Showing papers on "Nonpoint source pollution published in 2003"

Development of phosphorus indices for nutrient management planning strategies in the United States

Abstract: Phosphorus (P), an essential nutrient for crop and livestock production, can accelerate freshwater eutrophication, now one of the leading water quality impairments in the United States. In response, the U.S. Department of Agriculture and the Environmental Protection Agency proposed a new nutrient management policy, now addressing P as well as nitrogen (N), which each state must enact by 2008. There are three approaches that address P—agronomic soil test P recommendations, environmental soil test P thresholds, and a P index to rank fields according to their vulnerability to potential P loss. There are many versions of the P index now in use, demonstrating the robustness and flexibility of the indexing framework to better target remedial measures. Of the three P-based approaches, the P indexing approach has been most widely adopted with 47 states using this approach to target P management. This paper charts the development of the indexing approach, which ranks site vulnerability to P loss by accounting for source (soil test P, fertilizer, and manure management) and transport factors (erosion, runoff, leaching, and connectivity to a stream channel) and outlines modifications made among states that reflect local conditions and policy. Additional factors include flooding frequency, STP modifiers (texture, pH, P sorption, reactive aluminum [Al]), conservation practices, and priority of receiving waters. While computation of the final index value is additive in 20 states, 17 multiply source and transport factors to define critical source areas. Most states (47) have maintained the original indexing approach of assessing site vulnerability to P loss, with indices in three states quantifying P loss. We demonstrate using three management scenarios (changing the time of applied manure, riparian buffer establishment, and reduced feed P ration) that overall P index ratings can be decreased, giving farmers more options for manure management than by simply reducing application rates.

Global modeling of the fate of nitrogen from point and nonpoint sources in soils, groundwater, and surface water

Abstract: [1] We present a global model that describes the fate of nitrogen (N) from point and nonpoint sources in the hydrological system up to the river mouths at the 0.5° by 0.5° spatial and annual temporal resolution. Estimates for point sources are based on population densities, per capita human N emissions, and data on sanitation coverage and wastewater treatment. For nonpoint sources, we use spatial information on land use, climate, hydrology, geology, and soils, combined with data on N inputs (fertilizers and animal manure, biological N fixation, and atmospheric deposition), and outputs (N removal in harvested agricultural products, ammonia emissions). Denitrification in the root zone and nitrate leaching to groundwater are calculated with a model that combines the effect of temperature, crop type, soil properties, and hydrological conditions. The nitrate concentration of the outflow for shallow and deep groundwater layers is based on historical inputs of fertilizer N and the effects of residence time and denitrification. In-stream N retention is based on a global estimate of 30% of the N discharged to surface water. Calculated and reported total N concentrations of discharge near the river outlet agree fairly well. However, our model systematically overestimates total N concentrations for river basins with mean annual temperature >0°C.

Assessing water quality at large geographic scales: relations among land use, water physicochemistry, riparian condition, and fish community structure.

Abstract: Data collected from 172 sites in 20 major river basins between 1993 and 1995 as part of the US Geological Survey's National Water-Quality Assessment Program were analyzed to assess relations among basinwide land use (agriculture, forest, urban, range), water physicochemistry, riparian condition, and fish community structure. A multimetric approach was used to develop regionally referenced indices of fish community and riparian condition. Across large geographic areas, decreased riparian condition was associated with water-quality constituents indicative of nonpoint source inputs—total nitrogen and suspended sediment and basinwide urban land use. Decreased fish community condition was associated with increases in total dissolved solids and rangeland use and decreases in riparian condition and agricultural land use. Fish community condition was relatively high even in areas where agricultural land use was relatively high (>50% of the basin). Although agricultural land use can have deleterious effects on fish communities, the results of this study suggest that other factors also may be important, including practices that regulate the delivery of nutrients, suspended sediments, and total dissolved solids into streams. Across large geographic scales, measures of water physicochemistry may be better indicators of fish community condition than basinwide land use. Whereas numerous studies have indicated that riparian restorations are successful in specific cases, this analysis suggests the universal importance of riparian zones to the maintenance and restoration of diverse fish communities in streams.

