Watershed Assessment Research Articles

Runoff observation in a tropical Brantas watershed as observed from long-term globally available TerraClimate data 2001–2020

Runoff information and its dynamics are critical for supporting watershed management; however, spatio-temporal data about runoff is rare or unavailable in data-scarce regions. Information about the performance of remote sensing-based runoff and its potential application is limitedly known. In data-scarce regions, this condition impedes comprehensive watershed assessment especially in the midst of climate change impacts. This study examined the performance of globally available monthly runoff dataset provided by TerraClimate at ~ 4 km spatial resolution and employed them to assess the runoff dynamics in a humid tropic watershed. Monthly TerraClimate data shows a moderate performance with an r of 0.63, RMSE of 57–127 mm/month and NRMSE of 18–30% to the simulated runoff from a well-calibrated model. The upper region of Brantas watershed was found to be the hotspot of high runoff. About 25% of the study area belongs to high runoff (0–33rd percentile). Over the last two decades, runoff has been slightly increased across the study area. Green vegetation fraction (GVF), precipitation, and topography are critical for regulating runoff dynamics. While topography and precipitation impact on runoff are straightforward, the GVF’s role is complex and site-specific. High runoff was found mostly to be associated with high precipitation and steep slope. GVF appears to be less effective in representing ground cover against runoff generation due to high variability of actual ground cover types. Using time-series and change vector analysis (CVA) of runoff and GVF, the dynamics of watershed condition was examined. Long-term CVA analysis also found that the condition in Brantas watershed was fluctuated with slight increase in impaired condition. The study exemplified the potential use of the remote sensing-based runoff data in a tropical data-scarce region. Despite limitation of the runoff data due to its moderate performance, the globally available monthly runoff data from TerraClimate can be used to support regional water resource assessment in data-scare regions. Future improvement that includes downscaling and use of machine learning can be considered to improve the remotely sensed runoff data to deliver the bigger benefits of such data.

Sustainability assessment in the anthropocentric watershed based on emergy and decomposition methods: A case study of Erhai Lake Basin, southwest China

Assessment of anthropocentric watersheds’ sustainability and its driving forces is important for regional natural resources management and sustainable development. However, the impact of natural resources use on watersheds’ sustainability needs deeper exploration. This study employs emergy accounting and decomposition analysis methods to evaluate the sustainability and related key factors of Erhai Lake Basin (ELB) of Yunnan province in China -- a watershed facing urgently sustainable issues. Major results show that the environmental sustainability index (ESI) of ELB decreased with low production efficiency -- emergy yield ratio (EYR), and high environmental pressure -- environmental loading ratio (ELR) from 2000 to 2015. Four factors within the decomposition analysis have been identified, namely the emergy intensity factor (ΔUG), resource factor (ΔRF), water supporting factor (ΔWN) and water efficiency factor (ΔPW), as the major drivers of ESI changes. The economic development in ELB highly exceeded the carrying capacity of natural water resources, relying on imported resources and, in so doing, affecting sustainability levels. Accordingly, several suggestions are proposed which are helpful for sustainable watersheds governance.

Predicting the potential impact of forest fires on runoff and sediment loads using a distributed hydrological modeling approach

Forest fires profoundly affect the nature of watershed responses to precipitation, increases in runoff rate and volume, and post-fire sediment discharge. A post-fire watershed assessment to identify potential trouble spots for soil erosion and flooding can help land managers for decision-making on deploy mitigation, remediation measures, and restoration action plans. Predicting the potential impact of fires on runoff and soil erosion requires distributed hydrological modeling methods. This study used the Soil and Water Assessment Tool (SWAT), a rainfall-runoff model, to investigate the hydrological consequences of forest fires and their impact on sediment load under different burnt scenarios. For the pre-fire (baseline) scenario, the watershed is calibrated by using the measured discharge and suspended sediment concentration data from the weather station during the time step to estimate post-fire changes at the sub-catchment scale. The total water and sediment yield for the selected sub-catchment in the post-fire scenario with the highest spatial distribution of forest fire, due to the excessive surface runoff (an increase of 14.5%) increased significantly, resulted in 6.5 times increase in sediment yield. The results obtained from the study indicate a significant increase in sediment transport into the stream in the post-fire scenario. A large volume of soil losses occurred during the time step. In contrast, due to removing trees and vegetation from the ground, less evapotranspiration and infiltration occurred in selected sub-catchment areas after forest fires. In terms of watershed management, understanding the consequences of forest fires on hydrological services will be an effective method for sediment budget control. Therefore, applying the rainfall-runoff and erosion models for the watershed with developing plausible forest fire scenarios can be a productive method to deal with the threats and hydrological risks such as soil erosion and sediment transfer to the downstream environment.

