INTENSITY – DURATION – FREQUENCY EQUATION OF RAINFALL FOR LOCALITIES OF FORTALEZA AND PENTECOSTE, CEARÁ

Abstract

In this work data sets with 19 e 30 years were used for Pentecoste and Fortaleza - CE, respectively, with the aim to establish a relationship between rainfall intensity, duration and frequency. The theoretical model used was the Gumbel probability distribution. The maximum intensity rainfall was evaluated to 5, 10, 15, 20, 30, 45, 60, 90, 120, 180, 240, 360, 720 e 1440 minutes using rainfall gauge graphic. The fitted probabilistic model was tested by the Kolmogorov-Smirnov adherence test. The result showed that, the Gumbel model adjusted of data maximum intensity at a significance level of 20% in the all studied durations to Pentecoste station. The estimated values by general equation can show errors up to 40% for the location Pentecoste. This fact confirms the necessity of distinct equations for each return period. The values of probable maximum intensity calculated by developed equation can be used to estimate the rainfall intensity, except for 5 minutes duration in station of Fortaleza, which presented a tendency to underestimated the predictable values.