Application of the SWAT hydrological model in flow and solid discharge simulation as a management tool of the Indaia River Basin, Alto São Francisco, Minas Gerais

Aplicação do modelo hidrológico SWAT na simulação de vazão e descarga sólida como instrumento de gestão da bacia hidrográfica do rio Indaiá, Alto São Francisco, Minas Gerais

Abstract

Measurement and evaluation of soil erosion and consequent sediment yield are fundamental in the planning and management of watersheds, as they allow the identification of critical areas susceptible to erosive processes. This study analyzed the sediment yield generated by water erosion in the Indaia River Basin, Alto São Francisco, Minas Gerais, by using the SWAT hydrological model. From a regional/local scale, the initial simulation of the variables (flow and solid discharge) was performed on a monthly scale from 1988 to 2017. Then, parameter-sensitivity analysis, calibration, and validation of the model were executed. In the monthly calibration (1988 to 2007), the performance of the simulations for flow was R²=0.92 and NSE=0.91 and for total solid discharge R²=0.51 and NSE=0.50. In the monthly validation (2008 to 2017) for flow, R²=0.85 and NSE=0.82 was obtained and for total solid discharge R²=0.19 and NSE=0.16. Despite the unsatisfactory result in the validation stage, the model was able to analyze the distribution of sediment production by sub-basins or even by the Hydrologic Response Unit (HRU). Therefore, a sediment-yield map was generated which qualitatively indicated a tendency for greater erosive processes in the central portion of the basin. The results will support public policies mitigating environmental degradation of the Indaia River Basin.

Keywords:
calibration and validation of models; sediment yield; sensitivity analysis; water erosion