Future changes in urban drainage pressure caused by precipitation extremes in 285 cities across China based on CMIP6 models

High pressure on urban drainage systems caused by extreme precipitation events would lead to an increase risk of urban floods. Across China, future changes in urban drainage pressure (UDP) and its response to global-scale climate mitigation and local adaptation, have seldom been studied. Here, based on climate projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we assessed UDP changes from 2020 to 2099 under different scenarios in 285 cities across China. Under the shared socioeconomic pathway (SSP) 5-8.5 scenario, 30% larger increase of UDP relative to the baseline level (1985-2014), would occur in 22.80% and 79.65% cities over 2020-2049 and 2050-2099, respectively. Under climate mitigation (SSP2-4.5 scenario), UDP in northern China would decrease by 10-30% over 2020-2049. On this basis, 10% enhancement of underlying surface retention capacity (LID10% scenario) would reduce UDP by more than 10% particularly in northern and north-eastern China (23.51% cities). Pipe enlargement adaptation (Pipe10% scenario) would benefit UDP mainly in eastern China (46.31% cities), by postponing the first decade with 30% larger pressure relative to the baseline level by 1-3 decades.