Future Change Projections of Extreme Floods at Catchment Scale and Hydrodynamic Response of Its Downstream Lake Based on Catchment‐Waterbody Relationship Simulation

Abstract

AbstractExtreme riverine floods and hydrodynamic response of downstream lakes are the main focus of catchment flood control, especially under climate change. In this study, future changes in the extreme floods and their hydrodynamic responses are projected by driving the external coupling of the hydrological and hydrodynamic models using the precipitation and temperature outputs of the general circulation models (GCMs) in seven emission scenarios, and the impact of climate change is evaluated. The Baiyangdian Lake and its controlled catchment are selected as our study area. Results show that: (a) both the daily runoff and the lake water levels are well simulated, (b) compared with the baseline scenario, extreme riverine floods are projected to increase evidently throughout the catchment with mean rates of 33.2%, 14.1% and 10.9% in the RCP2.6, 4.5 and 8.5 scenarios, respectively because of increasing precipitation; consequently, the total lake inflow also increases by 13.5%–150.9%, most of which are from Zhulong, Xiaoyi, Tanghe, and Fuhe Rivers, and (c) the water level of the Baiyangdian Lake increases temporally during the flood seasons in all the scenarios, and the increase in water level is 0.27–1.29 m greater than that in the baseline scenario; consequently, the water depth in 55.8% and 73.4% of lake area increases over 1.0 m in the future short‐term and long‐term scenarios, respectively; the inundation area also increases by 23.4%–26.7% in the future scenarios, except in the long‐term RCP4.5 scenario. The northeastern and south‐central regions of Baiyangdian, which are near Xiong'an New Area, have a relatively high inundation risk.