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Effective management of water quality in watersheds is crucial because it is directly linked to the sustainability of aquatic ecosystems. In conventional watershed management, best management practices (BMPs) have been instrumental in addressing deteriorating water quality issues caused by non-point source pollution. Greenhouse gas (GHG) emissions have emerged as a global concern, necessitating immediate and diverse environmental actions to mitigate their impacts. This study aims to explore BMPs that maximize total phosphorus (TP) load removal efficiencies, while minimizing costs and GHG emissions within watersheds, using the Soil and Water Assessment Tool (SWAT) and non-dominated sorting genetic algorithm III (NSGA-III). The Yeongsan River Watershed between 2012 and 2021 was selected as the study area. Hydrological and BMP data were analyzed. Applying identical BMPs to the watershed showed that the BMPs with high TP removal efficiency may not be effective in terms of cost and GHG emissions. Therefore, the optimal combination of BMPs for the Yeongsan River Watershed was determined using NSGA-III considering TP removal efficiency, cost, and GHG emissions. This study is the first to consider GHG emissions at the watershed level when applying BMPs and is expected to contribute to the development of BMP implementation incorporating GHG emissions. [ABSTRACT FROM AUTHOR]

Central Chile's Concon City urbanization trend has severely affected local hydrological processes. This research hypothesizes that switching to sustainable land-use/land-cover (LULC) in three Concon watersheds reduces the severity of their corresponding hydrological responses. High sustainability LULC zones would decrease runoff and enhance interception and infiltration, generating hydrograph curves with extended lag time and moderate peak flows. The Hydrological Simulation Program FORTRAN (HSPF) is used for simulating watershed processes. Decreases in peak flows of 31.1%, 19.8%, and 54.5%, were estimated. Therefore, sustainable LULC reduces the severity of the hydrological responses, benefiting storm water management. Real-world applications in Europe and the USA achieved comparable results. Urban master plans in Chile have favored the alteration of natural landscapes (anthropization). Per national regulations, changes to urban plans can be made every ten years. The results of this research will be valuable in future revisions of Concon's urban plan. [ABSTRACT FROM AUTHOR]

Expanding markets for renewable energy feedstocks have increased demand for woody biomass. Concerns associated with forest biomass harvesting include increased erosion, the applicability of conventional forestry Best Management Practices (BMPs) for protecting water quality, and reduced woody debris retention for soil nutrients and cover. We regionally compared the data and results from three prior independent studies that estimated erosion, BMP implementation, and residual woody debris following biomass and conventional forest harvests in the Mountains, Piedmont, and Coastal Plain of Virginia. Estimated erosion was higher in the Mountains due to steep slopes and operational challenges. Mountain skid trails were particularly concerning, comprising only 8.47% of the total area but from 37.9 to 81.1% of the total site-wide estimated erosion. BMP implementation varied by region and harvest type, with biomass sites having better implementation than conventional sites, and conventional Mountain sites having lower implementation than other regions. Sufficient woody debris remained for BMPs on both harvest types in all regions, with conventional Mountain sites retaining twice that of Coastal Plain sites. BMPs reduced the estimated erosion on both site types suggesting increased implementation could reduce potential erosion in problematic areas. Therefore, proper BMP implementation should be ensured, particularly in Mountainous terrain, regardless of harvest type. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of future research and development needs to assess the effectiveness of nature-based solutions for climate adaptation in watersheds at scale using hydrological models. Two main questions are addressed: to what extent are hydrological model approaches able to support decision making on nature-based solutions and adaptation, and how well is this hydrological analysis embedded in the broader planning process? To support the research, case studies in Bhutan, Zimbabwe and the Netherlands are presented. The Climate Risk Informed Decision Analysis approach is used to structure the planning process. All three case studies demonstrate how the hydrological system and full landscape of land and water use in watersheds can be simulated to better understand hydrometeorological hazards under current and future climate. Also, simulations of nature-based solutions are demonstrated, which need creativity and profound expert knowledge. In contrast to the assessment of grey infrastructure, no rules or guidance exists for the hydrological assessment of nature-based solutions. Physically-based models are better able to support the understanding of the functioning of the ecohydrological system and, therefore, the effectiveness of adaptation using nature-based solutions. There are however trade-offs between the computational complexity, the computation time and the multiple scenarios and sensitivity analyses of adaptation options needed for climate stress testing. Often there is a lack of monitoring data for verification of model outcomes. Several recommendations on how to improve modelling in an adaptation process are given. In addition, it is recommended to develop and rectify a set of nature-based solutions performance indicators, rules and algorithms to be adopted in models in order to quantify the effectiveness of these solutions. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of future research and development needs to assess the effectiveness of nature-based solutions for climate adaptation in watersheds at scale using hydrological models. Two main questions are addressed: to what extent are hydrological model approaches able to support decision making on nature-based solutions and adaptation, and how well is this hydrological analysis embedded in the broader planning process? To support the research, case studies in Bhutan, Zimbabwe and the Netherlands are presented. The Climate Risk Informed Decision Analysis approach is used to structure the planning process. All three case studies demonstrate how the hydrological system and full landscape of land and water use in watersheds can be simulated to better understand hydrometeorological hazards under current and future climate. Also, simulations of nature-based solutions are demonstrated, which need creativity and profound expert knowledge. In contrast to the assessment of grey infrastructure, no rules or guidance exists for the hydrological assessment of nature-based solutions. Physically-based models are better able to support the understanding of the functioning of the ecohydrological system and, therefore, the effectiveness of adaptation using nature-based solutions. There are however trade-offs between the computational complexity, the computation time and the multiple scenarios and sensitivity analyses of adaptation options needed for climate stress testing. Often there is a lack of monitoring data for verification of model outcomes. Several recommendations on how to improve modelling in an adaptation process are given. In addition, it is recommended to develop and rectify a set of nature-based solutions performance indicators, rules and algorithms to be adopted in models in order to quantify the effectiveness of these solutions. [ABSTRACT FROM AUTHOR]

Future changes in land use, climate and downstream water demand can impact reservoir water supply performance. However, a comprehensive assessment that considers these factors poses challenges as it requires complex scenario simulations. To improve our understanding of potential combined effects and to facilitate analyses of reservoir performance, the Soil and Water Assessment Tool has been coupled with genetic optimization and applied to a case study, the Nuicoc multipurpose reservoir in Vietnam. Optimization analyses under a range of scenarios show that despite greater future rainfall, climate change combined with increases in urban area and agriculture resulted in 1–10% and 4–28% lower reliability and resilience, respectively, compared with the baseline. Reservoir sedimentation led to a vulnerability index increase of 0.1–10.5 and 150–400 Mm3/year greater water spillage. Reservoir performance can be improved by adjusting water allocation policies and best management practices in the watershed. [ABSTRACT FROM AUTHOR]

Agriculture alters the biogeochemical cycling of nutrients such as nitrogen (N), phosphorus (P), and silicon (Si) which contributes to the stoichiometric imbalance among these nutrients in aquatic systems. Limitation of Si relative to N and P can facilitate the growth of non-siliceous, potentially harmful, algal taxa which has severe environmental and economic impacts. Planting winter cover crops can retain N and P on the landscape, yet their effect on Si concentrations and stoichiometry is unknown. We analyzed three years of biweekly concentrations and loads of dissolved N, P, and Si from subsurface tile drains and stream water in two agricultural watersheds in northern Indiana. Intra-annual patterns in Si concentrations and stoichiometry showed that cover crop vegetation growth did not reduce in-stream Si concentrations as expected, although, compared to fallow conditions, winter cover crops increased Si:N ratios to conditions more favorable for diatom growth. To assess the risk of non-siliceous algal growth, we calculated a stoichiometric index to quantify biomass growth facilitated by excess N and P relative to Si. Index values showed a divergence between predicted algal growth and what we observed in the streams, indicating other factors influence algal community composition. The stoichiometric imbalance was more pronounced at high flows, suggesting increased risk of harmful blooms as climate change increases the frequency and intensity of precipitation in the midwestern U.S. Our data include some of the first published measurements of Si within small agricultural watersheds and provide the groundwork for understanding the role of agriculture on Si export and stoichiometry. [ABSTRACT FROM AUTHOR]

