Simulation and Assessment of Rainstorm Flood Risk in Mountainous Rural Settlements Under Climate Change Scenarios

Abstract

Climate change has significantly increased the intensity and frequency of extreme weather events, posing significant challenges to the hydrological ecological security of rural settlements in mountainous areas. There is an urgent need for research that predicts the flood risk of mountainous villages under future climate scenarios. Taking the mountainous area of the Yongding River Watershed in Beijing as an example, this study uses CMIP6 data and the Delta statistical downscaling method to predict precipitation with return periods of 20-a, 50-a, and 100-a under the SSP126, SSP245, and SSP585 scenarios at the end of this century. A two-dimensional hydrodynamic model combining SWMM and HEC-RAS has been employed to simulate the flood risks of the villages in the watershed. The results show that: 1) overall flood risk is higher for the villages located downstream of the Qingshui River and at the outlet of the Yongding River Gorge, with significantly increased inundation area ratio, maximum inundation depth, and the number of villages affected; 2) with the increase in radiative forcing values of the SSP pathways, the inundation area ratio increases by up to 8.22% by 2100, significantly increasing the flood control pressure on settlements in the future; 3) the correlation results between village spatial characteristics and flood risks show that the inundation area ratio is significantly negatively correlated with average river width and river sinuosity, and significantly positively correlated with river gradient and floodway proximity; the maximum inundation depth is significantly negatively correlated with average river width and significantly positively correlated with floodway proximity. Finally, this research suggests that it is necessary to integrate various spatial elements and resources from upstream and downstream areas by prioritizing the strategy of key area flood control and sustainable development, to reduce the flood risk to mountainous settlements under future climate change.

Keywords

Climate Change / CMIP6 / Mountain Settlement / Flood Risk / Yongding River Watershed / Spatial Characteristic / Extreme Rainfall Event

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Higher Education Press