Holistic Management Assessment of an Urbanized Watershed and Kettle Pond in Southern Wisconsin

A multidisciplinary assessment of a small pond and its fully urbanized watershed was conducted to understand physical, biological, and social factors influencing this natural resource. Originally an emergent wetland lacking natural drainage, Stricker’s Pond today is a resource shared by two municipalities which has been hydrologically connected (via a man-made outlet) to the larger Yahara River watershed in Wisconsin. The assessment involved water quantity and water quality measurement and modeling, vegetation and wildlife surveys, and community surveys and observation. Major findings include the following: increased flood risk caused by large storm events; high concentrations of nitrogen and phosphorus, likely contributed by a variety of natural and anthropogenic sources, resulting in full eutrophication; varied, but generally poor, vegetation biodiversity; limited wildlife diversity; and discrepancies between the management objectives of the two municipalities which share the resource and the surrounding community’s vision for the pond. To overcome these issues, a collection of recommendations are suggested for implementation. These recommendations range from minimal reoccurring maintenance and community engagement to specific management strategies and intermunicipal collaboration. With the recommendations provided within the assessment, a new, better pathway forward can be charted for Stricker’s Pond by decision makers and community members alike. By engaging with this case study, participants will be exposed to the complexity of water resources challenges occurring in this as well as their own communities. Thus, this case study can serve to participants as an example and a baseline of how similar holistic resource management assessments can be carried out in the future.

Soil erodibility assessment of laterite dominant sub-basin watersheds in the humid tropical region of India

Sub-basin prioritization is an essential aspect of watershed development initiatives as a part of the sustainable management program for natural resources. The present work aims to analyse the soil erodibility at sub-basin scale in the Pathro River Basin area of Jharkhand, India. Degradation of land resources is multifaceted, and its severity leads to soil detachment, thus rendering it a complex and interlinked system. Sixteen closely correlated morphometric attributes of the erosion process are considered for prioritizing watersheds by applying the frequency ratio (FR) method. This work assigns Support Vector Machine (SVM) algorithm to evaluate the existing soil risk condition with the help of twelve soil erosion influencing geo-environmental factors at the sub-basin area. Soil samples were examined using scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDX) to acquire the micro-graphic and physical condition of dominant soil forming minerals and their influences to develop susceptibility of peds to erode. The prioritisation results from both approaches show a reasonably similar output, identifying nine sub-watersheds as very high soil erosion-prone, while four sub-watersheds are recognised as low-risk. Field observation reveals that lowering of plunge pool and head retreat are dominant processes of gully extension in very high to high sub-basin prioritization areas. The final output provides a comprehensive platform for the urgency of policy interventions to minimize erosion risk and ecological damage in prioritized areas of Pathro River Basin, Jharkhand.

A Review on Sustainability of Watershed Management in Indonesia

This paper provides an overview of the implementation and obstacles of watershed management, and the alternative solutions based on a synoptic review of related studies and experiences across Indonesia. The review found that problems in the institutional aspect were hierarchical confusion, discrepancy, and asynchrony among regulations, and weak (participation, synchronization, and coordination) among watershed management stakeholders. The weaknesses in the planning stage are integration among sectors, a lack of community participation, and limited readiness to integrate watershed planning into regional planning. Stakeholders’ involvement is also a critical factor in successful implementation of degraded watershed rehabilitation, including in peatland and mangrove areas. Failure should be minimized by providing adequate information on degraded watershed characteristics, appropriate species choices, and effective mechanical construction for soil and water conservation. Community participation as the main factor in driving watershed management should be achieved by strengthening public awareness of the importance of a sustainable watershed and providing access for the community to be involved in each stage of watershed management. Another problem is data gaps which are essential to address from the planning to evaluation stages. The gaps can be bridged by using remotely sensed data and by applying hydrological-based simulation models. Simplified criteria for watershed assessment may also be required, depending on site-specific issues and the watershed scale.

