Abstract:Taking the small and medium-sized river basins by the upper Xiong’an New Area as a study area, selecting maximum precipitation for three consecutive days as flood hazard factor, using a combination of HBV hydrological model and FloodArea hydrodynamic model, flood inundation range and depth were simulated. Through building vulnerability curve of direct economic loss rate, combined with population and economic projections under SSPs, the economic loss risk of flood disaster was assessed. The results show that: (1)In the small and medium-sized river basins by the upper Xiong’an New Area, the maximum precipitation for three consecutive days during 1961-2019 was 335mm, with return period of once in 200 years. Under the SSP2-4.5 scenario, this precipitation return period will decrease to once in 150 years from 2021 to 2050, which will cause more than 60% of the Xiong’an New Area to be inundated by floods, with an average inundated water depth of 1.1m; (2) The area of urban and rural industrial and mining residential land affected by floods in Xiong’an New Area will be 119 km2, and more than 50% of the population and GDP will be exposed to floods. The largest amount of population and GDP exposed to floods will be mostly located in the southeastern part of Starting Area and most of Xiongxian County, which will be more than 10,000 people per km2 and 500 million Yuan per km2 respectively; (3) The economic loss of flood in Xiong’an New Area will be about 36.4 billion Yuan, accounting for about 8% of GDP. 85% of the whole region will belong to the low-risk area of economic loss, the areas with high risk of economic loss will be concentrated in the southeast of the starting area, and the urban and rural residential areas in Xiongxian County and Zangang Town, accounting for 2% of the total area.