Runoff Load Research Articles

Urban Stormwater Phosphorus Export Control: Comparing Traditional and Low-impact Development Best Management Practices.

Data from the International Stormwater Best Management Practices (BMP) Database were used to compare the phosphorus (P) control performance of six categories of stormwater BMPs representing traditional systems (stormwater pond, wetland basin, and detention basin) and low-impact development (LID) systems (bioretention cell, grass swale, and grass strip). Machine learning (ML) models were trained to predict the reduction or enrichment factors of surface runoff concentrations and loadings of total P (TP) and soluble reactive P (SRP) for the different categories of BMP systems. Relative to traditional BMPs, LIDs generally enriched TP and SRP concentrations in stormwater surface outflow and yielded poorer P runoff load control. The SRP concentration reduction and enrichment factors of LIDs also tended to be more sensitive to variations in climate and watershed characteristics. That is, LIDs were more likely to enrich surface runoff SRP concentrations in drier climates, when inflow SRP concentrations were low, and for watersheds exhibiting high impervious land cover. Overall, our results imply that stormwater BMPs do not universally attenuate urban P export and that preferentially implementing LIDs over traditional BMPs may increase TP and SRP export to receiving freshwater bodies, hence magnifying eutrophication risks.

Assessing Nitrate Leaching and Runoff Coefficients in the Dynamic Interplay of Seasonal Crop Biomass: A Study of Surface and Groundwater Nitrate Contamination in the Bilate Cropland Watershed

Effective water resource management and sustainable agricultural practices are contingent upon a thorough understanding of nitrate dynamics. This study investigates the utilization of seasonal average cropland runoff observations to improve the prediction accuracy of nitrate runoff loads to surface water originating from cropping zones. By integrating data from various sources, including seasonal rainfall/runoff observations and cropland parameters, the study explores the complex relationship between crop biomass growth, nitrogen fertilizer application, and seasonal rainfall over cropland. Monthly average observations of cropping zone rainfall/runoff in the cropping zone are analyzed to understand the response of seasonal crop biomass to nitrogen fertilizer application and seasonally calibrated rainfall/runoff in the cropland watershed. The study demonstrates the prototypical runoff observation from cultivated areas and statistically estimates seasonal runoff at downstream stream outlets. This shows a strong correlation with an R² of 0.9742 with a p-value less than 0.001 for seasonal rainfall climate parameters. Seasonal cropland runoff observations from EWX lite are presented for model calibration at downstream outlets, based on regional crop calendars, facilitating the estimation of nitrate loading to surface water and nitrate contamination from cropping zones. The findings reveal distinct cropping zones, particularly zones 5, 6, 11, and 13, which significantly contribute, each exceeding 50 mg/l of leaching load to groundwater. Moreover, more than ten zones surpass the threshold of 50mg/l in nitrate loading to surface water. These quantitative insights provide valuable spatial information regarding nitrate runoff relationships within the watershed, enabling the identification of specific zones with heightened nitrate contributions and offering actionable solutions for promoting sustainable agriculture and refining water resource management strategies.

Application of Porous Concrete Infiltration Techniques to Street Stormwater Inlets That Simultaneously Mitigate against Non-Point Heavy Metal Pollution and Stormwater Runoff Reduction in Urban Areas: Catchment-Scale Evaluation of the Potential of Discrete and Small-Scale Techniques

The expansion of pervious areas is an essential and common concept in mitigating non-point pollution runoff in urban areas. In this review, literature related to the expansion of pervious areas is introduced. In addition, the potential application of porous concrete as a medium for constructing the bottom and side walls of street stormwater inlets is investigated. The effectiveness of this medium in reducing (i) the stormwater runoff volume via porous concrete by exfiltrating from the bottom and the wall, and (ii) the heavy metal pollution runoff loads via infiltration through the porous concrete is assessed using data obtained by the author and published in the literature. The urban hydrological model Infoworks ICM (Innovyze) was used to estimate the exfiltration rates through the porous concrete plates set at the bottom and side walls of the street stormwater inlets. The exfiltration rates used in the pre-reported literature varied depending on the methods used. In the present study, sensitivity tests were performed by changing the exfiltration rates. The results of this study indicated that porous concrete used at only the bottom and side walls of the street stormwater inlets is suitable for reducing the runoff volume and removing any heavy metals from stormwater at a catchment scale.

