Climate Extremes and Groundwater Vulnerability in Pakistan and South Asia:Hydrogeological Impacts, Risks, and Future Challenges

Abstract

Groundwater is one of the most important freshwater resources supporting drinking water supply, agriculture, industry, and ecosystem sustainability across the world. In South Asia, particularly in Pakistan, increasing dependence on groundwater combined with climate change has created serious environmental and hydrogeological challenges. This study examines the impacts of extreme climate events, including floods, droughts, heatwaves, and El Niño episodes, on groundwater systems with a particular focus on Pakistan and the Indus Basin region. The research highlights how climate variability influences groundwater recharge, aquifer storage, groundwater quality, hydrochemical processes, and long-term groundwater sustainability.

The findings indicate that floods may temporarily increase groundwater recharge through infiltration and floodplain percolation; however, they also increase the risk of groundwater contamination through sewage infiltration, agricultural runoff, heavy metals, pathogens, and industrial pollutants. In contrast, droughts and heatwaves reduce groundwater recharge by increasing evapotranspiration and groundwater abstraction, resulting in declining water tables, salinity intrusion, and aquifer stress. The study further shows that El Niño-related weak monsoon conditions may significantly intensify groundwater depletion and groundwater droughts across Sindh, Southern Punjab, Balochistan, and other climate-sensitive regions of Pakistan.

Spatial vulnerability mapping and hydrogeological assessments identified lower Sindh, the Quetta Basin, Bahawalpur, Multan, Jacobabad, and the Thar Desert as major groundwater risk hotspots under future climate change conditions. The research also emphasizes the growing importance of modern technologies such as GRACE satellite observations, remote sensing, GIS-based vulnerability mapping, and climate-groundwater modeling for predicting future groundwater stress and supporting sustainable groundwater management.

The study concludes that climate change is already affecting groundwater quantity and quality across Pakistan and South Asia. Effective groundwater governance, climate adaptation strategies, managed aquifer recharge systems, and improved monitoring networks are essential for protecting groundwater resources and ensuring long-term water security under future climate uncertainty.