Applied Research Of Storm Water Management Model Based On GIS

In recent years,many cities represented by Beijing have continually suffered from storm water disasters,which have brought great security risks and economic losses to the resident.The application of the low impact development measures(LID)is of positive significance to reduce the urban runoff,reduce the load of drainage system,conserve groundwater,and increase urban aesthetic degree.This research is established storm water management model through the SWMM and GIS technology,combined with the engineering designs of pipe network and the content of low impact development measures based on the economic development project in Liujiang,compared with the runoff and infiltration of Liujiang in three states such as before,traditional and LID development,and verify the design of the pipe network.The main research contents and conclusions are as follows:(1)Summarizes the operation principle of SWMM and elaborated on the modeling steps.At the same time,this paper establishes a rain flood model about the economic development area in Liujiang which is combined with the GIS,Hongye and Water Desk.Dividing the sub-catchments through the Liujiang’s detailed planning and construction drawings,selecting underlay surfaces’ parameters from survey data and site investigation,and completing the modeling work.(2)Based on the parameter rate determination method proposed by Xingpo Liu et al.,the rate determination of rainfall and flood management model parameters in Liujiang is conducted and the reliability of the model is verified.This article selects for return period of one and two years of rainfall processes to rate the model parameters,and using the excessive rainfall process during 5 years returen period to verify the model is still suitable for use in conditions.(3)Combining with the engineering design to choose 2 years heavy rain intensity,this paper has selected a total of 5 rainfall processes in 1 year,2 years,5 years,10 years and 20 years for modeling work.Simulating with the rainfall during the three states such as before,traditional and LID development in Liujiang,and according to the model results,adjust the project design,verifying the runoff of the improved study area and putting forward the possible use of SWMM in engineering.(4)Changes in urban underlay surface caused by traditional development lead to increased runoff intensity and peak runoff in the study area.Compared to the Liujiang’s runoff under undeveloped conditions,the increase of total runoff in the study areas at the return period of 1 year,2 years,5 years,10 years and 20 years was 109.6%,91.4%,69.1%,57.3%,and 48.7%,respectively,which showed a trend of decrease.(5)Low-impact development measures can reduce the runoff generated by rainfall and enhance the infiltration effect of rain water.The reduction rate of total runoff in each recurrence period is 31.3%,24.8%,19.5%,16.8% and 14.8% respectively,showing a decreasing trend.(6)Through analysis of pipe network overload and node overflow in model simulation results,clearing the specific parts of pipe network overload and node overflow.The study renovates the serious parts of pipe network overload and node overflow and increases the flow capacity of the pipe network by expanding the pipe diameter and slope,simulates the modified model,and analyzes the changes in node overflow and pipe network overload,proves the SWMM can meet the application requirements in practical engineering.