遵循以防为主的防灾减灾救灾理念，提出一种集情景预估、预测预报、分级预警、应急预案和防洪预演为一体的城市暴雨洪涝灾害“五预”应对机制。包括：基于气候模式的城市暴雨洪涝灾害情景预估;耦合气象水文的城市暴雨洪涝灾害预测预报;多源信息融合的城市暴雨洪涝灾害分级预警;基于综合集成的城市暴雨洪涝灾害应急预案;基于数字孪生的城市暴雨洪涝灾害防洪预演。其中的关键技术包括：城市洪涝模拟、地球系统模式、滚动气候预测、数值天气预报、三维电子沙盘、综合集成平台和数字孪生城市。构建变化环境下城市暴雨洪涝灾害“五预”应对机制,可为城市防洪减灾决策提供有效支撑。

The sixth assessment report of the Intergovernmental Panel on Climate Change shows that global surface temperature has increased,causing more frequent and intensive extreme climate events such as floods and drought.The total annual flood losses are estimated to be 100 billion dollars worldwide and cause serious casualties.For example,3 563 floods happened over the past thirty years from 1980 to 2010 in 37 European counties.Four out of the top ten natural disasters were related to flooding in 2020 in China,causing 247 deaths and 2 255 billion direct financial losses.Urbanization plays a magnifying effect on the flood disaster.The urban heat and rain island effects make more precipitation extremes in urban areas.However,accurate precipitation prediction at the city scale is still a scientific problem.How to deal with urban rainstorm and flood disasters is a new challenge of global flood management. Under the influence of climate change and urbanization,urban rainstorm and flood disasters occur more frequently and extensively,causing serious casualties and economic losses.The problem of an urban rainstorm and flood control and disasters reduction has been paid wide attention by the government and scholars.To reduce the effects of the urban rainstorm and flood disasters,both adaptive engineering and nonengineering strategies can be considered.However,engineering strategies such as sponge city generally need tremendous investments for both construction and maintenance.The non-engineering strategies are focused on.However,the problems of forecast and prediction,monitoring and early warning, multi-department cooperative management for an urban rainstorm and flood disasters still need to be solved.Based on the concept of disaster prevention,mitigation,and relief,taking disaster prevention,a five-pre response mechanism for urban rainstorm and flood disasters is proposed,which integrates scenario projection,forecast and prediction,monitoring and early warning,emergency plan,and flood control rehearsal. The results show that the five-pre response mechanism for the urban rainstorm and flood disasters realizes the long term projection,the medium and short-term forecast and prediction,the near-real-time monitoring and early warning, the real-time emergency plan, and the urban rainstorm and flood disasters control and rehearsal before the disasters,which can provide a set of non-engineering measures capable of actual operation for the urban rainstorm and flood disaster response.The five-pre response mechanism for the urban rainstorm and flood disasters can be implemented as follows:Urban rainstorm and flood disasters scenario projection based on a climate model;urban rainstorm and flood disaster forecast and prediction based on coupling meteorology and hydrology;urban rainstorm and flood disasters monitoring and early warning based on multi-source information fusion;urban rainstorm and flood disasters emergency plan based on meta-synthesis platform;urban rainstorm and flood disasters control and rehearsal based on digital twin. The key technologies and supporting platforms of the five-pre response mechanism for the urban rainstorm and flood disasters are further expounded,which provide scientific support for urban rainstorm and flood disasters response.They include urban rainstorm and flood models,earth system models, rolling climate forecast technology,numerical weather prediction technology,three-dimensional digital sand table,metasynthesis platform,and digital twin city.The five-pre response mechanism provides a new idea to systematically resolve urban rainstorm and flood disasters.However,some of the technologies such as rainstorm projection and forecast at the urban scale,rainstorm accurate prediction are still scientific or technical problems that are unresolved,which need further investigation using interdisciplinary theories and technologies.