Study On Rainwater Utilization In Urban Community Based On SWMM Model

Urbanization process brings a lot of convenience at the same time,also triggered a large-scale urban floods.Bad rainstorms occur frequently in large and medium-sized cities.Due to the large intensity of heavy rain in a short period of time,it is difficult for the old drainage network to discharge it in a short time.The acceleration of the urbanization process undermines the original properties of the underlying surface and changes the original runoff coefficient in the catchment area.The increase of impervious water surface weakened the urban surface rainwater infiltration capacity,and the increase of runoff coefficient in the catchment area increased the surface runoff.The use of rainwater has attracted wide attention all over the world,and urban residential area is the carrier of people's life.Urban communities play an important role in rainwater harvesting and utilization.Based on the SWMM model,this paper builds a low impact development model in the district to study the environmental and economic benefits brought by the rainwater utilization project.The study is based on the basis of the technical information from the low impact development at home and abroad.The results show that:(1)The low impact development technology has a significant improvement in the rate of surface runoff reduction.Under the four different conditions of rainfall recurrence period 1a,2a,5a and 10 a,the low impact development technology is effective.The reduction rates were 12.45%,14.86%,16.45% and 22.31%,respectively,and the reduction rates were 14.36%,16.46%,20.35% and 24.24%respectively.(2)The reduction rates of COD were 6.84%,9.57%,12.04% and 13.24%respectively under the conditions of 1a,2a,5a and 10 a.And the reduction rate of SSwas 8.67%,11.46%,13.47% and 12.83%.The reduction rates of TN were 16.45%,18.58%,19.78% and 18.76%.It is concluded that when the rainfall recurrence period is5 a,10a,the rainfall intensity increases and the effect of low impact development measures on COD,SS and TN will decrease.(3)The increase of rainwater infiltration was 51.41%,53.56%,64.52% and75.39%,and the low impact development measures could increase the amount of rainwater infiltration and reduce the surface runoff.It can purify the role of regional environment.Finally,according to the simulation of runoff and rainfall infiltration in the area,the volume of the rainwater storage pool is 280m3,and the operating spending of the rainwater storage tank is further analyzed.It is concluded that the rainwater utilization system can create a direct economic benefit of 4.4 yuan / m3,while creating economic benefits while reducing pollution to the urban environment.Through the analysis,it is found that the rainwater storage tank can improve the utilization of rainwater resources,but also alleviate the flood discharge pressure of urban drainage,thus alleviating the urban water logging disaster.