Disponibilidade hídrica de pequenas bacias hidrográficas na região central do Rio Grande do Sul - indicadores regionais

Abstract

The natural water availability in a small hydrographic basin can be represented by its maximum, average and minimum flow. The knowledge of these values has a great importance for a proper planning of shared use and management, minimizing conflicts between its users. The purpose of this study is to simulate water availability and to estimate regional indicators in small hydrographic basins in the central region of Rio Grande do Sul by using the WIN_IPH2 model. The model was calibrated with short flow series and, after that, the extension of the flow series was realized from the historical precipitation long series. By using the extended flow series, permanence curves and the regional flow indicators were obtained. Results were satisfactory in calibration and validation, as it was obtained a good adjustment to parameters and a good Nash Suttciffe coefficient. For the flow duration curve, results from years 1961 to 2000 and from 2002 to 2015 were compared from the same pluviometric station (UFSM) for the Vacacaí Mirim hydrographic basin fluviometric stations, and no differences in average flow results were found. For the Ibicuí Mirim hydrographic basin, a result below the expected average was found. For the regional flow indicators, it was found values near the expected for the flood index and the rcp50 index (average flow). For the minimum flow indexes, values tended to zero because hydrographic basins were small and because an objective function for maximum and averages was used.