Microbial contamination of drinking water poses an important health risk which causes severe illnesses and epidemics. In order to improve surface and drinking water quality, the understanding of fecal pathogen contamination processes including their prevention and control needs to be enhanced. The watershed model soil water assessment tool (SWAT) is commonly used to simulate the complex hydrological, meteorological, erosion, land management and pollution processes within river basins. In recent years, it has been increasingly applied to simulate microbial contamination transport at the watershed scale. SWAT is used in this study to simulate Escherichia coli (E.coli) and fecal coliform densities for the agriculturally dominated Payne River Basin in Ontario, Canada. Unprecedented extensive monitoring data that consist of 30 years of daily hydrological data and 5 years of bi-weekly nutrient data have been used to calibrate and validate the presented model here. The calibration and validation of the streamflow and nutrients indicate that the model represent these processes well. The model performs well for periods of lower E. coli and fecal coliform loadings. On the other hand, frequency and magnitude of higher microbial loads are not always accurately represented by the model.

Doctor of Philosophy / The problem of water scarcity has become one of the most controversial topics in Australia over the past decades, with particular focus being the ‘sustainable’ allocation of water between extractive and environmental purposes. Geographical factors are defining the extreme variability in climate and water supply in Australia and, in the past, this was used as a rationale for the construction of large irrigation projects to deliver water to rural, urban, and industrial users. During this ‘expansionary’ phase of Australia’s water use sector, the cost of augmenting supply was relatively low and environmental considerations were secondary to the development imperative. As a result, water resources became over-allocated for extractive uses spurred on by consistent underpricing of water, which indicated a failure to reflect the true cost of water supply. As Australia’s water economy entered a ‘mature’ phase, it was no longer possible to increase supply cheaply as the most easily accessible water resources had already been captured. This was followed by widespread environmental degradation manifested in the Murray- Darling Basin, the nation’s largest river basin which hosts much of Australia’s agricultural production. Consequently, the focus shifted towards demand management, leading to a myriad of regulation aimed at increasing the allocative efficiency of scarce water resources. Towards this end, substantial government funding was injected into the various initiatives throughout the water reform process. Despite the on-going government activities in the area of water reform, the understanding of the actual economic impact and environmental outcomes of various water policies in practice remains limited. In the absence of such understanding, the effectiveness of various government water initiatives is ambiguous and inevitably compromised. The present study addresses this knowledge gap by establishing a method for evaluating the economic and environmental outcomes of environmentally-oriented polices that affect irrigated industries in a catchment. The method is based on an integrated biophysical and economic modelling approach, which enables spatial relationships to be captured accurately allowing a more realistic analysis. Information generated from a computer based biophysical simulation model form the basis of an economic optimisation model with constraints pertaining to environmental targets and water supply limits. The economic model consists of a linear programming and dynamic programming component, and involves the optimisation of resource use from a catchment manager’s perspective, seeking to achieve efficient resource use but at the same time conform to given environmental objectives. This embedded linear and dynamic programming approach was required to determine the optimal intra-seasonal and inter-seasonal water allocation, given various catchment environmental targets. The interdisciplinary approach enables the economic and ecological outcomes of the catchment management policies to be simulated and assessed at a spatially explicit scale, due to the link to Geographical Information Systems (GIS) in the biophysical model. The overall objective was to create a decision-making framework that could be used to determine the least-cost means of meeting environmental targets and resource constraints. The solutions to the analysis are directly applicable to the case study, the Mooki catchment in northern New South Wales (NSW), but with an adaptable framework that can be applied to other catchments. Specific objectives include an evaluation of the possibility of using alternative irrigation systems, as well as an evaluation of the benefits that can be realised by establishing water market, in the light of environmentally-oriented catchment policies for the case study. The economic cost of achieving environmental targets pertaining to environmental flow requirements and salinity reduction, in the form of end-of-valley salinity targets, was explicitly calculated through the economic model. While salinity targets have been set for NSW catchments, the practicality of such targets is in question, given the substantial reductions in water allocation to irrigation activities, which is one of the key contributors to deep-drainage. An additional objective in this study was therefore to investigate the value of having deep drainage targets. A further consideration is the effect of “external agents” in the form of government plans to buyback entitlements from irrigation districts, or the possibility of significant water rights purchases from mining industries. The implications of external water market entrants on the regional agricultural industry were examined.

