Federal and state programs have encouraged farmers in the Mississippi Delta region to implement best management practices (BMPs) to promote soil and water conservation. An onarm water storage (OFWS) system is a structural BMP that has several potential benefits, namely, the ability to capture and reuse rainwater and tailwater runoff, provide supplemental water for irrigation, reduce groundwater withdrawals, and improve downstream water quality. However, research demonstrating these benefits and providing new insights for downstream water quality improvement and nutrient-rich runoff management is limited. This dissertation addresses these research gaps by examining the ability of OFWS systems to mitigate off-site nutrient movement, analyzing the impacts of rainfall characteristics on the ability of OFWS systems to reduce NO3-N, studying the hydrological and physical-chemical characteristics of the volume of water exiting an OFWS system, and using the AnnAGNPS model to simulate runoff, nutrient, and sediment loads entering a tailwater recovery ditch and identify the critical contributing areas of non-point source pollution. Significant seasonal water quality improvements were observed at different locations throughout the OFWS system, and more importantly, highlight downstream nutrient reduction, particularly during winter and spring. However, recurrent and high intensity rainfall events can minimize the system’s effectiveness in reducing downstream nutrient pollution. The NO3-N concentrations observed in the ditch were strongly dependent on antecedent hydrological conditions with characteristics of next-to-last rainfall events playing a more influential role. The nutrient load was greater in winter, as this season produced the highest effluent discharge. Agricultural fields draining to the outlet of the system produced 7.1 kg NO3-N ha-1yr-1 and 2.3 kg TP ha-1yr-1 that was discharged with outflow events. AnnAGNPS simulations showed that larger fields coupled with poorly drained soils resulted in higher runoff, and this condition mirrored the annual rainfall patterns. High nitrogen loss was due to fertilization of corn and winter wheat. TP and sediment loss patterns were similar and influenced by the hydrological condition. This study can be used by stakeholders and agencies to better identify where these systems can be implemented to improve water quality and offer a supplemental source of surface water.

O trabalho teve como objetivos determinar os efeitos de inundações do sistema radicular em diferentes estádios de desenvolvimento sobre a produtividade das culturas da batata e da alface, identificar a velocidade mínima de rebaixamento do nível freático capaz de evitar prejuízos a estas culturas e obter relações entre a produtividade relativa das mesmas e o índice diário de estresse por excesso de água no solo. Para tal foram conduzidos dois experimentos em lisímetros construídos a partir de tubos de concreto, considerados como parcelas, de julho a outubro de 2001 com a cultura da batata, e de dezembro de 2001 a janeiro de 2002 com a cultura da alface. O delineamento experi-mental adotado foi inteiramente casualizado, arranjado em esquema fatorial [(3 x 4) + 1], com quatro repetições para a cultura da batata e três repetições para a cultura da alfa-ce. Para ambas as culturas os tratamentos consistiram de 3 períodos de aplicação do en-charcamento, 4 velocidades de rebaixamento do nível freático (30 cm em 24, 48, 72 e 96 horas), mais uma testemunha na qual não foi aplicado estresse por elevação do nível freático. A análise dos resultados revelou que dentre os três estádios nos quais o estresse foi aplicado, o que ocasionou maiores perdas para a cultura da batata foi o terceiro (apli-cado do 85o ao 88o dia após o plantio), enquanto que para a cultura da alface o estádio mais crítico foi o primeiro (aplicado do 12o ao 15o dia após o transplantio) . Não foi pos-sível determinar a velocidade de rebaixamento do nível freático mais adequada, pois mesmo com a maior velocidade testada (30 cm em 24 horas), houve decréscimos de cer-ca de 50% da produtividade, para ambas as culturas. Foram obtidas correlações lineares negativas entre as produtividades relativas de ambas as culturas e o índice diário de es-tresse por excesso de água no solo. / This work had as objectivies determinating the effects of root system flooding in three stages of growing of potato and lettuce crops, identifying the minimum water-table drawdown velocity necessary to avoid yield reductions and obtaining relations between relative yield and stress day index caused by excess of water in the soil. For these purposes two experiments were conducted in lisimeters, buit with concrete pipe, considered as parcels, from july to october of 2001, with potato crop, and from decem-ber of 2001 to january of 2002, with lettuce crop. The statistical experimental design was a complete randomizer in a factorial arrangement [(3 x 4) + 1], with four replicati-ons for potato crop and three replications for lettuce crop. For both crops the treatment consisted in 3 growing stages of water-logging application, 4 drawdown velocities (30 cm during 24, 48, 72 and 96 hours) and a control in wich was not applied the stress of rising of the water-table. The results analysis showed that among the three stages where the water-logging were applied, the one who caused bigger yield reduction was the third (applied from the 85th to the 88th day after planting), for the potato crop and the first (ap-plied from the 12th to the 15th day after re-planting), for the lettuce crop. It was not pos-sible to identify the more adequate water-table drawdown velocity because even using the biggest velocity (30 cm during 24 horas) there were a 50% yield reduction for both crops. The potato and the lettuce relative yields showed a negative linear relation with the stress day index.

