Abstract:Taking the small- and medium-sized river basins in the upper reaches of Xiong’an New Area as a study area, selecting maximum precipitation for three consecutive days as flood hazard factor and using a combination of HBV hydrological model and FloodArea hydrodynamic model, we simulated the flood inundation range and depth and assessed the economic loss risk of flood disaster through building vulnerability curve of direct economic loss rate in combination with population and economic projections under SSPs. The results show that in the small- and medium-sized river basins in the upper reaches of Xiong’an New Area, the maximum precipitation for three consecutive days during 1961-2019 was 335 mm, with a 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 1.1 m. The area of urban-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 the starting area and most of Xiongxian County, which will be more than 10 〖KG-*5〗000 people per km2 and 500 million Yuan per km2 respectively. The economic loss of flood in Xiong’an New Area will be about 36.4 billion Yuan, accounting for about 8% of GDP. Moreover, 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 also in the urban and rural residential areas in Xiongxian County and Zangang Town, which will take up 2% of the total area.