Disponibilidade hidríca na bacia hidrográfica do Rio Amambai – MS

Abstract

Characterized water availability in the Amambai River Basin. To that end, the study analyzed the annual and monthly average rainfall, as well as the potential and real contributions to the direct tributaries of the main river. The minimum reference outflows Q7,10, Q90, and Q95 were also studied, along with the regionalization of low flows (Q7,10 considering annual and quarterly periods, and Q90 and Q95 considering the annual period), based on the following methodologies: interpolation and extrapolation of flow, specific yield flow, and regression equations. It was concluded that rainfall and mean specific yield flow decrease from the river head toward the mouth of the basin. The sub-basins with the highest potential and real contributions to the formation of the Amambai River flow are: Verde River, Guaembeperi Stream, and Piratini River. The highest outlet coefficients are observed in the Taquara River and Saljú Stream, representing a gradual increase in the contribution rate of the right-bank tributaries of the Amambai River. The probability distribution functions that showed the best results were the Log-Normal and Gamma functions. The low flows for the annual periods, estimated using the three regionalization methods, presented the best results in terms of mean error and the Nash and Sutcliffe efficiency coefficient, especially for durations of 95%. When comparing regionalization methods—interpolation and extrapolation, and specific outflow—it is possible to observe consistent results between quarterly and annual periods. The best regionalization method studied was the one based on regression equations.