Examining the Water Scarcity Vulnerability in US River Basins Due to Changing Climate

Accurate assessment of changes in water availability with changing climate is vital for effective mitigation and adaptation. In this research, we employ a parsimonious Budyko curve method to evaluate changes in water availability under low- (SSP126) and high-emission (SSP585) scenarios for 331 river basins in the contiguous United States. We also assess the relative role of changes in precipitation (∆P) and potential evapotranspiration (∆PET) with changing climate on the increase in water availability vulnerability. Results highlight that around 43% (28%) of basins are projected to experience increased vulnerability to changing climate in high-emission (low-emission) scenarios. Sub-humid basins are most often impacted, while arid and semi-arid basins exhibit lower sensitivity to changes. Intriguingly, ∆PET emerges as the dominant control on vulnerability, surpassing ∆P, particularly under higher emission scenarios. The analysis prompts water managers to focus on long-term mitigation planning and scientists to further constraint climate and water budget forecasts in affected basins.