Research On Division Method Of Subcatchments For Urban Strom Water Simulation

As an effective non-engineering method for flood disaster management,urban storm water simulation can provide data and technical support for disaster forecast and analysis.The core of the simulation is the construction of urban rainfall-runoff model,and the first step of it is urban spatial discretization.A subcatchment is a kind of frequently-used discrete element,and used as a calculation unit for the model to calculate the runoff,so the results of division can directly affect the model simulation results.Division of urban rainwater subcatchments is the continuation and development of division of the natural watershed.Because the complex urban environment changes the natural flow path of rainwater,dividing urban rainwater subcatchments only on the basis of terrain can not meet the modeling requirements.In order to meet the modeling requirements,topography,rivers,roads,buildings and all kinds of artificial drainage facilities need to be considered.The existing division methods have the disadvantages of narrow consideration.Based on this,this paper combines the characteristics of urban rainwater confluence and puts forward the urban rainwater subcatchments division method considering the natural terrain and many kinds of artificial facilities in order to improve the quality of urban rainfall-runoff modeling.The main research contents and achievements of this paper are as follows:(1)Based on the analysis of the spatial characteristics of subcatchments in the urban rainfall-runoff models,a multilevel urban system of rainwater subcatchments is constructed on the basis of the spatial level of the urban drainage system,and the characteristics of each level of the urban rainwater subcatchments are clearly defined.Combined with the modeling demand of typical rainfall-runoff models,the expression method of hierarchical,spatial,non-spatial attribute and spatial correlation characteristics of subcatchments is proposed.(2)Combined with the influence of topography,rivers,roads,buildings and all kinds of artificial drainage facilities on the urban rainwater conflux process,propose a division method of urban rainwater subcatchments,which is based on the hydrological analysis method and GIS spatial analysis technique and follows the principle of dividing level by level.(3)Based on the urban rainwater subcatchments division method put forward in this paper,construct the urban rainfall-runoff models and take urban storm water simulation in Zhejiang,Lishui,district of Liandu.Compared with the results of traditional division method,the feasibility and effectiveness of this method is verified.The experimental results show that the results of the proposed division method much more fit the characteristics of urban rainwater conflux process and can effectively improve the effect of the simulation model.