Factor Analysis and Dynamics of Water Quality of the Songhua River Northeast China

Abstract: The water quality of the Songhua River (Northeast China) was of concern, especially in the 1980s and early 1990s, and there weremany studies carried out on this aspect However, only one or several independent water quality indiceswere used to consider the effects of pollutants on thewater quality, for instance, heavy metal and toxic organicpollutants The combined effects of multiple indices wereseldom studied In this article, based on the environmentalmonitoring data, the water quality of the Songhua River wasanalyzed using factor analysis, which comprehensivelyconsidered six indices of water quality of each monitoringsection The results showed that the main pollutants hadchanged to nitrogenous pollutants originated from nonpointsources, and water quality was variable in differenthydrological periods The results also showed that themethod was comprehensive and efficient in analyzing thedynamics of water quality

Integration of geographic information systems and simulation model for watershed management

Abstract: Simulation models are powerful tools in support of watershed analysis and assessment of management scenarios at the watershed scale. This paper integrates geographic information systems (GIS) and agricultural nonpoint source pollution model (AGNPS) to analyze the effect of land use change on nonpoint source pollution in a study watershed. ArcView nonpoint source pollution modeling (AVNPSM), an interface between ArcView GIS and AGNPS is developed to facilitate agricultural watershed modeling. The interface consists of six modules: a parameter generator, input file processor, model executor, output visualizer, statistical analyzer, and land use simulator. The interface requires input databases of soil, climate, digital elevation model, land use/cover, hydrography, and management practices. It was applied to study the watershed to simulate the impact of land use change on runoff, sediment, and nutrient yields based on a 25-year, 24-h period of single storm event of 114 mm. The simulation results show that expansion of urban land is likely to lead to an increase in surface runoff, peak flow, and soil erosion. The magnitude of the effect is related to the extent and proximity of proposed land use change to water bodies in the watershed.  2003 Elsevier Science Ltd. All rights reserved.

Xenobiotic organic compounds in runoff from fields irrigated with treated wastewater.

Abstract: Investigations of agricultural nonpoint source pollution typically focus on a relatively narrow range of targeted toxic and biostimulatory compounds (e.g., specific pesticides, nutrients). Regular application of numerous other organic compounds to agricultural fields in pesticide formulations, irrigation water, soil amendments, and fertilizers may result in their transport into surface waters via runoff. We examined whether potentially toxic dissolved and particle-associated “nontarget” organic compounds were present in surface runoff from agricultural fields irrigated with disinfected tertiary recycled water or wastewater effluent-dominated streamwater. Gas chromatographic−mass spectrometric analyses of filtered runoff samples revealed the presence of numerous nontarget compounds of potential toxicological significance including pesticide transformation products, pesticide adjuvant chemicals, plasticizers, flame retardants, pharmaceuticals, and personal care product ingredients. Although the toxicity of ...

Non-point source critical area analysis in the Gisselö watershed using GIS

Abstract: In the southeast in Norrk÷ping, Sweden, is a small fjord-like bay called SlΣtbaken. The water quality in SlΣtbaken - with its narrow outlet to the Baltic Sea - depends highly on the water quality o ...

Detention Pond Design and Land Use Planning for Watershed Management

Abstract: Nonpoint source management using wet detention ponds to reduce pollutant loading into receiving water bodies is a common practice. Design of these ponds is typically carried out individually to meet a target total suspended solids (TSS) removal level. An improvement to this approach is to generate cost-effective pond configurations that meet system-wide targets for removal of pollutant loadings, including TSS, total nitrogen, and total phosphorus, corresponding to a specific build-out land use plan. The amount of pollutant loading can be managed better through appropriate land use allocation planning conducted simultaneously with the design of detention pond configurations. This paper presents a modeling approach to address this problem and its solution via a genetic algorithm-based search procedure. Application of this approach is demonstrated using an illustrative case study involving the City Lake watershed in North Carolina. The results show cost improvements when considering land management simultaneously with the decisions for pond locations and sizes. Through iterative application of this method, the tradeoff between cost and removal level of each pollutant is also generated.

