Assessing the Susceptibility of Water Availability Due To Climate Change in China

Climate change has worsened water deficits worldwide, posing a particular challenge for water-stressed countries like China. Quantifying the dependence of water availability on climate change is crucial for effective mitigation and adaptation, yet such assessments have rarely been conducted at the administrative-unit level. The aim of this study is to: (a) employ a parsimonious Budyko framework to evaluate changes in water availability across 341 prefectures in China under low- (SSP126) and high-emission (SSP585) scenarios, and (b) assess the respective roles of changes in precipitation (ΔP) and potential evapotranspiration (ΔPET) in driving the shifts of susceptibility regimes. Results indicate that the number of susceptible prefectures (based on static parameter ω) are projected to gradually decrease from 2020 to 2100, dropping from 45.2% (46.9%) historically to future 26.1% (18.2%) under low-emission (high-emission) scenarios, while those based on time-varying ω decrease from 46.3% (49.6%) to 27.9% (31.7%). This decreasing susceptibility trend is mainly driven by ΔP, although the influence of ΔPET is increasing under future warming scenarios. We also identify numerous prefectures where water resources persistently decrease under both climate scenarios, which are unevenly distributed across China. This highlights the need for region-specific strategies in future water resource management to address the localized challenges posed by climate change. This study provides valuable information for formulating long-term mitigation strategies regarding water resources management with changing climate.