Vegetative buffer strips show limited effectiveness for reducing antibiotic transport in surface runoff.

Vegetative buffer strips (VBS) have been demonstrated to effectively reduce loads of sediment, nutrients, and herbicides in surface runoff, but their effectiveness for reducing veterinary antibiotic (VA) loads in runoff has not been well documented. The objective of this study was to determine the effectiveness of VBS vegetation and width on surface runoff loads of the VAs sulfamethazine (SMZ) and lincomycin (LIN). Experimental design of the plots (1.5×25m) was a two-way factorial with four vegetation treatments (tall fescue [Festuca aruninacea Schreb.]; tall fescue with switchgrass [Panicum virgatum L.] hedge; warm-season native grass mix; and continuous fallow control), and four buffer widths (0, 2, 5, and 9m). Turkey litter spiked with SMZ and LIN was applied to the source area (upper 7m) of each plot, and runoff was collected at each width. Runoff was generated with a rotating boom simulator. Results showed VA loads in runoff at the 0-m sampler ranged from 3.8 to 5.9% of applied, and overall VA transport in runoff was predominately in the dissolved phase (90% for SMZ and 99% for LIN). Among vegetation treatments, only tall fescue significantly reduced loads of SMZ and LIN compared with the control, with load reductions of ∼30% for both VAs. Estimated field-scale reductions in VA loads showed that source-to-buffer area ratios (SBARs) of 10:1 to 20:1 reduced VA loads by only 7 to 16%. Overall, the grass VBS tested here were less effective at reducing SMZ and LIN loads in surface runoff than has been previously demonstrated for sediment, nutrients, and herbicides.

Direct comparison of runoff of residual and knockdown herbicides in sugarcane using a rainfall simulator finds large difference in runoff losses and toxicity relative to diuron

Runoff losses of herbicides have rarely been compared simultaneously under the same conditions. Our aim was to directly compare herbicide runoff losses, normalised for the amount present (relative runoff loads) and in absolute terms. Toxicity and runoff concentrations were combined to provide a risk ranking relative to diuron. Four rainfall simulation trials were conducted in sugarcane in the Great Barrier Reef catchment. Herbicides studied were older PSII residuals (atrazine, ametryn, diuron, hexazinone), alternative residuals (isoxaflutole, imazapic, metribuzin, metolachlor, pendimethalin) and knockdown herbicides (glyphosate, 2,4-D, fluroxypyr) and the tracer bromide (Br). Simulations were conducted two days after spraying, before differences due to half-lives were apparent. Two trials had bare soil and two had sugarcane trash. Herbicide runoff losses and concentrations were closely related to the amount applied, runoff amounts and partitioning coefficients. Relative runoff losses and absolute losses were similar for most older and alternative residual herbicides, 2,4-D and Br. Glyphosate and pendimethalin relative runoff losses were low, due to greater sorption. Isoxaflutole, imazapic, and fluroxypyr are applied at much lower rates and runoff losses were low. Herbicides were lost in the dissolved phase, except pendimethalin. There was a large range in toxicity relative to diuron. There is a range of herbicide choices posing less offsite risk than diuron and ametryn, which have high application rates and high toxicity. Herbicide choice should consider application rate, runoff losses, sorption, and toxicity.

Sources of copper into the European aquatic environment.

