Evaluate And Analyze The Vulnerability Of Urban Stormwater System Based On SWMM

Rainwater drainage system is an important infrastructure of the city, it plays animportant security role in reducing and eliminating the water in the roads, and avoidingurban waterlogging. With the rapid development of the city and the apparent impact ofurban heat island, the flows of the urban surface runoff becomes large and the speedbecomes faster, these cause the urban rainwater system drainage load increased and theurban waterlogging risk increased. Therefore, it is necessary to adopt a scientific approachto carry out a comprehensive analysis of the overall drainage capability and safetransmission capacity of the existing stormwater system， for the preliminary work toimprove the drainage capacity and rainwater system rebuild.On the basis of analyzing the current status of urban rainwater system, puts forwardthe concept of urban rainwater system vulnerability, determines the vulnerability index ofthe rainwater system.Using analytic hierarchy process (AHP), constructs the rainwatersystem vulnerability evaluation index system， using the weighted synthesis method,establishes the urban rainwater drainage system vulnerability evaluation model, andaccording to the relationship of fragile degree, return period and security, initially sets theurban rainwater system vulnerability evaluation standard.The study put CL district as theresearch object， assessments the drainage system vulnerability of the community， thenconfirms the important factors that impact the vulnerability of the stormwater system. Andsimulate and analyse these important factors under different conditions by SWMM，confirms the affect extent that the important factors means to vulnerable degree and systemdrainage effect，and thus make the most effective measures to reduce the vulnerability ofrainwater drainage system， to provide relevant decision-making basis for the city’sconferring.This study assessments the rainwater system vulnerability of the CL district, theevaluation results show that the fragility of the drainage system of this district is0.7030,belongs to high vulnerability and the safety of the system performance is poor；When thecity suffered a rain its retune period year is from1to5years, the city is easy to form aslight waterlogging. Through analyzing the size of the attribute values and the index inproportion to the physics vulnerability of the system and social vulnerability of the system,determine the key indicators of the community factors are: pipe diameter, pump stationadjustment ability, the rain pool adjustment ability, the surface permeability rate and rainwater management level. Through SWMM simulation of different scenarios for eachkey indicators to determine the significance of vulnerability reduction effect measures:when the return period is3~5a year of rainfall, the effect of increasing the permeableground area to control the overflow of network nodes is the most significant, when the thereturn period is5~10a year of rainfall, the most significant effect measure is pumpstation and rain pool. The measures to reduce the vulnerability of the rainwater system as awhole, according to the significant from big to small is arranged in the order: add rainwaterpumping station and rain pool, add the rain pool, increase permeable ground area andincrease the pipe diameter. In actual rainwater system transformation, various measurescan be used in combination, can achieve better results.