Obtenção do index-flood para regiões homogêneas de Minas Gerais

Abstract

The evaluation of heavy rainfall is important because rainfall data are frequently used to design storm drainage and erosion control systems in agricultural areas. Because it is difficult to obtain local rainfall data, heavy rainfall regionalization techniques are necessary. One such technique is known as the index-flood method, which standardizes data obtained for different areas within a region considered homogeneous to use as a single sample set. The objectives of this study were to divide the state of Minas Gerais, Brazil, into hydrologically homogeneous regions and to use the return periods and duration to obtain the respective Index-Flood values for each state to aid the design rainfall estimation. Maximum annual rainfall and total annual rainfall data from 494 weather stations in Minas Gerais were used. K-means cluster analysis was used to identify homogeneous regions and generated a total of three groups in the state. For each group, the regional intensity–duration–frequency (IDF) relationships were generated and were related to the rainfall intensity values associated with different durations, resulting in the Index-Flood value. Subsequently, the regional dependent variable equations were obtained and were associated with the Index-Flood and the local rainfall value to obtain the local design rainfall used in the design storm drainage and erosion control systems in agricultural areas. The coefficient of determination was used to evaluate the accuracy of the estimates, and the r² values were close to 1.0 for all fittings, which indicated a good fit of the data and allowed the equations generated to be used in the design rainfall estimation.