Neste trabalho foi proposta uma estratégia de modelagem hidrológica para a transformação chuva vazão da Bacia do Ribeirão da Onça (B.R.O) utilizando-se técnicas de auto calibração com análise de incertezas e de ponderação de modelos. Foi utilizado o modelo hidrológico Soil and Water Assessment Tool (SWAT), por ser um modelo que possui uma descrição física e de maneira distribuída dos processos hidrológicos da bacia. Foram propostas cinco diferentes séries de precipitação e esquemas de interpolação espacial a serem utilizados como dados de entrada para o modelo SWAT. Em seguida, utilizou-se o método semiautomático Sequential Uncertainty Fitting ver.-2 (SUFI-2) para a auto calibração e análise de incertezas dos parâmetros do modelo e produção de respostas com intervalos de incerteza para cada uma das séries de precipitação utilizadas. Por fim, foi utilizado o método de ponderação bayesiana de modelos (BMA) para o pós-processamento estocástico das respostas. Os resultados da análise de incerteza dos parâmetros do modelo SWAT indicam uma não adequação do método Soil Conservation Service (SCS) para simulação da geração do escoamento superficial, juntamente com uma necessidade de maior investigação das propriedades físicas do solo da bacia. A análise da precisão e acurácia dos resultados das séries de precipitação em comparação com a resposta combinada pelo método BMA sugerem a última como a mais adequada para a simulação chuva-vazão na B.R.O. / This study proposed an approach to the hydrological modeling of the Ribeirão da Onças Basin (B.R.O) based on automatic calibration and uncertainty analysis methods, together with model averaging. The Soil and Water Assessment Tool (SWAT) was used due to its distributed nature and physical description of hydrologic processes. An ensemble, composed by five different precipitation schemes, based on different sources and spatial interpolation methods was used. The Sequential Uncertainty Fitting ver-2 (SUFI-2) procedure was used for automatic calibration and uncertainty analysis of the SWAT model parameters, together with generation of streamflow simulations with uncertainty intervals. Following, the Bayesian Model Averaging (BMA) was used to merge the different responses into a single probabilistic forecast. The results of the uncertainty analysis for the SWAT parameters show that the Soil Conservation Service (SCS) model for surface runoff prediction may not be suitable for the B.R.O, and that more investigations about the soil physical properties at the Basin are recommended. An analysis of the accuracy and precision of the simulations produced by the precipitation ensemble members against the BMA simulation supports the use of the latter as a suitable framework for streamflow simulations at the B.R.O.

Made available in DSpace on 2015-03-26T13:28:16Z (GMT). No. of bitstreams: 1 texto completo.pdf: 4305629 bytes, checksum: bea76d1e03a0b9ec81399e4e6223b32d (MD5) Previous issue date: 2013-02-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The inadequate occupation, lack of planning, management and conservation of watersheds have triggered environmental degradation processes, such as, reduced water infiltration into the soil, increasing runoff that contributes to the transport of sediments and nutrients to watercourses, and compromises environmental quality of aquatic systems and the environment. The main sources of these processes of deterioration of water bodies is a diffuse source pollution as a result of the intensification and expansion of agriculture and livestock without preparation techniques, soil management and conservation. Because of these numerous factors acting together, the river basin Piranga can be considered with a high level of environmental complexity and therefore deserves special attention. In order to identify and quantify the magnitude of these processes we used the Soil and Water Assement Tool (SWAT) which is a hydrologic model developed to simulate physical processes (natural and anthropogenic), streamflow forecasting, runoff, erosion and transport of sediment and nutrients from watersheds under different managements. To ensure consistency in the data generated after the simulation and the consequent applicability in the study area and its extrapolation to other areas, we performed a calibration and validation in order to extract the maximum potential of the model and features. The calibration and validation made use of the optimization algorithm Sequential Uncertainty Fitting version 2 (SUFI-2) which provided an uncertainty analysis by graphical analysis bands than 95PPU together with the R-factor and Rfactor. Also available is a statistical summary which shows the efficiency coefficient of Nash and Sutcliffe and Determination R2. It was used as a reference fluviometric seven seasons and three monitoring stations of sediment and nutrients. The loads (in kg.ha-1) of sediment yield and nutrient losses, nitrate (NO3) and total phosphorus (TP), are presented considering the hydrological response units (HRU) for the use and occupation. The results of the calibration and validation of the model for flow, sediment and nutrients were satisfactory considering the complexity of multiple