Study On The Disaster Analysis Modal Of Urban Storm Flood Accumulation Based On GIS

With the development of urbanization, urban storm process becomes much more complicated and increase the degree of harm, the old drainage system cannot meet the needs of the urban flood control project. Questions such as the urban water accumulation that caused by the urban storm, have seriously affected the normal production and life, which caused a huge loss to the country and the people’s lives and property.The study integrated using GIS technology and PCSWMM model, systematically analysis storm waterlogging principle of the Jiading, Fuyun Road, and built the rainstorm waterlogging model by value-numerical computation combined with hydrological analysis to carry out the waterlogging spatial analysis and dynamic simulation for different returning periods of heavy rain. The main conclusions of the study are obtained listed as follows:(1) Feature analysis of urban stormAccording to the research and application of urban storm runoff, as well as The Drainage Design and the rainfall intensity formula, the paper chooses the rainfall model of Huff with the returning periods of2a,5a,10a,100a by the study location and geographical environment.(2) Building the GIS refined model of runoff generation and convergenceUsing the method of tradition hydrological analysis to establish the water catchment area, the paper constructed a refined runoff generation and convergence model, which is suitable for the modeling district storm process. Integrate the measured data to calibration of model parameters, and adopt the model sensitivity analysis to describe the response of model calibration parameters. Then, improve the accuracy of the model simulation from above-mentioned.(3) Process simulation on storm runoff based on circumstancesSum up GIS technology and PCSWMM model to estimate the waterlogging situation of different return period of the study area. The storm runoff simulation analysis will develop from two parts of the macro and micro:From macro level, elaborate the peak flow and total flow of catchment surface, inspection wells peak over-flow and total over-flow, length time of pipes full flow, and outlet flow from different return periods of rainfall intensity on this four aspects. From micro level, selecting the sample pipe OF2-J25-OF5, clarify ground surface runoff, the inspection wells depth, pipeline flow and diameter from the process of change with time in3hours. The simulation results show that:Within return period growth, the pipeline peak flow and total flow increases, the overflow time beforehand, the overflow duration growth, that causing the waterlogging disasters level becomes deep.(4) Spatial distribution and zoning of urban surface waterloggingUsing the water balance principle and combined with inspection wells overflow, the paper carry out the algorithm of the flooding depth of catchment within a threshold value, which apply the method of MATLAB programming to realize the calculation of the waterlogging elevation in catchment. In the light of the classification rules of urban waterlogging forecasts, the paper conduct the waterlogging risk zoning in flooding region from the grid cell water depth and two types indicators of inundation area ratio. Results can be expressed as two aspects:From spatial distribution perspective, the central and southern region is higher than northern region in risk level. From temporal distribution point of view, with the heavy rainfall return period increases, submerged depth range expanded above25cm.A model of an independent storm drainage network system in Jiading is established by above method, and union the urban natural geography factor to analysis submerging reasons and settle counter-measures. The feasibility and the practicability of this technical method have been illustrated by this case.