Will a nonstationary change in extreme precipitation affect dam security in China

Abstract Due to the changing climate and environment, the stationary assumption used to calculate the design precipitation or flood of dams is no longer suitable, threatening dam reliability and safety. To see whether nonstationary changes in extreme precipitation will impact existing dams in China, we quantify the exceedance of extreme precipitation over the design intensity by the impact level (R), where the future extreme precipitation intensity is calculated from the nonstationary generalized Pareto (GP) distribution. We mainly focus on medium- (reservoir capacity greater than 0.1 billion m3), large- (reservoir capacity greater than 1 billion m3), and super-sized dams (reservoir capacity greater than 10 billion m3), which have design return periods longer than 100 years. We find that about 15 %-20 % of regions in China may have significant increases in extreme precipitation in the future, mainly in the southeast and northwest. 15 % of medium- and large-sized dams of China may be significantly affected (R greater than 50 %), and more dams are expected to be affected by 1-DAY (156) and 3-DAY (149) precipitation, compared as opposed to 5-DAY (128) precipitation. For super-sized dams, there is no possible significant impact in any of the basins (all R