollution is a major threat to water quality in Iowa. Iowa uses a majority of its land for row crop agriculture and maintains a large livestock population, which together cause high nitrate loads in streams. High-frequency stream nitrate data can aid policy decisions for reducing nitrate emissions by identifying streams with high nitrate loads, historical trends of improvement or deterioration in nitrate loads, and land use or practice changes that affect water quality. We developed a time series regression model framework to supplement existing sensor data and predict daily nitrate loads in Iowa streams lacking nitrate monitoring. Using nitrate data from statewide and national resources, this framework was trained and validated using 11 study sites of diverse geography and land use in Iowa. Partial least squares regression (PLSR) was used with geographical predictors, including land use, hydrogeology, and meteorology, to predict streamflow-nitrate load relationships across the study sites. The developed PLSR model, combined with daily streamflow data, was then used to predict daily nitrate loads with high accuracy over a three-year study period with a mean Kling–Gupta Efficiency of 0.74. Our framework was then used to estimate mean nitrate concentrations at 34 sites that lack nitrate sensors, demonstrating a low-cost, facile method for the accurate prediction of daily nitrate loads in Iowa streams.</p>\u0000 </div>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cascade Reservoirs Multiobjective Optimal Scheduling Based on an Improved Two-Stage Particle Swarm Optimization Algorithm","authors":"Zhaocai Wang, Haifeng Zhao, Zhiyuan Yao, Tunhua Wu","doi":"10.1111/1752-1688.70032","DOIUrl":"https://doi.org/10.1111/1752-1688.70032","url":null,"abstract":"<div>\u0000 \u0000 <p>The multiobjective scheduling of cascade reservoir systems faces challenges due to high-dimensional nonlinearity, where traditional optimization methods struggle to achieve globally balanced solutions. This study proposes a Two-Stage Multi-Objective Particle Swarm Optimization (TSMOPSO) algorithm, incorporating two innovative components to enhance optimization performance. The first component employs Piecewise mapping, adapts weights and introduces two operators to improve optimization efficiency and convergence speed. The second component features a two-stage refinement mechanism, implementing a two-level adjustment of upstream and downstream water levels based on constraint evaluations, effectively alleviating constraint limitations. A case study is conducted on cascade reservoirs system in the Jinsha River Basin of the Upper Yangtze River (JRBUY), with a multiobjective model integrating power generation, power output, and navigation demands. Numerical experiments demonstrate that TSMOPSO achieves remarkable performance under wet-year conditions: power generation of 2087.46 KW h, power output of 16,435.75 MW, and a navigation index of 3052.92 m<sup>3</sup>/s. Compared wtih other algorithms, TSMOPSO exhibits significant advantages in hypervolume (<i>HV</i>) indicators and solution set coverage. Pareto front analysis reveals competitive mechanisms among the three objectives. This approach provides a novel technical pathway for multiobjective optimization of complex cascade reservoir systems.</p>\u0000 </div>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144473003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Is Hot Drought a Risk in the US Mid-Atlantic? A Potomac Basin Case Study","authors":"C. L. Schultz, A. Seck, S. N. Ahmed","doi":"10.1111/1752-1688.70031","DOIUrl":"https://doi.org/10.1111/1752-1688.70031","url":null,"abstract":"<p>Interannual variability of streamflow will increase under a future climate, but at the regional scale, there is uncertainty regarding changes in drought severity, and in particular, changes in extreme hydrological drought that could necessitate new water supply infrastructure. This is due to the wide range of regional projections for precipitation and the challenge of estimating statistics in a nonstationary climate. We assess changes in annual streamflow in the Potomac River Basin using a nonparametric approach based on a climate response function and the K-nearest neighbor method, which is relied on to construct time series of sufficient length to compute extreme quantile values. Our results indicate that future Potomac River flows will be impacted by “hot drought”, that is, increasing drought severity caused by rising temperatures coupled with natural variability in precipitation. Average precipitation is projected to increase in the Potomac basin by 9%–12% in the period 2039–2069 and by 11%–16% by 2070–2099. Average streamflow increases more modestly, by 4%–7% in 2039–2069 and by 2 to 9% in 2070–2099, whereas annual flows in an extreme drought year decrease by 3 to 26% in 2039–2069 and by 2%–49% in 2070–2099, assuming a medium sensitivity of flow to temperature. Our approach can provide multi-model consensus inputs for water supply planning models to support decision-making regarding new infrastructure.