Excessive nutrient loads represent a major source of water pollution globally. Best Management Practices (BMPs) are typically implemented in agricultural and urban landscapes to reduce nutrient losses at individual parcels. However, the effectiveness of BMPs in reducing nutrient loads at regional watershed domains remains an open question. This study aims to evaluate the effectiveness of parcel-based agricultural and urban BMP implementations in reducing watershed-wide phosphorus (P) and nitrogen (N) loads. The Lake Okeechobee watershed in Florida (USA), covering 10,600 km2 of mixed agricultural and urban land-use/land-cover, is used as a case study. Hydrological and nutrient transport processes were simulated using the Watershed Assessment Model (WAM). The model was calibrated and validated for river discharge and nutrients for each of the six sub-watersheds, with R2 values ranging from 0.43 to 0.80 for flows and 0.24 to 0.85 for nutrients. Four what-if scenarios were simulated representing different regional BMP implementations: No BMPs implemented, current conditions (1032 km2 area influenced), maximum potential scenario (5923 km2 area influenced), and optimal BMP placement. Simulations indicated that currently implemented BMPs could be reducing P loads from 482 to 468 tons/year (3%) and N loads from 4384 to 3796 tons/year (13%). Implementation of all potential BMPs could reduce P to 307 tons/year (36%) and N to 3036 tons/year (31%). Dividing the watershed into subwatersheds illustrated that BMPs in Taylor Creek-Nubbin Slough (50% agriculture) have the potential to reduce P by 55%, and in Upper Kissimmee (23.5% urban) BMPs have the potential to reduce N by 42%. In addition, optimal BMP spatial distributions in each subwatershed could reduce P loads and N loads by 10% and 4%, respectively, providing a cost-effective solution to nutrient pollution mitigation. Our simulations suggest that other strategies would be needed to further reduce P and N, especially in subwatersheds that have low BMPs reduction potential. [ABSTRACT FROM AUTHOR]

Nitrate pollution of surface water from farms and urban runoff is widespread – impairing drinking water supplies, recreation, and wildlife habitat. The scale of the problem in rivers has overwhelmed most watershed-based best management practices. A new paradigm is needed. In this paper we highlight the 119 ha (294 acres) Prado Wetlands in southern California, USA as an example of a gravity-enabled, free surface flow vegetated wetlands to treat a river – the nitrate-rich, effluent-dominated Santa Anna River. The wetland treats ∼1–2 m3/s of the 7.1 m3/s (250 cfs) flow of the river in 28 wetland cells in two parallel trains (residence time 2–4 d, hydraulic loading rate 10–20 cm/d). The cleaner water is returned to the river and infiltrated downstream into a managed groundwater basin supplying 2.4 million customers. Since 1998, ∼1200 t of nitrate-N have been permanently removed from the river and released as N 2 -gas into the air. Over 24 years, in the warm summers an average of 6.1 mg-N/L entered the wetland and 3.7 mg-N/L flowed out, a removal efficiency of 57%. In the cooler winters, an average of 6.4 mg NO 3 -N/L entered and 2.6 mg NO 3 -N/L flowed out, a removal efficiency of 45%. Individual months varied widely in concentration removal efficiency from 7% (winter) to 98% (high summer). Areal summer removal averaged 137 mg NO 3 -N/m2/d and the apparent "k" was around 46 m/y. All-year rates were 129 mg NO 3 -N/m2/d or 47 g/m2/y, a reasonable performance considering the size of the system and its configuration for both nitrate removal and duck hunting (i.e., more open water). Annual average nitrate removal efficiency increased substantially over time (45 to 72% for 1998–2004 versus 2016–22) and is attributed to an increase in hydraulic residence time, upgraded internal plumbing, and increased winter temperatures (+3C°). Prado Wetlands also removes phosphorus, though not as well as nitrate; average warm season removal efficiency was 23% (inflow 1.20 mg PO 4 -P/L, outflow 0.93 mg PO 4 -P/L). The aerial removal rate was high at 23 mg P/m2/d or 8.5 g/y, probably due to the high inflowing P-concentrations and the hard water. Wildlife was also enhanced. Least Bell's Vireo (Vireo belli pusillus) , an endangered bird in the Prado Basin, increased from 19 pairs (1998) to a recent average of 444 pairs due to habitat improvement and reduction of cowbird parasitism. Results from the Prado Wetlands show that cleaning up rivers via diversion through wetlands benefits both water quality and wildlife. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is naturally present in soils. However, urbanization can promote additional inputs of P into the soil that lead to saturation of the binding sites exceeding the maximum sorption capacity. Soils saturated with P act as important diffuse sources of pollution of water resources. The flow of P from the soil to aquatic ecosystems is an aggravating factor for water scarcity, especially in the semiarid region. Knowing phosphorus dynamics in the soil is essential to protect water quality and ensure its multiple uses. In this paper, a total of fifty soil samples, twenty-five from natural soils and twenty-five from urban soils, were evaluated for the effect of urbanization on P sorption characteristics and their relationship with the physical and chemical attributes of the soil. The soil samples were characterized physically and chemically, and the P sorption characteristics were obtained from the adjustment of Langmuir and Freundlich equations by nonlinear regression. Urbanization results in increased soil P saturation and reduced P sorption capacity. Our results show that the sandy texture of the soils studied had a standardizing effect on the soil's physical properties, maintaining, even after urbanization, the physical quality similar to natural soil. In contrast, pH (in water and KCl), base saturation, sodium saturation, potential acidity, exchangeable Al3+, exchangeable Mg2+, available P, and P-rem are valuable indicators in the segregation between natural and urban soils. The reduction of P sorption capacity in urban soils increases the risks related to P loads in aquatic ecosystems that experience urban expansion worldwide. These data serve as a basis for decision-making regarding the appropriate soil monitoring and management of urban expansion areas in watersheds to control P flow to aquatic systems. [Display omitted] • Knowledge about P saturation index of soil leads to better water quality management. • Urban sandy soils have a lower P sorption capacity and a higher P saturation index. • After urbanization, risks of P pollution in water bodies should not be neglected. • P saturation index is associated with higher pH and base saturation. [ABSTRACT FROM AUTHOR]

Winter manure application contributes substantial nutrient loss during snowmelt and influences water quality. The goal of this study is to develop best management practices (BMPs) for winter manure management. We compared nutrient concentrations in snowmelt runoff from three dates of feedlot solid beef manure application (November, January, and March) at 18 tons ha-1 on untilled and fall-tilled plots. The manure was applied at a single rate. Sixteen 4 m² steel frames were installed in the fall to define individual plots. Treatments were randomly assigned so that each tillage area had two control plots, two that received manure during November, two in January, and two in March. Snowmelt runoff from each individual plot was collected in March and analyzed for runoff volume (RO), ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total dissolved phosphorus (TDP). Snowmelt runoff concentrations and loads of NH4-N, TKN, TP, and TDP were significantly higher in runoff from manure application treatments compared to control. The concentration of NH4-N and loads of NH4-N and TDP were significantly (p = 0.05) greater (42%, 51%, and 47%, respectively) from untilled compared to fall-tilled plots. The November application significantly increased RO, NH4-N, and TDP concentrations and loads in the snowmelt runoff compared to January and March applications. Results showed that nutrient losses in snowmelt runoff were reduced from manure applications on snow compared to non-snow applications. The fall tillage before winter manure application decreased nutrient losses compared to untilled fields. [ABSTRACT FROM AUTHOR]

