| With the development of the city,the city is more crowded,and the use of land in the city is more and more frequent,and the hardened area of various roofs and pavements is increasing,producing more surface runoff and causing urban waterlogging.On the other hand,the surface runoff also contains many pollutants,such as heavy metals,organic matter and silt,which are harmful to human beings,such as heavy metals,organic substances and silt,which are doped in the surface runoff and enter nature,causing the deterioration of the water body and the aggravation of the urban source pollution.The ecological rainwater system is a new urban rainwater,which combines the natural ecological environment and artificial drainage measures without changing the natural ecological environment and the natural ecological environment and artificial drainage measures.It emphasizes that the green facilities are used to make the urban parties face the rainwater collection and utilization to achieve the maximum value of the resources and maintain the recycling of urban rainwater resources management methods.Combined with the actual situation of Qihe County,the project simulates the planning of the ecological rainwater system of Qilu high tech Zone in Qihe County of Dezhou city by SWMM model,and solves the problem of the urban waterlogging and the pollution caused by a large number of industrial land caused by the risk of the inverted irrigation and breakwater of the the Yellow River river.This paper first analyzes the Qihe County Qilu Hi-tech Zone,mainly analyzes its comprehensive status,rainfall law,regional water balance and the concentration of rainfall pollutants,and obtains some basic data.Based on the basic data of the SWMM rainwater management model,the basic data are used to model Qilu high tech Zone,mainly to study it.The generalization of the drainage system and the selection of related hydrologic and hydraulic parameters;secondly,the traditional pipe network analysis is carried out on the model constructed,and the sensitivity analysis and rate determination of hydrologic and hydraulic parameters are carried out before the analysis,and the model after the parameter rate is obtained and simulated,and the simulation results are analyzed.According to the simulation results,the high and new Qilu is determined.The ecological rainwater system is used in the area.The field experiment is mainly used to study the interception effect of the concave green space,green roof and pervious pavement on the water quality and water.Finally,the results of the field experiment are brought into the original SWMM model.According to the model law,the SWMM model of the ecological rain water system in Qilu hi-tech zone is constructed and simulated.Compared with the traditional network,the necessity of constructing the ecological rainwater system in Qilu high tech Zone is achieved.Through the above research content,we can come to the following conclusions:(1)The annual average rainfall of Qihe county is 668.4mm,the annual average evaporation is 1987.7mm,the rainfall is mainly distributed in 4~10 month,accounting for 92.15% of the total annual rainfall,of which 6~9 month(summer)is the most,and the natural rainwater of 61.21% Qilu high new zone,which accounts for the annual rainfall,satisfies the grade V of the surface water of COD,TP and TN,and SS meets the level of urban sewage of three grade standard.(2)Based on the rainstorm intensity formula of Ji'nan,the rain type process line of Chicago Qilu high tech Zone is synthesized.In the 2H rainfall duration,45~50min will peak rainfall intensity,and with the focus on current increases,the greater intensity of rainfall.According to relevant reference documents and data,the Manning roughness coefficient is 0.25,and the Manning roughness coefficient of the water permeable area is 0.012;the reservoir of the permeable area is 6.5mm,the reservoir of the water zone is 3.5mm;the maximum infiltration rate of Horton(Horton)is 76.2 mm/h,the minimum infiltration rate is 3.18 mm/h,the infiltration decay constant is 2.75;the Manning rough of the pipeline The roughness coefficient is 0.013.(3)The hydrologic hydraulic parameters of SWMM model in Qilu high tech Zone are determined by Morris screening method and runoff coefficient method.The runoff coefficient of SWMM model is 0.661 under the rainfall sequence of 5 years,which meets the runoff coefficient of Qilu high tech Zone(0.5~0.7).The SWMM model was selected as the rainfall sequence of 2 years and 10 years of rainfall as the rainfall sequence.The runoff coefficient was 0.625 and 0.686,which all met the requirements of the standard.(4)The rain gauges are taken as time series in the period of 1 years,2 years,3 years,5 years and 10 years.The rainfall duration is 2h,and SWMM simulation of the rainwater pipe network after parameter calibration is carried out.The results show that in the 1 year recurrence period,there are 9 nodes overloading,9 nodes have a flood,the time is about 01:00,and the peak time of the rainfall is similar;there are 9 pipe segments overloading the canal.(5)Through the simulation of the concave green space system through the experimental device,there is no water surface runoff,the average removal rate of COD is 48.60%,the average removal rate of SS is 63.17%,the average removal rate of TN is 45.06%,and the average removal rate of TP is 54.19%.With the built green roof as the experimental object,there is no overflow of rainwater in the case of rain and rain and rain.The average removal rate of COD is 90.21%,the average removal rate of SS is 69.27%,the average removal rate of TN is 27.61%,and the average removal rate of TP is 92.68%.Through the simulation of the permeable paving system with an experimental device,the surface runoff of the effluent does not exist.The average removal rate of COD is 56.12%,the average removal rate of SS is 55.17%,the average removal rate of TN is 46.35%,and the average removal rate of TP is 51.78%.(6)Through the combination of concave green space,green roof and permeable pavement,the ecological rainwater system planning of Qilu high tech Zone is planned.The simulation results show that there is no surface runoff in the planning area after the planning of the ecological rainwater system in the low present period,which can delay the runoff generation of 15~30min,the delayed peak flow rate is 5~14min,the average runoff total reduction rate is 85%,the average runoff peak reduction rate is 87,and there is no pipe network under the low heavy current period.Overload,high current,overload conditions are not serious. |
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