Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 154-161). Also available on the Internet.

Thesis (Ph. D.)--Texas State University--San Marcos, 2009. / Vita. Appendices: leaves 133-163. Includes bibliographical references (leaves 16-20, 52-53, 87-91, 116-119, 130-132). References in more than one sequence of leaves. Also available on microfilm.

Thesis (M.A.)--The University of North Carolina at Greensboro, 2008. / Directed by Roy Stine; submitted to the Dept. of Geography. Title from PDF t.p. (viewed Aug. 17, 2009). Includes bibliographical references (p. 44-48).

Thesis (M.S.)--Ohio University, June, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 123-129)

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 140-146).

Riparian buffers in agricultural landscapes are designed to trap pollutants in overland flow by slowing, filtering, and infiltrating surface runoff entering the buffer via sheet flow. However, observational evidence suggests that concentrated flow is prevalent from agricultural fields. Also, over time sediment can accumulate in riparian buffers forming berms that restrict sheet flow from moving into the buffers; these berms ultimately back up surface runoff, resulting in an eventual breakthrough which concentrates runoff. Breakthrough by concentrated flow can lead to gully formation that may reduce the filtering capacities of buffer systems by providing direct conduits to stream channels. This study explores the frequency of concentrated flow paths in riparian buffers at both the field and watershed scale. At the field scale, intensive topographic surveys were conducted at 10 field sites in southern Illinois to characterize concentrated flow paths, accumulated berm sediments, and field area drained by concentrated flow. Detailed digital elevation models (DEMs) were created for each site and riparian buffer and agriculture field characteristics were analyzed to assess the development and occurrence of concentrated flow paths. At each site, soil samples were analyzed to characterize sediment deposition patterns within the buffer. To assess the prevalence of concentrated flow paths at the watershed scale, three watersheds in southern Illinois were selected for walking stream surveys. Five stream segments, approximately 1000 m long, were randomly selected within each watershed and surveyed for the occurrence and size of concentrated flow paths. These data were analyzed with respect to riparian buffer vegetation, buffer width, and surrounding land cover data. Concentrated flow paths were identified in all topographic surveys and all walking stream surveys indicating a common occurrence in agricultural watersheds of southern Illinois. Among field scale sites, concentrated flow accounted for 82.5-100% of the drainage areas contributing to riparian buffers. Results from the watershed scale analysis suggest that concentrated flow paths are significantly more abundant in agricultural land cover, than forested land. Current riparian buffer design principles are based on the assumption that sheet flow is the primary form of surface runoff entering buffers. Furthermore, buffers are installed and not maintained which can lead to berm accumulation and buffer failure. Results from this study indicate that concentrated flow was the prevalent form of runoff at field scale sites. Managers need to consider the occurrence of concentrated flow paths when designing riparian buffers to protect stream water quality.

Seasonal hypoxia in the northern Gulf of Mexico has been mapped extensively and is known to overlap the habitat of the brown shrimp Farfantepenaeus aztecus on the Louisiana continental shelf. Yet the impacts of Gulf hypoxia on the profitable brown shrimp fishery in Louisiana remain largely unknown. The problem is primarily attributable to nonpoint source pollution in the Mississippi River, but awareness of the problem has not resulted in an effective policy solution to stem this pollution to date. Using the combination of a quantitative data analysis to look for a correlation between Farfantepenaeus aztecus and hypoxic water, a survey mailed to shrimp fishers in Louisiana, and qualitative interviews with shrimp fishers and environmental activists and lawyers in Louisiana, I will examine the potential of a legal tool, the Public Trust doctrine, to slow nonpoint source pollution into the Mississippi River.