processes working in Piranga River watershed. / A ocupação inadequada, a falta de planejamento, manejo e conservação das bacias hidrográficas têm desencadeado processos de degradação ambiental, tais como, redução da capacidade de infiltração de água no solo, aumento do escoamento superficial que contribui para o transporte de sedimentos e nutrientes para os cursos d água, e compromete a qualidade ambiental do sistema aquático e do meio ambiente. As principais fontes causadoras desses processos de deterioração dos corpos hídricos é a poluição de origem difusa, como resultado da intensificação e expansão da agricultura e pecuária sem técnicas de preparo, manejo e conservação do solo. Devido a esses inúmeros fatores atuando conjuntamente, a bacia hidrográfica do Rio Piranga pode ser considerada com alto nível de complexidade ambiental e, portanto merece atenção especial. Com a finalidade de identificar e quantificar a magnitude desses processos utilizou-se o Soil and Water Assement Tool (SWAT) que é um modelo hidrológico desenvolvido para simular processos físicos (naturais e antrópicos), previsão de vazões, escoamento superficial, erosão e transporte de sedimentos e nutrientes de bacias hidrográficas submetidas a diferentes manejos. Para garantir consistência aos dados gerados após a simulação e à conseqüente aplicabilidade na área em estudo ou sua extrapolação a outras áreas, foi realizada a calibração e a validação a fim de se extrair o máximo das potencialidades e recursos do modelo. A calibração e a validação fizeram uso do algoritmo de otimização Sequential Uncertainty FItting versão 2 (SUFI-2) que forneceu uma análise de incerteza através de análise gráfica das bandas de 95% de predição de incerteza (95PPU), acompanhado do R-fator e P-fator. Também é disponibilizado um sumário estatístico onde são apresentados os coeficientes de eficiência de Nash e Sutcliffe e o de Determinação R2. Utilizou-se como referência sete estações fluviométricas e três estações de monitoramento de sedimento e nutrientes. As cargas (em kg.ha-1) de produção de sedimentos, e perdas de nutrientes, nitrato (NO3) e fósforo total (PT), são apresentadas considerando as unidades de resposta hidrológica (HRU) quanto ao uso e ocupação. Os resultados da calibração e validação do modelo para vazão, sedimentos e nutrientes foram satisfatórios considerando a complexidade de vários processos atuantes na Bacia Hidrográfica do Rio Piranga.

Neste trabalho foi proposta uma estratégia de modelagem hidrológica para a transformação chuva vazão da Bacia do Ribeirão da Onça (B.R.O) utilizando-se técnicas de auto calibração com análise de incertezas e de ponderação de modelos. Foi utilizado o modelo hidrológico Soil and Water Assessment Tool (SWAT), por ser um modelo que possui uma descrição física e de maneira distribuída dos processos hidrológicos da bacia. Foram propostas cinco diferentes séries de precipitação e esquemas de interpolação espacial a serem utilizados como dados de entrada para o modelo SWAT. Em seguida, utilizou-se o método semiautomático Sequential Uncertainty Fitting ver.-2 (SUFI-2) para a auto calibração e análise de incertezas dos parâmetros do modelo e produção de respostas com intervalos de incerteza para cada uma das séries de precipitação utilizadas. Por fim, foi utilizado o método de ponderação bayesiana de modelos (BMA) para o pós-processamento estocástico das respostas. Os resultados da análise de incerteza dos parâmetros do modelo SWAT indicam uma não adequação do método Soil Conservation Service (SCS) para simulação da geração do escoamento superficial, juntamente com uma necessidade de maior investigação das propriedades físicas do solo da bacia. A análise da precisão e acurácia dos resultados das séries de precipitação em comparação com a resposta combinada pelo método BMA sugerem a última como a mais adequada para a simulação chuva-vazão na B.R.O. / This study proposed an approach to the hydrological modeling of the Ribeirão da Onças Basin (B.R.O) based on automatic calibration and uncertainty analysis methods, together with model averaging. The Soil and Water Assessment Tool (SWAT) was used due to its distributed nature and physical description of hydrologic processes. An ensemble, composed by five different precipitation schemes, based on different sources and spatial interpolation methods was used. The Sequential Uncertainty Fitting ver-2 (SUFI-2) procedure was used for automatic calibration and uncertainty analysis of the SWAT model parameters, together with generation of streamflow simulations with uncertainty intervals. Following, the Bayesian Model Averaging (BMA) was used to merge the different responses into a single probabilistic forecast. The results of the uncertainty analysis for the SWAT parameters show that the Soil Conservation Service (SCS) model for surface runoff prediction may not be suitable for the B.R.O, and that more investigations about the soil physical properties at the Basin are recommended. An analysis of the accuracy and precision of the simulations produced by the precipitation ensemble members against the BMA simulation supports the use of the latter as a suitable framework for streamflow simulations at the B.R.O.