Watershed Response to Legacy Phosphorus and Best Management Practices in an Impacted Agricultural Watershed in Florida, U.S.A.

Soil phosphorus (P) built up due to past management practices, legacy P, in the Lake Okeechobee Watershed (LOW) in south-central Florida, U.S.A., is often discussed as the root cause of lake eutrophication. Improvement of the lake’s water quality requires the identification of critical P sources and quantifying their contributions. We performed a global sensitivity analysis of the Watershed Assessment Model (WAM), a common evaluation tool in LOW environmental planning, using the Morris method. A pre-calibrated WAM setup (Baseline) of the LOW sub-watershed, Taylor Creek Nubbin Slough (TCNS), was used as a test case. Eight scenarios were formulated to estimate the contributions of various P sources. The Morris analysis indicated that total phosphorus (TP) loads were highly sensitive to legacy P in improved pastures, the major land use covering 46.2% of TCNS. The scenario modeling revealed that legacy P, inorganic fertilizers, and other sources contribute 63%, 10%, and 32%, respectively, to the Baseline TP load of 111.3 metric tons/y to the lake. Improved pastures, dairies, citrus, and field crops are the top TP load contributors. Our results have important implications for water quality improvement plans in the LOW and highlighted the need for accurate spatial mapping of legacy P and incorporation of such information in modeling efforts for watersheds demonstrating legacy P problems.

Hydrological Modeling of Green Infrastructure to Quantify Its Effect on Flood Mitigation and Water Availability in the High School Watershed in Tucson, AZ

Green Infrastructure (GI) practices are being implemented in numerous cities to tackle stormwater management issues and achieve co-benefits such as mitigating heat island effects and air pollution, as well as water augmentation, health, and economic benefits. Tucson, Arizona is a fast-growing city in the semiarid region of the southwest United States and provides a unique landscape in terms of urban hydrology and stormwater management, where stormwater is routed along the streets to the nearest ephemeral washes. Local organizations have implemented various GI practices, such as curb cuts, traffic chicanes, roof runoff harvesting, and retention basins, to capture the excess runoff and utilize it on-site. This study models the 3.31 km2 High School watershed in central Tucson using the Automated Geospatial Watershed Assessment (AGWA) tool and the Kinematic Runoff and Erosion (KINEROS2) model. Each parcel in the watershed was individually represented using the KINEROS2 Urban element to simulate small-scale flow-on/flow-off processes. Seven different configurations of GI implementation were simulated using design storms, and we stochastically generated 20 years of precipitation data to understand the effects of GI implementation on flood mitigation and long-term water availability, respectively. The design storm analysis indicates that the configuration designed to mimic the current level of GI implementation, which includes 175 on-street basins and 37 roof runoff harvesting cisterns, has minimum (<2%) influence on runoff volume. Furthermore, the analysis showed that the current level of GI implementation caused an increase (<1%) in peak flows at the watershed outlet but predicted reduced on-street accumulated volumes (>25%) and increased water availability via GI capture and infiltration. When the GI implementation was increased by a factor of two and five, a larger reduction of peak flow (<8% and <22%, respectively) and volume (<3% and <8%, respectively) was simulated at the watershed outlet. The 20-year analysis showed that parcels with roof runoff harvesting cisterns were able to meet their landscape irrigation demands throughout the year, except for the dry months of May and June. Additionally, stormwater captured and infiltrated by the on-street basins could support xeric vegetation for most of the year, except June, where the water demand exceeded volume of water infiltrated in the basins. The current level of GI implementation in the High School watershed may not have significant large-scale impacts, but it provides numerous benefits at the parcel, street, and small neighborhood scales.

