Tempo de concentração em pequenas bacias hidrográficas na região de Uberlândia, Minas Gerais

Abstract

The time of concentration (tc) is a hydrological parameter of great importance that allows to visualize the behavior of a basin as the response of the superficial runoff in relation to the occurrence of rainy events. The knowledge of this time in watersheds is fundamental, because it is an indispensable parameter in hydraulic engineering projects for dimensioning bridges, culverts, gallery, spillways and among others. The time of concentration can be reached directly by monitored unit hydrograms or by empirical equations already existent in the literature. In this sense, the present work aims to estimate the time of concentration in three experimental watersheds, in the region of Uberlândia, Minas Gerais, from the analysis of 62 observed hydrograms and compare them with the performance of 23 empirical equations used in studies hydrological. The mean concentration time of the hydrographs collected for the experimental watersheds of the Água Vermelha Stream (BHEAV), Fundo Stream (BHEFU) and Glória Stream (BHEGL) were 615 min, 55 min and 215 min, respectively. The equations that showed the best performance when compared to the values the time of concentration each hydrograph obtained were those of Izzard, Giandotti, Ventura and Carter with statistical erros of variation up to 40%. Finally, it was proposed a mathematical equation capable of estimating the time of concentration to small watersheds in the region of Uberlândia-MG and also in any watershed with similar hydrological characteristics. The proposed equation, which took into account the variables of the basin area and longitudinal slope of the main course, was well consistent and with good accuracy when it revealed a coeficiente of determination 0.93 and Nash-Sutcliffe coefficient 0.87.