Study On The Stormwater System Reconstruction Of High Density Community With LID Measures

High speed urbanization process resulted the increase of impermeable underlying surface area in China and the change of original structure and function of the underlying surface.Urbanization also has an influence on the city climate characteristics,lead to frequent storms.In addition to the low construction standard for urban drainage system resulted serious waterlogging and water pollution occur when cities in our country encounter heavy storms,they can cause losses to citizens' lives and properties and destroy city daily order.As the main mode of residential construction in our country,the high-density building area is also the starting point of urban rainwater drainage system.The effect of rainwater management in this area is of great significance to the whole urban rainwater system.The low-impact development technology is a scientific and reasonable way tosolve the rainwater problems.For the sustainable management on rainwater,low-impact development transform on housing estate without delay.By learning from the advanced theory and practical experience,and based on the present situation of Wuhan,this paper designs the LID measures for a high density housing estate in Wuhan,according to the designed runoff control rate.On this basis,the low impact development stormwater system model was built and applied to the demonstration project in housing estate.Through the rainy season were actual rainfall monitoring and water sampling testing before and after the demonstration area of LID transformation,and with the actual test data and simulation data comparison,using the transformation of the former data model analysis,the improved LID data reconstruction effect prediction analysis.In the design rainfall return period were 1 years,3 years,5 years under the simulation of the area in the before the LID transformation and after the transformation,analysis of the changes of total emissions and pollutant emissions,runoff flow and pollutant concentration in the whole area of the drainage volume of contrast.In different rainfall return period,drainage flow peak cut rate reached 40%,39.1%,34.7% and 33.3% respectively,the pipeline discharge of pollutants removal rates were 43.4%,43%,42%,41.48%;the total amount of pollutants removal area put respectively.42.1%,39.86%,39.16%,37.11%;after the transformation of LID,the overflow of inspection wells in the district was greatly reduced,85.7%,63.6%,62.2% and 50% respectively.The results show that low impact development can effectively reduce the runoff,reduce pollutant emissions,reduce the overflow risk of storm water network and improve the runoff pollution of rainfall.In order to meet the requirement of runoff control rate,this paper puts forward some suggestions for the improvement of the original LID,and the transformation of the green roof and the rain bucket in the transformation scheme,the peak discharge rate of the district is 71.05%,without overflow.On the transformation of the project cost estimates,in the LID transformation project,the cost of the cost of hardening pavement reconstruction accounted for up to 81%.The actual engineering and simulation combined study of LID before and after the transformation of residential rainwater system,has an important practical significance to the high density residential area of our country in the future of the rainwater drainage system planning and stormwater management plan.