Semi-arid regions, like the Okanagan Basin of British Columbia, Canada, are often faced with the difficulty of managing limited groundwater and surface water resources while accommodating rapid population growth and increasing land development. In the South Okanagan Basin, a better understanding of groundwater recharge sources, groundwater availability and susceptibility of water supplies to anthropogenic contamination is needed to best direct and protect the regions water resources. The purpose of this study was: (1) to characterize the regional hydrogeological setting of the South Okanagan Basin by establishing an isotopic and geochemical framework that included precipitation and surface waters of the Okanagan Basin and groundwaters of the South Okanagan Basin; and (2) to characterize nitrate contamination and its sources in shallow groundwaters of the Osoyoos area. Stable isotopes of water, nitrate and dissolved oxygen, groundwater chemistry, water levels and enriched tritium, tritium/helium and/or radiocarbon age dating techniques were used. Two provisional local meteoric water lines were established for the Okanagan Basin: &delta2H=6.06&delta18O31.21 (Osoyoos) and &delta2H=7.03&delta18O-12.68 (West Kelowna). Surface waters of the Okanagan River system were sources of irrigation water in the South Okanagan Basin valley and irrigation-return flow was the primary source of recharge for shallow groundwaters. Fractured bedrock in highlands east and west of the valley were not a significant source of recharge for shallow valley groundwater, however, may recharge deeper, or basal, valley deposits. As irrigation-return flow controls shallow groundwater dynamics in the valley sediments, groundwater quality is susceptible to anthropogenic contamination. In Osoyoos, nitrate was present in shallow groundwaters at concentrations of up to 24.4 mg/l N as a result of fertilizer nitrogen applied at the soil surface, mostly at orchards. Two agricultural drainage systems in north Osoyoos discharge roughly 1,900 kg N/year from nitrate-contaminated groundwater directly into Osoyoos Lake and may contribute in part to its eutrophication.