Este estudo visa à estimativa dos fluxos de calor à superfície a partir de imagens orbitais, com os modelos SEBAL/METRIC e aplicação na modelagem hidrológica, com o modelo SWAT. Para isso, foram utilizados os dados da torre micrometeorológica da Ilha do Bananal, coletados durante os Experimentos do LBA, e os dados pluviométricos e fluviométricos. Os dados utilizados compreendem o período de outubro de 2003 a dezembro de 2006 da sub-bacia do rio Lajeado, localizada na bacia do rio Tocantins- Araguaia no estado do Tocantins. O clima na área de estudo tem sazonalidade bem definida, com períodos chuvosos de outubro a março e secos de abril a setembro. As estimativas a partir dos modelos SEBAL/METRIC variaram em função do tipo de solo, com estimativas coerentes dos fluxos de calor à superfície. Em geral, as estimativas dos fluxos de calor representam uma subestimativa de 10% para todo o período estudado. No entanto, sazonalmente observou-se subestimativas de 17% no período chuvoso e de 35% no período seco. De maneira geral, os resultados da utilização da evapotranspiração estimada por sensores remotos no modelo SWAT foi satisfatória. A assimilação da evapotranspiração a partir de imagens orbitais resultou em valores de COE que variaram de 0,57 a 0,84 com os dados diários e de 0,69 a 0,77 com os dados mensais de vazão. Isto indica melhoria no ajuste do modelo, devido a uma melhoria de 0,27 de COE no dado diário e de 0,08 no mensal. Observou-se ainda, que em termos percentuais a vazão simulada pelo modelo SWAT na bacia do rio Lajeado, após a assimilação dos dados de evapotranspiração, apresentou uma redução no erro, de 13% (superestimativa) para 3% (subestimativa) na vazão diária e de 9% para 7% (subestimativa) na vazão mensal. / This study presents estimate of the heat flow to the surface from orbital images with the models SEBAL / METRIC for use in hydrological modeling with the SWAT model. For this, we used data from micrometeorological tower of Island Bananal, collected during the experiments the LBA, rainfall and hydrological data. The data used is defined for the period October 2003 to December 2006, in the State Tocantins of catchments river Tocantins- Araguaia of the basin river Lajeado. We observed that the climate in the study area is seasonally well-defined with the rainy season from October to March and the dry are from April to September. Estimates from the models SEBAL / METRIC, varied according to soil type, are consistent with estimates of heat fluxes to the surface. In general, estimates of heat fluxes indicated underestimate of 10% for the period studied. However, seasonally there was an underestimates of 17% in the rainy season and of 35% in the dry season. The results of the hydrologic model can be judged satisfactory by the COE values which vary from 0.57 to 0.84 when comparing the streamflow daily data and from 0.69 to 0.77 with streamflow monthly data, with assimilation of evapotranspiration. This indicates benefits to the model, because was observed an improvement of 0.27 in the COE as daily and of 0.08 as monthly. It was also observed that in percentage terms the streamflow simulated by the SWAT model in the basin river Lajeado after the assimilation of evapotranspiration data showed a reduction error of 13% (overestimation) to 3% (underestimate) to the daily flow and from 9% to 7% (underestimate) to the monthly flow.