Chemical contamination from point source discharges in developed (resource-rich) countries has been widely regulated and studied for decades; however, diffuse sources are largely unregulated and widespread. In the European Union (EU), large dischargers report releases of some chemicals, yet little is known of total emissions (point and diffuse) and their relative significance. We estimated copper loadings from all significant sources including industry, sewage treatment plants, surface runoff (from traffic, architecture, and atmospheric deposition), septic tanks, agriculture, mariculture, marine transport (antifoulant leaching), and natural processes. A combination of European datasets, literature, and industry data were used to generate export coefficients. These were then multiplied by activity rates to derive loads. A total of approximately 8 kt of copper per annum (ktpa) is estimated to enter freshwaters in the EU, and another 3.5 ktpa enters transitional and coastal waters. The main inputs to freshwater are natural processes (3.7 ktpa), agriculture (1.8 ktpa), and runoff (1.8 ktpa). Agricultural emissions are dominated by copper-based plant protection products and farmyard manure. Urban runoff is influenced by copper use in architecture and by vehicle brake linings. Antifoulant leaching from boats (3.2 ktpa) dominates saline water loads of copper. It is noteworthy that most of the emissions originate in a limited number of copper uses where environmental exposure and pathways exist, compared with the bulk of copper use within electrical and electronic equipment and infrastructure that has no environmental pathway during its use. A sensitivity analysis indicated significant uncertainty in data from abandoned mines and urban runoff load estimates. This study provided for the first time a methodology and comprehensive metal load apportionment to European aquatic systems, identifying data gaps and uncertainties, which may be refined over time. Source apportionments using this methodology can inform more cost-effective environmental risk assessment and management. Integr Environ Assess Manag 2023;19:1031-1047. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Land Cover Change Associated with Unconventional Oil and Gas Development in the Appalachian Region

Unconventional oil and gas (UOG) wells from the Marcellus and Utica shale plays have expanded greatly across the Appalachian region of the United States (US) since the early 2000s. This region is now the single largest natural gas producing area of the US. The local and regional impacts of this industry on the landscape make it critical to understand for future planning efforts. This study investigated land cover change associated with over 21,000 unconventional wells representing 4,240 well pads permitted from 2007 to 2017 in Pennsylvania, West Virginia, and Ohio. The goal was to characterize UOG disturbance to document development patterns and extents in the region. Supervised classification was used to map land use and land-cover changes within a 25-ha buffer of well pads identified in the region. On average, disturbance related to unconventional development impacted 6.2 ha in Pennsylvania, 4.7 ha in Ohio and 4.4 ha in West Virginia and 5.6 ha over the region. Forest and grassland were found to be the most impacted cover types, with increases in impervious surface areas being a significant contributor to land-use classification change. These conversions can contribute to increased forest fragmentation and edge, which can in turn adversely impact biodiversity indicators at the regional level. Additionally, increases in impervious surface in small headwater watersheds can lead to increased sediment and runoff loads in receiving streams. Local and regional land use planning should be implemented during the well pad permit review process to help minimize environmental impacts over larger geographic scales.

Nitrogen and Phosphorus Concentrations and Their Ratios as Indicators of Water Quality and Eutrophication of the Hydro-System Danube–Tisza–Danube

Conserving clean and safe freshwater is a global challenge, with nitrogen (N) and phosphorus (P) as frequent limiting factors affecting water quality due to eutrophication. This paper provides a critical overview of the spatiotemporal variability in both nutrient concentrations and their total mass ratio (TN:TP) in the canal network of the Hydro system Danube–Tisza–Danube at 21 measuring locations monitored by the Environmental Protection Agency of the Republic of Serbia over a length of almost 1000 km, collected once a month during the last decade. A spatiotemporal variation in nutrient concentrations in the tested surface water samples was confirmed by correlations and cluster analyses. The highest TN concentrations were found in winter and early spring (non-vegetation season), and the highest TP concentrations in the middle of the year (vegetation season). The TN:TP mass ratio as an indicator of the eutrophication pointed out N and P co-limitation (TN:TP 8–24) in 64% of samples, N limitation (TN:TP < 8) was detected in 27% and P limitation (TN:TP > 24) in the remaining 9% of water samples. Such observations indicate slow-flowing, lowland water courses exposed to the effects of non-point and point contamination sources as nutrient runoff from the surrounding farmlands and/or urban and industrial zones, but further investigation is needed for clarification. These results are an important starting point for reducing N and P runoff loads and controlling source pollution to improve water quality and underpin recovery from eutrophication in the studied watershed.