<p>Land and water resources degradation are the major problems on the Ethiopian highlands. Poor land use practices and improper management systems have played a significant role in causing high soil erosion rates, sediment transport and loss of agricultural nutrients. So far limited meas-ures have been taken to combat the problems. In this study a physically based watershed model, SWAT2005 was applied to the Northern Highlands of Ethiopia for modelling of the hydrology and sediment yield. The main objective of this study was to test the performance and feasibility of SWAT2005 model to examine the influence of topography, land use, soil and climatic condi-tion on streamflows, soil erosion and sediment yield. The model was calibrated and validated on four tributaries of Lake Tana as well as Anjeni watershed using SUFI-2, GLUE and ParaSol algo-rithms. SWAT and GIS based decision support system (MCE analysis) were also used to identify the most erosion prone areas in the Lake Tana Basin. Streamflows are more sensitive to the hy-drological response unites definition thresholds than subbasin discretization. Prediction of sedi-ment yield is highly sensitive to subbasin size and slope discretization. Baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. There is a good agreement between the measured and simulated flows and sediment yields with higher values of coefficients of determination and Nash Sutcliffe efficiency. The an-nual average measured sediment yield in Anjeni watershed was 24.6 tonnes/ha. The annual aver-age simulated sediment yield was 27.8 and 29.5 tonnes/ha for calibration and validation periods, respectively. The SWAT model indicated that 18.5 % of the Lake Tana Basin is erosion potential areas. Whereas the MCE result indicated that 25.5 % of the basin are erosion potential areas. The calibrated model can be used for further analysis of the effect of climate and land use change as well as other different management scenarios on streamflows and soil erosion. The result of the study could help different stakeholders to plan and implement appropriate soil and water conser-vation strategies.</p>

Land and water resources degradation are the major problems on the Ethiopian highlands. Poor land use practices and improper management systems have played a significant role in causing high soil erosion rates, sediment transport and loss of agricultural nutrients. So far limited meas-ures have been taken to combat the problems. In this study a physically based watershed model, SWAT2005 was applied to the Northern Highlands of Ethiopia for modelling of the hydrology and sediment yield. The main objective of this study was to test the performance and feasibility of SWAT2005 model to examine the influence of topography, land use, soil and climatic condi-tion on streamflows, soil erosion and sediment yield. The model was calibrated and validated on four tributaries of Lake Tana as well as Anjeni watershed using SUFI-2, GLUE and ParaSol algo-rithms. SWAT and GIS based decision support system (MCE analysis) were also used to identify the most erosion prone areas in the Lake Tana Basin. Streamflows are more sensitive to the hy-drological response unites definition thresholds than subbasin discretization. Prediction of sedi-ment yield is highly sensitive to subbasin size and slope discretization. Baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. There is a good agreement between the measured and simulated flows and sediment yields with higher values of coefficients of determination and Nash Sutcliffe efficiency. The an-nual average measured sediment yield in Anjeni watershed was 24.6 tonnes/ha. The annual aver-age simulated sediment yield was 27.8 and 29.5 tonnes/ha for calibration and validation periods, respectively. The SWAT model indicated that 18.5 % of the Lake Tana Basin is erosion potential areas. Whereas the MCE result indicated that 25.5 % of the basin are erosion potential areas. The calibrated model can be used for further analysis of the effect of climate and land use change as well as other different management scenarios on streamflows and soil erosion. The result of the study could help different stakeholders to plan and implement appropriate soil and water conser-vation strategies. / QC 20101123