Controlling Storm-Water Runoff with Tradable Allowances for Impervious Surfaces

Abstract: Storm-water flow from an impervious surface can lead to stream degradation, habitat alteration, low base flows, and increased toxic loadings from nonpoint sources, a problem that has resisted traditional command and control regulatory approaches. We explore the thesis that a well-designed, tradable runoff allowance system can create economic incentives for landowners to employ low-cost runoff management practices to reduce excess stormwater flow to more ecologically sound levels. Attributes such as percent impervious surface, soil type, and so on, determine a given land parcel’s runoff potential and management alternatives and, by extension, its allowance requirements. Using a small watershed in Cincinnati, Ohio, as a case study, we show that a tradable runoff allowance system carries promise as a low-cost method for attaining reductions in storm-water runoff.

Impacts of Urbanization on Nutrient Concentrations in Small Southeastern Coastal Streams

Abstract: Coastal watersheds in the southeastern United States are rapidly changing due to population growth and attendant increases in residential development, industry, and tourism related commerce. This research examined spatial and temporal patterns of nutrient concentrations in streams from 10 small watersheds (< 4 km2) that drain into Murrells Inlet (impacted) and North Inlet (pristine), two high salinity estuaries along the South Carolina coast. Monthly grab samples were collected during baseflow during 1999 and analyzed for total and dissolved inorganic and organic forms of nitrogen and phosphorus. Data were grouped into forested wetland creeks (representing predevelopment reference sites), urban creeks, and urban ponds. DON and NH4 concentrations were greater in forested streams than in urban streams. NO3 and TP concentrations were greatest in urban streams. Seasonally, concen- trations were highest during summer for TN, NH4, DON, and TP, while NO3 concentrations were greatest during winter. Nutrient ratios clearly highlighted the reduction in organic nitrogen due to coastal development. Multiple regression models to predict instream nutrient concentrations from land use in Murrells Inlet suggest that effects are not significant (small r2). The findings indi- cate that broad land use/land cover classes cannot be used to pre- dict nutrient concentrations in streams in the very small watersheds in our study areas. (KEY TERMS: nonpoint source pollution; urbanization; water qual- ity; watershed management; nutrients; coastal streams.)

A watershed perspective on nutrient enrichment, science, and policy in the Patuxent River, Maryland: 1960–2000

Abstract: The Patuxent River, Maryland, is a nutrient-overenriched tributary of the Chesapeake Bay Nutrient inputs from sewage outfalls and nonpoint sources (NPS) have grown substantially during the last four decades, and chlorophyll a levels have increased markedly with concomitant reductions in water quality and dissolved oxygen concentrations The Patuxent has gained national attention because it was one of the first river basins in the US for which basin-wide nutrient control standards were developed These included a reduction in NPS inputs and a limit on both nitrogen (N) and phosphorus (P) loadings in sewage discharges intended to return the river to 1950s conditions Full implementation of point source controls occurred by 1994, but population growth and land-use changes continue to increase total nutrient loadings to the river The present paper provides the perspectives of scientists who participated in studies of the Patuxent River and its estuary over the last three decades, and who interacted with policy makers as decisions were made to develop a dual nutrient control strategy Although nutrient control measures have not yet resulted in dramatic increases in water quality, we believe that without them, more extensive declines in water quality would have occurred Future reductions will have to come from more effective NPS controls since future point source loadings will be difficult to further reduce with present technology Changing land use will present a challenge to policy makers faced with sprawling population growth and accelerated deforestation

Predicted and measured levels of azinphosmethyl in the Lourens River, South Africa: Comparison of runoff and spray drift

