Risk assessment of waterlogging in Beijing Municipal Administrative Center by hierarchical analysis

Flood risk assessment framework of “risk-exposure-vulnerability” was adopted to construct a flood risk assessment system for the Beijing Municipal Administrative Center by hierarchical analysis, index values were obtained by model simulation, GIS spatial analysis and other methods．Risk assessment of waterlogging in the study area was carried out under the scenarios of rainfall once every 10, 20 and 50 years．The current drainage capacity of the Municipal Administrative Center was found to meet the requirement of rainfall once every 10 years only, far from the planning standard of once every 50 years．The middle and high risk areas were found concentrated in the former old towns of Tongzhou west of the North Canal, south of the Tonghui River, area north of the river, east of the Xiaozhong River, and the lower concave bridge area along the Beijing-Qin Railway．The risk degree of ponding was inconsistent with risk degree of waterlogging, evaluation of waterlogging risk seemed more scientific and instructive．The “one site, one policy” strategy should be adopted to formulate emergency plans in high risk areas to improve flood forecasting and early warning capabilities．