In view of the construction requirements of digital twin system for fl ood control and water supply of Taipu river,a digital twin data base is developed based on multi-source heterogeneous data UAV aerial photography data, monitoring information and shared information with the tools of UE engine,GIS. Through the Taipu river model platform and visualization engine,an event-driven “four pre” system is formed,which can support Taipu river fl ood control and water supply forecasting,early warning,rehearsal and pre-planning. A mapping relationship between historical information with fl ood,rainfall,projects operation,water quality,and scheduling plans of Taipu river is established,so as to correlate scenarios with plans and realize the intelligent recommendation of emergency response. The whole process of “four pre” of fl ood control and water supply in Taipu river is constructed in a scenario-based manner,which serves the comprehensive scheduling and provides a case reference for the “four pre” system in the digital twins of the plain tidal river network.