The Research Of Engineering Construction Mode And Rainwater Recycling Based On The Sponge City

With the rapid development of economy in china,the problem of water resources is worsening.The urbanization process directly leads to the increasing rate of Impervious land,thus the problems of groundwater recharge and urban waterlogging to become more serious every single day.The rainwater usually forms runoff and directly flows into the river nearby,which not only wastes water resources,but also causes serious pollution as the non-point source pollution.At present,water quantity and quality problems influence each other,and the urban water crisis is getting worse and worse.Therefore,how to manage urban storm water and reuse rainwater after purification is both an opportunity and a challenge.Based on the sponge city,this paper analysis the runoff Management technology at home and abroad as well as investigating the LID（Low Impact Development）facilities.Using the SWMM（Storm Water Management Model）to study the engineering construction mode combined with the principle of sponge city and the regional characteristics in our country.But beyond that,the writer analyzed the purification effect of rainwater by wetland and optimized the design parameter of wetland.In summary,the specific research contents and results are as follows:（1）according to the applicability analysis of single sponge facilities,it is concluded that the permeable pavement and the sunken green space can be used as the main facilities in a wide range,and bio-retention cell,vegetative swale and green roof should be used as auxiliary facilities.Combined construction mode（90%permeable pavement+50%sunken green space+green roof+vegetative swale）can effectively control the rainfall in high and low recurrence interval.（2）Measuring the quality of the initial rain in zhengzhou,and getting conclusions that the concentrations of COD,TN and TP were 140.25 mg/l,13.31 mg/l and 0.35 mg/l,respectively.Meanwhile,the rainfall in zhengzhou was alkaline with high carbon-nitrogen ratio.（3）Through the detection of the inlet and outlet water quality,it is found that the wetland system has excellent removal effect on COD and NO₃^--N,with the average removal efficiency as high as 84.07%and 95.88%.The results showed that zeolite enhanced the removal of nitrogen,and vermiculite had the strongest adsorption on phosphorus.The experimental study on the horizontal-flow wetland showed that the reed wetland had the best purification effect,and the purification capacity of the horizontal-flow wetland was slightly stronger than the vertical-flow wetland.（4）Through the analysis of plants and microorganisms,it can be concluded that the plants will release nitrogen and phosphorus to cause pollution when wilting,so the plants should be harvested in time.The carbon sources of microorganisms are mainly carbohydrates and amino acids,and the microbial communities in each wetland have different composition and metabolism characteristics.（5）The initial rainwater can be used as urban miscellaneous water,landscape water,industrial water and irrigation water with the advanced treatment of wetland,which can alleviate the water shortage problem in a certain extent.Sponge city is a strategic decision of water resource management at present.This paper puts forward the typical construction mode to build a sponge park,and makes Suggestions on the design parameters of rainwater wetland.On the whole,it has certain reference value and application significance to the promotion of sponge city and the reuse of rainwater.