GIS-based hazard and vulnerability assessment of a torrential watershed

Torrents are ephemeral streams which usually carry heavy bedload and flash flows. The frequent changes in its course caused by meandering and migration lead to extensive damage to environment in valley and alluvial land. In the present study, application programming interface (API) was developed to analyze temporal Landsat data in Google Earth Engine(GEE) to understand land use/land cover and vegetation characteristics in the Tangri (Dangri) River, India, and Indian Remote Sensing Satellites data were used for hazard and vulnerability assessment. It is observed that because of various conservation activities as well as due to watershed inhabitants’ intervention, the areas under cropland, orchard/plantation and grass/scrub have increased. The monthly mean enhanced vegetation index (EVI) has also increased in the watershed. Although, the average annual soil loss is high, i.e., 40.4 t/ha/yr. It is highest for mountain physiographic unit (67.6 t/ha/yr.) and scrub forest (61.5 t/ha/yr.). Based on flood inundation modeling, it is estimated that for two-, five-, ten-, twenty-five-, fifty- and hundred-year return periods, 1.42–16.14% areas of watershed are likely to get inundated. Torrents’ vulnerability analysis was carried out using analytical hierarchy process (AHP) to derive composite vulnerability index by aggregating weights of various parameters and sub-parameters. The alternatives for the treatment of vulnerable sections in torrential regime were evaluated using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and ELimination Et Choice Translating REality (ELECTRE) models. The methodology demonstrated has potential to analyze torrential systems and also for their proficient planning, monitoring and management.

Investigating the Status of Some Indicators of Assessment of Watersheds and Prioritizing Sub-Catchments in Terms of Erosion Reduction (Case Study of Karkheh Watershed)

Investigating the Status of Some Indicators of Assessment of Watersheds and Prioritizing Sub-Catchments in Terms of Erosion Reduction (Case Study of Karkheh Watershed)

Geoecological integrity index for assessment and prioritisation of watersheds in the Indian northwestern Himalayan region using geoinformatics

Biotic, abiotic and anthropogenic factors are considered in isolation for prioritisation of watersheds. Instead, it requires a multidisciplinary geoecolocical approach. The geoecology based prioritisation provides opportunities to assess the region by evaluating these multiple factors in combination. Thus, Geoecological Integrity Index (GII) was developed for prioritisation of Baner River watersheds of Indian northwestern Himalayan region by integrating biotic, abiotic and anthropogenic factors as the region is facing geological and ecological instability. Forest cover density and net primary productivity were used as biotic factors and drainage morphometry, soil erosion, and patches were used as abiotic factors. Population density of the watershed was considered as an anthropogenic factor. Weighed overlay analysis was carried out to understand the influence of each of these factors on watershed prioritisation. These factors were integrated to arrive at cumulative weights (GII) for micro-watersheds. With the help of GII, out of 110 micro-watersheds, 11 were prioritised as very high actionable, 32 as high actionable, 52 as moderately actionable and 15 as of minimal action, requiring suitable actions in a prioritised manner to conserve and manage. The study presents an approach for geoecological assessment of watersheds that can be replicated in watersheds of other Himalayan regions or areas having similar geoecological conditions.

Modeling estrogenic activity in streams throughout the Potomac and Chesapeake Bay watersheds.

Endocrine-disrupting compounds (EDCs), specifically estrogenic endocrine-disrupting compounds, vary in concentration and composition in surface waters under the influence of different landscape sources and landcover gradients. Estrogenic activity in surface waters may lead to adverse effects in aquatic species at both individual and population levels, often observed through the presence of intersex and vitellogenin induction in male fish. In the Chesapeake Bay Watershed, located on the mid-Atlantic coast of the USA, intersex has been observed in several sub-watersheds where previous studies have identified specific landscape sources of EDCs in tandem with observed fish health effects. Previous work in the Potomac River Watershed (PRW), the largest basin within the Chesapeake Bay Watershed, was leveraged to build random forest regression models to predict estrogenic activity at unsampled reaches in both the Potomac River and larger Chesapeake Bay Watersheds (CBW). Model outputs including important variables, partial dependence plots, and predicted values of estrogenic activity at unsampled reaches provide insight into drivers of estrogenic activity at different seasons and scales. Using the US Environmental Protection Agency effects-based threshold of 1.0ng/L 17 β-estradiol equivalents, catchments predicted to exceed this value were categorized as at risk for adverse effects from exposure to estrogenic compounds and evaluated relative to healthy watersheds and recreation access locations throughout the PRW. Results show immediate catchment scale models are more reliable than upstream models, and the best predictive variables differ by season and scale. A small percentage of healthy watersheds (< 13%) and public access sites were classified as at risk using the "Total" (annual) model in the CBW. This study is the first Potomac River Watershed assessment of estrogenic activity, providing a new foundation for future risk assessment and management design efforts, with additional context provided for the entire Chesapeake Bay Watershed.

