Secas no semiárido paraibano análise de extremos pluviométricos e vulnerabilidade nos municípios de Picuí, Sousa e Sumé

Abstract

Climate change corresponds to persistent alterations in climate patterns, evidenced by variations in temperatures, in the frequency of extreme events, and in the functioning of atmospheric and oceanic systems, affecting ecosystems and human activities at different scales. In this context, semi-arid regions tend to show greater sensitivity to climate variability, particularly regarding water availability and the occurrence of droughts. Given this scenario, the main objective of this study was to analyze the behavior of the rainfall regime and drought vulnerability in the municipalities of Picuí, Sousa, and Sumé, located in the semi-arid region of the state of Paraíba, Brazil. The adopted methodology included the analysis, for the period from 1994 to 2023, of the Consecutive Dry Days Index (CDD) and the Consecutive Wet Days Index (CWD), as well as the statistical analysis of time series using the Mann-Kendall, Sen’s slope, and Pettitt tests. In addition, drought vulnerability was calculated through a composite index structured from indicators of exposure, sensitivity, and adaptive capacity. The results indicate few consecutive days with precipitation, highlighting the municipality of Sousa, with a maximum value of nine CWD in the years 2008, 2018, and 2020. On the other hand, long drought intervals were observed, particularly in Sumé, which recorded nearly one year of CDD. A statistically significant increasing trend in CDD was observed in the municipality of Sumé, indicating an intensification of dry periods over time, while Picuí and Sousa did not show defined trends. The analysis also revealed low water recovery capacity after dry periods, especially in Picuí and Sumé. The drought vulnerability assessment pointed to differences among the municipalities, with higher vulnerability in Sumé, associated with the intensification of dry periods and adaptive limitations, and relatively lower vulnerability in Sousa, influenced by lower sensitivity and support from external water infrastructure. It is concluded that drought vulnerability in these municipalities is strongly conditioned by the temporal irregularity of rainfall and by how the territories are structured to respond to climate extremes, reinforcing the need for integrated and territorially differentiated adaptive strategies.