Streamflow hydrographs summarize the behavior of watersheds. Their separation into quick and slow components requires hydrological knowledge of the specific drainage area. To better understand the hydrological response of 14 small agricultural watersheds in Québec, Canada, covering different physiographic attributes ranging from lowlands to hilly and steep landscapes, streamflow electrical conductivity was used as a geochemical tracer. These agricultural watersheds have undergone significant management practices, including artificial drainage. The objective of this research was to evaluate the performance of existing automated filter methods for hydrograph separation (BFLOW, UKIH, PART, FIXED, SLIDE, LOCMIN, and Eckhardt). The geochemical method was used as a reference for comparison with the filter methods. Comparison of the slow flow estimates from non-calibrated filters, using a MANOVA model, showed that the filter performance increased under conditions with high contributions of quick runoff to the stream, such as during snowmelt (spring season), during heavy precipitation, and in subwatersheds with landscape conditions more prone to quick runoff. However, filter performance decreased as hydrological processes predisposed more flow to slower pathways, typically in summer and fall, as well as in lowland landscapes generally associated with high rates of tile drainage rather than in hilly and steep relief. Underlying the filter assumptions is the classic concept of a rainfall event with quick runoff as the main source of the drainage area response. Thus, slow flow is associated with a low threshold response. Eckhardt filter simulations were in good agreement with the geochemical method after calibration, based on model statistical measures (R, NSE, and PBIAS). However, larger errors were associated with higher flow values. The slow flow overestimations were more pronounced during periods of extreme events, i.e., spring runoff and heavy precipitation. The linear concept of the Eckhardt filter yields no information on slow flow response behavior that could be useful in capturing its temporal variability. Because the routing of water has been managed to improve agricultural productivity, these hydrological modifications resulted in a more complex slow flow response. The performance of filtering methods is thus affected. Therefore, simplifications of filter assumptions are less likely to provide more effective estimates of slow flow. Furthermore, given the heterogeneity of hydrological processes due to seasonal climatic characteristics, the routine application of basic filter concepts is not sufficient to address the variable nature of the hydrological response. The variability scale of geochemical separation, from regional (agro-climatic) to local (adjacent watersheds), proved that it is always relevant to have adequate separation. However, the validation of filters without a tracer is limited and almost unsuitable for these agricultural watersheds. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in soils has worsened with rapid economic development. The combined method with principal component analysis/absolute principal component scores) and random forest models successfully reveals the total sources contribution structure and the specific influence process of industrial activities on heavy metals concentration in soils of the three urban agglomerations. Through statistical analysis, Cd in the Jing-Jin-Ji Metropolitan Region, Pb, Cu, Hg, Cd and As in the Yangtze River Delta, and Hg, As, Cd, Cu and Pb in the Pearl River Delta had relatively high mean concentrations and coefficient of variation (CV), which indicates that the contamination may be caused by human activities. Through PCA/APCS analysis, industrial activities contributed more than 60% of the Cd, Hg and Pb concentrations in soils in JJJ, YRD and PRD. A random forest simulation revealed that heavy metal pollution in soils is the combined result of natural processes and human activities in the three urban agglomerations. The heavy metals concentration in JJJ is mainly caused by industrial activities through land-based emission. The industrial activities presented more significant impact on heavy metals concentration in the soil of YRD compared with other two urban agglomerations. The elevation variation controlled the pattern of heavy metal concentration through influencing the spatial clustering feature of industrial activities. The distance from the sample location to the nearest industrial enterprise is the most important factor in determining the heavy metal concentration. The number of enterprises within a 5 km radius of the sample locations makes a greater contribution to the amount of Hg pollution than other heavy metals. The results of this study could provide support for better management of soil pollution prevention practices such as specific industrial governance and layout optimization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Continuous nutrient load series were estimated from discrete monitoring data. • Q – C relationships were obtained to determine load series for monitored basins. • Loads in unmonitored basins were assessed through ecohydrological regionalisation. • The developed method was applied to the Lake Como watershed over 2000–2019. • This work is a first step for the ecohydrological regionalisation of nutrient loads. Continuous series of nutrient loads released into a water body are essential for nutrient budgeting, water quality modelling and watershed management activities. A quintessential example of pursued data are the series of total nutrient loads flowing from multiple tributaries into a lake. However, except for extraordinary cases in which high-frequency monitoring (HFM) stations are installed for both discharge and concentrations, measured nutrient loads are available on a discrete basis. Such observations are typically obtained by governmental agencies for environmental monitoring purposes, with an at best monthly resolution, yet commonly with gaps spanning years. Usually, monitoring activities are limited to major inflows, neglecting minor ones. However, the latters can play a more relevant role in nutrient load budgets than in hydrological ones, in response to different natural features and pollution among tributary watersheds. In this work, we present a methodology we developed to estimate long-term series of total nutrient loads flowing into a water body, employing as case study Lake Como, a large deep lake in the Italian Alps with manifold monitored and unmonitored tributary watersheds. The method uses observed long-term relationships between discharges and concentrations (Q – C) and available discharge measurements and hydrological estimations to estimate continuous load series for the monitored basins. For the unmonitored watersheds, Q – C relationships are estimated from those of the monitored basins, given the observed dependence of the power-law coefficients on basin hydromorphological parameters. This equals to extending the regionalisation approach applied in hydrology for rainfall and discharges to the ecohydrological field for nutrient load estimation. The application of the method to the case study led to overall annual load estimations congruent to traditional techniques and revealed interesting Q – C watershed dynamics at interannual time scales which could not be disclosed through previous approaches. This work represents an exploratory development and application of ecohydrological regionalisation techniques, whose future development is fostered. [ABSTRACT FROM AUTHOR]

Highlights • Soil degradation will be exacerbated by the increasing population and climate change. • Some countries have successfully adopted CA and other improved technologies. • Adopting BMPs of SI has potential and challenges. Abstract The "4 per Thousand" and "Adapting African Agriculture" are bold and innovative initiatives adopted at COP21 in Paris and COP22 in Marrakesh, respectively. These initiatives are soil-centric and based on adoption of soil-restorative and improved agricultural practices. The objective of this article is to discuss the merits and challenges of South–South Cooperation (SSC) in promoting the adoption of best management practices (BMPs) such as conservation agriculture (CA) and sustainable intensification (SI). Basic principles of CA are: retention of crop residue mulch, incorporation of cover crops and complex rotations, integrated nutrient management and elimination of soil disturbance. The strategy of SI is to produce more from less by enhancing the eco-efficiency, reducing waste, and restoring soil health. Whereas CA has been successfully adopted in Brazil, Argentina, Chile and other regions of South America, its potential of harnessing agronomic and ecologic benefits has not been realized in Sub-Saharan Africa, South Asia, and elsewhere in The Global South. The strategy of SSC is pertinent because of the ten basic principles or tenets: lack of hierarchy, equal participation in all decision-making processes along with transparency, trust, mutual respect, and accountability. However, several concerns have been raised regarding issues such as land grab, and access to resources etc. Based on the scientific concepts of SI, producing more from less, even a triangular cooperation (TAC) or South-South-North (SSNC) cooperation can be developed to achieve adaptation and mitigation of climate change, advance food security, improve degraded soils and restore soil health through soil organic carbon (SOC) sequestration, and advance Sustainable Development Goals (SDGs) of the U.N. A widespread adoption of CA and SI through SSC, TAC or SSNC can advance SDGs including #1 (end poverty), #2 (eliminate hunger), #6 (clean water), #13 (climate action), and #15 (life on land). Of the global cropland area under CA estimated at ∼180 million hectare (Mha) in 2015–16, land area under CA is only 2.7 Mha in Africa and 13.2 Mha in Asia. SSC, TAC and SSNC can build upon the existing and on-going initiatives by national and international organizations. [ABSTRACT FROM AUTHOR]

Abstract Best management practices (BMPs) are conservation efforts implemented to address environmental challenges associated with agricultural production. One such BMP, a tailwater recovery (TWR) system, has a dual purpose aimed at mitigating solids and nutrient losses from agricultural landscapes and creating an additional surface water source for irrigation. This study analyzes the costs of using five TWR systems to reduce solids, nutrients, and retain water. All systems were located in the Lower Mississippi Alluvial Valley and were used to irrigate crops including rice (Oryza sativa), corn (Zea mays), and soybeans (Glycine max). Costs to reduce solids and nutrients were calculated using annual payments and revenue losses due to lost tillable area from implementation of TWR systems. Similarly, cost to save and irrigate a mega-liter (ML) of water was determined as the annual payment for TWR systems, revenue losses and measured pumping cost. The range of mean total cost to reduce solids using TWR systems was $0 to $0.77 per kg; P was $0.61 to $3315.72 per kg; and N was $0.13 to $396.44 per kg. The range of mean total cost to retain water using TWR systems was $189.73 to $628.23 per ML, compared to a range of mean cost of groundwater of $13.99 to $36.17 per ML. Compared to other BMPs, TWR systems are one of the least expensive ways to reduce solid losses but remain an expensive way to reduce nutrient losses. The costs of using TWR systems to provide an additional irrigation water source range from less expensive than common conservation practices used to improve water use efficiency to more expensive and comparable to practices such as desalination. Therefore, TWR systems may be a prohibitively more expensive BMP to retain nutrients and water on some agricultural landscapes than other solutions. Highlights • Tailwater Recovery (TWR) systems are one of the least expensive practices to mitigate solid losses. • Tailwater Recovery systems are one of the most expensive practices to mitigate phosphorus and nitrogen losses. • Cost to reduce solids using TWR systems was $0–0.77 per kg; P was $0.61–3,316 per kg; and N was $0.13–396 per kg. • The cost to retain water using TWR systems was $190–628 per ML, compared to a cost of groundwater of $14–36 per ML. [ABSTRACT FROM AUTHOR]

Abstract Effects of mitigation measures in agriculture on abating eutrophication are difficult to evaluate by assessments of catchment monitoring data. Estimates of improved water quality by specific agricultural Best Management Practices (BMPs) are therefore often dependent on simulation modeling. A main objective was thus to assess the probable reductions in total phosphorus (TP) loading achieved by implemented agricultural mitigation measures. The case-study site was a catchment in southeastern Norway. Simulation modeling was conducted by use of The Soil and Water Assessment Tool (SWAT). The aim of this present study was to understand the model uncertainty associated both with calibration/validation (baseline) and TP loading scenarios based on BMP. The modeled decrease in TP loading by the set of implemented BMPs was assessed by comparing simulated baseline output with output where the set of abatement actions were removed. The model was set up for the years 2006–2010 and calibrated against observed monitoring data, including daily discharge, sediment- and TP fluxes. Model simulations were performed including and excluding the implemented set of mitigation measures. The simulated set of mitigation measures include decrease in amount of phosphorus fertilization, establishment of vegetated buffer strips along streams and constructed wetlands in the water courses, no autumn tilling and removal of point TP sources from scattered dwellings. Model calibration and uncertainty estimation are performed using an algorithm for Sequential Uncertainty Fitting (SUFI2; ver. 2). Probabilistic risk for given magnitudes of increased TP loading if existing BMPs were not implemented was assessed. Using this novel approach it was possible to state, with a 80th percentile confidence level, that the average annual TP loading would have been about 26% higher if no mitigation measures were implemented in the catchment. This was possible to assess even though the difference between baseline and BMP scenario was not significant. Highlights • Assessing improved water quality by agricultural BMPs usually involves modeling. • SWAT modeling using stochastic methods for simulating BMP scenarios • 80% confidence that TP loading decreases by 26% with implemented BMPs. [ABSTRACT FROM AUTHOR]