Monitoring ungauged watersheds for investigating the variability of flow and salinity to implement the possible removal of salt fill sites.

Salinity is a crucial environmental problem leading to profound consequences in wetland plants and aquatic habitats including the rapid development of Phragmites australis in the marshland. These Phragmites australis are extremely vulnerable to capture fire, which might eventually affect the overall ecosystem of the marsh. However, in order to restore the marsh, a hydrologic investigation is needed, which is possible if a watershed is gauged, and long-term data are available. In this study, a systematic approach has been presented to conduct hydrologic modeling and salinity prediction in an ungauged watershed in order to implement the possible removal of salt fill sites. The stage and electrical conductivity were measured continuously, whereas stream cross sections and velocity of the streamflow were recorded intermittently in the Blackbrook Creek to develop a rating curve and generate continuous streamflow data. The watershed model Soil and Water Assessment Tool (SWAT) was calibrated and validated to a monthly scale with good model performance. In the next step, critical sources of salinity were identified from the two tributaries in order to implement the removal of salt fill sites for the possible reduction of salinity in the marsh. While salinity loading was approximately 10 times higher from Marsh Creek (65.63tons to 2028.13tons per month) compared with Blackbrook Creek (10.23tons to 163.98 per month), the analysis suggested that salinity concentration was higher from Blackbrook Creek, which was particularly due to abandoned salt fill sites near the Creek. The salinity loadings were linearly correlated with streamflow on a monthly (R2 = 0.81) scale, which was utilized to generate the salinity loadings that were diverted due to the rerouting of the Creek through the new location in order to avoid salt fill sites and reduce salinity in the Mentor Marsh. Our analysis suggested that approximately 74kg/day salinity was being rerouted from the Marsh; however, the salt fill sites contribute salinity to the Marsh equivalent to 63kg/day, which still needs to be removed. The research findings are expected to be helpful for monitoring small ungauged watersheds.

Long-term flood risk assessment of watersheds under climate change based on the game cross-efficiency DEA

Climate change has significantly increased extreme precipitation and altered regional hydrological cycle, aggravating flood in the watershed. The effective measurement of the risk brought by climate change is an effective way to cope with flood hazard in the future. At the same time, the quality of the simulation of climate change scenarios will also affect the accuracy of flood risk assessment. Therefore, a comprehensive method is needed to measure the long-term disaster risk. However, the current method of subjectively assigning indicator weights is still subjective and difficult to be promoted and applied. So a new model for assessing watershed risk is constructed in this study. Based on the game cross-efficiency data envelopment analysis method and the combination of simulations of climate scenarios, the model can determine the input factors of the assessment and the influencing level of the input factors by using the Principal Component Analysis and Tobit model. The model comprehensively evaluates the flood risk level in the watershed with the results of the simulation of hazard in different climate scenarios, hazard exposure and social vulnerability as input factors, and the degree of disaster loss as the output factor. Results: (1) the hazard, exposure, and social vulnerability are spatially mismatched; (2) the overall risk in the watershed presents such a pattern: upstream (0.751) > downstream (0.418) > midstream (0.362); (3) the long-term flood hazard may be reduced under the influence of climate change. The research is helpful to formulate long-term flood mitigation strategies in the future.

Evaluating watershed health in Costa Rican national parks and protected areas

Although the biodiversity of Costa Rican national parks, forests, and wetlands has been extensively surveyed, there has not been a watershed assessment that reflects their baseline water quality. Undoubtedly, the influx of 3.1 million visitors annually can lead to deterioration. Additionally, the country’s movement toward 100% carbon neutral energy means reliance on capturing water for the production of hydroelectricity. The missing hydrologic data set is of immediate concern, as watershed health predicts total ecosystem health. This field-based project measures eight parameters (pH, temperature, fecal coliform, dissolved oxygen, biochemical oxygen demand, nitrates, total phosphates, turbidity) needed to assign a watershed quality index (WQI) value at nine national parks or protected areas. Overall, the WQI for the systems surveyed reflect good water quality. Results compared with US Environmental Protection Agency (EPA) and World Health Organization (WHO) drinking water standards indicate limited levels of contamination at most sites, with elevated signatures of nitrates, phosphates, turbidity, and/or fecal coliforms at few. The parks selected include coastal lowlands and central highlands; they also experience diverse tourist activities, degrees of use, and forest type that are challenges when managing land sustainably.