A redução dos impactos da poluição difusa é ainda pouco explorada no Brasil, havendo ausência de critérios legais quanto à sua mitigação. Contudo, na esfera científica o seu impacto é reconhecido. Seguindo evidências de que há uma carência no tratamento de poluição difusa no país, este trabalho se propõe a analisar wetlands construídas como medidas de controle de poluição difusa, através de modelagens, para 4 áreas na bacia do córrego do Mineirinho. A exploração dessa proposta se deu por três abordagens paralelas. Na primeira, as wetlands foram projetadas para tratar o escoamento superficial de uma chuva crítica, de 61 minutos. Na segunda abordagem, foi utilizada uma chuva crítica de 24 horas de duração. Na terceira, utilizou-se o índice de precipitação anual. O escoamento superficial foi calculado conforme os coeficientes de runoff. Atribuíram-se valores de concentrações médias de evento para DBO e Fósforo aos tipos de uso e ocupação, obtendo-se concentrações médias nas águas pluviais a serem tratadas. O modelo P-k-C* foi empregado na primeira e terceira abordagens, para dimensionar os sistemas com base no desempenho de remoção de cargas. Os resultados obtidos demonstraram a aptidão dos sistemas em reduzir cargas e/ou concentrações na bacia, apresentando como principal limitação técnica o espaço demandado para sua implantação. Houve influência majoritária da infiltração na remoção de cargas, que agiu em conjunto com o decaimento de poluentes ao longo dos sistemas. Na primeira abordagem, o modelo P-k-C* apresentou limitações em prever o desempenho dos sistemas por não comportar vazões variáveis. A segunda abordagem foi a mais simples, baseada apenas no armazenamento do evento crítico, entretanto, há uma carência de relações empíricas traçadas experimentalmente para prever seu desempenho. A terceira abordagem se mostrou a mais adequada ao modelo P-k-C*, podendo ser aprimorada de duas formas: adaptações nas constantes cinéticas ou vazões equivalentes, a fim de descrever uma média anual de desempenho. Concluiu-se que wetlands construídas demonstram potencial para o tratamento de poluição difusa, porém há uma necessidade de estudos a fim de se adaptar as ferramentas de modelagem disponíveis. / Nonpoint source pollutions impacts are still a rarely explored theme in Brazil, in which there are no legal criteria for its treatment. Although, in the scientific sphere its impacts are well known. Following evidence that there is a lack of nonpoint source pollution treatment in Brazil, this study proposes to analyze constructed wetlands as a nonpoint source pollution control measure, through modelling, for four different areas in the Mineirinho stream watershed. This proposal was explored through three different approaches. At first, the wetlands were designed to threat a critic rainfall for flood estimation, with detailed hydrographs. On the second approach, the wetlands were design to fully contain a 24-hour critic rainfall. On the third approach, the wetlands were designed to treat the average annual rainfall. The runoff volumes were estimated by runoff coefficients, and event mean concentrations for BOD and TP were assigned to each source area, resulting in the stormwater quality estimation. The P-k-C* model was applied to calculate systems performance on the first and third approaches. The results showed the aptitude of the systems for reducing loads and concentrations in the watershed, although mainly limited by the availability of areas. Infiltration had a major hole in reducing loads, although there were also significant amounts of pollutant removed by the systems. At the first approach, the P-k-C* model presented limitations on describing stormwater treatment, because of its unsteady and intermittent characteristics. The second approach was the simplest, based on containing the whole runoff volume, but it also showed a lack of studies stablishing empiric relations to estimate its performance. The third approach was the most adequate to the P-k-C* model, which usage could be improved by two adaptations in its parameters: kinetic coefficient adaptations or the adoption of equivalent steady flows, to describe the annual wetland performance. The study concluded that constructed wetlands show great promise for treating nonpoint source pollution in the watershed, but there is a need of more studies to regionalize empiric solutions available in the scientific literature, to apply the designing techniques with greater precision.

<p>A survey of farmers was conducted to determine the extent of cost-share and non-costshare BMP implementation and to evaluate the impact of socio-economic variables of the adoption of BMPs in Virginia's Chesapeake Bay drainage basin. Farmers in 67 counties in Virginia were randomly selected using VirGIS land use data and GRASS 4.1. All of the counties included in the study had at least 90 percent of their total land in the Chesapeake Bay drainage basin. Surveys were mailed to approximately 5,850 farm operators and 1,377 responses were returned, with approximately 1,099 estimated to farm in the Chesapeake Bay basin.</p> <p> A concern for pollution in the Chesapeake Bay was evident by farmers throughout the Bay basin, as 80 percent of the respondents indicated being concerned about water pollution in the Chesapeake Bay. However, only 33 percent believed that their farm contributed to water quality problems. The most often indicated perceived causes of pollution were runoff from urban or paved areas, industrial waste or factory discharge, sewer systems, and litter or garbage.</p> / Master of Science

This study discusses the monitoring requirements of an effluent credit trading system that allows point source discharges to purchase effluent reductions by financing agricultural nonpoint source best management practices. It describes the results of a national survey of existing trading programs that assessed how each program determines nonpoint source baseline pollutant discharges, pollutant reductions attributable to best management practices, verification of best management practice(s) installation and maintenance activities, and how often this verification is performed. This study surveyed the nonpoint source discharge monitoring programs of several of the successful effluent credit trading systems in the U.S. It documents and discusses specific characteristics of nonpoint source pollutant discharge monitoring strategies. Finally, this thesis compares trading program discharge monitoring characteristics to the current Virginia Cost-Share nonpoint source monitoring program. The goal of this study is to recommend elements of a nonpoint source discharge monitoring strategy to the Commonwealth of Virginia that can be used in a trading program of its own. The study shows that the majority of existing effluent credit trading programs use watershed models and land use evaluation algorithms to indirectly monitor nonpoint source pollutant discharges on a watershed basis rather than relying on empirical sampling and analysis activities for individual farms of fields. Monitoring takes a variety of forms to provide the diverse information necessary to indirectly determine nonpoint source discharges. Most trading programs monitoring strategies are no more comprehensive than agricultural cost-share programs even though many stakeholders believe that a trading program's monitoring activities should be exact enough to determine contributions from individual nonpoint sources to support the payments for individual activities. This objection is a barrier to the acceptance of trading programs by the public. A Virginia trading program must enhance its agricultural best management practice cost-share program monitoring practices to track nonpoint source discharges from individual farms or fields to be accepted and successful. / Master of Engineering