Effects of climate change on peak runoff and flood levels in Qu River Basin, East China

The impact of climate change on regional hydrological extreme events has been a research topic that has received much attention in recent years. This paper aims to provide a general overview of changes on future runoffs and water levels in the Qu River Basin, upper reaches of Qiantang River, East China by combining future climate scenarios, hydrological model and 1D hydraulic model. The LARS-WG (Long Ashton Research Station Weather Generator) statistical downscaling method is used to downscale the GCM (Global Climate Model) outputs (including BCC, BNU, CanESM and CSIRO under RCP4.5 and RCP8.5 scenarios) and generate 50 years of synthetic precipitation and maximum and minimum temperatures to drive the GR4J hydrological model and the 1D hydraulic model for the baseline period 1971-2000 and the future period 2021-2050. Finally, the POT (Peaks over Threshold) method is applied to analyze the change of extreme events in the study area. The results show that design runoffs and water levels all indicate an increasing trend in the future period for Changshangang River and Jiangshangang River at most cases, especially for small return periods, and for Qu River the increase becomes larger, which suggests that the risk of flooding will probably become greater and appropriate adaptation measures need to be taken.