Índices de sazonalidade para regionalização hidrológica de vazões de estiagem no Rio Grande do Sul

Abstract

Information on stream flows in dry season is crucial in the context of water resources management, however, the existing stream flows gauging network in Brazil does not satisfy the demand of practitioners. Under these circumstances, regional analysis might be applied to estimate low stream flows at sites with no gauging or sites with little stream flow records. The objective of this study was to verify the potential of three seasonality measures applied to the evaluation of the temporal and spatial regime of low stream flows in Rio Grande do Sul, in such a way that they can be used as technical support for regionalization in hydrologically homogeneous regions. In applying the methods, Seasonality Ratio (SR), Seasonality Index (SI) and Seasonality Histogram (SH), based on historical series of 108 stream flow gauging stations, it was found that there is a pronounced seasonality of low flows in this State. Among the three seasonality measures, SI and SH were more appropriate due to specific hydrological characteristics in the state, therefore, they can be considered as relevant methodologies to delineate hydrologically homogeneous regions for the regionalization of low stream flows.