Rain Probability for the City of Rio Branco in the Western Brazilian Amazon

Abstract

The need to predict the occurrence of rainfall events is essential for planning urban and rural activities. Thus, the objective of this work was to estimate the probable values of rainfall at different levels of probability for the city of Rio Branco, Acre, from the total monthly rainfall records, computed from the historical series from 1970 to 2021. The method of maximum-likelihood was used for estimate the parameters of the Gamma distribution. In the evaluation of the historical rainfall series, it was observed that from june to august is considered the period with less rainfall, while from november to march it is considered the rainy period in the study region. The estimated values of rainfall at different levels of probability for the city of Rio Branco, Acre, allowed verifying that during the period from 1970 to 2021, the estimates comprised in the range of 50% of probability were similar to the monthly average values of the rainfall recorded in the municipality. Therefore, the rainfall values estimated in the present study are tools to support decision-making, especially with regard to planning and undertaking urban and rural activities in the city of Rio Branco.