Research On A Distributed Rainfall-Runoff-Inundation Model And Its Application

Recent years,extreme rainstorm events have occurred frequently due to climate change.Floods and associated disasters have become a great threaten to regional development.A numerical model is essential to a regional flood risk management department,which can accurately simulate the rainstorm and flood process.At present,there are some deficiencies in the common hydrological model simulating rainstorm and flood in our country.Thus,this article adopted a distributed Rainfall-Runoff-Inundation(RRI)Model from International Center for Water Hazards and Risk Management to solve some of the above problem.Based on detailed explanation and analysis of the core formulas and principles of this model,the article validates and analyzes applicability of RRI model in Takahashi river basin in Japan and Wangmaogou and Tuwei river basins in the Loess Plateau of China,explores the application of RRI model in prevention planning of multi-scenario water disaster,and analyzes the application characteristics of RRI model in flood process,inundation process and plain waterlogging process.The main conclusions are as follows:(1)The RRI model discretizes the watershed into slope and river grids.Runoff formation at the natural storage and runoff formation in excess of infiltration modes are used on the slope.Two-dimensional diffusion wave model and one-dimensional diffusion wave model are used on the slope and river,respectively.The fifth-order Runge-Kutta method with adaptive time-step control is applied to solve the equations.Open MP parallel program and supporting GUI program are adopted to improve the efficiency and convenience of the model.(2)The verification results of Takahashi River Basin in Japan show that RRI model can simulated this area accurately,and can simulate well in the flow process of the river and the extent of inundation on the land.There are significant similarities between Koumoto sub-basin and Mimurogawa sub-basin in geographical features and flood,but the underlying surface condition of Tarui sub-basin is quite different from that of other basins.The Shinnarinagawa dam can effectively reduce the flood area and level after adding alarm storage system:the peak flow rate at the downstream of the reservoir is decreased by 178m~3/s,the peak flow time is postponed by 90 minutes,and the submerged depth in the downstream flood area is reduced up to 2m.(3)The verification results of Wangmaogou and Tuwei river basins show that RRI model can simulate this area accurately,meeting the simulation need of rainstorm-flood process in this area.The situation of flood events in the Tuwei River Basin is complicated with both the processes of"rapidly rise and rapidly fall"and"slowly rise and slowly fall",but mainly focused on the“rapidly rise and rapidly fall”process.Inundation areas are mostly distributed on two sides of the main river and tributaries and lower areas,and farmland is the main possible flood target.There is a high inundation risk on both sides of the river between Hutoumao and Heshita of the Tuwei river.(4)The spatial distribution of rainstorms in the Tuwei River Basin has a significant impact on the flood process.The time to peak flow reaches earliest when rainstorm center appears in downstream.Soil and water conservation measures can effectively postpone time to peak flow,reduce peak flow,and alleviate regional inundation.Ecological measures have the best delay effect on low peak flow,while engineering measures have the best reduction effect on peak flow.