Showing papers on "Nonpoint source pollution published in 2004"

Riparian deforestation, stream narrowing, and loss of stream ecosystem services

Abstract: A study of 16 streams in eastern North America shows that riparian deforestation causes channel narrowing, which reduces the total amount of stream habitat and ecosystem per unit channel length and compromises in-stream processing of pollutants. Wide forest reaches had more macroinvertebrates, total ecosystem processing of organic matter, and nitrogen uptake per unit channel length than contiguous narrow deforested reaches. Stream narrowing nullified any potential advantages of deforestation regarding abundance of fish, quality of dissolved organic matter, and pesticide degradation. These findings show that forested stream channels have a wider and more natural configuration, which significantly affects the total in-stream amount and activity of the ecosystem, including the processing of pollutants. The results reinforce both current policy of the United States that endorses riparian forest buffers as best management practice and federal and state programs that subsidize riparian reforestation for stream restoration and water quality. Not only do forest buffers prevent nonpoint source pollutants from entering small streams, they also enhance the in-stream processing of both nonpoint and point source pollutants, thereby reducing their impact on downstream rivers and estuaries.

Using a topographic index to distribute variable source area runoff predicted with the SCS curve-number equation

Abstract: Because the traditional Soil Conservation Service curve-number (SCS-CN) approach continues to be used ubiquitously in water quality models, new application methods are needed that are consistent with variable source area (VSA) hydrological processes in the landscape. We developed and tested a distributed approach for applying the traditional SCS-CN equation to watersheds where VSA hydrology is a dominant process. Predicting the location of source areas is important for watershed planning because restricting potentially polluting activities from runoff source areas is fundamental to controlling non-point-source pollution. The method presented here used the traditional SCS-CN approach to predict runoff volume and spatial extent of saturated areas and a topographic index, like that used in TOPMODEL, to distribute runoff source areas through watersheds. The resulting distributed CN–VSA method was applied to two subwatersheds of the Delaware basin in the Catskill Mountains region of New York State and one watershed in south-eastern Australia to produce runoff-probability maps. Observed saturated area locations in the watersheds agreed with the distributed CN–VSA method. Results showed good agreement with those obtained from the previously validated soil moisture routing (SMR) model. When compared with the traditional SCS-CN method, the distributed CN–VSA method predicted a similar total volume of runoff, but vastly different locations of runoff generation. Thus, the distributed CN–VSA approach provides a physically based method that is simple enough to be incorporated into water quality models, and other tools that currently use the traditional SCS–CN method, while still adhering to the principles of VSA hydrology. Copyright  2004 John Wiley & Sons, Ltd.

History of Innovative Best Management Practice Development and its Role in Addressing Water Quality Limited Waterbodies

Abstract: Best management practices (BMPs) are practical control measures (including technological, economic, and institutional considerations) that have been demonstrated to effectively minimize water quality impacts. The use of BMPs is widely accepted as the most appropriate method of controlling nonpoint sources of pollution because BMPs prevent or minimize pollution rather than retrospectively respond to it. Still, there is a stigma that BMPs do not afford quite the same degree of protection or assurance of pollution control that effluent treatment and process controls do for point sources. Here we provide a brief history of BMPs and their emergence as a practical water pollution control tool for nonpoint source activities, with a focus on the history of forestry BMPs. This history demonstrates the variety of BMPs used to avoid or minimize the generation of nonpoint source pollutants or reduce delivery of these materials to streams. It also demonstrates the extensive testing of BMP effectiveness that has been c...

Farm-level optimization of bmp placement for cost-effective pollution reduction

Abstract: With best management practices (BMPs) being used increasingly to control agricultural pollutant losses to surface waters, establishing the environmental effectiveness of these practices has become important. Additionally, cost implications of establishing and maintaining environmentally effective BMPs are often a crucial factor in selecting and adopting BMPs. This article considers both water quality and economic concerns and presents a methodology developed for determining cost-effective farm- or watershed-level scenarios through optimization. This optimization technique uniquely incorporates three existing tools: a genetic algorithm (GA), a watershed-level nonpoint-source model (Soil and Water Assessment Tool, SWAT), and a BMP tool. The GA combines initial pollutant loadings from SWAT with literature-based pollution reduction efficiencies from the BMP tool and with BMP costs to determine cost-effective watershed scenarios. The methodology was successfully applied to a 300 ha farm within the Cannonsville Reservoir watershed, a phosphorus (P) restricted reservoir within New York City's water supply system. An average reduction in dissolved P of 60% over the lifetime of the BMPs was set as the pollutant target. A baseline scenario was established to represent practices on the farm before BMP implementation. The most cost-effective scenario for the farm, under the presented methodology, achieved a cost-effectiveness of 0.6 kg dissolved P reduction per dollar spent per year. Additionally, the methodology determined alternative scenarios for the farm, which met the pollution reduction criterion cost-effectively. The methodology, as developed, is extendable to multi-farm or watershed-level evaluations.