Stochastic Determination of Combined Sewer Overflow Loads for Decision-Making Purposes and Operational Follow-Up

Characterizing the emissions and impact of combined sewer overflows (CSOs) remains one of the key challenges in the field of urban wastewater. Considering the large number of existing CSOs, decision-makers need a pragmatic approach that allows fairly easy, hands-on determination of emissions (particularly loads) without compromising accuracy. This philosophy is incorporated in the Cockle tool presented here, which uses stochastically processed input from a vast amount of pre-registered water quality data (pollutant concentrations) in combination with spill flow time series either generated from hydrodynamic models or converted from monitored overflow water levels. Uncertainty is intrinsically covered by the statistical output range of the reported results. As a fully automated tool, Cockle allows to readily assess emissions within a chosen time frame, facilitating more accurate guidance for further remediation actions and/or mapping of the current state for operational follow-up.

Event mean concentration and first flush from residential catchments in different climate zones

Most studies on EMC (Event mean concentration) and first flush are reported as local studies; however variations of EMC and first flush across catchments in different climate zones has not been studied. This research collected continuous flow and discrete water quality data and rainfall measurements from 17 catchments, EMC and rainfall data from 14 catchments, and an additional dataset where only average EMC values are reported (19 catchments). The data are from residential sites across temperate, tropical, dry, and continental climate zones and include water quality parameters in particulate (total suspended solids), mixed (total nitrogen and total phosphorus) and dissolved (orthophosphate and ammonium nitrogen) forms. Our study shows that EMC differs significantly between climate zones. The average EMC is highest in dry followed by continental and temperate, with lowest in the tropical zone. Pearson's correlation analysis revealed that the rainfall depth is negatively correlated with EMC for particulate and mixed form parameters for the tropical, temperate and dry zones, but positively correlated for the continental zone. The discrete time-series data from the 17 catchments were used to evaluate first flush and it was found that catchments in the tropics exhibit stronger first flush than temperate zone catchments, for all the water quality parameters with particulate showing a stronger first flush compared to dissolved forms. Based on the distribution of the data, new limits for very strong, strong, moderate, and very weak to no first flush are suggested for TSS for different climate zones. The new limits were quantified by fitting the function L^=V^bwhere L^and V^are the normalized cumulative runoff load and volume, respectively. For catchments in the tropics, this corresponds to b < 0.47, 0.6 > b > 0.47, 0.76 > b > 0.6 and b > 0.76, respectively. For the temperate zone, b < 0.5, 0.67 > b > 0.5, 0.85 > b > 0.67 and b > 0.85, are appropriate. From a design perspective, the FF20 concept defined as the load corresponding to 20% runoff volume, is often used. The ranges FF20 < 0.27, 0.36 > FF20 > 0.27, 0.45 > FF20 > 0.36 and FF20 > 0.45 and FF20 < 0.24, 0.31 > FF20 > 0.24, 0.31 > FF20 > 0.39 and FF20 > 0.39 are proposed for tropical and temperate catchments, respectively. Other limits for TP, TN, OP and NH4-N are also suggested. This is the first study of its kind and an expended dataset especially for continental and dry regions is needed to further validate the findings.

Hydrological variation and hydro-sediment interrelation of the Luozha River in the Lancang River Basin

Abstract The research on water and sediment variations is of great importance for regional resource and watershed management. Studying the relationship between precipitation, runoff and sediment load, traditional methods are based on observational data fitted or artificial intelligence predictions, whose accuracy is directly dependent on the quality and quantity of the data. This paper developed a new approach for researching the relationship between precipitation, runoff and sediment load. Based on the sliding accumulative anomaly method, the M-K mutation analysis and the wavelet functions, variation of precipitation and runoff annually were discussed. The results indicated the annual variation trend of the precipitation and runoff have been consistent since 1969, both with a 28-year main cycle, and runoff variations were less subject to human influence in the Luozha River. Therefore, the formula of the relationship between annual runoff and sediment load can be obtained by integrating discrepancy in the magnitude of its variation in the natural state, which was verified by the observational data and was applicable to acquisition of annual sediment load. The current work broadens the current knowledge of recent changes in the Lancang River Basin and improves the recognition of the water-sediment interrelation in the river.

