Study On Water Quality Regulation Rules Of Storage Tank Under The Background Of Sponge City

With the rapid development of urbanization,the water environment problems caused by urban rainfall runoff has become a key factor in the current urban development.Sponge city construction is a new model proposed in this context,which has a good effect on alleviating urban shackles.Among them,the storage pool has economic benefits and practicability for the new rainwater system or the renovation of the existing drainage system.However,the research results based on the control rules of surface source pollution storage pool are still rare.Based on this,this paper builds a SWMM model with the hydrological division of Zaohe River in Xi'an City,and the runoff coefficient method of designing rainfall in different return periods is used to verify.Combine the function and use conditions of the storage pool in the sponge city to establish the system goal.By comparing the simulation operation results under different intensity rainfall conditions,the operation rules of the storage pool are formulated and verified by actual rainfall data.The m ain findings are as follows:(1)The catchment area,pipeline network structure and waterlogging point of the storage tank in the storage system are generalized.The ArcGIS software is used to rationalize the sub.water district and the rainwater pipe network in the study area,and the underlying surface distribution map,the drainage network generalization map and the land use distribution map are obtained.Statistically study the deterministic parameters in the region,and build SWMM model based on measured data.The coefficient of variation by the runoff coefficient method was 4.71%,4.27%,and 2.79%,respectively,which met the requirement of±5%,and the model was reliable.(2)Combining the function and operation effect of the storage pool facility in the sponge city,from the overall construction of the city,and analyzing the rules and methods for the rational operation of the storage pool.Determine the system requirements,aiming at the reduction rate of rainwater runoff pollutants,and select the water level change rate of the inlet as the control variable to form the regulation relationship between the operating water level and the opening or closing of the inlet sluice.Establish a storage pool operation rule model to achieve the purpose of storage and decontamination.(3)The underground storage pool located in South Daming Palace is selected as a typical design to simulate the impact of the operation of the storage pool on urban runoff and water quality under different rainfall intensities.The overflow phenomenon occurs in the area where the rainfall return period is more than two years.The larger the recurrence period,the larger the overflow ratio and the longer the node overflow time.It is finally determined that when the rainfall restart period is less than two years,the reduction rate of rainwater runoff pollutants are the main control targets,and the operation rules of the storage pool are determined.When the water level rise rate of the water inlet node of the storage tank reaches 0.5cm/min,the gate is adjusted and stored.Using three measured rainfalls and long-sequence rainfall events to verify the effect of storage pool rules on urban stormwater runoff pollutants reduction.The reduction rate of rainwater runoff pollutants reached more than 30%,which provided reference for the design of pollution control facilities in actual proj ects.