The Research And Majorization In Subsided Green Land Of Spongy City

With the process of urbanization accelerating,the scale of the city has been expanding,and the contradiction between people and urban ecosystem has become increasingly prominent.Among them,the urban road water ecological problems seriously affect the carrying capacity of urban ecological environment and challenge the resilience of urban development.Urban waterlogging frequent,road surface runoff serious pollution,lack of road green structure is the traditional urban road water ecological problems of the three major performance.With the natural accumulation,natural infiltration,natural purification as the essence of the "sponge city" concept proposed,and the low impact of the practical application of the development of technology to solve the urban road water ecological problems provide specific technical measures.Among them,the sunken green space has been widely used in the construction of urban road green space because of its outstanding reduction of flood peak,control of road runoff pollution and creating beautiful green environment.In this paper,the collection and sampling of pavement runoff,green soil and greenbelt plants in subsidence-type greenbelt were collected by means of meteorological and hydrological,soil optimization and plant matching.Aiming at the outstanding problems such as soil degradation and poor plant growth in the degraded green space in the real environment,the specific methods of the optimization of the subsidence green space were discussed by experiments,laboratory simulation and design improvement.This study has achieved the following results:1.The seasonal distribution of rainwater distribution in Fengxi New Town is obvious.From May to September in summer,rainfall accounts for 32% ~ 39% of annual rainfall.Autumn is 10 to 11 months,about 31% to 36%;winter 12 to February the least rainfall,about 3% to 5%;spring 3-5 months accounted for 24% of the annual rainfall to 29%;The COD,SS,TN and TP contents of the runoff pollutants were determined.The peak value of COD was 289 mg / L,which was 2.5 times of that of the "Integrated Wastewater Discharge Standard".The pollution of the runoff was serious.2.The soil water quality and soil total porosity of average water were 4.32 g / cm3 and 1.39 mm / h,respectively.The soil water quality and soil total porosity of average water were 4.25 g / In general,the water quality of soil quality in the urban green space of Fengxi New City is high,and the saturated water conductivity of soil is low,which causes the circulation of water in the soil to be poor,which affects the growth of the plant.At the same time,the average reduction rate of COD,SS,TN and TP was 28.10% ~ 39.34% in the runoff reduction experiment.In the calculation,in accordance with the local conditions of the sunken green land subsidence elevation should be 210 mm.3.Fengxi New Town Road,there are 59 kinds of subsets of green plant species,belonging to 52 families,102 genera.Among them,there are 11 kinds of trees or small trees,there are 23 kinds of shrubs,25 kinds of herbs.The road has nine typical plants,but some of the plant growth is bad.By simulating five kinds of unfavorable environmental conditions,nine kinds of typical green plants were resistant to bad environment,such as Ceratophyllum demersum and Hemerocallis fulva,and were suitable for the plant species.4.Design three kinds of modified methods of soil organic matter,and through the poor physical properties of soil improvement,the improvement of road surface runoff pollution reduction efficiency,for the promotion of 9 kinds of typical plant growth of data analysis.Organic material improvement method 3(soil): green plant waste: organic fertilizer = 7:5:2:1)decrease the soil mass moisture content by 31 percent,improve the soil saturation conductivity of about 64.4 times;The removal rate of COD,SS,and TP was increased by about 25% on average.The average height of the nine species of plants increased by 35.6%,the leaf area increased by 25.6%,and the average chlorophyll content was 42.1%.The improvement of reduction efficiency,the optimization of soil character and the promotion of plant growth are most remarkable.Compared with the analysis,the synthesis effect of organic material improvement method 3 is optimal.