Climate change increased the compound extreme precipitation-flood events in a representative watershed of the Yangtze River Delta, China

Abstract

A compound perspective on hydrological extreme events is of paramount signi cance as it may lead to damages with larger losses. In this study, an integrated framework, based on downscaled climate variables and hydrological model, i.e. the Soil and Water Assessment Tool, was applied to generate extreme precipitation (Rx1day) and extreme stream ow (Sx1day) series under historical and future climate conditions. Then the potential impacts of climate change for univariate and bivariate joint frequency of extreme precipitation and ood in Xitiaoxi River Basin (XRB), a representative watershed of the Yangtze River Delta, is detected. The compound risk of extreme precipitation and ood under different levels of joint return period for historical and projected periods are estimated by copula-based two-dimensional approaches. Major ndings can be summarized: (1) The Rx1day and Sx1day under future scenarios increased by -0.4 ~ 11.7% and 0.7 ~ 20.4%, respectively, compared to historical period based on univariate frequency analysis, indicating the increasing magnitude of the ood in the future. (2) Climate change with different emission scenarios all have a driving effect on the rising coactivity of extreme precipitation and ood under compound ooding frequency analysis. In addition, the enhancement of climate change to extreme events is more apparent for extremes with higher return period and under the periods of 2080s. (3) Moreover, the ood frequency designs are deduced by bivariate joint distribution are safer than that by univariate distribution. This study may provide actionable insights to formulate the planning scheme of ood control and disaster reduction under the changing environment. IntroductionGlobal precipitation characteristics and ood situations are expected to undergo signi cant changes as a consequence of global climate change including increasing temperatures and varying precipitation patterns projected for the future climate (IPCC, 2014). The incessant increase in magnitude and frequency of weather extremes (

Extreme Flood Levels during the Operation of Cascade Reservoirs: A Case Study of the Lower Yangtze River in 2020

“…In the last 20 years, high flood levels in the lower Yangtze River have appeared more frequently [30]. In the future, under the influence of climate change, extreme precipitation and river flow in the Yangtze River basin will continue to increase, indicating that flood risk has the potential to increase [31][32][33]. Moreover, the extreme flood frequency in the Yangtze River basin, represented by the three hydrometric stations, namely, Cuntan, Yichang, and Datong, will increase significantly [34,35].…”