Optimal Location and Sizing of Stormwater Basins at Watershed Scale

Abstract: Nonpoint source pollution control requires the implementation of best management practices (BMPs) at various locations in a watershed. One important aspect of the watershed strategy is to find the optimal placement and design of BMPs so that their combined effect is most cost-effective. An innovative method is presented for optimizing the placement and configurations of BMPs at the watershed scale. Heuristic optimization techniques are coupled with a watershed model, which is the agricultural Nonpoint Source Pollution model (AnnAGNPS) in this case, and BMP simulation module to find a least cost set of solutions that meet the pollutant load reduction requirements. An impoundment module imbedded in AnnAGNPS, and modified to address the sediment accumulation and resuspension effect, is used to provide the means of evaluating the long-term performance of detention ponds. A scatter search algorithm is applied to finding the least cost solution. The optimization framework developed herein provides a tool for stormwater management practitioners to examine and analyze the treatment efficiencies of stormwater control alternatives and to determine a robust and cost-effective design of stormwater treatment systems.

Evaluation of the swat model's sediment and nutrient components in the piedmont physiographic region of maryland

Abstract: Mathematical watershed-scale models are among the best tools available for analyzing water resources (quantity and quality) issues in spatially diverse watersheds since continuous water quality monitoring is expensive and spatially impractical in mixed land use watersheds. However, models without appropriate validation may lead to misconceptions and erroneous predictions. This study used six years of hydrologic and water quality data to calibrate and validate the capability of SWAT (Soil and Water Assessment Tool) model in assessing nonpoint source pollution for a 346 ha watershed in the Piedmont physiographic region. The evaluation of the hydrology component of SWAT completed in a previous study pointed out that SWAT has no mechanism to account for subsurface flow contributions from outside the watershed. For this evaluation, all nutrient loadings leaving the watershed were adjusted to subtract the chemical transport via subsurface flow contributions from outside the watershed. Evaluation results indicated a strong agreement between yearly measured and simulated data for sediment, nitrate, and soluble phosphorus loadings. However, simulations of monthly sediment and nutrient loadings were poor. Overall, it was concluded that SWAT is a reasonable watershed-scale model for long-term simulation of different management scenarios. However, its use on storm-by-storm or even on monthly basis may not be appropriate for watersheds with similar physiography and size. Additionally, ignoring the subsurface contribution of water and chemicals from outside the watershed into the watershed aquifer could cause significant errors in model prediction.

Water quality in agricultural, urban, and mixed land use watersheds

Abstract: Water quality and nonpoint source (NPS) pollution are important issues in many areas of the world, including the Inner Bluegrass Region of Kentucky where urban development is changing formerly rural watersheds into urban and mixed use watersheds. In watersheds where land use is mixed, the relative contributions of NPS pollution from rural and urban land uses can be difficult to separate. To better understand NPS pollution sources in mixed use watersheds, surface water samples were taken at three sites that varied in land use to examine the effect of land use on water quality. Within the group of three watersheds, one was predominately agriculture (Agricultural), one was predominately urban (Urban), and a third had relatively equal representation of both types of land uses (Mixed). Nitrogen (N), phosphorus (P), total suspended solids (TSS), turbidity, pH, temperature, and streamflow were measured for one year. Comparisons are made among watersheds for concentration and fluxes of water quality parameters. Nitrate and orthophosphate concentrations were found to be significantly higher in the Agricultural watershed. Total suspended solids, turbidity, temperature, and pH, were found to be generally higher in the Urban and Mixed watersheds. No differences were found for streamflow (per unit area), total phosphorus, and ammonium concentrations among watersheds. Fluxes of orthophosphate were greater in the Agricultural watershed that in the Urban watershed while fluxes of TSS were greater in the Mixed watershed when compared to the Agricultural watershed. Fluxes of nitrate, ammonium, and total phosphorus did not vary among watersheds. It is apparent from the data that Agricultural land uses are generally a greater source of nutrients than the Urban land uses while Urban land uses are generally a greater source of suspended sediment.

