Abstract: The study of urban rain flood risk issues is of great significance to improve the accuracy of urban flood disaster monitoring and forecasting, and to promote the decision-making process of urban flood control. Because the high-precision urban 3D models can provide rich geographical information, it is convenient for accurate analysis of flooding. With the aim to solve the problem that the current urban flood model is highly sensitive to terrain data and the accuracy of flood risk assessment research is limited by the accuracy of terrain data, this paper innovatively proposes to use UAV tilt photography technology to reconstruct high-precision real-world three-dimensional model. Combined with the spatial analysis function of GIS and the key index of submergence depth, we carry out flood risk assessment in the study area. By extracting the inundation depth information of the research area under different reproduction periods and performing visual rendering to realize the three-dimensional flooding analysis, the flooding situation of the research area can be visualized for the risk management of the urban rain flood, which also provides valuable reference for the urban planning.

Key words: UAV, 3D reconstruction of tilt photography, urban flood model, submergence analysis, risk assessment