Análise espaço-temporal de tendências de precipitação no semiárido brasileiro

Abstract

The Brazilian Semi-Arid region is home to over 28 million people, covering 12% of the national territory. In this region, any action to ensure water access must consider the aspects of source, transportation, and treatment. Due to the absence of perennial rivers, the Semi-Arid region has the lowest percentage of stored water in the country, around 3%, making rainfall, with annual averages below 800 millimeters, its primary water source—a resource of vital importance. In this context, this study presents a spatiotemporal analysis of rainfall in the Brazilian Semi-Arid region from 2003 to 2023, using data from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS). The study analyzed precipitation behavior at 43 points distributed throughout the region, investigating annual, seasonal, and rainfall trend patterns. The indices of Consecutive Dry Days (CDD) and Consecutive Wet Days (CWD) were applied, along with non-parametric statistical tests such as Mann-Kendall and Theil-Sen to assess trends. The results indicated an average precipitation of 763 mm during the period, with maximum values of 2,069 mm and minimum values of 181 mm. Seasonal analysis identified Summer as the wettest period and Winter as the driest. The northern region of Bahia showed severe water scarcity, being considered the first arid area in Brazil. Trend analyses identified points with a significant reduction in annual precipitation in the central part of Bahia and western Alagoas. Seasonally, a decreasing trend in rainfall was observed mainly in the Autumn in the southern part of the Semi-Arid region, while Spring showed an increasing trend in specific areas of Piauí and Ceará. Regarding the indices, 2008 and 2014 recorded the highest and lowest number of consecutive wet days, respectively, while 2017 and 2022 showed the highest and lowest number of consecutive dry days. Therefore, considering these results, this study contributes to understanding rainfall patterns in the Brazilian Semi-Arid, providing potential support for water resource planning and management in the region.