Avaliação dos períodos de estiagem no estado do Ceará através da aplicação de índices de secas

Abstract

The Brazilian Northeast is a region historically affected by drought periods, characterized by low annual water availability, reduced precipitation, and long dry periods, along with climatic instability that contributes to local aridity. This phenomenon, known as drought, can be defined as a reduction in precipitation over a given period, resulting in water availability below the historical average. In the state of Ceará, specifically, the impacts of these events are evident and intense, to the point that drought is considered not only a meteorological phenomenon but also an essentially social issue. Given this context, the present study seeks to recognize and characterize the occurrence of drought events in Ceará. The objective is to understand the behavior, intensity, and frequency of this phenomenon, thereby enabling strategies to mitigate its impacts. To this end, this work employs three widely used drought characterization indices: the Standardized Precipitation Index (SPI), the Standardized Precipitation and Evapotranspiration Index (SPEI), and the Palmer Drought Severity Index (PDSI). The adopted methodology includes the collection and processing of climate data, the determination of parameters such as evapotranspiration and water balance based on monthly data, as well as the calculation of the aforementioned indices. The results allowed for the identification of historical drought patterns in Ceará, as well as the quantification of the magnitude and frequency of these events. Additionally, a comparison between the indices was conducted, analyzing their behavior and the relationship between the obtained results. It was observed that the SPI index had a greater capacity to capture short-duration events, reflecting a higher frequency of mild droughts. On the other hand, the PDSI demonstrated greater efficiency in detecting severe and extreme events. The SPEI, in turn, exhibited an intermediate behavior between both. Based on the classification tables of the indices, the characterization of dry and wet periods throughout the analyzed period was made possible. Thus, this study contributes to the understanding and analysis of drought events in Ceará, as well as providing support for the formulation of adaptation and mitigation strategies to address their impacts.