Comportamento temporal do armazenamento de água subterrânea em bacias hidrográficas de cabeceira

Abstract

Understanding how climate change is influencing hydrological processes in different regions is of great importance for measuring water availability and supporting the management of water resources. The objectives of this study were i) to evaluate the temporal behavior of groundwater storage in four headwater river basins located in contrasting regions of Brazil (Rio Aiuruoca – Serra da Mantiqueira, MG; Rio Bonito – southern Bahia; Rio Pelotinhas – Planalto Catarinense, SC; and Arroio Fragata – south of Rio Grande do Sul); ii) evaluate the behavior of hydro climatological variables in these locations over the years and iii) evaluate the impacts of climate change on groundwater storage based on hydrological simulation in the headwater region of the Aiuruoca River basin. The results indicate that climatic variations are affecting hydrological and climatic conditions differently in different regions, with a tendency to reduce groundwater storage in the river basins of the Aiuruoca and Rio Bonito Rivers and an increase in the Rio Pelotinhas. At the same time, the Arroio Fragata did not show a significant trend. Precipitation, among the 3 variables tested (precipitation, evapotranspiration and temperature), was the climate variable that showed the highest correlation with groundwater storage in these river basins, indicating that changes in rainfall patterns directly affect water recharge and availability in aquifers. The hydrological modeling carried out using the LASH model introduced in the R programming language (F-LASH) presented good results in the calibration and validation processes, proving to be a robust model to represent the hydrological conditions in the southern Minas Gerais. From the hydrological simulation with projected future climate data, long periods of drought and below-average rainfall were observed, mainly towards the end of the 21st century, which reduces the runoff in the BHRA and, consequently, the groundwater storage. These results demonstrate that groundwater storage in some regions of Brazil is decreasing, directly impacting socioeconomic development, suggesting the need for actions that can reduce the impact of climate change on water resources.