Agroforestry as an approach to minimizing nutrient loss from heavily fertilized soils: The Florida experience

Abstract: Nutrient buildup in the soil caused by increased animal manure and fertilizer use in agricultural and forestry practices may increase the potential for their loss from the soil, leading to groundwater contamination and nonpoint source pollution. Studies in the tropics have suggested that agroforestry practices can reduce such nutrient (especially nitrogen) losses because of enhanced nutrient uptake by tree and crop roots from varying soil depths, compared to more localized and shallow rooting depths of sole crop stands. In temperate systems, such benefits have been well documented for riparian forest buffer practices. Currently, other temperate agroforestry practices are also being considered for their potential to reduce runoff and leaching of chemicals and thereby improve environmental quality within the agricultural landscape. In this regard, the ‘Florida P-Index,’ which considers both phosphorus transport characteristics and management practices, may be a useful tool in the evaluation of nutrient management practices and environmental benefits of agroforestry. Preliminary results from an alleycropping site and a silvopastoral site on two different soil types in Florida suggest that both of these agroforestry practices will likely reduce nutrient loss compared to conventional agricultural practices. The primary aspects of P-Index include consideration of transport factors such as soil erosion, soil runoff class, leaching potential, and distance from a water body along with management factors such as soil test P, P application method, and source and rate of P application. P-Index evaluation of these studies indicates that both agroforestry sites can be on a nitrogen-based nutrient management program. The relevance of some management practices such as application of manure vs. inorganic fertilizer is also discussed in light of the P-Index and the two agroforestry practices.

Estimation of Agricultural Non-Point Source Pollution in China and the Alleviating StrategiesI. Estimation of Agricultural Non-Point Source Pollution in China in Early 21 Century

Abstract: Since 1970s, the N and P eutrophication of major Chinese lakes and water systems has been getting worserapidly. Investigation revealed that non-point source pollution from agriculture and rural region is the leading source ofwater pollution. The contribution of non-point source pollutants from fertilization of crop land, rural animal husbandry andliving sewage of transition region between rural and urban area is much greater than that of point-source from wastes of civildomestic and industry in urban area with developed wastewater pipe nets. Since 1980s, the acreage of vegetables, fruits andflowers has been increased by 4.4 times. Due to high profit, it is common using very high rates of N and P fertilizers on thesecrops. The average fertilizer application rate is 569-2000 kg (pure nutrient)ha-1 in single crop, about 10 times as that forgrain crops. The increasing vegetable area with high fertilizer input is one of the biggest potential problems for eutrophicationof water bodies in watersheds. At the same time, animal breeding farmers in rural region intended to be developed in apattern that certain townships with very high concentration of animal breeding farmers. N and P amount from animalhusbandry in such concentrated region has reached very high level, as much as 1721 kg N and 639 kg P2O5 per hectareagricultural land area, far more surpassing the acceptance capacity of soil to these organic nutrients. In almost all of theimportant watersheds in China, non-point source N- and P-discharge to aquatic ecosystem from animal husbandry isbecoming a crucial pollution source. Fast expansion of new city zones without wastewater pipe nets in transition regionbetween rural and urban area makes such zones the main non-point source pollution. The research results also showed thatalthough the non-point source pollution is already serious in the country, the growing influence factors will lead to evenworse situation in the early 21 century. The non-point source pollution from agriculture and rural area will become one of thebiggest challenges to sustainable development of China.

Runoff, erosion, and nutrient losses from compost and mulch blankets under simulated rainfall

Abstract: Control of soil erosion and associated nonpoint source pollution is essential to improving water quality. The use of compost or mulch blankets as a soil cover can help control soil erosion and provide sustainable alternatives to disposal for many biomass resources. The objective of this study was to investigate the amounts of runoff, erosion, and nutrient losses obtained under simulated rainfall using a variety of compost and mulch materials. Treatments included aged poultry litter, two different types of poultry litter compost, municipal solid waste compost, biosolids compost, food waste compost, yard waste compost, three different types of wood mulch, and bare soil. Results indicated that all of the treatments except for aged poultry litter were effective at reducing total solids loss in the runoff. Nutrient losses from most of the compost treatments, however, were higher than those from bare soil or mulch treatments. Treatments with lower respiration rates and nitrate-nitrogen concentrations tended to have less erosion and transport of solids. Nitrate-nitrogen content, respiration rates, soluble salt, sodium, and potassium contents were good indicators of ammonium and phosphorus losses.

