Application Of SWMM In Urban Rainfall Simulation And Prevention Of Internal Warts

In recent years,the economic development of Shenmu County has been rapid,but the city’s flood control and drainage system has not been effectively improved.The pace of urbanization far exceeds the construction of urban flood prevention and drainage systems.Therefore,whenever a storm hits,it will appear "The phenomenon.This article regards the Jinjie Industrial Park and its neighboring area in Shenmu County,Yulin City as the research object,simulates the indigence situation in the study area under different return periods,analyzes the causes,proposes the engineering transformation,adds additional LID measures,and adds rainwater storage tanks,thereby increasing the Study the drainage capacity of the area to achieve the purpose of preventing and treating internal disasters.The quantitative results of the improved results are analyzed and the results are as follows:(1)Under P = 1a,P = 2a,the flow patterns of the six outlets were analyzed and it was found that they were in line with the general rules of urban stormwater.According to the simulation results,only some nodes overflow when P=1a and 2a,but when P=5a,about 60% of nodes overflow.According to actual investigations,the rainwater pipe network of Jinjie Industrial Park in Shenmu County was laid based on the specification of outdoor drainage,and the return period of the heavy rain was used once every two years.The actual easy-to-fly area was in good agreement with the simulation area.Prove the accuracy and applicability of the model.(2)The current rainwater system is simulated under five different rainstorm periods of P=1a,2a,5a,10 a,and 20 a,and the number of overflow nodes,the number of pipe overloads,the overflow start time,and the overflow The quantitative analysis wasperformed for the duration of time.The results showed that as the return period of design storms continued to increase,the number of overflow nodes,number of overloaded pipes,and flood peaks in the drainage network system in the study area were also increased,and the time for flood peaks was also increased.In advance,the overflow duration also increases.(3)According to the reasons for the limited drainage capacity of the existing rainwater pipe network,reasonable technical measures are proposed to improve:engineering transformation,adding LID measures and adding rainwater storage tanks.In the SWMM model,simulations under different return periods P=1a,2a,5a,10 a,and20a indicate that the reduction rate of the number of node overflows after the engineering transformation is: 66.67%,67.86%,53.03%,respectively.25.35% and8.97%;the number of node overflows after the LID measures were added decreased:100.00%,96.43%,87.87%,70.13%,and 60.27%;the reduction rate of the number of node overflows after the addition of a rainwater storage tank was reduced.It is:100.00%,42.86%,46.97%,15.50%,0.00%;the reduction rate of the number of node overflows after combined improvement is: 100.00%,100.00%,100.00%,0.82%,and8.97%.It can be concluded that the three technical measures can effectively reduce the number of node torrents,but the combined effect of the three technologies is the best.Therefore,three combinations of measures are often used in the project to reduce the risk of urban internal pollution.