Vulnerability of urban water infrastructures to climate change at city level

Urban water infrastructures are facing substantial risks from floods and droughts aggravated by global climate change, while the adaptation is highly dependent on local conditions. The fine-grained vulnerability analysis is necessary but little has been done. A quantitative indicator-based approach for vulnerability assessment of urban water infrastructures was developed, by successively quantifying exposure, sensitivity, and adaptive capacity at the city level. When a spatial downscaling was used to project local precipitations for measuring exposures to urban flooding and drought, 33 indicators were designed to characterize the sensitivity and adaptive capacity of water-related infrastructures in a city. The method was tested with 22 provincial capital cities of China under two emission scenarios including RCP8.5 and RCP4.5. The sensitivity analysis on indicator weights indicates adequate stableness of the assessment system. Around 40 similar to 50% case cities would confront the challenges to better coping with flooding or/and drought hazards due to vulnerable infrastructures. Showing no spatial distribution pattern, the vulnerability mechanism at the city level is multifactorial driving and heterogeneous, while different dimensions of sensitivity and adaptive capacity may dominate separately or synthetically. These findings highlight the necessity of more city-level assessments and city-specific responses of urban infrastructures. The assessment system could serve as a practical tool to facilitate further understanding of climatic vulnerabilities and development of effective adaptation policies.