A Data-Driven Approach to Stormwater Quality Analysis in Two Urban Catchments

The StormTac Web model, representing a low-complexity conceptual model (LCCM), was applied to two urban catchments featuring stormwater quality controls, a stormwater pond or a biofilter. The model calculates annual average runoff from annual precipitation and land-use specific volumetric runoff coefficients and baseflows (in storm sewers), which are multiplied by the corresponding mean stormwater quality constituent concentrations obtained from the recently upgraded StormTac Database, to yield constituent loads. The resulting runoff loads pass through the stormwater quality control facilities (a stormwater pond or a biofilter) where treatment takes place and its efficacy is described by “reduction efficiencies”. For the four selected stormwater quality constituents (TP, Cu, Zn, TSS) and two study catchments, a 201-ha residential Ladbrodammen and an 8.2-ha Sundsvall traffic corridor, the compositions of stormwater entering and leaving the control facilities were calculated by StormTac Web and compared against the measured data. In general, the calculated concentrations were smaller than the measured ones, and these differences were reduced, but not eliminated in all cases, by considering uncertainties in both calculated and measured data. Uncertainties in calculated values consisted of two components, a flow component (assumed as 20%) and a concentration component, which was assumed equal to the relative standard error (RSE) of the data in the StormTac Database. Explanations of differences in calculated and measured stormwater data were discussed with respect to temporal changes and trends in environmental practices and stormwater quality monitoring and enhancement by treatment.

Retrofitting urban land through integrative, subsoils-based planning of green stormwater infrastructure: a research framework

Abstract We present a research framework that integrates native subsoil performance and surface retrofitting into coordinated green stormwater infrastructure (GSI) planning. This framework provides communities a strategy to move beyond opportunistic GSI, which can be limited to capturing marginal amounts of stormwater, toward more impactful, coordinated GSI planning that restores the lost hydrologic functioning of the pre-development landscape. We create this framework by establishing critical performance-based relationships among four variables: (1) saturated hydraulic conductivity of native subsoils (∼upper 2 m below urban compaction and fill); (2) GSI design depth for both rain gardens and permeable pavement (in increments of 6″ from 12–30″ for planted and paved GSI); (3) loading ratio, defined as the ratio of GSI retrofit area to upstream impervious surface runoff area (from 1:2 to 1:5 for planted GSI; and 1:1 and direct infiltration for paved GSI); and (4) design storms (rainfall quantity up to 5-inches over 2 h and 24 h durations). We model the four variables using GSI models (built in the US Environmental Protection Agency’s Storm Water Management Model) and reliability analysis, a risk-assessment method adapted to characterize the reliability of GSI in response to varying stormwater runoff loading. The outcome of the modeling is a set of fragility curves and design prototypes, adjustable to catchment and sub-catchment scales, to assist municipalities in early funding and investment decisions to retrofit urbanized land through GSI. We also share two piloted applications in which we use the research framework within the Chicago-Calumet region in Illinois, USA, to conduct site-specific subsoil sampling and determinations of saturated hydraulic conductivity and to develop urban-scale GSI retrofit scenarios. Our framework is transferable to other urban regions, and particularly useful where a lack of integrating native subsoil performance into GSI design hinders decision-making, coordinated GSI planning at scale, and achieving high runoff reduction targets.

Evaluation of ammonia and nitrate distribution and reduction within stormwater green infrastructure with different woody plants under multiple influencing factors

