Aplicação do modelo SWAT (Soil and Water Assessment Tool) na simulação hidrossedimentológica em bacia hidrográfica da Serra da Mantiqueira, MG

• Ano de defesa: 2011
• Autor(a) principal: Pinto, Daniel Brasil Ferreira
• Orientador(a): Silva, Antônio Marciano da
• Banca de defesa: Mello, Carlos Rogério de, Coelho, Gilberto, Pompeu, Paulo dos Santos, Silva, Fernando das Graças Braga da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: UNIVERSIDADE FEDERAL DE LAVRAS
• Programa de Pós-Graduação: DEG - Programa de Pós-graduação
• País: BRASIL
• Palavras-chave em Português: Modelos hidrológicos; SWAT; Poluição difusa; Qualidade da água; Transporte de sedimentos; Hydrologic simulation; Diffuse pollution; Water quality; Sediment yield
• Área do conhecimento CNPq: CNPQ_NÃO_INFORMADO
• Link de acesso: https://repositorio.ufla.br/handle/1/3150

Hydrological and water quality models have been widely employed for evaluation of pollution caused by diffuse sources in watersheds. The goal of this study was to verify the performance of the SWAT model (Soil and Water Assessment Tool) with respect to the simulation of stream flow, sediment yield, suspended sediment concentration and water quality in the Lavrinha Creek Watershed (LCW), which is situated in the Mantiqueira Range region (Minas Gerais State, Brazil). This model requires some maps, such as Digital Elevation Model, land-use map and soil map. Temporal series associated to climatic variables, stream flow and suspended sediment concentration were obtained from an existing hydrological monitoring that has been conducted at or near the LCW´s outlet since January of 2006. Eight months (January 2006 - August 2006) were chosen as warm-up period of the SWAT model, while two years (September 2006 - August 2008) were considered for the model calibration and two years (September 2008 - August 2010) for the model validation. September 2007 to July 2009 was the period used for nutrient and water quality simulation. A statistical index known as Nash-Sutcliffe (COE) was employed to evaluate the model performance. Firstly, simulations of stream flow and suspended sediment concentration were carried out on a daily basis. During daily stream flow simulations COE values were 0.81 and 0.79 for calibration and validation respectively. When simulating daily suspended sediment concentration the results indicated COE values of 0.68 and 0.65 for calibration and validation, respectively. The next step was to apply the SWAT model taking into account a monthly time step, resulting in the following COE values: calibration - 0.85 and 0.68 for stream flow and suspended sediment concentration, respectively; validation - 0.82 and 0.66 for the same hydrological variables. Relative to the variables associated to nutrients, SWAT model was applied to simulate total nitrogen (COE = 0.39) and total phosphorus (COE = 0.41). Such model was also used to analyze results of some water quality parameters, presenting COE of 0.59 for dissolved oxygen, 0.69 for biochemical oxygen demand and 0.64 for bacteria (Echerichia coli). Finally, two land-use change scenarios were tested as follows: Scenario 1 - conversion of areas with pasture into eucalyptus; Scenario 2 - current land use considering a riparian zone (30-m buffer) along the drainage network. According to the results obtained, Scenario 1 would result in a 47% reduction in sediment yield in the watershed and for Scenario 2, a 38% reduction in suspended sediment concentration in the creek. The SWAT model was considered adequate to simulate stream flow, sediment yield, suspended sediment concentration and water quality in the LCW, thus constituting in an important tool for water resources management in the Mantiqueira Range region.