Abstract A rapid progress of low-impact development type of best management practices for urban storm water runoff quantity and quality control at a global scale has occurred in the past decade. In-depth research on low-impact development type of best management practices as useful technologies and measures to control stormwater runoff is being conducted worldwide. This paper presents a literature review of the environmental and economic evaluation of low-impact development type of best management practices through life cycle perspective. Research gap and future agenda are also proposed. Results show that life cycle assessment or life cycle cost analysis for low-impact development type of best management practices are widely documented. However, certain challenges still exist. Most works involved only on-site or facility scale or just considered certain environmental effect aspect. In addition, the lack of onsite monitoring data of water quality and quantity affects further research on low-impact development type of best management practices evaluation. In most emerging and developing countries, low-impact development type of best management practices implementation is still in the start-up stage. Quantitative life cycle assessment or life cycle cost analysis studies of low-impact development type of best management practices can provide necessary and useful information for decision-makers in regional scale low-impact development type of best management practices arrangement. Low-impact development type of best management practices database based on specific regions should also be established to support further in-depth research. Finally, low-impact development type of best management practices can offer various benefits to urban eco-systems. Researchers should provide a combination of environmental, economic, and social benefits of low-impact development type of best management practices to fulfill sustainability. Graphical abstract Image 109192 Highlights • Operation stage of LID-BMPs can generate much environmental benefit. • Construction and maintenance generate high environmental and economic burdens. • Most emerging countries lack indigenized research on LID-BMPs. • Regional scale implementation of LID-BMPs is significant for city planning. • LID-BMPs provide economic benefits by reducing cost of water treatment. [ABSTRACT FROM AUTHOR]

Highlights • The coupled SWAT-MODFLOW model is able to effectively predict stream flow, sediment, and nutrients on long term and high resolution configuration. • The groundwater and surface water shows strong interactions in terms of the exchanges of both water quantity and quality between streams and aquifer. • The agricultural best management practices (BMPs), particularly combined BMPs, are effective in reducing NPS pollution loads in a predominately agricultural coastal watershed. Abstract The predominantly agricultural coastal watershed located in tropical–subtropical Island has served as a pathway for nonpoint source (NPS) pollution loading into the downstream coastal ecosystems. The present study aims to assess watershed hydrology and water quality by applying a watershed model to long–term high–resolution monitoring data, and to evaluate the reduction of nonpoint–source pollution by implementing best management practices (BMPs) in a small agricultural watershed located in southwestern Japan. The Soil Water and Assessment Tool (SWAT) was coupled to a groundwater model (MODFLOW) and applied to simulate stream flow, sediment, and nutrients discharges. The results revealed that the model successfully predicted hourly stream flow, sediment, and nutrients concentrations in the study watershed and that the model could be further used to evaluate BMP scenarios. This is the first attempt to quantify the impacts of multiple agricultural mitigation measures on long-term water quality for sediment, nitrate, and phosphate at an hourly resolution. From the model results, the land cover conversion and mulching scenarios achieved a significant reduction in sediment, followed by the cover crop, alternative tillage, and filter strip scenarios. Moreover, conversion of all summer sugarcane to pasture farmland and fertilizer control scenarios gave the superior reduction in nitrate load, while other scenarios were minimally effective. On the other hand, most of the scenarios significantly achieved the reduction of phosphate load. The results further indicated that the BMPs recommended in this study are appropriately combined scenarios, which achieved the significant reduction in all NPS loads. Although this study revealed some effective mitigation measures to improve the water quality in the study watershed, actual implementation of correct ones may be practically challenging unless other environmental and economic risks (e.g. the increase of other pollutants and reduction in agricultural productivity) are also taken into considerations. [ABSTRACT FROM AUTHOR]

Highlights • Concentration-discharge (C-Q) dynamics may vary across alternative time-scales. • Anthropogenic inputs and stormflow were investigated by using C-Q approach. • Temporal relationships between fertilizer input and watershed flux were identified. Abstract Impacts of agricultural activities and hydrologic variables on nitrogen (N) loads have been investigated previously, but interactions among these factors are still poorly addressed across alternative time-scales. The concentration-discharge (C-Q) dynamics at short time-scales could be useful to disentangle the impacts of agricultural activities because it can provide more information about the interaction between N export and input. In this study, total dissolved N (TDN) concentrations/fluxes-discharge dynamics across different time-scales (annual, daily and hourly) were used to investigate the potential influences of agricultural activities and the interaction with hydrologic variables. At the long-term scale, streamflow and instream TDN concentrations exhibited the same inter-annual variations. At daily scale, higher temporal variations of streamflow (compared to instream TDN concentrations) occurred during stormflow-dominated periods. It highlighted the importance that stormflow may have substantial impact over N concentration changes over time. At the smaller time scale, direct influence of fertilizer application on watershed N export was unraveled by the difference in stream TDN concentrations and export fluxes between the early growing period (with more fertilizer application) and the later period (with less). In addition, the differences may increase with increasing flow conditions, which indicated that the impact of agricultural activities could be affected by hydrologic variables. These findings provide important information for improved best management practices (BMPs) to reduce N pollution from nonpoint sources (NPS). [ABSTRACT FROM AUTHOR]

Abstract The diffuse nature of nonpoint source (NPS) pollution as well as that of the effectiveness of best management practices (BMP) to control NPS pollution necessitates BMP evaluation at the field scale. In this study, a web interface was developed for application of the Agricultural Policy Environmental eXtender (APEX) model at the field scale. The interface contains background databases for field location, soil, agricultural management and climate across the contiguous United States. Users can specify properties to run the model for an individual field and compare the results under various land management and conservation practice choices. A case study was conducted to demonstrate the capability of the web interface for simulating various land management scenarios. This tool can help provide on-site information for NPS pollution management related policies and serve as a communication tool among scientists, engineers, and stakeholders. Highlights • An efficient web-interface for the APEX model was developed. • Databases for model inputs and management operations can be systematically prepared. • Multiple modeling outputs can be visibly demonstrated through the interface. • Evaluation of hydrologic and water quality processes can be conducted efficiently. [ABSTRACT FROM AUTHOR]

Abstract Although formal simulation-optimization approaches have been shown to be able to identify near-optimal outcomes for a range of stormwater management problems, stakeholder acceptance of these solutions can be problematic, especially if there is a lack of familiarity with the optimization processes and simulation model used to arrive at these solutions. To address this problem, a portfolio optimization problem formulation is introduced that allows stormwater best management practices (BMPs) to be evaluated by stakeholders before the portfolio selection process. This enables the search space to be constrained before the BMP optimization process, ensuring that model results are transparent and only represent solutions that are trusted by experienced practitioners. This has the effect of reducing reliance on simulation-optimization involving complex stormwater simulation models, and increasing buy-in to the optimization results. The portfolio optimization formulation is applied to a catchment management problem in Australia, using a typical many-objective optimization approach including visualization techniques. Highlights • Many-objective optimization formulation for selecting catchment stormwater projects. • Reduces optimization search space for many-objective analysis. • Enhances multi-criteria decision analysis used in practice with optimization. [ABSTRACT FROM AUTHOR]

Low-impact development (LID), a land planning and engineering design approach for managing urban stormwater runoff, has been widely adopted across the globe. LID best management practices (BMPs) are man-made features that rely on natural processes to manage stormwater water quantity and quality. In this article, recent literature (published after the year 2008) related to nine BMPs was reviewed to highlight the ranges in treatment efficiencies for 21 of the most frequently investigated runoff parameters. The primary function, pros and cons, and factors affecting performance of each BMP were discussed. A frequency analysis of the reviewed parameters showed that total suspended solids, total phosphorous, total nitrogen, runoff reduction, and zinc concentrations were the most frequently investigated stormwater runoff parameters. Five recurring themes were observed with regards to knowledge gaps and conflicting objectives for research related to LID BMPs that include: (i) lack of consensus on which parameters to measure for effective LID adoption, (ii) BMP performance is highly variable, (iii) many BMPs are known exporters of nutrient pollutants, (iv) lack of cold weather performance-specific studies for individual BMPs, and (v) lack of human pathogen-related stormwater quality studies for individual BMPs. Suggestions for future research are discussed to address these knowledge gaps. [ABSTRACT FROM AUTHOR]