Semi-arid regions, like the Okanagan Basin of British Columbia, Canada, are often faced with the difficulty of managing limited groundwater and surface water resources while accommodating rapid population growth and increasing land development. In the South Okanagan Basin, a better understanding of groundwater recharge sources, groundwater availability and susceptibility of water supplies to anthropogenic contamination is needed to best direct and protect the regions water resources. The purpose of this study was: (1) to characterize the regional hydrogeological setting of the South Okanagan Basin by establishing an isotopic and geochemical framework that included precipitation and surface waters of the Okanagan Basin and groundwaters of the South Okanagan Basin; and (2) to characterize nitrate contamination and its sources in shallow groundwaters of the Osoyoos area. Stable isotopes of water, nitrate and dissolved oxygen, groundwater chemistry, water levels and enriched tritium, tritium/helium and/or radiocarbon age dating techniques were used. Two provisional local meteoric water lines were established for the Okanagan Basin: &delta2H=6.06&delta18O31.21 (Osoyoos) and &delta2H=7.03&delta18O-12.68 (West Kelowna). Surface waters of the Okanagan River system were sources of irrigation water in the South Okanagan Basin valley and irrigation-return flow was the primary source of recharge for shallow groundwaters. Fractured bedrock in highlands east and west of the valley were not a significant source of recharge for shallow valley groundwater, however, may recharge deeper, or basal, valley deposits. As irrigation-return flow controls shallow groundwater dynamics in the valley sediments, groundwater quality is susceptible to anthropogenic contamination. In Osoyoos, nitrate was present in shallow groundwaters at concentrations of up to 24.4 mg/l N as a result of fertilizer nitrogen applied at the soil surface, mostly at orchards. Two agricultural drainage systems in north Osoyoos discharge roughly 1,900 kg N/year from nitrate-contaminated groundwater directly into Osoyoos Lake and may contribute in part to its eutrophication.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-05-09T15:00:57Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE (NAILZA ARRUDA) VERSÃO FINAL.pdf: 5115698 bytes, checksum: 1e7e7d4013f4b50363520bb26e8ee9c4 (MD5) / Made available in DSpace on 2016-05-09T15:00:57Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE (NAILZA ARRUDA) VERSÃO FINAL.pdf: 5115698 bytes, checksum: 1e7e7d4013f4b50363520bb26e8ee9c4 (MD5) Previous issue date: 2015-07-15 / FACEPE / O aporte de nutrientes é um dos fatores determinantes para estabelecer o estado trófico de reservatórios. O fósforo é o elemento nutrício limitante na produção primária da maioria desses ecossistemas aquáticos, o que torna seu controle muito importante para a gestão ambiental. A análise integrada dos teores, formas e efeitos do fósforo nas águas e sedimentos de fundo dos reservatórios, consiste numa ferramenta poderosa quando considera informações relacionadas às práticas adotadas para implantação e suporte das atividades econômicas desenvolvidas no entorno ou dentro dos reservatórios. No semiárido brasileiro, reservatórios artificiais de grandes dimensões são utilizados prioritariamente para abastecimento humano, produção de hidroeletricidade, agricultura irrigada e mais recentemente, a piscicultura intensiva vem se consolidando como arranjo produtivo importante na geração de trabalho e renda para população local. Neste contexto, a adoção de práticas sustentáveis desde a concepção dessas atividades econômicas, ganha cada dia mais destaque na gestão de perdas de nutrientes, contribuindo para redução do aporte para os reservatórios e dos riscos de eutrofização cultural desses corpos hídricos. Esta pesquisa tem como objetivo apresentar estratégias para minimizar o aporte de nutrientes em reservatórios, utilizando o fósforo como elemento de controle e possibilitando ao gestor a realização de análise integrada às atividades econômicas. Para isso, utilizou-se como área de estudo o Perímetro Irrigado de Icó-Mandantes, inserido nos municípios de Petrolândia e Floresta, no entorno do reservatório de Itaparica, localizado no trecho Submédio do rio São Francisco. Para atingir este objetivo, foi realizada uma avaliação integrada das atividades antrópicas instaladas na margem pernambucana do reservatório. Inicialmente, foi avaliada a qualidade da água de drenagem agrícola oriunda do Perímetro Irrigado de Icó-Mandantes, em seguida foi realizado caracterização das principais fontes pontuais e difusas de fósforo. Também foi verificada a ocorrência de fósforo no sedimento de fundo da Baía de Icó-Mandantes e a avaliação foi complementada com o levantamento do perfil socioeconômico dos agricultores sobre as práticas adotadas para fertilização do solo. Como resultado, obteve-se uma água de drenagem agrícola com concentrações de fósforo dentro de padrões aceitáveis. Quanto aos sedimentos de fundo, as quantidades representativas de fósforo se encontram nas formas adsorvidas e não biodisponíveis à curto prazo. Em geral, os agricultores têm baixa escolaridade e desenvolvem práticas inadequadas para de fertilização do solo. Foram propostas estratégias de controle do aporte de fósforo baseadas em boas práticas de manejo e manejo integrado de nutrientes para as atividades de agricultura irrigada e piscicultura em tanques-rede. Os resultados obtidos confirmaram a hipótese de que as práticas adotadas para fertilização do solo, a piscicultura desenvolvida em tanques-rede e o lançamento de esgotos sanitários aumentam o risco de eutrofização dos reservatórios pela contribuição do aporte de fósforo na água e nos sedimentos de fundo. / The supply of nutrients is one of the determining factors to establish the trophic state of reservoirs. Phosphorus is the limiting foster-element in the primary production for most of these aquatic ecosystems, which makes its control very important for the environmental management. The integrated analysis of the concentration, shape and effects of phosphorus in waters and sediments of the bottom of reservoirs is a powerful tool when considering information related to adopted practices for implantation and support of economic activities developed inside or around reservoirs. In the Brazilian semi-arid region, artificial reservoirs of great dimensions are used primarily for human supply, hydroelectricity production, irrigated agriculture and more recently, for intensive fish farming, which has become an important productive arrangement in generating jobs and income for the local people. In this context, the adoption of sustainable practices from the design of these economic activities, earns each day more emphasis on managing nutrient losses, contributing to reduce the supply to the reservoirs and the risks of cultural eutrophication of these water bodies. This research aims to develop a methodology to manage the supply of nutrients in reservoirs, utilizing the phosphorus as the checking element and allowing the manager to conduct integrated analysis to the selected practices in the economic activities. For that, the study area utilized was the county of Petrolândia and the irrigated perimeter of Icó-Mandantes, based around the Itaparica reservoir, located in the submedium of the São Francisco River. To achieve this goal, an integrated evaluation of the anthropogenic activities settled in the Pernambuco margin of the reservoir was conducted. Initially, the quality of the agricultural drain water from the irrigated perimeter of Icó-Mandantes was evaluated, and then a characterization of the major point and non-point sources of phosphorus was carried out. It were also checked the occurrence of phosphorus in the sediment of the bottom of the Icó-Mandantes Bay and the evaluation was complemented with the survey of the socioeconomic profile of farmers and the adopted practices for soil fertilization. As a result, the obtained agricultural drain water had concentration of phosphorus within the acceptable standards for agricultural areas. As for the bottom sediments, the representative quantities of phosphorus were found in adsorbed forms, not in bioavailable of short term. In general, the farmers have low education and develop inadequate practices for soil fertilization. It was proposed phosphorus intake control strategies based on good management practices and integrated nutrient management for irrigated agriculture and fish farming in cages activities. The acquired results confirmed the hypothesis that the practices for soil fertilization, the fish farming developed in cages and the release of sewage increase the risk of eutrophication of reservoirs by phosphorus intake contribution in water and bottom sediments.

