Groundwater storage trend in headwater basins in different Brazilian regions

Climate change has impacted hydrological processes worldwide, and understanding such impacts is fundamental to assessing water availability and supporting water resource management. The present study aimed to assess groundwater storage temporal trends in four headwater basins (Aiuruoca River – southern Minas Gerais River; Bonito River – southern Bahia State; Pelotinhas River – Santa Catarina Highlands, SC; and Arroio Fragata – south Rio Grande do Sul State) based on daily streamflow historical series and the Brutsaert method. The results showed that climate variations have affected water availability and patterns differently. It tends to reduce groundwater storage in the Aiuruoca and Bonito River Basins and increase it in the Pelotinhas River. Arroio Fragata did not present any significant trend in groundwater storage. Rainfall was the main driver of changes in groundwater storage, and it decreased over time in most of the basins while temperature increased in all of them, with an increase in potential evapotranspiration. These outcomes have shown reduced groundwater storage, directly impacting Brazil’s socioeconomic development and the environment.