Integrating hydroclimatic and social indicators for groundwater risk mapping in tropical and semiarid environments

Water security in tropical and semi-arid regions faces unprecedented challenges from climate change and land-use dynamics. This study integrates hydroclimatic, hydrochemical, and social indicators to map groundwater risk across three distinct biomes: Atlantic Forest, Cerrado (Savanna), and Caatinga (Semi-arid). An analysis of a 20-year time series (2005-2024) was conducted using Mann-Kendall trend tests, Spearman correlations, and multitemporal land-use mapping to identify drivers of degradation. Results reveal that the Caatinga is the most critical region, characterized by extreme climate vulnerability (IMVC = 1.0), low recharge resilience, and increasing arsenic and salinity trends driven by evapoconcentration. In the Cerrado, deep oxisols facilitate the vertical leaching of agricultural inputs, leading to significant mineralization trends for hardness ions (Ca²⁺, Mg²⁺) and sulfate. Conversely, the Atlantic Forest exhibited the highest resilience, with stable water quality despite urban expansion, benefiting from high adaptive capacity. The integration of the Water Quality Index (WQI) with social metrics suggests that groundwater risk is amplified by socioeconomic disparities. These findings provide a framework for adaptive water management, emphasizing the need for biome-specific strategies to ensure the sustainability of invisible water reserves in similar geological contexts worldwide.