Este estudo visa à estimativa dos fluxos de calor à superfície a partir de imagens orbitais, com os modelos SEBAL/METRIC e aplicação na modelagem hidrológica, com o modelo SWAT. Para isso, foram utilizados os dados da torre micrometeorológica da Ilha do Bananal, coletados durante os Experimentos do LBA, e os dados pluviométricos e fluviométricos. Os dados utilizados compreendem o período de outubro de 2003 a dezembro de 2006 da sub-bacia do rio Lajeado, localizada na bacia do rio Tocantins- Araguaia no estado do Tocantins. O clima na área de estudo tem sazonalidade bem definida, com períodos chuvosos de outubro a março e secos de abril a setembro. As estimativas a partir dos modelos SEBAL/METRIC variaram em função do tipo de solo, com estimativas coerentes dos fluxos de calor à superfície. Em geral, as estimativas dos fluxos de calor representam uma subestimativa de 10% para todo o período estudado. No entanto, sazonalmente observou-se subestimativas de 17% no período chuvoso e de 35% no período seco. De maneira geral, os resultados da utilização da evapotranspiração estimada por sensores remotos no modelo SWAT foi satisfatória. A assimilação da evapotranspiração a partir de imagens orbitais resultou em valores de COE que variaram de 0,57 a 0,84 com os dados diários e de 0,69 a 0,77 com os dados mensais de vazão. Isto indica melhoria no ajuste do modelo, devido a uma melhoria de 0,27 de COE no dado diário e de 0,08 no mensal. Observou-se ainda, que em termos percentuais a vazão simulada pelo modelo SWAT na bacia do rio Lajeado, após a assimilação dos dados de evapotranspiração, apresentou uma redução no erro, de 13% (superestimativa) para 3% (subestimativa) na vazão diária e de 9% para 7% (subestimativa) na vazão mensal. / This study presents estimate of the heat flow to the surface from orbital images with the models SEBAL / METRIC for use in hydrological modeling with the SWAT model. For this, we used data from micrometeorological tower of Island Bananal, collected during the experiments the LBA, rainfall and hydrological data. The data used is defined for the period October 2003 to December 2006, in the State Tocantins of catchments river Tocantins- Araguaia of the basin river Lajeado. We observed that the climate in the study area is seasonally well-defined with the rainy season from October to March and the dry are from April to September. Estimates from the models SEBAL / METRIC, varied according to soil type, are consistent with estimates of heat fluxes to the surface. In general, estimates of heat fluxes indicated underestimate of 10% for the period studied. However, seasonally there was an underestimates of 17% in the rainy season and of 35% in the dry season. The results of the hydrologic model can be judged satisfactory by the COE values which vary from 0.57 to 0.84 when comparing the streamflow daily data and from 0.69 to 0.77 with streamflow monthly data, with assimilation of evapotranspiration. This indicates benefits to the model, because was observed an improvement of 0.27 in the COE as daily and of 0.08 as monthly. It was also observed that in percentage terms the streamflow simulated by the SWAT model in the basin river Lajeado after the assimilation of evapotranspiration data showed a reduction error of 13% (overestimation) to 3% (underestimate) to the daily flow and from 9% to 7% (underestimate) to the monthly flow.

The thesis continues with the bachelor thesis which had dealt with preparation bases for simulation draining and carrying materials in SWAT model. Simulation should have been realized within basin of the Jenín stream, which watershed is 4,65 km2 large. SWAT model is primary developed for the larger watersheds where simulated values doesn't attain tolerances. Because of this is thesis focused on the methodic of simulation itself, discussion of the problem when is SWAT model almost useless for the small watersheds and presentation of the calibrated values which had served as basis for verification.