Abstract Agricultural nonpoint source pollution is the leading source of water quality degradation in United States, which has led to the development of programs that aim to mitigate this pollution. One common approach to mitigating nonpoint source pollution is the use of best management practices (BMPs). However, it can be challenging to evaluate the effectiveness of implemented BMPs due to polices that limit data sharing. In this study, the uncertainty introduced by data sharing limitations is quantified through the use of a watershed model. Results indicated that BMP implementation improved the overall water quality in the region (up to ∼15% pollution reduction) and that increasing the area of BMP implementation resulted in higher pollution reduction. However, the model outputs also indicated that uncertainty caused by data sharing limitations resulted in variabilities ranging from −160% to 140%. This shows the importance of data sharing among agencies to better guide current and future conservation programs. Highlights • This study evaluated uncertainty related to the data privacy in agricultural sector. • The aggregated implementation areas for conservation practices were identified. • Different scenarios were evaluated corresponding to the implementation areas. • The privacy introduced a large degree of uncertainty in measuring a success of a program. [ABSTRACT FROM AUTHOR]

Abstract Stormwater runoff transports contaminants, including gross pollutants (GPs) accumulated on surfaces to nearby receiving water bodies. These may clog storm drainage systems, seal side entry pits and increase dissolved pollutants in receiving water bodies. Best management practices (BMPs) such as oil and grit separators, grassed swales, vegetated filter strips, retention ponds, and catch basin inserts (CBIs) are implemented to reduce stormwater pollutants in urban runoff. However, the information on physicochemical characteristics of the pollutants are still few in literature but important to improve the design of BMPs, considering qualitative aspects, and their operation. CBIs are devices used to remove GPs at source without requiring any extra land use because they are typically mounted within a catch basin (e.g. side entry pit) or existing drain. In this study, improvement of stormwater quality was investigated at two different sites (Subiaco, a residential area and Hillarys Boat Harbour, a commercial-marine-recreational area; Western Australia) where a new CBI made of non-woven polypropylene geotextile was installed in side entry pits to capture GPs at source. Influent and effluent water from the CBIs was collected and analyzed for BOD, COD, TSS and PO 4 -P with maximum improvements in water quality of 90%, 88%, 88% and 26% respectively. The heavy metals in influent and effluent water were found very low and below the guideline values. Analysis of particle size distribution, specific surface area of solids, SEM images and heavy metal content (Cu, Fe, Ni, Pb, Zn, Cd) in solids showed that the residential area contained more finer particles than the commercial area but that solids in the commercial area contained greater concentrations of heavy metals than those from the residential area. The specific surface area was found to be higher in the residential area and particles were thought to be largely sourced from traffic. However, these characteristics may be monitored for longer term for more CBIs installed in different locations. Graphical abstract Image Highlights • Pollutant removal by catch basin inserts (CBI) was assessed under field conditions. • Gross pollutant characteristics from two different land use types were compared. • Particle size distribution, specific surface area in captured solids were analyzed. • Source characterization of heavy metals captured in CBI was investigated. • CBI could remove 80% suspended solids, 90% BOD and 26% nutrients from stormwater. [ABSTRACT FROM AUTHOR]

Nonpoint source (NPS) pollution from agricultural and urban development is a primary source of nutrients and decreased water quality in aquatic systems. Installation of best management practices (BMPs) within critical source areas of the watershed can be helpful at reducing the transport of nutrients to waterbodies; however, prioritizing these areas may be difficult. The objective of this study was to develop several potential frameworks for prioritizing subwatersheds using baseflow water chemistry data in relation to a simple human development index (HDI; total percent agriculture and urban development). At a monthly interval, samples were collected at 26 sites throughout the Oklahoma portion of the Lake Wister Watershed (LWW) and analyzed for total nitrogen, total phosphorus, total suspended solids, and chlorophyll a. Changepoint analysis for each parameter found significant thresholds for each of the parameters ranging from 20 to 30% HDI. Changepoint analysis summary statistics were used to develop prioritization frameworks for the LWW that could be used to target subwatersheds where BMP installation would have the greatest effect at improving water quality. Additionally, regression models developed from the relationships between water quality parameters and HDI values serve as realistic targets for improving water quality, with the modeled line representing the target concentration for a given HDI value. After BMPs have been implemented, baseflow monitoring should continue at the subwatershed scale to track changes in water quality. Focusing monitoring efforts at the subwatershed scale will provide an earlier indication of the effectiveness of BMPs, as it may take several decades to detect improvements in water quality at the larger watershed scale. [ABSTRACT FROM AUTHOR]

Highlights • Systematically calibrating and validating both hydrological and water quality model. • Using satellite imagery to detect possible tail water recovery system in study watershed. • Using reservoir function in SWAT to simulate tail water recovery ponds grouped by sub-basins in watershed wide. • Using management schedule function in SWAT with dynamic analysis of crop rotation scenario. Abstract For an agricultural watershed, best management practice (BMP) is a conservational way to prevent non-point source pollution and soil and water loss. Three BMPs, including tail water recovery pond, conservational tillage, and crop rotation, were evaluated in order to demonstrate the impacts of BMPs on water quality and quantity. Satellite imagery was used to estimate potential tailwater recovery ponds in this study. The Soil and Water Assessment Tool (SWAT) was applied to evaluate BMPs. Results showed that the use of conservational tillage reduced cumulative sediment, total nitrogen (TN), and total phosphorus (TP) yields. In the crop rotation scenario analysis, it was found that sediment and flow were not sensitive to crop rotation management. The corn-soybean rotation scenario had higher TN and lower TP yields than those of the continuous corn scenario. Continuous soybean scenario showed the lowest TN and low TP yields, which may because of the higher nitrogen fertilization demands, greater crop yield, and greater residue of corn than soybean crop. Based on the SWAT model simulation results, the tailwater ponds can reduce sediment yield and improve groundwater storage. [ABSTRACT FROM AUTHOR]

Abstract Miyun reservoir watershed is a major source of drinking water for China's capital, Beijing, which has a population of 21.75 million. Recently, the capacity of the Miyun reservoir to supply clean drinking water has been threatened by increasing eutrophication (or algae bloom), mainly due to the discharge of wastewater and excessive fertilization application in the upstream watershed. Therefore, there is an urgent need to design effective best management practices (BMPs) to reduce upstream nutrient load and improve water quality in the Miyun reservoir. In this study, we built a watershed model (the Soil and Water Assessment Tool) for the Miyun Reservoir Watershed (MRW) and calibrated and validated it using long-term sediment, nitrogen (N) and phosphorus (P) data. Furthermore, we developed a Markov Chain based multi-objective optimization program to explore optimal BMPs with tradeoffs between economic costs and water quality responses. Using the watershed model and multi-objective optimization algorithms, we explored the potential effectiveness of BMPs under two scenarios that are currently being considered. Scenario 1 assumes that funding for BMP implementation comes from national grants and targets high water quality standards, whereas scenario 2 assumes funding is provided by farmers and targets water quality that meet the drinking water standards. We found substantial discrepancies between the two scenarios with respect to the types and spatial configurations of BMPs and associated economic costs, highlighting the need to reconcile concerns from different stakeholders in order to arrive at a BMP plan that all parties will agree upon. In addition, we found that cross-subwatershed coordination and targeting flood season instead of year-round water quality standards could pronouncedly reduce the economic costs of BMP implementations without substantially degrading water quality. The watershed scale optimization method developed here holds promise to serve as an effective tool to explore tradeoffs between economic costs, water quality improvements, and decision makers' and stakeholders' concerns in BMP design, thereby informing sustainable watershed scale water resources management and ecosystem maintenance. [ABSTRACT FROM AUTHOR]

Intensive tillage (IT) in potato crops is considered as one of the main non-point sources (NPS) of local water eutrophication in the Fuquene Lake of Colombia. Therefore, the local government has invested in several programs aiming at the adoption of principles of conservation tillage (CT) which would allow for developing and applying the agricultural best management practices (BMPs). The complexity of hydrological and geological heterogeneity makes the degree of benefit that CT has in different locations uncertain. In this study, the Soil and Water Assessment Tool (SWAT) was used to assess the impacts of changing IT for CT on nitrogen (N ) and phosphorus ( P ) losses in surface water runoff from the potato crop in the Fuquene watershed. This is done at field and watershed levels. A two-year study quantified the changes in surface water runoff pollutants for three potato crop cycles under the traditional IT practice and CT practice - which included reducing tillage, green manure, and permanent soil cover - at twelve runoff plots installed in the Fuquene watershed ( Quintero and Comerford, 2013 ). This information was used to build, calibrate and validate the SWAT model. The results suggest that CT for the Fuquene watershed can be reduced up to 26% of the sediment yield and 11% of the surface runoff compared with IT, which means an overall reduction of load. The main CT effect on nutrient losses in runoff is an increase in the total N and P (2% to 18% respectively) compared to IT. However, the results at watershed level showed different patterns from those obtained at field level. Despite the model uncertainties, the results show a possibility of using hydrological models to assess the effectiveness of various field management practices in agriculture. [ABSTRACT FROM AUTHOR]