Adapting the Index of Watershed Integrity for Watershed Managers in the Western Balkans Region.

Sustainable development supports watershed processes and functions. To aid the sustainable development of the western Balkans' transboundary river and lake basins, the Regional Environmental Center for Central and Eastern Europe and the US Environmental Protection Agency (EPA) adapted the EPA's Index of Watershed Integrity (IWI) following the devasting 2014 floods in Albania, Bosnia and Herzegovina, Kosovo, North Macedonia, Montenegro, and Serbia. The IWI evaluates six watershed functions based on a suite of anthropogenic stressors (e.g., impervious surfaces, reservoirs). A key feature of the IWI is its ability to accumulate the impact of upstream activities of any specific location in a river network. A novel feature of the IWI, compared with other watershed assessment tools, is its capacity to provide actionable information at the local scale. IWI scores-ranging from 0 (low integrity) to 1 (high integrity)-calculated for the 1084 catchments of the study area indicated highest integrity in the Alpine geographic region (mean = 0.55, standard deviation (SD) = 0.11) and intermediate to lowest integrity within the Mediterranean (mean = 0.49, SD = 0.12) and Continental (mean = 0.40, SD = 0.10) geographic regions. The IWI results are presented hierarchically for data analysts (stressor, functional component, Index of Catchment Integrity and IWI), ecologists (stream/catchment, watershed, basin), and managers (local, national, international). We provide real-world examples for managers, and suggestions for improving the assessment.

Evaluation of the predictive reliability of a new watershed health assessment method using the SWAT model.

The purpose of watershed assessments is to give information about conditions of water quality, stream morphology, and biological integrity to identify the sources of stressors and their impacts. In recent decades, different watershed assessment methods have been developed to evaluate the cumulative impacts of human activities on watershed health and the condition of aquatic systems. In the current research, we propose a new approach for assessing watershed vulnerability to contamination based on spatial analysis by using geographic information systems (GIS) and the analytic hierarchy process (AHP) technique. This new procedure, designed to identify vulnerable zones, depends on six basic factors that represent watershed characteristics: land use/land cover, soil type, average annual precipitation, slope, depth to groundwater, and bedrock type. The general assumptions for assessing watershed vulnerability are based on the response of watersheds to different contamination impacts and how the six selected factors interact to affect watershed health. The new watershed vulnerability assessment technique was used to create maps showing the relative vulnerabilities of specific sub-watersheds in the Eagle Creek Watershed in central Indiana. The results showed a remarkable difference in watershed susceptibility between the sub-watersheds in their vulnerability to pollution. To test the reliability of the proposed vulnerability assessment technique, the SWAT (Soil and Water Assessment Tool) model was applied to predict the water quality in each sub-watershed. Using the SWAT model, some parameters (e.g., total suspended solids [TSS] and nitrate) were tested based on the availability of the data needed for comparison. Both the SWAT and the newly proposed method produced good results in predicting water quality loads, which validated the proposed method. Hence, the results of the evaluation of the predictive reliability of the watershed vulnerability assessment method revealed that the proposed approach is suitable as a decision-making tool to predict watershed health.

Rapid assessment of river watershed health and vulnerability level for restoration strategy: a study of river systems in Indramayu, West Java, Indonesia

Climate change triggers a vulnerable level of a watershed. The assessment of watershed was conducted in rivers in Indramayu. Indramayu has terrible water quality due to several factors. The research aims to state the vulnerability level of Indramayu sub-watershed. The research analyzed several locations: Cimanuk sub-river and Muara Kali Prajagumiwang. The river health and vulnerability were assessed according to physical, land use, and water quality indicators in rivers. The other indicators are proposed according to the previous studies to enrich the future study result. The study finds out the possible future indicators: watershed landscape, hydrology, stream geomorphology, aquatic habitat, and biological conditions. The research uses a watershed vulnerability sequential analysis to obtain the result. The study analyzes the parameter, problems, and triggering factors from the sites. The assessment of stream corridor involves the rare species, sensitive fishes, macro-invertebrates availability, fish movement, normalization, water quality, river-land interaction, water spring, and geomorphology. The research concludes that rivers in Indramayu indicate fair and restorable impacted sub-watershed characteristics. This condition indicates that the streams have bad water quality, but they still could support a sustainable environment if it restored.