Submitted by BRUNO PAVANELLI ZANELLA null (brunopzanella@gmail.com) on 2016-02-26T19:05:23Z No. of bitstreams: 1 TESE BRUNO PAVANELLI ZANELLA.pdf: 21746898 bytes, checksum: dfe54ee2f810b98550af3d99f8c3d4a7 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-02-29T13:55:20Z (GMT) No. of bitstreams: 1 zanella_bp_dr_guara.pdf: 21746898 bytes, checksum: dfe54ee2f810b98550af3d99f8c3d4a7 (MD5) / Made available in DSpace on 2016-02-29T13:55:20Z (GMT). No. of bitstreams: 1 zanella_bp_dr_guara.pdf: 21746898 bytes, checksum: dfe54ee2f810b98550af3d99f8c3d4a7 (MD5) Previous issue date: 2016-01-28 / Fundação para o Desenvolvimento da UNESP (FUNDUNESP) / A avaliação do potencial de produção de sedimentos de uma bacia hidrográfica contribuinte de uma hidrelétrica é de extrema importância para a análise da viabilidade de implantação de uma planta geradora, sobretudo quando se trata de uma Pequena Central Hidrelétrica (PCH), pois o assoreamento pode comprometer a longevidade do empreendimento. Este estudo teve como objetivo aplicar e avaliar modelos de predição de aporte de sedimentos na bacia hidrográfica contribuinte da PCH Costa Rica, no Estado de Mato Grosso do Sul, gerados pelos softwares SWAT e InVEST. A bacia contribuinte desta PCH, com aproximadamente 1.200km², é integrante da bacia do Alto Rio Sucuriú, e apresenta escassez de dados de séries históricas de hidrologia e sedimentologia. A modelagem pelo software SWAT e InVEST permitiu verificar que a produção de sedimentos ocorre em altas taxas na bacia contribuinte desta PCH. A perda total de solo nesta bacia obtida pelo InVEST foi de 19,23 Mg ha-1 ano-1 (2.392.353,10 Mg ano-1), superior em 2,2 vezes o valor gerado pelo software SWAT, de 8,54 Mg ha-1 ano-1 (1.062.402,15 Mg ano-1). O total de sedimentos que efetivamente chega ao canal de adução da PCH Costa Rica estimada pelo InVEST foi de 100.674,20 Mg ano-1 de sedimentos, enquanto o SWAT apresentou um total 10,43 vezes superior (1.049.521,72 Mg ano-1). A diferença obtida entre os dois modelos pode ser atribuída às peculiaridades de cada software, sendo utilizada no InVEST, a relação máxima do aporte de sedimento definida em 80% que não é aplicada no SWAT representa a capacidade máxima de retenção possível em cada célula. A modelagem da perda de solo em bacias hidrográficas realizada pelos softwares SWAT e InVEST mostrou-se promissora, com elevada correlação entre si e com o Método de Einsten Modificado. Estes sedimentos são carreados e se acumulam nos cursos d’água, gerando problemas operacionais para esta PCH, que necessita de dragagem constante para permitir o funcionamento do empreendimento, gerando custos que não foram previstos na concepção do projeto. Diante deste cenário foi proposta a recomposição vegetal das áreas degradadas por processos erosivos intensos, com a utilização de biotecnologia, em sistema de plantio direto de espécies nativas do Cerrado em consórcio com leguminosas inoculadas com rizóbio. A simulação do InVEST para o cenário futuro com recomposição vegetal de 13,78 km2 das APPs hídricas desta bacia gerou uma redução na produção de sedimentos de 6.464,99 Mg ano-1, demonstrando que a adoção de práticas conservacionistas pelos produtores da bacia contribuinte da PCH Costa Rica pode amenizar os processos erosivos, aumentar a capacidade produtiva dos solos e diminuir os custos desta hidrelétrica com o desassoreamento do canal de adução. / The evaluation of sediment production potential in a hydroelectric watershed is extremely important for the deployment of assessing the feasibility of a generating plant, especially in the case of a Small Hydroelectric Plant (SHP) because the sediment deposition may compromise the longevity of the project. This study aimed to implement and evaluate sediment delivery prediction models in the watershed of SHP Costa Rica in the state of Mato Grosso do Sul, generated by SWAT and InVEST software. The basin of this SHP, with approximately 1.200km², is an upper portion of the Sucuriú river basin and presenting scarcity of data time series of hydrology and sedimentology. Modeling by SWAT and InVEST software has shown that the production of sediments occurs at high rates in the basin of this SHP. The total soil losses in watersheds of this SHP obtained by InVEST was 19,23 Mg ha-1 ano-1 (2392353,10 Mg ano-1), higher than the value obtained by SWAT software with 8,54 Mg ha-1 ano-1 (1062402,15 Mg ano-1). The sediment that reaches the adduction channel of SHP Costa Rica estimated by InVEST is 100,674.20 Mg year-1 of sediments, while the SWAT has a total 10.43 times higher (1.049.521,72 Mg ano-1). The difference obtained between the two models can be attributed to the peculiarities of each