Abstract: Runoff and spray drift are important sources of nonpoint pesticide pollution in surface waters, but few studies have directly compared these routes of input in an exposure assessment scenario. To this end, a runoff formula suggested by the Organization for Economic and Cooperative Development (Paris, France) and basic drift values (95th percentiles) were integrated into a geographical information system (GIS) to predict runoff and spray drift-related loading of azinphosmethyl (AZP) in the Lourens River (LR), South Africa. The GIS-integrated calculations were first validated in the tributaries of the river, where measured loads were well predicted for both runoff (r(20 = 0.95; p < 0.0001; n = 9) and spray drift (r(2) = 0.96; p = 0.0006; n = 8). Through extrapolation to the catchment scale containing 400 ha of orchards, the GIS-integrated calculations predicted similar loads of AZP as measured in the Lourens River mainstream for six runoff (between a factor of 1.03 and 1.86 lower) and six spray drift (between a factor of 1.1 and 2.4 higher) events. Mean measured loads per event were significantly (p = 0.004) higher for runoff (27.8 +/- 19.1 g) than for spray drift (0.69 +/- 0.32 g). Based on long-term meteorological data and average application regimes, runoff leads to a higher annual load (47.6 g) than spray drift (5.5 g) in the Lourens River. Runoff is clearly a more important source of nonpoint pollution in the studied catchment, and mitigation strategies should focus first on addressing this aspect on a catchment scale and second on addressing problem areas on a subcatchment scale.

Lessons about Effluent Trading from a Single Trade

Abstract: Despite many years of existence, programs that allow transferable discharge permits to control water pollution have had quite limited success. This paper discusses a single trade that recently took place in the Lake Dillon drainage basin between point and nonpoint pollution sources. This trade demonstrates many of the challenges that are faced in effluent trading but also highlights the potential efficiency gains that can be achieved through such programs.

Watershed-scale simulation of sediment and nutrient loads in Georgia Coastal Plain streams using the annualized AGNPS model

Abstract: Sediment and nutrient loadings in the Little River Research Watershed in south central Georgia were modeled using the continuous simulation Annualized Agricultural Nonpoint–Source Pollution (AnnAGNPS) model, part of the AGNPS suite of modeling components. Specifically, nitrogen, phosphorus, sediment, and runoff were predicted over a seven–year period. Land under cultivation makes up approximately 25% of the 333 km2 watershed. Livestock facilities include swine, poultry, dairy cows, and beef cattle. Results from the simulation were compared to seven years of monitoring data at the outlet of five nested subwatersheds and at the outlet of the Little River Research Watershed (LRRW). The average annual predicted runoff in the upper part of the watershed was one–third to half of observed runoff. In contrast, predicted runoff in the lower part of the watershed was close to observed, and was 100% of observed at the outlet of the watershed. Runoff underprediction was attributed to the method of landcover discretization. The extent of forest land in the upper watershed (55% to 63%) and the fragmented landscape that has relatively small fields surrounded by riparian forests and tracts of forest resulted in overestimation of forested area in the watershed. In addition to runoff, sediment and nutrient loads were also underpredicted in the upper part of the LRRW. Two factors are most likely responsible for underprediction. Runoff is underpredicted at these sites, which reduces the carrying capacity of sediment loads. In addition, the overestimation of forested areas at these sites coincides with underestimation of sediment–producing areas, such as cropland. In contrast to the upper part of the watershed, sediment and nutrient loads were overpredicted in the lower part of the watershed. This may have resulted from inadequately simulating nonpoint–source pollution attenuation by the extensive riparian forests and forested in–stream wetland areas found in these watersheds. Prediction results can be improved through better input into the model, as well as modification of the processes within the model to account for forest and riparian conditions.

