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 ( increment P) and potential evapotranspiration ( increment 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, increment PET emerges as the dominant control on vulnerability, surpassing increment P, particularly under SSP585 scenario. 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. Assessment of changes in water availability because of the changing climate is useful for mitigation and adaptation planning. In this study, water availability change in river basins in the contiguous United States is assessed. Which basins will become more vulnerable in terms of reduced water availability in the future climate and how the vulnerability changes within different aridity zones is studied. The study presents a novel methodology to assess and quantify whether the changes in potential evapotranspiration or precipitation are the main driver of future water vulnerability. We find that vulnerability increase due to an increase in potential evapotranspiration to be large. From the different aridity zones, sub-humid basins are projected to most often experience an increase in vulnerability. Changes in water availability under climate change scenarios are evaluatedSub-humid basins are most often impactedVulnerability increase is large due to increase in Potential Evapotranspiration