software being used in InVEST, the maximum ratio of sediment contribution set at 80% which is not applied in SWAT is the maximum capacity possible retention in each cell. The modeling of soil loss in river basins performed by SWAT and InVEST software proved promising, with high correlation with each other and the method of Modified Einstein. These sediments are carried and accumulate in streams, creating operational problems for SHP Costa Rica, which requires dredging to allow operation, and generates costs that were not anticipated in the initial project. In this scenario was proposed a plant recovery of degraded areas with the use of biotechnology in no-tillage system of native Cerrado species intercropped with legumes inoculated with Rhizobium. The simulation of InVEST for future scenario with plant recovery of 13.78 km2 of hydric permanent preservation areas in the SHP Costa Rica basin generated a reduction of 6464.99 Mg year-1 in the total loss of sediment in small watersheds. The adoption of conservation practices by farmers of the SHP Costa Rica basin can mitigate the erosive processes, increase the productive capacity of soils and reduce the costs of this hydropower plant with dredging in the adduction channel. / FUNDUNESP: 1886/2011

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-13T17:34:56Z No. of bitstreams: 1 FRANCISCO MIQUÉIAS SOUSA NUNES – DISSERTAÇÃO (PPGECA) 2018.pdf: 6096167 bytes, checksum: 209e0b24de3463f67f79ee188f4a1bc5 (MD5) / Made available in DSpace on 2018-04-13T17:34:56Z (GMT). No. of bitstreams: 1 FRANCISCO MIQUÉIAS SOUSA NUNES – DISSERTAÇÃO (PPGECA) 2018.pdf: 6096167 bytes, checksum: 209e0b24de3463f67f79ee188f4a1bc5 (MD5) Previous issue date: 2018-02 / Capes / O crescimento populacional desordenado juntamente com a intensificação das atividades humanas estão acelerando as modificações dos ecossistemas naturais acarretando vários problemas ambientais, em particular , aos recursos hídricos. A necessidade da humanidade por esse recurso vem crescendo de forma rápida e incompatível com a capacidade de recuperação da natureza, causando a escassez e prejuízo na sua qualidade. Além disso, as diversas finalidades para as quais esses recursos são utilizados têm gerado um grande número de conflitos do uso e também degradação qualitativa e quantitativa dos corpos hídricos.No semiárido brasileiro, a situação de escassez hídrica compromete o desenvolvimento econômico e social da região. Assim, torna-se necessário desenvolver ferramentas adequadas para apoiar a tomada de decisão quanto ao uso dos recursos hídricos. Alterações no uso e na ocupação do solo afetam o comportamento do escoamento superficial, e a análise das tendências na vazão dos cursos d’água é importante para o planejamento do uso dos recursos hídricos e do solo. As variações no regime pluviométrico devido às mudanças climáticas também afetam a disponibilidade hídrica nas bacias hidrográficas.Este trabalho tem por objetivomodelar os processos de geração de escoamento superficial, erosão do solo e a recarga potencial subterrânea na bacia do Rio Sucuru a jusante da barragem de Sumé-PB utilizando o modelo SWAT. Foram utilizados dados de precipitação, temperatura, do período de 1994 a 2015, além de mapas de tipos de solo, uso e ocupação do solo com as mudanças observadas no período.Os parâmetros CANMAX, GWQMN, GW_REVAP, ESCO, EPCO e CN foram identificados como os mais influentes sobre o processo de geração de escoamento superficial. O valor do parâmetro GWQMN foi fixado em 2000 mm, pois nenhuma sondagem realizada na bacia indica uma profundidade do solo maior que 2,0 m. Os parâmetros CANMX, ESCO, EPCO e CN se mostraram muito influentes, pois qualquer pequena alteração para mais ou para menos, provocava uma superestimação e/ou subestimação da lâmina escoada, necessitando assim de muitas tentativas antes de obter seus valores finais. Os resultados demosntram a eficiência do modelo SWAT em quantificar e avaliar comparativamente os processos hidrossedimentologicos na região do cariri paraibano. A contribuição deste trabalho se dá pela formulação de uma metodologia para a realização de estudos hidrossedimentologicos em regiões onde não existem dados de escoamento superficial ou de produção de sedimento pela erosão. / Disorganized population growth coupled with the intensification of human activities is accelerating changes in natural ecosystems, leading to a number of environmental problems, in particular water resources. The need of mankind for this resource has been growing rapidly and incompatible with nature's capacity for recovery, causing scarcity and damage in its quality. In addition, the various purposes for which these resources are used