O trabalho teve como objetivos determinar os efeitos de inundações do sistema radicular em diferentes estádios de desenvolvimento sobre a produtividade das culturas da batata e da alface, identificar a velocidade mínima de rebaixamento do nível freático capaz de evitar prejuízos a estas culturas e obter relações entre a produtividade relativa das mesmas e o índice diário de estresse por excesso de água no solo. Para tal foram conduzidos dois experimentos em lisímetros construídos a partir de tubos de concreto, considerados como parcelas, de julho a outubro de 2001 com a cultura da batata, e de dezembro de 2001 a janeiro de 2002 com a cultura da alface. O delineamento experi-mental adotado foi inteiramente casualizado, arranjado em esquema fatorial [(3 x 4) + 1], com quatro repetições para a cultura da batata e três repetições para a cultura da alfa-ce. Para ambas as culturas os tratamentos consistiram de 3 períodos de aplicação do en-charcamento, 4 velocidades de rebaixamento do nível freático (30 cm em 24, 48, 72 e 96 horas), mais uma testemunha na qual não foi aplicado estresse por elevação do nível freático. A análise dos resultados revelou que dentre os três estádios nos quais o estresse foi aplicado, o que ocasionou maiores perdas para a cultura da batata foi o terceiro (apli-cado do 85o ao 88o dia após o plantio), enquanto que para a cultura da alface o estádio mais crítico foi o primeiro (aplicado do 12o ao 15o dia após o transplantio) . Não foi pos-sível determinar a velocidade de rebaixamento do nível freático mais adequada, pois mesmo com a maior velocidade testada (30 cm em 24 horas), houve decréscimos de cer-ca de 50% da produtividade, para ambas as culturas. Foram obtidas correlações lineares negativas entre as produtividades relativas de ambas as culturas e o índice diário de es-tresse por excesso de água no solo. / This work had as objectivies determinating the effects of root system flooding in three stages of growing of potato and lettuce crops, identifying the minimum water-table drawdown velocity necessary to avoid yield reductions and obtaining relations between relative yield and stress day index caused by excess of water in the soil. For these purposes two experiments were conducted in lisimeters, buit with concrete pipe, considered as parcels, from july to october of 2001, with potato crop, and from decem-ber of 2001 to january of 2002, with lettuce crop. The statistical experimental design was a complete randomizer in a factorial arrangement [(3 x 4) + 1], with four replicati-ons for potato crop and three replications for lettuce crop. For both crops the treatment consisted in 3 growing stages of water-logging application, 4 drawdown velocities (30 cm during 24, 48, 72 and 96 hours) and a control in wich was not applied the stress of rising of the water-table. The results analysis showed that among the three stages where the water-logging were applied, the one who caused bigger yield reduction was the third (applied from the 85th to the 88th day after planting), for the potato crop and the first (ap-plied from the 12th to the 15th day after re-planting), for the lettuce crop. It was not pos-sible to identify the more adequate water-table drawdown velocity because even using the biggest velocity (30 cm during 24 horas) there were a 50% yield reduction for both crops. The potato and the lettuce relative yields showed a negative linear relation with the stress day index.

No description available.

Low grade rip rap weirs installed in agricultural surface drainage ditches manage downstream eutrophication by slowing water flow, allowing sediments time to settle out of the water column and phosphorus (P) to sorb to soil. A laboratory experiment was conducted in microcosm chambers to simulate increased hydraulic residence time caused by weirs and two field studies were conducted to compare experimental data with field data and determine sediment deposition rates. One field study monitored weirs monthly after installation and the other measured weirs of varying ages. Weirs retained significantly more water and sediment than controls. Longer inundation times led to abiotic factors known to release P during hydrologic flux, but did not translate to reduced P storage. By converting intermittently inundated sediments into more consistently saturated sediments, weirs function as a viable conservation practice for about a year until temporary P retention mechanisms and sediment retention capacities are reached.

No description available.

No description available.