Simulation And Analysis Of Sponge City Drainage System Based On SWMM

The report of the 19 th National Congress pointed out that the urbanization rate in China has increased by an average of 1.2 percentage points over the past five years.The “heat island effect” and “turbidity island effect” caused by the ongoing urbanization process will increase the frequency of extreme rainstorms in the city.The proportion of impervious "gray" areas in cities has continuously increased,and the interception ability and infiltration capacity of the ground have been greatly reduced.The drainage system of the newly built urban area in the city cannot be well connected with the existing drainage system.The original drainage system of the city cannot adapt to the expansion and development of the city,which will increase the possibility of the occurrence of urban floods.In order to cope with the frequent urban hail disasters and the pollution of stormwater runoff,China proposed the construction of a “sponge city” stormwater management concept.Nowadays,more and more cities have begun to join the tide of spongy city construction,whether in the construction of sponge cities.In the engineering design,it is still important to use the rainfall runoff model to simulate the construction effect of the sponge city.In this context,this project is based on a sponge city construction project in southeastern China as an example.SWMM was used to accurately model the rainfall runoff model before and after the construction of the sponge city in the region: Arc Map software in Arc GIS was used to collect the collected pipe network.The data were generalized.The use of the Tyson polygon method was used to partition the catchment area.Using the Chicago model,six types of artificial rainfall time series for the typical rainfall return period were designed.The model was checked using the measured data.The model was validated.The Nash-Sutcliffe efficiency coefficient reaches 0.7 or more.After the construction of the sponge city in the study area,the stormwater conditions under the six design rain patterns were simulated.The runoff situation,pipe network overflow,and pipeline pressure conditions were analyzed.The waterlogging points of the pipe network in the inspection well were identified: J41-1,J23,J24.After comparing the results of the simulations before and after the construction of the sponge city under the four design rain patterns,it was found that after the construction of the sponge city,the runoff control rate was over 60% in the face of a small return period of rainfall,and the pipe network overflow situation and pipeline bearing.The pressure situation has been greatly improved,and the discharge peak discharge volume has been reduced by about 50%,and the peak time has been delayed by about 9 minutes.Germany is one of the countries with the most perfect rainwater management system in the world.This paper also introduced the HYSTEM-EXTRAN hydrological hydraulic simulation model in Germany.This model is compared with the SWMM model in detail from four aspects of the model principle,modeling process,model function,and simulation results.The comparison shows that the simulation results are in good agreement with each other,which further validates the accuracy of the SWMM model in the study area.