Research On Application Of Low Impact Development Of Rainstorm Facilities Planning Based On Sustain

Urbanization promote the increase of urban impervious area, rainfall runoff volume and peak runoff, flood peak is formed time is shortened and waterlogging frequent incidents. The traditional stormwater management mode has been unable to adapt to the characteristics of rainfall, urban stormwater control and utilization has become a hot issue in the world.This study analyzed the structure, mechanism, parameters, advantages, disadvantage, and the applicable conditions of the low impact development stormwater facilities which is divided into water quantity control, water quality control and both water quantity and quality control. Take block A of YN area in a large city in North China as study object, according to the soil types, rainfall, topography, evaporation and groundwater, simulate and analysis the runoff volume and peak runoff for 1 year to 100 years period.The results show that the peak runoff discharge and runoff volume has significantly improved either before and after the series set and arranged in parallel low impact development stormwater facilities, reduce the efflux of water of the downstream channel and the municipal pipe network, ease the load of urban drainage system. So, it can provide technical support for the control and utilization of urban rainwater. Due to the detention volume of the parallel set did not get maximum utilization, the runoff reduction was lower than that of the series system. For high intensity rainstorm, parallel set can make full use of the unused volume in the antecedent rainfall to control runoff, which make the reduction decreased slowly in series connection.The simulation results for the rainfall of 1 year, 5 years and 50 years in the YN area show that the sand filter, green roofs, penetration pavement, infiltration ditch, rain garden, sunken green, grass ditch and dry ponds is applicable. Low impact development facilities in block and street can store all runoff generated from 1 year rainfall; runoff coefficient of rainfall of 5 years can be decreased from 0.58 to 0.14, in line with the standard of new districtdrainage of runoff coefficient which is less than 0.4; for 50 years of rainfall, the rainfall intensity, peak flow and total runoff are much higher that block and street level low impact development facilities can not reduce the large amount transient runoff, dry pond which is located in watershed can store the runoff effectively that the total outflow is 0. Low impact development facilities improve the city's flood control standards, increase the rate of utilization of rainwater and reduce the loss of flood disaster.