Influência da precipitação no uso do método silveira para bacias hidrográficas entre 800 a 1000 km²

Abstract

The increasing demand for water resources, for the most diverse purposes, has evidenced a still deficient scenario in relation to fluviometric monitoring, especially in river basins with areas smaller than 1000 km², in large part of the regions of Brazil. Inevitably, these demands are linked to water availability and your determination in lack of measured data becomes necessary to resort to techniques such as regionalization of flows, or the simulation through rain-flow models. However, a period of hydrological monitoring data is still necessary to enable the application of these methodologies. In 1997 it was proposed a method that uses a few samplings of local flow measurements for the determination of the minimum flows through a rain-flow model, whose mathematical process involves two parameters, the Cinf and the Ksub. The first is related to water balance and the second to the river depletion. The objective of this work was to verify the influence of precipitation in the application of this methodology in basins between 800 and 1000 km² in order to subsidize information about the elaboration of a protocol of use of the method. For the case study, four basins with areas between 817 and 965 km² were used, with the availability of fluviometric and pluviometric data series. The methodology used was based on the Silveira method. Initially, rainfall scenarios were elaborated in the four basins for later selection of the drought events, which along with the rainfall scenarios, resulted in a total of 1407 simulations using the Silveira method. For each simulation, a flow continuity curve was generated. The determination of the errors was performed between the pairs of simulated flows and those observed for the considered percentiles. It was observed a tendency of improvement in the results of the simulations, translated by the smaller dispersion of errors, when the precipitation information from more than one pluviometric station is used. Regarding the spatial position of the pluviometric stations, it was verified that there were no significant impacts on the errors when data from the stations located at different points inside the basin and your surroundings.