SLAMM, the Source Loading and Management Model

Abstract: The Source Loading and Management Model (SLAMM) was originally developed to better understand the relationships between sources of urban runoff pollutants and runoff quality. It has been continually expanded since the late 1970s and now includes a wide variety of source area and outfall control practices (infiltration practices, wet detention ponds, porous pavement, street cleaning, catchbasin cleaning, and grass swales). SLAMM is strongly based on actual field observations, with minimal reliance on pure theoretical processes that have not been adequately documented or confirmed in the field. SLAMM is mostly used as a planning tool, to better understand sources of urban runoff pollutants and their control. Special emphasis has been placed on small storm hydrology and particulate washoff in SLAMM, common areas of misuse in many stormwater quality models. Many currently available urban runoff models have their roots in drainage design where the emphasis is on very large and rare rains. In contrast, stormwater quality problems are mostly associated with common and relatively small rains. The assumptions and simplifications that are legitimately used with drainage design models are not appropriate for water quality models. SLAMM therefore incorporates unique process descriptions to predict more accurately the sources of runoff pollutants and flows for the storms of most interest in stormwater quality analyses. However, SLAMM can be effectively used in conjunction with drainage design models to incorporate the mutual benefits of water quality controls on drainage design. SLAMM has been used in many areas of North America and has been shown to predict stormwater flows and pollutant characteristics accurately for a broad range of rains, development characteristics, and control practices. As with all stormwater models, SLAMM needs to be accurately calibrated and then tested (verified) as part of any local stormwater management effort. 4

Evaluation of Ann Agnps Nitrogen Loading in AN Agricultural Watershed

Abstract: Pollutants entering a water system can be very destructive to the health of that system. Best Management Practices (BMPs) are used to reduce these pollutants, but understanding the most effective practices is very difficult. Watershed models are an effective tool to aid in the decision-making process of selecting the BMPs that are most effective in reducing the pollutant loading and are also the most cost effective. The Annualized Agricultural Nonpoint Source Pollution model (AnnAGNPS 2.0) is a technological tool that can be used to estimate watershed response to agricultural management practices. The main purpose of this paper is to test the performance of AnnAGNPS 2.0 on nitrogen loading using comparisons with measurements from the Deep Hollow watershed of the Mississippi Delta Management Systems Evaluation Area (MDMSEA) project. Previous work has demonstrated the capability of the model to simulate runoff and sediment. From sensitivity analyses in this study, initial nitrogen concentration in the soil and crop nitrogen uptake had the most impact on the nitrogen loadings. AnnAGNPS simulations of monthly nitrogen loadings are poor. However, statistical test (t-test) showed that the predicted nitrogen loading is not significantly different from observed nitrogen loading at the 95 percent level of confidence.

Using Multiple Antibiotic Resistance and Land Use Characteristics to Determine Sources of Fecal Coliform Bacterial Pollutiion

Abstract: Multiple Antibiotic Resistance (MAR) analysis and regression modeling techniques were used to identify surface water areas impacted by fecal pollution from human sources, and to determine the effects of land use on fecal pollution in Murrells Inlet, a small, urbanized, high-salinity estuary located between Myrtle Beach and Georgetown, South Carolina. MAR analysis was performed to identify areas in the estuary that are impacted by human-source fecal pollution. Additionally, regression analysis was performed to determine if an association exists between land use and fecal coliform densities over the ten-year period from 1989 to 1998. Land-use variables were derived using Geographic Information System (GIS) techniques and were used in the regression analysis.

Assessing TMDL effectiveness using flow-adjusted concentrations: a case study of the Neuse River, North Carolina.

Abstract: Integrated control of both point and nonpoint source water pollution using Total Maximum Daily Load (TMDL) assignments will be a major regulatory focus over the next decade. We propose the use of “flow-adjusted” pollutant concentrations to evaluate the effectiveness of manage ment actions taken to meet approved TMDLs. Pollutant concentrations are usually highly correlated with streamflow, and flow is strongly weather-dependent. Thus, pollutant loads, which are calculated as pollutant concentration multiplied by streamflow, have a large weather-dependent variance component. This natural variation can be removed by calculating flow-adjusted concentrations. While such values are not a direct measure of pollutant load, they make it easier to discern changes in streamwater quality. Additionally, they are likely to be a better predictor of pollutant concentrations in the receiving waterbody. We demonstrate the use of this technique using long-term nutrient data from the Neuse River in North Carolina. The Neuse ...