</p>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1752-1688.70031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quantifying the Impact of Iowa's Flood-Mitigation Reservoirs on Sediment and Nutrient Loss","authors":"Elliot S. Anderson, Keith E. Schilling","doi":"10.1111/1752-1688.70035","DOIUrl":"https://doi.org/10.1111/1752-1688.70035","url":null,"abstract":"<p>Flood-mitigation reservoirs have long been known to impact pollutant transport by retaining or removing incoming sediment and nutrients. However, historical reductions in these systems have rarely been well quantified. In this study, we used water quality data to estimate inputs and outputs of total suspended solids (TSS), two phosphorus (P) forms, and three nitrogen (N) forms in three Iowa reservoirs (Coralville, Red Rock, and Saylorville). We also explored the influence of reservoir residence times on removal rates. Annual residence times were largely consistent across the basins, ranging from roughly 6 to 100 days (mean of 19 days). Between 2001 to 2023, most TSS (~ 80%) entering the reservoirs was retained. This sedimentation corresponded to average volume losses in the reservoirs' normal storage pools of 0.37%–0.85%/year. About 40% of P and 12% of N were likewise reduced—driven mainly by decreases in particulate P and nitrate. Residence time appeared unrelated to removal rates of TSS and particulate nutrient forms, but longer residence times coincided with increased nitrate loss. Reservoir impact on statewide nutrient export was significant, with loads in Iowa's major rivers being reduced by 9.8% (for P) and 4.7% (for N) due to reservoir capture. These findings suggest that reservoir operators may be able to facilitate further nitrate removal by lengthening storage durations without incurring additional sedimentation or generating other nutrient forms.</p>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1752-1688.70035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144299744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zachary Easton, Kurt Stephenson, Brian Benham, J. K. Böhlke, Anthony Buda, Amy Collick, Lara Fowler, Ellen Gilinsky, Andrew Miller, Gregory Noe, Leah H. Palm-Forster, Leonard Shabman, Theresa Wynn-Thompson
{"title":"The Nonpoint Source Challenge: Obstacles and Opportunities for Meeting Nutrient Reduction Goals in the Chesapeake Bay Watershed","authors":"Zachary Easton, Kurt Stephenson, Brian Benham, J. K. Böhlke, Anthony Buda, Amy Collick, Lara Fowler, Ellen Gilinsky, Andrew Miller, Gregory Noe, Leah H. Palm-Forster, Leonard Shabman, Theresa Wynn-Thompson","doi":"10.1111/1752-1688.70034","DOIUrl":"https://doi.org/10.1111/1752-1688.70034","url":null,"abstract":"<p>This document examines the Chesapeake Bay watershed response to nutrient and sediment reduction efforts under the Clean Water Act's total maximum daily load (TMDL) regulation. As the 2025 Chesapeake Bay TMDL deadline approaches, water quality goals remain unmet, primarily because of nonpoint source pollution, the largest remaining source of nutrients and sediment, and the primary obstacle to meeting the TMDL. We focus on the factors influencing the gap between the expected effect of management to reduce nonpoint source loads reaching the Bay and empirical evidence suggesting that decades of effort have not produced the expected improvement. This gap may be caused by both insufficient scale and type of implemented water quality management practices and by an overestimation of practice effectiveness. Reasons water quality goals remain unmet include legacy nutrients and lag times masking or delaying the effects of management efforts, areas with large nutrient mass imbalances contributing disproportionate loads, and the difficulty of incentivizing behavior change in voluntary nonpoint source programs. Closing the response gap may require fundamental changes to nonpoint source programs. Apart from seeking additional funding, nonpoint source programs could develop policies to more effectively incentivize behavior change, identify and target treatment of high loading areas with appropriate management actions, and address nutrient mass imbalances.</p>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1752-1688.70034","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nicholas Chin, David Kaplan, Maitane Olabarrieta, Viyaktha Hithaishi Hewageegana, Luming Shi