Highlights • Assessing ecological effects of selective harvesting on subtropical streams is rare. • Paired-catchment experiments with pools nested in streams are powerful tests. • Selective forest harvesting did not alter stream particulate organic matter dynamics. • Invertebrate detritivores varied among pools yet were not altered by harvesting. • Best management practices protect these facets of subtropical stream ecosystems. Abstract Best management practices (BMPs) for forestry activities have been developed to mitigate the impacts of timber harvesting on stream ecosystems in New South Wales, Australia. These BMPs include selective harvesting within the catchment, exclusion of harvesting in riparian zones, and restrictions on harvesting and machinery operations during wet weather or on steep slopes. The few studies assessing the ecological effects of forestry BMPs have largely focussed on operations in temperate climates and are often based on a single pair of control and impact streams. But what are the effects in subtropical regions where climatic and hydrological variability may be greater? Are the effects of selective harvesting dependent on the proximity of harvesting to the locations of monitoring? We used a multiple paired-catchment study to assess effects of forestry BMPs on standing stocks of benthic coarse particulate organic matter (CPOM) and densities of invertebrate detritivores in streams draining subtropical eucalypt catchments that were either harvested using BMPs (‘impact’) or unharvested (‘control’). CPOM and detritivores in three pools in each of the four streams were sampled multiple times before and after the impact catchments were harvested. Harvesting intensity and proximity of harvesting to stream monitoring sites differed between ‘impact’ catchments. Benthic CPOM was dominated by leaves and leaf fragments in all streams. There were no post-harvesting differences in CPOM composition, standing stocks of different CPOM fractions or densities of detritivorous stream invertebrates in two feeding groups (collector-gatherers and shredders) between stream pairs despite differences in the proximity (minimum of ∼50 m and 1.6 km) of harvesting to monitoring sites. We conclude that relative to matched control sites, selective forestry BMPs do not alter CPOM stocks and stream detritivore densities in this subtropical Australian eucalypt forest, implying that these BMPs are effective in mitigating effects of harvesting across similar subtropical forests. [ABSTRACT FROM AUTHOR]

Excessive phosphorus loading to inland freshwater lakes around the globe has resulted in nuisance plant growth along the waterfronts, degraded habitat for cold-water fisheries, and impaired beaches, marinas, and waterfront property. The direct atmospheric deposition of phosphorus can be a significant contributing source to inland lakes. The atmospheric deposition monitoring program for Lake Simcoe, Ontario, indicates roughly 20% of the annual total phosphorus load (2010-2014 period) is due to direct atmospheric deposition (both wet and dry deposition) on the lake. This novel study presents a first-time application of the genetic algorithm (GA) methodology to optimize the application of best management practices (BMPs) related to agriculture and mobile sources to achieve atmospheric phosphorus reduction targets and restore the ecological health of the lake. The novel methodology takes into account the spatial distribution of the emission sources in the airshed, the complex atmospheric long-range transport and deposition processes, cost and efficiency of the popular management practices, and social constraints related to the adoption of BMPs. The optimization scenarios suggest that the optimal overall capital investment of approximately $2M, $4M, and $10M annually can achieve roughly 3, 4, and 5 tonnes reduction in atmospheric P load to the lake, respectively. The exponential trend indicates diminishing returns for the investment beyond roughly $3M per year and that focusing much of this investment in the upwind, nearshore area will significantly impact deposition to the lake. The optimization is based on a combination of the lowest cost, most beneficial and socially acceptable management practices that develops a science-informed promotion of implementation/BMP adoption strategy. The geospatial aspect to the optimization (i.e., proximity and location with respect to the lake) will help land managers to encourage the use of these targeted best practices in areas that will most benefit from the phosphorus reduction approach. Implications: Excessive phosphorus loading to inland freshwater lakes around the globe has resulted in nuisance plant growth along the waterfronts, degraded habitat for cold water fisheries, and impaired beaches, marinas and waterfront property. This novel study presents a first-time application of the Genetic Algorithm methodology to optimize the application of best management practices related to agriculture and mobile sources to achieve atmospheric phosphorus reduction targets and restore the ecological health of the lake. The novel methodology takes into account the spatial distribution of the emission sources in the airshed, the complex atmospheric long-range transport and deposition processes, cost and efficiency of the popular management practices and social constraints related to the adoption of BMPs. [ABSTRACT FROM AUTHOR]

A Bayesian total uncertainty analysis framework is presented to assess the model estimates of the effectiveness of watershed management practices in reducing nonpoint source (NPS) pollution. The framework entails a two-stage procedure. First, various sources of modeling uncertainties are characterized during the period before implementing Best Management Practices (BMPs). Second, the effectiveness of BMPs are probabilistically quantified during the post-BMP period. The framework was used to assess the uncertainties in effectiveness of two BMPs in reducing daily total nitrogen (TN) loads in a 54 ha agricultural watershed in North Carolina using the SWAT model. The results indicated that the modeling uncertainties in quantifying the effectiveness of selected BMPs were relatively large. Assessment of measured data uncertainty revealed that higher errors were observed in simulating TN loads during high flow events. The results of this study have important implications for decision-making under uncertainty when models are used for water quality simulation. [ABSTRACT FROM AUTHOR]

Benthic algae are the nutritional base of most freshwater food webs. Here we consider the nutritional contribution of benthic algae in the form of fatty acids (FAs) over multiple seasons and years. Our study was conducted in the Upper Delaware River watershed (New York, USA), where best-management practices (BMPs) had been implemented over varying numbers of years (BMP age) to mitigate effects of agricultural activities in the watershed. We defined 4 BMP categories by the presence and duration of management used in each stream drainage prior to initiating our study: 1) reference (unaffected), 2) no BMP (agriculturally affected), 3) new (agriculturally affected, BMP ≤ 2 y), and 4) old (agriculturally affected, BMP ≥ 3 y). Our results indicate that BMPs were able to reduce agricultural effects, as evidenced by a significantly lower benthic algal total FA content in reference than in agricultural streams. However, FA content did not differ between BMP-age categories, a result suggesting that BMPs were rapidly effective (within 1-2 y). Among essential molecules, amount of essential FA precursors (α-linoleic acid 18:3ω3 and linolenic acid 18:2ω6) were inversely related to their derivatives (arachidonic acid 20:4ω6, eicosapentaenoic acid 20:5ω3, docosahexaenoic acid 20:6ω3) across BMP-age categories. These outcomes suggest that BMP practices are important for maintaining the quality of the New York City metropolitan area water supply. [ABSTRACT FROM AUTHOR]

Climate change is a primary driver that alters water pollution hotspots in watersheds, which complicates the use of Best management practices (BMPs) for diffuse pollution mitigation strategies. The objective of this study is to evaluate future changes in BMPs on total phosphorus (TP) loads to the river system, depending on climate change. Current weather data were collected from 2000 to 2010 and future weather data from 2040 to 2050 were obtained from regional climate model simulations based on Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5 scenarios. This study describes various BMP implementation plans at affordable cost that are adapted to different weather conditions, current (for 2000–2010) and future climate scenarios (for 2040–2050). The Soil and Water Assessment Tool (SWAT), i.e., one of the deterministic models for watershed management, was used to estimate total phosphorus (TP) removal efficiency of various types of BMP at two crop fields (rice paddy and soybean fields) in the Yeongsan River (YR) watershed of Korea. The Non-dominated Sorting Genetic Algorithm II (NSGA-II), i.e., one of the artificial intelligence (AI) models for decision support framework, was applied to obtain allow for trade-off analysis between two conflict objectives, the maximum TP load reduction against implementation costs. The SWAT simulation results showed that the model performance based on the Nash-Sutcliffe efficiency and percent bias was acceptable for simulating three parameters; daily flow discharge, monthly sediment loads, and TP loads in the river. As a result, monthly sediment loads and TP loads increase remarkably under all future climate change scenarios except for July, when a comparable amount of precipitation is recorded during the present and future conditions. New implementation of BMPs, therefore, will be required for future climate change scenarios to achieve 50% TP load reduction in the given watershed condition. Interestingly, parallel terraces which showed good efficiency in reducing TP loads at both fields under the current weather condition cannot be effective any more under the worst-case weather scenario in the future climate. In such a case, detention ponds can be proposed as BMP alternative to parallel terraces. Overall, this study not only demonstrates that watershed management plans using BMPs should be adjusted according to climate change scenarios, but also that the hybrid use of SWAT model and AI can help in refining existing and future BMPs at affordable cost. [ABSTRACT FROM AUTHOR]