have generated a large number of use conflicts and also qualitative and quantitative degradation of water bodies. In the Brazilian semi-arid, the situation of water scarcity compromises the economic and social development of the region. Thus, it is necessary to develop adequate tools to support the decision making regarding the use of water resources. Changes in soil use and occupation affect the behavior of surface runoff, and the analysis of trends in water flow is important for planning the use of water resources and soil. Variations in pluviometric regime due to climate change also affect water availability in river basins. This work aims to model the processes of generation of runoff, soil erosion and potential underground recharge in the Sucuru River basin downstream of the Sumé-PB dam using the SWAT model. Precipitation and temperature data were used from 1994 to 2015, as well as maps of soil types, land use and occupation with changes observed in the period. The parameters CANMAX, GWQMN, GW_REVAP, ESCO, EPCO and CN were identified as the most influential on the process of generation of surface runoff. The value of the GWQMN parameter was set at 2000 mm, since no survey conducted in the basin indicates a soil depth greater than 2.0 m. The parameters CANMX, ESCO, EPCO and CN were very influential, because any small changes for more or less, caused an overestimation and / or underestimation of the drained sheet, thus requiring many attempts before obtaining their final values. The results demonstrate the efficiency of the SWAT model in quantifying and comparing the hydrosedimentological processes in the Paraíba region. The contribution of this work is given by the formulation of a methodology for the realization of hydrosedimentological studies in regions where there is no data of surface runoff or sediment production.

Este estudo visa à estimativa dos fluxos de calor à superfície a partir de imagens orbitais, com os modelos SEBAL/METRIC e aplicação na modelagem hidrológica, com o modelo SWAT. Para isso, foram utilizados os dados da torre micrometeorológica da Ilha do Bananal, coletados durante os Experimentos do LBA, e os dados pluviométricos e fluviométricos. Os dados utilizados compreendem o período de outubro de 2003 a dezembro de 2006 da sub-bacia do rio Lajeado, localizada na bacia do rio Tocantins- Araguaia no estado do Tocantins. O clima na área de estudo tem sazonalidade bem definida, com períodos chuvosos de outubro a março e secos de abril a setembro. As estimativas a partir dos modelos SEBAL/METRIC variaram em função do tipo de solo, com estimativas coerentes dos fluxos de calor à superfície. Em geral, as estimativas dos fluxos de calor representam uma subestimativa de 10% para todo o período estudado. No entanto, sazonalmente observou-se subestimativas de 17% no período chuvoso e de 35% no período seco. De maneira geral, os resultados da utilização da evapotranspiração estimada por sensores remotos no modelo SWAT foi satisfatória. A assimilação da evapotranspiração a partir de imagens orbitais resultou em valores de COE que variaram de 0,57 a 0,84 com os dados diários e de 0,69 a 0,77 com os dados mensais de vazão. Isto indica melhoria no ajuste do modelo, devido a uma melhoria de 0,27 de COE no dado diário e de 0,08 no mensal. Observou-se ainda, que em termos percentuais a vazão simulada pelo modelo SWAT na bacia do rio Lajeado, após a assimilação dos dados de evapotranspiração, apresentou uma redução no erro, de 13% (superestimativa) para 3% (subestimativa) na vazão diária e de 9% para 7% (subestimativa) na vazão mensal. / This study presents estimate of the heat flow to the surface from orbital images with the models SEBAL / METRIC for use in hydrological modeling with the SWAT model. For this, we used data from micrometeorological tower of Island Bananal, collected during the experiments the LBA, rainfall and hydrological data. The data used is defined for the period October 2003 to December 2006, in the State Tocantins of catchments river Tocantins- Araguaia of the basin river Lajeado. We observed that the climate in the study area is seasonally well-defined with the rainy season from October to March and the dry are from April to September. Estimates from the models SEBAL / METRIC, varied according to soil type, are consistent with estimates of heat fluxes to the surface. In general, estimates of heat fluxes indicated underestimate of 10% for the period studied. However, seasonally there was an underestimates of 17% in the rainy season and of 35% in the dry season. The results of the hydrologic model can be judged satisfactory by the COE values which vary from 0.57 to 0.84 when comparing the streamflow daily data and from 0.69 to 0.77 with streamflow monthly data, with assimilation of evapotranspiration. This indicates benefits to the model, because was observed an improvement of 0.27 in the COE as daily and of 0.08 as monthly. It was also observed that in percentage terms the streamflow simulated by the SWAT model in the basin river Lajeado after the assimilation of evapotranspiration data showed a reduction error of 13% (overestimation) to 3% (underestimate) to the daily flow and from 9% to 7% (underestimate) to the monthly flow.