The Watershed Structures in Controlling Runoff - Case Study of Sardasht Basin in IRAN

In order to investigate the performance of constructed structures in Sardasht watershed, Soil and Water Assessment Tools model for simulation of runoff and sediment during the studied period of 1996-2012 was carried out for two cases of existence and absence of flood control structures. From 2007 onwards by performing watershed operations in these sub-basins, the average runoff rate decreased about 250 l/s for sub-basin 1 and 150 l/s for sub-basin 3. This indicates the flood was controlled in these basins. On average, the runoff volume has decreased by 0.25 and 0.15 m3 in the sub-basins 1 and 3 respectively in the presence of the structure compared to the absence of structures. A daily, Monthly simulation time stage and a continuous-time step restrict the usage of the SWAT pattern for comprehensive, occurrence-based flood simulation. The occurrence of acridities and unexpected projections in numerous sectors of IRAN, also the density on basic conveniences precious by mass growth, has owing to a broader difference in deliberation to the problematic of water straight in the alliance. Calibrating a hydrologic model of Sardasht Basin. Using SWAT. Subjective Workload Assessment Technique (SWAT) is a multidimensional scaling method designed to assess time load, mental effort load and stress load. According to the results of Mann-Kendall Test, Watershed management in the Sardasht basin for flood control and runoff can be considered acceptable. Before the watershed operation, the occurrence of runoff with the probability of 80% was zero, which after the operation, the probability of occurrence was reduced by 60%, indicating a positive effect construction of flood and sediment control structures in the Sardasht basin. The results of the hydrological regime curve show that the changes in the monthly runoff ratio to the average monthly runoff before the watershed operations had been more. Due to the limitations, current Soil and Water Assessment Tools simulations in tropical and subtropical regions face a series of problems related to relative humidity, water balance and sediment. Soil and Water Assessment Tools model is also used to estimate the maximum daily flow rate.

Effects of combined conservation practices on soil and water quality in the Central Mississippi River Basin

Conventional cultivation of claypan soils leads to soil and water quality degradation because of high runoff and associated soil erosion. The Goodwater Creek Experimental Watershed, which is part of the USDA Agricultural Research Service Benchmark Conservation Effects Assessment Project, Watershed Assessment Studies, was established to address these issues. Plot studies have highlighted trade-offs between erosion control and herbicide or nutrient runoff. There is a need for long-term field-scale evaluation of combined practices that reduce sediment, nutrient, and herbicide losses by runoff. A 36 ha field located in Missouri was under a conventional corn (<i>Zea mays</i> L.)–soybean (<i>Glycine max</i> L.) system from 1993 to 2003 with fertilizer application and tillage prior to planting in the spring. A precision agriculture system defined by two main management zones was implemented from 2004 to 2014: wheat (<i>Triticum aestivum</i> L.) and soybean in 60% of the field, and corn and soybean in the remaining 40%. The system included no-till, cover crops, atrazine split-applications based on weed pressure, variable rates of nitrogen (N), and variable rates of fall-applied phosphorus (P). The objective of this study was to compare runoff water quality from the two management systems, based on flow and load duration curves, cumulative distribution functions, and conclusions from replicated plot studies. The precision agriculture system did not affect annual runoff, but it did increase the frequency of low flows. Sediment losses were reduced by 87% as a result of no-till and cover crops. Atrazine and P losses were lower than expected, despite the lack of incorporation into the soil. Atrazine losses were possibly lower because of the wheat area acting as a buffer, greater atrazine adsorption and retention in the field, and faster decay. Dissolved P losses as a fraction of applied remained the same, likely because of greater adsorption and lower runoff risk when applying P. Finally, nitrate-N (NO₃-N) losses decreased and resulted in an overall decrease of N losses despite a slight increase of ammonium-N (NH₄-N) losses. Explanations included a greater soil water content, a different timing of N applications, and N uptake by cover crops. Building on these successes, an aspirational management system is proposed to further improve on the performance and practicality of the precision agriculture system.