Simulation Of Rain Flood Control Effect On Urban Community Using LID Measures Based On SWMM Model

In recent years,with the large-scale development of urbanization in China,the proportion of population density and impervious area in cities is increasing.With the increase of large urban population,the water demand and sewage quantity of the city also increase sharply,and a large amount of impermeable underwater surface seriously hinders the infiltration of rainfall,which causes a large amount of rainfall to form surface runoff,resulting in the loss of a large amount of rainwater resources and may also lead to urban flood hazards.low impact development measures(Low Impact Development,LID)have the ability to reduce rainfall discharge and reduce flood peak,which can effectively reduce urban runoff and play an important role in urban flood control,improvement and protection of ecological environment.The effect of rain flood control can be saved by simulating the effect of LID measures under different rainfall intensity by SWMM model,and the LID measures after planning can be simulated by model before developing the site.According to the relevant regulations and indicators to adjust the amount of measures to reduce the blindness of project development and construction,can provide a reference for the design planning of similar real estate projects.A housing land project located in the southeast of Huairou District is selected as the study area,and the SWMM model and related measures parameters are established according to its natural situation and actual construction situation.On the basis of the relevant domestic norms and policies,two short-duration rainfall data of 3 years,5 years,10 years and 20 years h recurrence period were selected,and the SWMM model of the study area was established.On the basis of the characteristics of LID measures and the actual situation of the study area,4 measures of green roof,permeable pavement,rainwater garden and concave green space commonly used in real estate projects were selected,and the SWMM model was used to simulate the development before and after development.After nomeasures,use of single measures and use of rainwater harvesting measures four scenarios,from the infiltration,runoff,flood peak flow and water storage comparative analysis,the following conclusions are drawn :(1)when using a single LID measure,the rain flood control effect of each measure decreases with the increase of rain intensity,and the rain flood control effect of water permeable pavement and green roof in the four measures is better.The effect of reducing flood peak flow is better than that of lower concave green space when the rain intensity is small,and that of lower concave green space when the rain intensity is large is better than that of green roof.Green roof and water permeable pavement have better effect on reducing rainfall efflux and increasing water storage.The effect of reducing rainfall efflux on the green roof is better than that on the permeable pavement when the rain is strong.(2)The effect of rain flood control using a single measure is limited,the effect of rain flood control using rainwater harvesting and utilization measures is better than that of a single measure,and the goal of using LID measures after development to restore the hydrological characteristics of the study area before development is achieved.The effect of increasing infiltration and reducing flood peak flow increases with the increase of rain intensity,and the effect of reducing surface runoff decreases with the increase of rain intensity.(3)This paper uses SWMM to simulate the hydrological characteristics of the study area,which is practical and practical The results show that the use of rainwater harvesting and utilization measures is better than the common development model,and has certain reference value for similar project development planning.Above all,reasonable use of LID measures and their combinations can effectively reduce rainfall runoff,reduce flood peak discharge,make the rain water indicators stipulated in the Technical Guide for the Construction of Sponge City meet the requirements,basically achieve the development goal of maintaining the same hydrological characteristics before and after the development of the study area,and minimize the adverse effects of development and construction on the hydrological characteristics of the region.