Análise dos extremos de precipitação no Nordeste do Brasil com base em índices climáticos e estimativas de período de retorno.

Abstract

This study aimed to analyze extreme rainfall events in the Northeast region of Brazil, applying the RClimdex software. For this purpose, data from the National Institute of Meteorology (INMET) for the period 1961-2020 were used. Indices of extreme rainfall events were determined, including the duration of dry periods (CDD) and continuous rainfall (CWD), as well as extreme precipitation events (RX5DAY and R95P), in addition to trends and changes in the time series, using the Mann-Kendall and Pettit statistical tests. Subsequently, statistical modeling was performed with the Generalized Extreme Value (GEV) distribution to estimate the return periods of these events and to evaluate significant differences in the behavior of extreme indices between regions. The results showed a significant reduction in total precipitation and extreme events, with expressive spatio-temporal variations, mainly in the eastern Northeast and the state of Piauí. Cluster analysis identified five (05) homogeneous regions, highlighting Group 4, with greater statistical significance. Groups 1 and 5 showed greater water vulnerability, with prolonged droughts and lower frequency of extreme events. Groups 2 and 3 recorded more intense rainfall and more favorable water conditions. The trends indicated an increase in the frequency and intensity of rainfall, along with the lengthening of dry periods, which exacerbates regional vulnerability. These results further reinforce the need for specific regional strategies that consider the spatial and temporal variability of extreme events, aiming to minimize socio-environmental impacts and strengthen resilience in the face of adverse climatic conditions.