{"title":"Quantifying the Effects of National Water Model Freshwater Flux Predictions on Estuarine Hydrodynamic Forecasts","authors":"Nicholas Chin, David Kaplan, Maitane Olabarrieta, Viyaktha Hithaishi Hewageegana, Luming Shi","doi":"10.1111/1752-1688.70033","DOIUrl":"https://doi.org/10.1111/1752-1688.70033","url":null,"abstract":"<div>\u0000 \u0000 <p>Accurate streamflow forecasts are critical for modeling and managing estuarine water quality, as freshwater fluxes significantly influence coastal dynamics. The National Water Model (NWM) provides high-resolution streamflow predictions, which are valuable for hydrodynamic modeling in poorly gauged coastal regions. However, inaccuracies in NWM forecasts can limit our ability to predict estuarine and nearshore water quality effectively. First, this study evaluates the accuracy of NWM predictions for 14 coastal reaches in southwest Florida's Charlotte Harbor and Caloosahatchee River estuaries from 2018 to 2024, where hydrologic management has impacted water quality. NWM forecasts showed varying bias and variance, with Nash-Sutcliffe efficiencies (NSE) ranging from −2.26 to 0.77. Next, hydrodynamic simulations for the flow-managed Caloosahatchee River Estuary (CRE) were performed using both NWM forecasts and observed streamflows, revealing that errors in NWM predictions during high-flow events caused significant deviations in the position of ecologically relevant isohalines, lasting weeks. Finally, to address these issues, a Long Short-Term Memory (LSTM) network was developed to bias-correct NWM forecasts, improving NSE from 0.41 to 0.53. However, the LSTM's inability to “learn” managed discharge schedules highlights the need for advanced data assimilation and simulation techniques in flow-managed coastal systems.</p>\u0000 </div>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Impact of the Water Resource Tax on Efficiency of Industrial Water Resources Use: Evidence From Hebei Province, China","authors":"Ming Chen, Qin Wang, Yifan Li, Yutong Zhao","doi":"10.1111/1752-1688.70024","DOIUrl":"https://doi.org/10.1111/1752-1688.70024","url":null,"abstract":"<div>\u0000 \u0000 <p>China is facing a serious water shortage. The government's implementation of a water resource tax policy is an important step in the ecological protection of water resources. This paper constructs a stochastic frontier production function model to measure the industrial water resource utilization efficiency in Hebei Province under the consideration of water resource tax. Then, this paper constructs a model of the impact of water resource tax policy on industrial water resource utilization efficiency using the double difference method to evaluate the causal effect of the policy. The research findings of this article are: (1) Through discontinuity regression, it was found that the water resources tax policy has a significant positive correlation with the improvement of water resource utilization efficiency in Hebei Province. The implementation of the water resources tax policy has successfully improved the industrial water resource utilization in Hebei Province. (2) Although the implementation of the water resources tax policy has improved the efficiency of industrial water use in Hebei Province, the overall efficiency of industrial water use in Hebei Province is still low, and many problems have arisen during the advancement of the water resources tax policy. In response to the problems that occurred during the pilot period in Hebei Province, this article proposes some policy solutions to accelerate the advancement of water resource tax policies across the country.</p>\u0000 </div>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrea Albright, Alisa W. Coffin, Oliva Pisani, David D. Bosch, Timothy C. Strickland
{"title":"A Pilot Study for Water Storage and Carbon Variability in an Irrigation Pond of the Southeastern Plains, USA","authors":"Andrea Albright, Alisa W. Coffin, Oliva Pisani, David D. Bosch, Timothy C. Strickland","doi":"10.1111/1752-1688.70026","DOIUrl":"https://doi.org/10.1111/1752-1688.70026","url":null,"abstract":"<p>Farm ponds are a common feature of agricultural landscapes for irrigation of crops. Yet small water bodies have been ignored as reservoirs and carbon balance features despite their ubiquity in the global landscape. These ponds contain surface water from precipitation and runoff, but in South Georgia, USA, groundwater supplementation is required to maintain a supply for irrigation. Key characteristics of these ponds, such as capacity and dynamics describing fluxes in quantity and quality, are not well known. In this area, irrigation ponds supplemented by groundwater have water quality issues that affect producers. In a pilot study to address this