Non-point source pollution: determination of replication versus persistence of Escherichia coli in surface water and sediments with correlation of levels to readily measurable environmental parameters.

Abstract: Racine, Wisconsin, located on Lake Michigan, experiences frequent recreational water quality advisories in the absence of any identifiable point source of pollution. This research examines the environmental distribution of Escherichia coli in conjunction with the assessment of additional parameters (rainfall, turbidity, wave height, wind direction, wind speed and algal presence) in order to determine the most probable factors that influence E. coli levels in surface waters. Densities of E. coli were highest in core samples taken from foreshore sands, often exceeding an order of magnitude greater than those collected from submerged sands and water. Simple regression and multivariate analyses conducted on supplementary environmental data indicate that the previous day's E. coli concentration in conjunction with wave height is significantly predictive for present-time E. coli concentration. Genetic fingerprinting using repetitive element anchored PCR and cellular fatty acid analysis were employed to assess the presence of clonal isolates which indicate replication from a common parent cell. There were relatively few occurrences of clonal patterns in isolates collected from water, foreshore and submerged sands, suggesting that accumulation of E. coli, rather than environmental replication, was occurring in this system. Non-point source pollution, namely transport of accumulated E. coli from foreshore sands to surface waters via wave action, was found to be a major contributor to poor recreational water quality at the Lake Michigan beaches involved in this study.

Quantification and index of non-point source pollution in Taihu Lake region with GIS.

Abstract: The contribution of phosphorus and nitrogen from non-point source pollution (NPS) in the Taihu Lake region was investigated through case study and surveying in the town of Xueyan, From experimental results coupled with survey and statistics in the studied area, the distribution of nitrogen and phosphorus input to the water body is achieved from four main sources: agricultural land, village, the town center and the poultry factory. The results showed that about 38% of total phosphorus (TP) and 48% of total nitrogen (TN) discharged is from agricultural land, 33% of TP and 40% TN from village residents, 25% of TP and 10% of TN from the town center and 4% of TP and 2% of TN from the poultry factory. The Agricultural Non-point Pollution Potential Index (APPI) system for identifying and ranking critical areas of NPS was established with a Geographic Information Systems (GIS)-based technology. Quantification of the key factors in non-point sources pollution was carried out utilizing the following: Sediment Production Index (SPI), Runoff Index (RI), People and Animal Loading Index (PALI) and Chemical Use Index (CUI). These are the core parts of the model, and the weighting factor of each index was evaluated according the results of quantification. The model was successfully applied for evaluating APPI in Xueyan. Results from the model showed that the critical area identified for NPS control in Xueyan. The model has several advantages including: requiring fewer parameters, easy acquirement of these parameters, friendly interface, and convenience of operation. In addition it is especially useful for identifying critical areas of NPS when the basic data are not fully accessible, which is the present situation in China.

Education and changes in residential nonpoint source pollution

Abstract: Urban areas contribute pollutants such as excess nitrogen and bacteria to receiving water bodies. The objective of this project was to determine if stormwater quality could be improved by educating homeowners and implementing best management practices (BMPs) in a suburban neighborhood. The paired watershed design was used, where a control and treatment watershed are monitored during a calibration and treatment period. Treatment consisted of the education of homeowners and structural changes designed to minimize nonpoint pollution. Some changes in measured behavior were reported. According to the treatment period survey, 11% of respondents in the treatment watershed began fertilizing their lawn based on the results of a soil test, whereas none had done so previously. In addition, 82% of respondents in the treatment watershed stated that they left clippings on the lawn compared to 62% from the initial survey. Twelve of 34 lots (35%) adopted some BMPs following education efforts, indicating a significant (P = 0.001) increase in BMP use overall. However, a χ2 analysis of survey data indicated no significant changes in measured behavior with regard to specific questions. Analysis of covariance (ANCOVA) results indicated that a 75% reduction in nitrite + nitrate - N (change in intercept, P = 0.001) and a 127% reduction in fecal coliform bacteria (change in slope, P = 0.05) concentrations occurred. However, the treatment period regression was nonsignificant for bacteria. Total nitrogen, total phosphorus, and ammonia-N concentrations did not change significantly. Intensive education efforts produced BMP implementation and measurable water quality improvements.

