Equations of intensity, duration and frequency of precipitation for the municipality of Petrolina-Pernambuco

Abstract

Knowledge about heavy rainfall based on the equations of intensity, duration and frequency is an important tool in urban planning and sizing of hydraulic projects, as well as in planning the cultivation of crops of agricultural interest. The municipality of Petrolina-PE has an urban land area of 244.8 km², with an average population density of 76.5hab./km², and often suffers from flooding problems. In this sense, this work aimed to determine the maximum rainfall associated with different return periods using probabilistic methods to obtain the parameters of the regionalized equation of intense rainfall for the municipality of Petrolina-PE. For this purpose, a 40-year historical series was used, which was adjusted by the distribution of extremes, or Gumbel distribution, to obtain the maximum precipitations. The parameters of the equation were determined through the application of power regression, after the disaggregation of rains of 24 hours in shorter times of duration. The durations used were 60, 120, 180, 240, 300, 360, 480, 720, 1080 and 1440 minutes. The results of the parameters obtained for IDF equations were K= 114,4840, m=0,4211 and n=-0.61926, with a coefficient of determination R²=0.9790, thus presenting good estimates for use in planning applications in relation to the municipality of Petrolina-PE.