knowledge gap, storage dynamics and water quality, that is, dissolved organic carbon (DOC), were characterized from measurements of a regionally typical irrigation pond in 2022. Field surveys of pond depth and terrain were fused to create a topobathymetric elevation model of the pond and its environs. The pond has a volume of 5.06 +/- 0.29 ha-m that was used for irrigation during the growing season and was mostly replaced with groundwater. Concentrations of DOC ranged from 1.77 to 19.9 mg/L. Dissolved organic matter (DOM) indices reveal a shift from terrestrial-derived DOM earlier in the year to more microbial-derived DOM later. Together this integrated analysis of an irrigation pond in South Georgia analyzes water inflows and outflows, quantifies DOC, characterizes DOM, and models pond storage volumes.</p>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1752-1688.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Erich T. Hester, Nathalie Voisin, Natalie A. Griffiths, Shih-Chieh Kao
{"title":"Intersection of Hydrologic Change and Hydropower in the United States: Needs for Future Research and Practice","authors":"Erich T. Hester, Nathalie Voisin, Natalie A. Griffiths, Shih-Chieh Kao","doi":"10.1111/1752-1688.70020","DOIUrl":"https://doi.org/10.1111/1752-1688.70020","url":null,"abstract":"<p>Hydropower is crucial for electric-grid stability in the context of variable renewables but faces threats from changing hydrology. Here, we summarize the state of the science at the intersection of hydropower operations and planning, hydrologic science, and climate. We focus on the United States, outlining research, development, and training needs. Key knowledge gaps include the risk that intensification of compound extreme events poses to future generation, as well as uncertainties surrounding greenhouse gas emissions from hydropower reservoirs with relevance to hydropower's role in energy decarbonization. Quantifying such impacts and reducing uncertainty are critical where possible, but remaining irreducible or deep uncertainty will require new approaches. Future monitoring and modeling methods must provide a better understanding of the complexity inherent in large watersheds that is critical to managing both hydropower and watersheds in the context of hydrologic change. Yet, research and development will have little impact if they do not inform practice. Standardization and consolidation of platforms are essential for data, modeling, and tool translation to local scales and small operators. An enhanced industry-academia dialog is pivotal for fostering a robust pipeline of hydropower professionals. Collaboration among researchers, policymakers, authorities, and industry stakeholders emerges as a recurring theme, highlighting the imperative for collective efforts.</p>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1752-1688.70020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Distributed Unit Hydrograph Modeling for Flood Simulation in the Plain River Network Regions","authors":"Gang Chen, Yue Yu, Tianshu Zhang, Chuanhai Wang, Shen Yang, Pengxuan Zhao","doi":"10.1111/1752-1688.70029","DOIUrl":"https://doi.org/10.1111/1752-1688.70029","url":null,"abstract":"<div>\u0000 \u0000 <p>This study proposes a distributed unit hydrograph (DUH) method to address the challenge of simulating overland flow concentration in plain river network regions. The DUH framework defines generalized river network polygons (RNPs) to represent flow convergence zones and estimates runoff travel times based on a calibrated confluence velocity parameter, circumventing the need for high-resolution topographic data. The method was applied to the Taihu Basin, where 16 subregions were analyzed under different spatial scales and overland flow velocities. Results show that the DUH method significantly enhances model performance compared to the traditionally used proposed unit hydrograph (PUH) approach. Specifically, DUH reduced the root mean square error (RMSE) of simulated water levels by up to 40%, improved the coefficient of determination (<i>R</i><sup>2</sup>) by 0.1–0.2, and reduced the average flood peak lag from 2.1 days to 0.7 days. The model exhibited optimal accuracy at a grid scale of 200 × 200 m, achieving a balance between smooth hydrograph formation and computational efficiency. These findings underscore the DUH method's applicability for flood simulation and decision-making in low-relief, hydraulically complex regions with limited microtopographic data availability.</p>\u0000 </div>","PeriodicalId":17234,"journal":{"name":"Journal of The American Water Resources Association","volume":"61 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144197062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}