Análise de sensibilidade de parâmetros do modelo hidrológico SWAT em função de diferentes características de bacias hidrográficas
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Data
2017-10-09
Autores
Teixeira, Laíza Fernanda Curti
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Universidade Federal do Espírito Santo
Resumo
Evaluation of mathematical models components behavior can be performed through sensitivity analysis, uncertainties and calibration techniques. In the study, it was sought to use these resources specifically for the hydrological Soil and Water Assessment Tool (SWAT) model, with the purpose of evaluating the application conditions to simulate flow in a watershed in Espírito Santo State, in Brazil and, later, simulate alternative land use and occupation scenarios in the basin. In the global sensitivity analysis, the most sensitive parameters were those related to surface and base flow. The SWAT showed, after parameters calibration, to be effective in the representation of the flow variable. The Nash and Sutcliffe (NSE) coefficient calculated for the monthly simulation was 0,72 and the bias percentage (PBIAS) 9,40, both considered satisfactory, according to the literature. However, for daily flow modeling the NSE index was very low, 0,21. It was observed that the highest values present in the daily data series strongly affected the NSE coefficient values. After calibration, three distinct scenarios were considered for the sub-basin: native forest, eucalyptus and pasture. The manual sensitivity analysis for the scenarios showed that there were no significant differences for most parameters. However, for the number curve (CN2) value eucalyptus and pasture scenarios were influenced in greater magnitude than native forest. A correlation between parameters of different movements processes was observed. In the evaluation of modeled output variables, for different scenarios, large differences were not observed for monthly averages. For the daily simulations, the particularities between the scenarios were better observed, mainly for greater precipitations events. The native forest showed higher flow rates for drought times, due to the higher base flows, while the pasture scenario returned superficial flow superior to the corresponding to other situations.
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Sensitivity analysis , Calibration , Land use and occupation scenarios , SWAT , Análise de sensibilidade , Calibração , Cenários de uso e ocupação do solo