EQUATIONS OF INTENSITY, DURATION AND FREQUENCY FOR THE PERUÍPE, ITANHÉM AND JUCURUÇU RIVER BASINS

Abstract

The intense rainfall equations present a great technical interest for hydraulic works projects. In the State of Bahia, there are only 19 equations of intensity, duration and frequency modeling, requiring a greater number of equations for the State. The most recent ones are almost 15 years old, with only two in the Peruípe, Itanhém and Jucuruçu river basins. Thus, the objective of this work was to determine the parameters of the equations of intensity, duration and frequency (IDF) of the rainfall stations for different locations of the basins of the Peruípe, Itanhém and Jucuruçu rivers, located in the far southern Bahia State. Initially, 59 stations were selected, out of which only those with over 20 year-old data and records from 1980 onwards. Rainfall disaggregation was carried out using the method proposed by Cetesb (Environmental Company of the State of São Paulo, Brazil) and the parameters (K, a, b and c) were adjusted through nonlinear multiple regression using the nonlinear-generalized reduced gradient interaction method, where adjustment was evaluated by the coefficient of determination (R2). In the end, 29 equations were adjusted, with coefficient of determination greater than 0.99, therefore, improving the perspective of planning hydraulic works in the region. This correlation could also be observed by the regression equation of the observed data with the adjusted ones, where the slope coefficient of the line was close to 1.0 for all rainfall stations.