This paper presents a technical approach to link a watershed model and surface water quality model to study the effects of agricultural conservation practices on the water quality of a receiving water body. The AnnAGNPS watershed model was applied to simulate runoff and loads of sediment and nutrients into Beasley Lake. The simulated results were used as boundary conditions for CCHE-WQ water quality model to simulate the concentrations of water quality constituents in the oxbow lake. In this model, the interactions between sediment and water quality constituents were considered. This integrated modeling system can be used to simulate flow, sediment and nutrient processes in both the watershed and waterbody systematically. Two modeling were calibrated and validated using measured data in Beasley Lake Watershed. The validated modeling system was applied to analyze the effects of cropping and tillage systems on the water quality of the receiving water body. • An integrated modeling system was developed to link AnnAGNPS and CCHE-WQ to study water quality throughout the entire watershed. • The models were calibrated and validated using measured data in Beasley Lake Watershed. • The modeling system was applied to analyze the lake water quality response to cropping and tillage systems. • The modeling system can be used to analyze the effects of agricultural practices on watershed runoff and lake water quality. • The integrated modeling system can be used to evaluate the effectiveness of conservation practices on water quality improvement. [ABSTRACT FROM AUTHOR]

Targeting nonpoint source (NPS) pollution hot spots is of vital importance for placement of best management practices (BMPs). Although physically-based watershed models have been widely used to estimate nutrient emissions, connections between nutrient abatement and compliance of water quality standards have been rarely considered in NPS hotspot ranking, which may lead to ineffective decision-making. It’s critical to develop a strategy to identify priority management areas (PMAs) based on water quality response to nutrient load mitigation. A water quality constrained PMA identification framework was thereby proposed in this study, based on the simulation-optimization approach with ideal load reduction (ILR-SO). It integrates the physically-based Soil and Water Assessment Tool (SWAT) model and an optimization model under constraints of site-specific water quality standards. To our knowledge, it was the first effort to identify PMAs with simulation-based optimization. The SWAT model was established to simulate temporal and spatial nutrient loading and evaluate effectiveness of pollution mitigation. A metamodel was trained to establish a quantitative relationship between sources and water quality. Ranking of priority areas is based on required nutrient load reduction in each sub-watershed targeting to satisfy water quality standards in waterbodies, which was calculated with genetic algorithm (GA). The proposed approach was used for identification of PMAs on the basis of diffuse total phosphorus (TP) in Lake Dianchi Watershed, one of the three most eutrophic large lakes in China. The modeling results demonstrated that 85% of diffuse TP came from 30% of the watershed area. Compared with the two conventional targeting strategies based on overland nutrient loss and instream nutrient loading, the ILR-SO model identified distinct PMAs and narrowed down the coverage of management areas. This study addressed the urgent need to incorporate water quality response into PMA identification and showed that the ILR-SO approach is effective to guide watershed management for aquatic ecosystem restoration. [ABSTRACT FROM AUTHOR]

Queensland grazing industries operate in one of the world’s most variable climates and face enormous challenges to achieve profitability and sustainability. To assist grazing enterprises, the Queensland Government has developed an operational online information system – FORAGE, to facilitate best management practice for grazing land. The FORAGE system provides land managers with property-scale information relating to rainfall, ground cover, soil erodibility, land types, tree density, seasonal climate outlooks and pasture growth simulated using the GRASP grazing system model. This information is site-specific and tailored to facilitate on-ground management decisions common to Queensland grazing enterprises. The FORAGE system makes complex remotely-sensed data, information from a range of databases and pasture growth models more accessible and relevant to land managers. This paper describes the structure, resources (e.g. software, databases and models), information generating processes, delivery mechanisms and information products of the FORAGE system. [ABSTRACT FROM AUTHOR]

Mismanagement of urban runoff can result in inundation which causes serious problems in providing urban services. Best management practices (BMPs) are used for urban runoff management. In this study, a method is proposed to determine the robust optimal set of BMPs for runoff management in data-poor catchments in urban areas. This method includes five main steps: (1) Sensitivity analysis to determine effective parameters in rainfall-runoff simulation model, (2) Calibration of the rainfall-runoff model based on selected effective parameters, (3) Developing a multi-objective optimization model to obtain the optimal sets of BMPs, (4) Selecting the final solutions using the Nash approach for ranking, (5) Evaluation of the robustness of the selected solution using the Management Option Rank Equivalence method. The proposed method is examined in an urban basin located in the north of Tehran, Iran. The results show that the proposed approach provides reliable results for urban runoff management in data-poor areas. [ABSTRACT FROM AUTHOR]

Best management practices (BMPs) are popular approaches used to improve hydrology and water quality. Uncertainties in BMP effectiveness over time may result in overestimating long-term efficiency in watershed planning strategies. To represent varying long-term BMP effectiveness in hydrologic/water quality models, a high level and forward-looking modeling framework was developed. The components in the framework consist of establishment period efficiency, starting efficiency, efficiency for each storm event, efficiency between maintenance, and efficiency over the life cycle. Combined, they represent long-term efficiency for a specific type of practice and specific environmental concern (runoff/pollutant). An approach for possible implementation of the framework was discussed. The long-term impacts of grass buffer strips (agricultural BMP) and bioretention systems (urban BMP) in reducing total phosphorus were simulated to demonstrate the framework. Data gaps were captured in estimating the long-term performance of the BMPs. A Bayesian method was used to match the simulated distribution of long-term BMP efficiencies with the observed distribution with the assumption that the observed data represented long-term BMP efficiencies. The simulated distribution matched the observed distribution well with only small total predictive uncertainties. With additional data, the same method can be used to further improve the simulation results. The modeling framework and results of this study, which can be adopted in hydrologic/water quality models to better represent long-term BMP effectiveness, can help improve decision support systems for creating long-term stormwater management strategies for watershed management projects. [ABSTRACT FROM AUTHOR]

To better understand, implement, and integrate best management practices (BMPs) in agricultural watersheds, critical information on their effectiveness is required. A representative agricultural watershed, Beasley Lake, was used to compare runoff water quality draining through an integrated system of BMPs from row crop cultivated subdrainages as part of the national Conservation Effects Assessment Project (CEAP). From 2011 to 2014, runoff samples were collected across three subdrainages representing two integrated BMPs and three subdrainages representing row crop cultivation. Best management practice sites studied were two vegetated drainage ditches (east [EDV] and west [WDV]) that subsequently flowed into a vegetated sedimentation pond (SP). A suite of critical water quality parameters were assessed and included total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), and orthophosphate-phosphorus (PO4-P). During the four-year study period, integrated BMPs were effective at mitigating TSS runoff loads relative to row crop, but less effective at mitigating nutrient runoff loads. Runoff from WDV and SP were only moderately effective in mitigating nutrients in runoff with only TN and TP consistently reduced relative to row crop. Effectiveness of BMPs were primarily a result of the amount of area in tillage practices and crops planted relative to BMP within subdrainage basin area. Decreasing tillage:BMP and/or crop:BMP area ratios produced a subsequent decrease in runoff loads with the exception of NH4-N and PO4-P. [ABSTRACT FROM AUTHOR]

Soil erosion can be reduced through the strategic selection and placement of best management practices (BMPs) in critical source areas (CSAs). In the present study, the Soil Water Assessment Tool (SWAT) model was used to identify CSAs and investigate the effectiveness of different BMPs in reducing sediment yield in the Joumine watershed, an agricultural river catchment located in northern Tunisia. A cost-benefit analysis (CBA) was used to evaluate the cost-effectiveness of different BMP scenarios. The objective of the present study was to determine the most cost-effective management scenario for controlling sediment yield. The model performance for the simulation of streamflow and sediment yield at the outlet of the Joumine watershed was good and satisfactory, respectively. The model indicated that most of the sediment was originated from the cultivated upland area. About 34% of the catchment area consisted of CSAs that were affected by high to very high soil erosion risk (sediment yield > 10 t/ha/year). Contour ridges were found to be the most effective individual BMP in terms of sediment yield reduction. At the watershed level, implementing contour ridges in the CSAs reduced sediment yield by 59%. Combinations of BMP scenarios were more cost-effective than the contour ridges alone. Combining buffer strips (5-m width) with other BMPs depending on land slope (> 20% slope: conversion to olive orchards; 10–20% slope: contour ridges; 5–10% slope: grass strip cropping) was the most effective approach in terms of sediment yield reduction and economic benefits. This approach reduced sediment yield by 61.84% with a benefit/cost ratio of 1.61. Compared with the cost of dredging, BMPs were more cost-effective for reducing sediment loads to the Joumine reservoir, located downstream of the catchment. Our findings may contribute to ensure the sustainability of future conservation programs in Tunisian regions. [ABSTRACT FROM AUTHOR]