Implications of On-Ground Nitrogen Loading and Soil Transformations on Ground Water Quality Management

Abstract: This paper presents a modeling approach based on a geographic information system (GIS) to estimate the variability of on-ground nitrogen loading and the corresponding nitrate leaching to ground water. The methodology integrates all point and nonpoint sources of nitrogen, the national land cover database, soil nitrogen transformations, and the uncertainty of key soil and land use-related parameters to predict the nitrate mass leaching to ground water. The analysis considered 21 different land use classes with information derived from nitrogen sources such as fertilizer and dairy manure applications, dairy lagoons, septic systems, and dry and wet depositions. Simulations were performed at a temporal resolution of one month to capture seasonal trends. The model was applied to a large aquifer of 376 square miles in Washington State that serves more than 100,000 residents with drinking water. The results showed that dairy manure is the main source of nitrogen in the area followed by fertilizers. It was also seen that nitrate leaching is controlled by the recharge rate, and there can be a substantial buildup of soil nitrogen over long periods of time. Uncertainty analysis showed that denitrification rate is the most influential parameter on nitrate leaching. The results showed that combining management alternatives is a successful strategy, especially with the use of nitrification inhibitors. Also, change in the land use pattern has a noticeable impact on nitrate leaching.

A Watershed-Scale Model for Predicting Nonpoint Pollution Risk in North Carolina

Abstract: The Southeastern United States is a global center of freshwater biotic diversity, but much of the region's aquatic biodiversity is at risk from stream degradation. Nonpoint pollution sources are responsible for 70% of that degradation, and controlling nonpoint pollution from agriculture, urbanization, and silviculture is considered critical to maintaining water quality and aquatic biodiversity in the Southeast. We used an ecological risk assessment framework to develop vulnerability models that can help policymakers and natural resource managers understand the impact of land cover changes on water quality in North Carolina. Additionally, we determined which landscape characteristics are most closely associated with macroinvertebrate community tolerance of stream degradation, and therefore with lower-quality water. The results will allow managers and policymakers to weigh the risks of management and policy decisions to a given watershed or set of watersheds, including whether streamside buffer protection zones are ecologically effective in achieving water quality standards. Regression analyses revealed that landscape variables explained up to 56.3% of the variability in benthic macroinvertebrate index scores. The resulting vulnerability models indicate that North Carolina watersheds with less forest cover are at most risk for degraded water quality and steam habitat conditions. The importance of forest cover, at both the watershed and riparian zone scale, in predicting macrobenthic invertebrate community assemblage varies by geographic region of the state.

A distributed non-point source pollution model: calibration and validation in the Yellow River Basin

Abstract: The applicability of a non-point source pollution model--SWAT(soil and water assessment tools) in a large river basin with high sediment runoff modulus(770 t/km2 in the Yellow River) was examined. The basic database, which includes DEM, soil and landuse map, weather data, and land management data, was established for the study area using GIS. A two-stage "Brute Force" optimization method was used to calibrate the parameters with the observed monthly flow and sediment data from 1992 to 1997. In the process of calibration automated digital filter technique was used to separate direct runoff and base flow. The direct runoff was firstly calibrated, and the base flow, then the total runoff was matched. The sediment yield was calibrated to match well. Keeping input parameters set during the calibration process unchanged, the model was validated with 1998--1999's observed monthly flow and sediment. The evaluation coefficients for simulated and observed flow and sediment showed that SWAT was successfully applied in the study area: relative error was within 20%, coefficient of determination and Nash-Suttcliffe simulation efficiency were all equal to or above 0.70 during calibration and validation period.

Assessment of best management practices to minimise the runoff of manure-borne phosphorus in the United States

Abstract: Phosphorus (P), an essential nutrient in crop and livestock agriculture, can cause and accelerate freshwater eutrophication. Intensification of farming systems has resulted in local accumulations of P in some agricultural watersheds with related increases in P runoff. In most cases, continual land application of manure at rates exceeding crop P removal is the proximate cause of P runoff. To mitigate associated water quality impairments, P‐based agricultural best management practices (BMPs) are now becoming a part of farm nutrient planning. This planning involves the selection, timing, and implementation of source and transport BMPs at field, farm, and watershed scales. Source measures include balancing P imports and exports, improved livestock feed management, chemical and physical treatment of manures, appropriate rate, method, and timing of land application based upon regular soil and manure testing, adequate manure storage and transport infrastructure, and composting. Transport measures aim to...