| Mountain torrents and mudslides are geological disasters caused by heavy rainfall in mountainous areas,which usually poses a serious threat to local economy and society.Taking a typical debris flow single gully Beijing as an example,in this paper,a hydrodynamic and FLO–2D coupling model was established for mountain torrent and debris flow simulation.Then,the early warning model and hazard assessment model were established based on the calculation results of the coupled model,which can provide technical support for the early warning of mountain flood and debris flow.The main research work and achievements are as follows:(1)A two-dimensional hydrodynamic model for mountain rainfall runoff simulation was established.The production flow was calculated by Horton model.Confluence calculation was completed by two-dimensional shallow water equations based on Navier-Stokes equations.In this process,the finite volume method of unstructured grid was used for discretization,and the whole modified channel flow was introduced to reduce the influence of false flow.(2)The established two-dimensional hydrodynamic model was verified and applied.Taking a typical debris flow single gully in mountainous area of Beijing as an example,the process of constructing rainfall-runoff model in mountainous area was demonstrated in detail,including topographic data processing,grid division,data processing of geological and vegetation conditions and rainfall data processing.This model can output the distribution of water accumulation,velocity distribution and flow in any section according to the rainfall process line.So it can be used for the early warning of mountain torrent.This model was verified to be reasonable and feasible through two actual rainfall data.The model was used to simulate the mountain torrents in the study area under four recurrence periods and to find the waterlogged spots in the study area.Compared with the previous research results,the results of the coupling model were proved to be reasonable and accurate.(3)The rainfall-runoff and FLO-2D coupling model was established to simulate the debris flow at different frequencies in the study area.Based on the mathematical model,debris flows under four recurrence periods in the study area were simulated,and the distribution of depth and velocity of mountain torrents and debris flows under the corresponding recurrence periods were obtained.Then an early warning model and hazard assessment system,which can provide reference for the construction of disaster prevention projects,were built based on these two parameters. |
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