The impact of stormwater green infrastructures (GIs) with different woody plants on nitrogen (N) distribution is still poorly understood. Laboratory experiments were conducted for GIs without or with Sophora japonica and Malus baccata to investigate the distribution of NH3–N and NO3–N. The test data was utilized to calibrate and validate the HYDRUS-2D. The validated model was subsequently used to analyze the distribution of NH3–N and NO3–N within the different GIs under three different rainfall conditions: inflow/runoff pollutant concentration, rainfall recurrence interval (runoff amount of a rainfall event), and number of dry days (during which no rainwater infiltrates into the soil). The average NH3–N and NO3–N concentrations in the upper soil (0–30 cm) of the GIs were about 4.8 and 2.4 times those of the lower layer (30–60 cm). Compared to the control (Vc), the average NH3–N concentrations in soil with Sophora japonica (Vs) and Malus baccata (Vm) decreased by 15.8% and 35.1% while those of NO3–N decreased by 15.5% and 27.2%, respectively. Degrees of influence by the three factors on the average soil NH3–N and NO3–N concentrations were inflow concentration > number of dry days > recurrence interval. The number of dry days was the smallest influence factor for the overflow N load while the inflow concentration was the most significant influence factor for the outflow, bio-utilization, and soil nitrogen loads. Compared to the control, outflow (groundwater recharge) loads of NO3–N from the Vs and Vm increased by 14.0–16.6% and 3.7–6.8%, respectively under different conditions. The overflow (runoff) loads from Vs and Vm decreased by 16.8–36.3% and 6.6%–8.4%, respectively. A multiple regression equation was used to establish a quantitative coupling relationship between N pollutant load reduction rates and influence factors (R2 ≥ 0.83). This relationship can be used to estimate the runoff treatment effectiveness of green infrastructure on target pollutants.

Continuous Simulation of Highly Urbanized Watershed to Quantify Nutrients’ Loadings

The United States has witnessed various extreme land use changes over the years. These changes led to alterations in watersheds’ characteristics, impacting their water quality and quantity. To quantify this impact in highly urbanized watersheds such as the Chicago Metropolitan Area, it is crucial to examine the characteristics and imperviousness distribution of urban land uses and available point and non-point sources. In this paper, the effect of urban runoff and nutrient loadings to water bodies in the Chicago River Watershed resulting from level (III) detailed urban land uses is investigated. A watershed scale hydrologic and water quality simulation using BASINS/HSPF model was developed for the highly urbanized watershed. Appropriate considerations were given to the effective impervious area (EIA). The results from the five-year calibrated water quality simulation were reasonably reflected with observed data in the study area and nutrient loadings of both point and non-point sources for 44 different land uses were found. The export coefficients (EC) values obtained are site-specific depending on conditions and variables at the watershed level such as physical characteristics, land use management practices, hydro-meteorological and topographical data, while using a continuous simulation approach and watershed perspective analysis. This is the first attempt to measure and model nutrients’ loadings using detailed land use types in the Chicago River Watershed. The proposed continuous calibrated and validated model can be used in the investigation and analysis of different scenarios and possible future conditions and land utilization.

Annual nitrate load patterns in an agricultural watershed in consecutive dry years

Abstract Nitrate (NO3-N) load characteristics in consecutive dry years in the Huai River Basin (HRB), China, were examined using streamflow and NO3-N concentration data. The data set spanned 12 years including three consecutive dry years. Baseflow separation, load estimation, and nonparametric linear regression were applied to separate point source (PS), baseflow, and surface runoff NO3-N loads from the total load. The mean annual nonpoint source (NPS) load was 2.84 kg·ha−1·yr−1, accounting for 90.8% of the total load. Baseflow contributed approximately one-fourth of the natural runoff and half of the NPS load. The baseflow nitrate index (i.e., the ratio of baseflow NO3-N load to total NPS NO3-N load) was 25.4% higher in consecutive dry years than in individual dry years. This study demonstrated that baseflow is the preferential hydrological pathway for NO3-N transport in the HRB and that baseflow delivers a higher NO3-N percentage to streams under long-term drought than under short-term drought. This study highlights the alarming evidence that continuous drought caused by climate change may lead to a higher rate of nitrogen loss in agricultural watersheds.

A Reliable U-trough Runoff Collection Method for Quantifying the Migration Loads of Nutrients at Different Soil Layers under Natural Rainfall