In this research, an export coefficient based inexact fuzzy bi-level multi-objective programming (EC-IFBLMOP) model was developed through integrating export coefficient model (ECM), interval parameter programming (IPP) and fuzzy parameter programming (FPP) within a bi-level multi-objective programming framework. The proposed EC-IFBLMOP model can effectively deal with the multiple uncertainties expressed as discrete intervals and fuzzy membership functions. Also, the complexities in agricultural systems, such as the cooperation and gaming relationship between the decision makers at different levels, can be fully considered in the model. The developed model was then applied to identify the optimal land use patterns and BMP implementing levels for agricultural nonpoint source (NPS) pollution management in a subcatchment in the upper stream watershed of the Miyun Reservoir in north China. The results of the model showed that the desired optimal land use patterns and implementing levels of best management of practices (BMPs) would be obtained. It is the gaming result between the upper- and lower-level decision makers, when the allowable discharge amounts of NPS pollutants were limited. Moreover, results corresponding to different decision scenarios could provide a set of decision alternatives for the upper- and lower-level decision makers to identify the most appropriate management strategy. The model has a good applicability and can be effectively utilized for agricultural NPS pollution management. [ABSTRACT FROM AUTHOR]

Bioretention is a typical low-impact development (LID) technology. This work used four different filler combinations of bioretention tank pilot test devices. Experiments on influence factors and intermittent operation were conducted. A continuous-run experiment was also performed to determine the purification ability of bioretention system on heavy metals. Results showed that the removal efficiency of heavy metals by fly ash tank was the most efficient, with a removal rate reaching 85.57%. The removal effect on highinfluent concentrations in filter was better than that in low-influent concentrations. With increased rainfall time intervals (antecedent dry time), heavy-metal removal efficiency improved. Temperature did not affect the removal efficiency of heavy metals on the whole based on the long duration of intermittent operation experiments. Moreover, the effluent heavy-metal concentration presented a descending trend during each simulation rainfall runoff event. During continuous operation test, heavy metals did not reach the exhaustion point in the experimental tanks, while the effluent concentration increased with increased water volume. According to PLS regression analysis, rainfall time interval was the most important factor affecting Zn removal rate, followed by filler characteristics, influent volume, and influent concentration. [ABSTRACT FROM AUTHOR]

A five-year study was conducted in Orange County, California to document the presence of standing water and the presence or absence of larval mosquitoes within 23 stormwater treatment Best Management Practices (BMPs) installed along State Route 73 by the California Department of Transportation. Findings were used to guide incremental improvements to BMP design and function with the aim of reducing the occurrence of standing water that persisted more than 96 h after precipitation. During the first year of monitoring, a number of structural and non-structural factors were identified as causes for standing water within BMPs suitable for mosquitoes. Uneven grades, inlet design and construction, and novel structural features were most frequently responsible for standing water, often exacerbated by sediment and debris accumulations and periodic or perennial non-stormwater flows. Subsequent modifications to BMPs eliminated or reduced the size of persistent standing water pools. The study demonstrated that mosquito larval habitat can be mitigated in BMPs designed to remain dry between precipitation events by collecting field data that identifies where post-construction structural and managerial changes are needed to eliminate or reduce unintended sources of standing water. [ABSTRACT FROM AUTHOR]

The article discusses the in-field best management practices (BMPs) to reduce the nutrient losses from agricultural fields with subsurface drainage.

This paper reviews the characteristics, benefits, and drawbacks of agricultural ditches and wetlands, as well as strategies for applying agricultural best management practices (BMPs) at the watershed scale for improving water quality. This synthesis focuses on the Great Lakes Region and the Mississippi River Basin in the United States, and specifically crop production systems in watersheds with subsurface drainage. The USDA Natural Resources Conservation Service (NRCS) has developed conservation practice standards for open channels and wetlands, which mitigate nutrient and sediment loading to surface water bodies from agricultural lands. Practices that use agricultural ditches to improve water quality, such as the two-stage ditch, have emerged in the last two decades and are starting to see a greater application in the region. Using wetlands as water treatment systems has a long history in a range of settings and over the past several decades is seeing more widespread application in agriculture. Water quality and watershed models are increasingly used to develop watershed strategies for reducing nutrient exports with agricultural BMPs. Models are also helpful in evaluating combinations of practices from the farm scale to the watershed scale. Application and limitations of several models commonly used in these regions of the United States are discussed. Finally, successful conservation strategies at the watershed scale must consider the human dimensions of watershed management, and we summarize the literature in this region on farmer perceptions and adoption of practices. [ABSTRACT FROM AUTHOR]

Increasing fertilizer inputs in tea ( Camellia sinensis L.) fields, especially in hilly areas, poses serious potential risks of surface water contamination. Best management practices (BMPs) have been extensively implemented to control nutrient loads from non-point sources. However, little research has been conducted to evaluate the effects of dynamic BMPs on nitrogen (N) load reductions in tea fields with different slope gradients. This study is conducted in subtropical tea fields in the Machuan River watershed, which adjoins Huangshan Mountain of Anhui Province in China. Three BMP scenarios, viz., avoiding fertilizing before rain, contour planting and applying slow-release fertilizers, are simulated to model the N load reduction using the Soil and Water Assessment Tool (SWAT). The objectives of this study are as follows: (1) to build a calibrated SWAT model for the Machuan River watershed, (2) to evaluate and compare the effects of three BMPs on N load reduction in tea fields with different slope gradients, and (3) to identify critical slope gradients and BMPs for effective N load control. The results indicate that three BMP scenarios significantly impact N losses reduction in tea fields and that their effects vary among different slopes and months. Compared with the baseline condition, the N losses rate could be reduced by approximately 24%, 28%, and 66% for three scenarios, respectively. Generally, tea planted on steep-sloping land leads to great losses of N, and tea fields on slopes exceeding 15° should be prioritized for BMP implementation as tea fields planted here tend to have the highest N losses. This will offer sound information for the development of better pollution-control strategies for tea fields in the Machuan River watershed. [ABSTRACT FROM AUTHOR]

Nutrient loading from the Maumee River watershed is a significant reason for the harmful algal blooms (HABs) problem in Lake Erie. The nutrient loading from urban areas needs to be reduced with the installation of green infrastructure (GI) practices. The Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 (L-THIA-LID 2.1) model was used to explore the influences of land use (LU) and climate change on water quantity and quality in Spy Run Creek watershed (SRCW) (part of Maumee River watershed), decide whether and where excess phosphorus loading existed, identify critical areas to understand where the greatest amount of runoff/pollutants originated, and optimally implement GI practices to obtain maximum environmental benefits with the lowest costs. Both LU/climate changes increased runoff/pollutants generated from the watershed. Areas with the highest runoff/pollutant amount per area, or critical areas, differed for various environmental concerns, land uses (LUs), and climates. Compared to optimization considering all areas, optimization conducted only in critical areas can provide similar cost-effective results with decreased computational time for low levels of runoff/pollutant reductions, but critical area optimization results were not as cost-effective for higher levels of runoff/pollutant reductions. Runoff/pollutants for 2011/2050 LUs/climates could be reduced to amounts of 2001 LU/climate by installation of GI practices with annual expenditures of $0.34 to $2.05 million. The optimization scenarios that were able to obtain the 2001 runoff level in 2011/2050, can also reduce all pollutants to 2001 levels in this watershed. [ABSTRACT FROM AUTHOR]

Best management practices (BMPs) have been widely used to address hydrology and water quality issues in both agricultural and urban areas. Increasing numbers of BMPs have been studied in research projects and implemented in watershed management projects, but a gap remains in quantifying their effectiveness through time. In this paper, we review the current knowledge about BMP efficiencies, which indicates that most empirical studies have focused on short-term efficiencies, while few have explored long-term efficiencies. Most simulation efforts that consider BMPs assume constant performance irrespective of ages of the practices, generally based on anticipated maintenance activities or the expected performance over the life of the BMP(s). However, efficiencies of BMPs likely change over time irrespective of maintenance due to factors such as degradation of structures and accumulation of pollutants. Generally, the impacts of BMPs implemented in water quality protection programs at watershed levels have not been as rapid or large as expected, possibly due to overly high expectations for practice long-term efficiency, with BMPs even being sources of pollutants under some conditions and during some time periods. The review of available datasets reveals that current data are limited regarding both short-term and long-term BMP efficiency. Based on this review, this paper provides suggestions regarding needs and opportunities. Existing practice efficiency data need to be compiled. New data on BMP efficiencies that consider important factors, such as maintenance activities, also need to be collected. Then, the existing and new data need to be analyzed. Further research is needed to create a framework, as well as modeling approaches built on the framework, to simulate changes in BMP efficiencies with time. The research community needs to work together in addressing these needs and opportunities, which will assist decision makers in formulating better decisions regarding BMP implementation in watershed management projects. [ABSTRACT FROM AUTHOR]