Effectiveness of a coastal wetland in reducing pollution of a laurentian great lake: hydrology, sediment, and nutrients

Abstract: The ability of coastal wetlands of the Laurentian Great Lakes to reduce pollution from tributaries has not been documented in detail or over multiple seasons. This study developed a surface-water budget for a coastal wetland along Lake Erie and estimated monthly, annual, and storm-related exports of total suspended solids and selected nutrients from the wetland. Water-budget measurements included precipitation, evaporation, surface discharge into the wetland, and net surface discharge into Lake Erie. Water samples collected upstream and downstream and composite dryfall-precipitation samples were analyzed for total suspended solids (TSS), total phosphorus (TP), soluble reactive phosphorus (SRP), nitrate + nitrite nitrogen (NO2+3), ammonia nitrogen (NH3), total Kjeldahl nitrogen (TKN), soluble reactive silica, chloride, and specific conductance. Seasonal and storm-related concentration patterns and a wide variation in monthly, seasonal, and annual loads from the tributary into the wetland were typi...

Watershed optimization of agricultural best management practices: Continuous simulation versus design storms

Abstract: Nonpoint source (NPS) models and expert opinions are often used to prescribe best management practices (BMPs) for controlling NPS pollution. An optimization algorithm (e.g., a genetic algorithm, or GA) linked with a NPS model (e.g., Annualized AGricultural Nonpoint Source pollution model, or AnnAGNPS), can be used to more objectively prescribe BMPs and to optimize NPS pollution control measures by maximizing pollutant reduction and net monetary return from a watershed. Pollutant loads from design storms and annual loads from a continuous simulation can both be used for optimizing BMP schemes. However, which strategy results in a better solution (in terms of providing water quality protection) for a watershed is not clear. The specific objective of the study was to determine the differences in watershed pollutant loads, in an experimental watershed in Pennsylvania, resulting from optimization analyses performed using pollutant loads from a series of five 2-yr 24-hr storm events, a series of five 5-yr 24-hr storm events, and cumulative pollutant loads from a continuous simulation of five years of weather data. For each of these three different event alternatives, 100 near optimal solutions (BMP schemes) were generated. Sediment (Sed), sediment nitrogen (SedN), dissolved N (SolN), sediment organic carbon (SedOC), and sediment phosphorus (SedP) loads from a different five-year period (an evaluation period) suggest that the optimal BMP schemes resulting from the use of annual cumulative pollutant loads from a continuous simulation of five years of weather data provide smaller cumulative NPS pollutant loads at the watershed outlet.

SWAT Model Background and Application Reviews

Abstract: Watershed scale hydrologic and nonpoint source pollution models must be thoroughly tested by applying them to watersheds of different sizes and characteristics and from different geographic and geologic locations before using them to assess environmental conditions, evaluate best management practices, and making water resources management decisions. A clear understanding of a model is important for its appropriate use. In an earlier study, eleven watershedscale hydrologic and nonpoint-source pollution models were reviewed: SWAT, HSPF, AGNPS, AnnAGNPS, ANSWERS, ANSWERS-Continuous, PRMS, KINEROS, DWSM, CASC2D, and MIKE SHE, and the mathematical bases of different components of these models were identified and compiled. Among the fully developed hydrologic and nonpoint source pollution models having all the three major components: hydrology, sediment, and chemical, SWAT was found to be one of the promising models for long-term continuous simulations in predominantly agricultural watersheds. Applications of SWAT and a few other promising models, as available in the literature, are currently being reviewed. In this paper, applications of the SWAT model are compiled and discussed, along with a brief background of the model.

A preliminary study on coastal water quality monitoring and modeling.

Abstract: The overall objective of this study was to assess the impact of individual rainfall events on Lake Pontchartrain water quality and risk to swimmers Indicator organisms in lake water under dry weather conditions, in storm water runoff (prior to dilution with lake water), and in the outfall plume within the lake following storm events were monitored and quantified Results indicated that drainage canals constitute a significant microbial loading to lake waters Significant reductions of indicator microbes are observed in the water column following two to three days after storm pumping events into the lake A mathematical model incorporating advection, dispersion, and bacterial die-off gives fairly good prediction on E coli, enterococcoi, and fecal coliform titers The somewhat under estimation by model suggests re-suspension of sediment and re-introduction of the indicator organisms that attached to the sediment back into the water column Future direction of model development should include the mechanism of re-suspension and survival of indicator organisms in sediment