Long-term quantification of the migration loads of subsurface runoff (SSR) and its collateral soil nutrients among different soil layers are still restricted by the runoff collection method. This study tested the reliability of the U-trough collection methods (UCM), compared with the seepage plate collection method (SPM), in monitoring the runoff, sediment and nutrient migration loads from different soil layers (L1: 0–20 cm depth; L2: 20–40 cm depth; L3: 40–60 cm depth) for two calendar years under natural rainfall events. The results suggested that the U-trough could collect nearly 10 times the SSR sample volume of the seepage plate and keep the sampling probability more than 95% at each soil layer. The annual SSR flux from L1 to L3 was 403.4 mm, 271.9 mm, and 237.4 mm under the UCM, 14.35%, 10.56%, and 8.41% lower than those under the SPM, respectively. The annual net migration loads of sediment, TN, and TP from the L1 layer under the UCM were 49.562 t/km2, 19.113 t/km2 and 0.291 t/km2, and 86.62%, 41.21% and 81.78% of them were intercepted by the subsoil layers (L2 and L3), respectively. While their migration loads under the SPM were 48.708 t/km2, 22.342 t/km2 and 0.291 t/km2, and 88.24%, 53.06% and 80.42% of them were intercepted, respectively. Under both methods, the average leached total n (TN), total p (TP) concentrations per rainfall event and their annual migrated loads at each soil layer showed no significant difference. In conclusion, the UCM was a reliable quantitative method for subsurface runoff, sediment, and soil nutrient migration loads from diverse soil layers of purple soil sloping cultivated lands. Further studies are needed to testify the availability in other lands.

Conservation management practices reduce non-point source pollution from grazed pastures

Producers in Northwest Arkansas and globally need alternative management practices to ensure long-term sustainable and economical use of poultry litter, which is an abundant source of valuable carbon (C), nitrogen (N) and phosphorus (P). Project objectives were to measure the efficacy of conservation management practices (i.e., pasture aeration and subsurface litter incorporation) to reduce nutrient runoff compared to poultry litter surface applications from small watersheds under rainfed and grazed conditions. Watersheds (0.23 ha each) were assigned a treatment [pasture aeration, subsurface litter incorporation, or surface application of litter (positive control)] on a Leadvale (fine-silty, siliceous, thermic Typic Fragiudult) silt loam. Poultry litter was applied annually to each watershed from 2007-2012. Over the 4-yr study period, runoff loads of NO3–N, total nitrogen (TN), soluble reactive phosphorus (SRP), and total phosphorus (TP) varied per conservation practice (P ≤ 0.05). Specifically, average annual loads of NO3–N, TN, SRP, and TP loads were reduced 49, 42, 28, and 35% following pasture aeration and by 78, 72, 55, and 59% from subsurface applying poultry litter, relative to surface applications, respectively. Greatest annual N loads and runoff corresponded with surface poultry litter applications, followed by pasture aeration, with subsurface incorporation of poultry litter resulting in lowest (P ≤ 0.05) TN and NO3–N loads. Overall, subsurface incorporation of poultry litter and pasture aeration are two promising conservation practices for reducing non-point source pollution in watersheds with nutrient imbalances. Further work needs to be done on factors influencing the efficacy of these conservation practices under rainfed conditions, as well as the economic feasibility of these conservation agricultural practices.

Effectiveness of environmental management institutions in sustainable water resources management in the upper Hanjiang River basin

The Han River valley plays an important strategic role in the water resources allocation system in China. A parallel hybrid approach was used in the study, using both qualitative and quantitative data collection and analysis techniques. Twenty self-administered questionnaires were sent to the heads of the environment bureaus of 17 districts (counties) and 3 cadres of the natural resources bureaus. Three in-depth interviews were conducted with the head of the water authority in the basin. Runoff, water quality and sediment load data were collected over a 17-year period and trends were analyzed using Mann-Kendall and regression analysis statistics to predict future water levels. The results show that the positive linear correlation between runoff R and sediment load is R2 = 0.1718, while the negative linear correlation between sediment load and pH value is R2 = 0.0329. According to the Mann-Kendall analysis(p &gt; 0.05) , no statistically significant trend was found in the data. The study concluded that there was a lack of effective regular interaction and cooperation between water and environmental management at the basin level. Effective Coordination of environmental management remains key to achieving sustainable water resources management in the Han River River Basin.

Phosphorus Runoff Loads from a Group of Paddy Fields and a Forested Watershed in the Sengari Reservoir Basin

Phosphorus Runoff Loads from a Group of Paddy Fields and a Forested Watershed in the Sengari Reservoir Basin