Índice de abstração inicial em pequenas bacias hidrográficas de Uberlândia – MG.

Abstract

This work aimed to adjust the initial abstraction index in two small experimental watersheds in the city of Uberlândia, MG. The initial abstraction (Ia) consists of the first portion of rain that is produced from the beginning of precipitation until the moment that the runoff originates, constituting the part of the rain that infiltrates the soil, which can be intercepted by vegetation and / or stored in land depressions. In Brazil, small basins suffer from a lack of hydrological data, requiring in-depth monitoring and hydrological studies. The methodology used to determine the initial abstraction was the SCS-CN method, the values calculated from rain and flow data. The index of initial abstraction in the Experimental Hydrographic Basin of Córrego Glória ranged from 0.01 to 18.78%, with an average of 1.95%. The Experimental Hydrographic Basin of the Água Vermelha Stream presented a range of 0.05 to 44.09% and an average of 2.70%. The two basins studied presented mean values of abstraction index lower than the values indicated in the literature, equivalent to 20% of the water storage capacity in the soil.