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Kyle R. Mankin / The overall goal of this study was to evaluate and apply the Soil and Water Assessment Tool (SWAT) model for fecal bacteria modeling. Methods were developed to characterize fecal coliform bacteria (FCB) from livestock, human, and wildlife sources to use as input in the model. Model sensitivity to predict FCB concentration was evaluated for the model parameters and input parameters using both SWAT 2000 and 2005 versions. Sensitivity of input parameters generally, ranked as Bacteria concentration ≥ TBACT > Wildlife source loads > Livestock stocking rate ≥ Livestock manure production rate > BACTKDQ for SWAT 2000 whereas it was ranked as BACTKDQ > TBACT > Bacteria concentration > WDLPQ > WDLPS for SWAT 2005. Sensitivity of model and input parameters were found changed from SWAT 2000. The SWAT (2005) model was calibrated and validated for daily flow, sediment, and fecal bacteria concentration using one year of measured data (January to December, 2004). The SWAT model predicted results with poor to very good agreement when compared with measured data with coefficient of determination (R2) and Nash-Sutcliffe Efficiency Index (E) range of 0.10 to 0.89 for daily flows, sediment, total phosphorus, total nitrogen and total FCB concentration. More extensive in-stream data are needed for more comprehensive model assessment. The SWAT model (2005) was evaluated for source-specific FCB modeling using three years (2004-2006) of observed modified deterministic probability of bacteria source tracking (BST) data. The FCB sources were modeled with three combinations (livestock and human, livestock and wildlife, wildlife and human) and each single source to evaluate the source-specific FCB concentrations. The SWAT model determined poor to good agreement for the combined source of FCB (R2, E range from -2.92 to 0.71) but determined generally decreased agreement for each single source of bacteria (R2, E range from -5.03 to 0.39) potentially due to BST uncertainty, spatial variability and source characterization. The SWAT model identified critical sub-watersheds in the watershed where implementing vegetative filter strips (VFS) could be most effective to abate fecal bacteria pollution. The targeting method of VFS application to the watershed sub-basins was found to be more effective in reducing both FCB (60% vs. 42%) and sediment yield (63% vs. 33%) as compared to a random approach. The FCB source characterization methods for modeling developed in this study are general and have the potential to be extended to other watersheds. The results of this study demonstrate that the SWAT model can be used to characterize the distribution of bacteria sources within a bacteria impaired watershed and assist with developing total maximum daily loads (TMDLs) and watershed restoration strategies.

Microbial contamination of drinking water poses an important health risk which causes severe illnesses and epidemics. In order to improve surface and drinking water quality, the understanding of fecal pathogen contamination processes including their prevention and control needs to be enhanced. The watershed model soil water assessment tool (SWAT) is commonly used to simulate the complex hydrological, meteorological, erosion, land management and pollution processes within river basins. In recent years, it has been increasingly applied to simulate microbial contamination transport at the watershed scale. SWAT is used in this study to simulate Escherichia coli (E.coli) and fecal coliform densities for the agriculturally dominated Payne River Basin in Ontario, Canada. Unprecedented extensive monitoring data that consist of 30 years of daily hydrological data and 5 years of bi-weekly nutrient data have been used to calibrate and validate the presented model here. The calibration and validation of the streamflow and nutrients indicate that the model represent these processes well. The model performs well for periods of lower E. coli and fecal coliform loadings. On the other hand, frequency and magnitude of higher microbial loads are not always accurately represented by the model.