Study On The Influence Of Greening Roof On Hydrological And Water Quality Characteristics Of Water-deficient Urban Districts In North China

In recent years,the construction of sponge cities has gradually become an effective measure to alleviate the shortage of water resources,urban waterlogging,and rainwater runoff pollution in cities.The government has paid more and more attention to the construction and research of sponge cities.Greening roof is one of the important measures of sponge city.This paper investigates and studies the characteristics of rainwater runoff pollution of flat roof roof in Dalian City,a northern water-deficient city.According to the characteristics of roof runoff pollutants,a water-storage greening roof is designed,and the greening roof test and SWMM simulation study of northern water-deficient city are carried out.The main research results are as follows:(1)The characteristics of pollutants in roof rainwater runoff of water-deficient cities in North China were studied.Taking the roof runoff of Wankelang Runyuan Community in Ganjingzi District of Dalian City as the monitoring object,this paper analyzed the variation law of pollutants in runoff from different flat roof materials,and obtained that the pollutant concentration of roof runoff increased first and then decreased under the same rainfall intensity.Moreover,the pollutant concentration of asphalt felt roof runoff was higher than that of cement roof under different rainfall intensity conditions;under different rainfall intensity,the pollutant concentration of asphalt felt roof runoff was higher than that of cement roof.The larger the roof pollutant scouring effect is,the faster the change of pollutant concentration in roof runoff.(2)Optimizing test of green roof matrix material: select coal slag and light stone as matrix material,carry on single pipe penetration experiment of matrix material under sing le particle size,different particle size gradation and different material proportion,get sing le particle size,different particle size gradation,and so on.The permeability coefficient a nd pollutant removal efficiency of matrix materials with different material ratios were det ermined as follows:5-2.5mm:2.5-1.25mm:1.25-0.05mm=1:3:1,When the ratio of coal slag t o light stone is 7:3,the removal efficiency of pollutants is better.(3)Simulation test of hydrologic and water quality characteristics of greening roof: analysis of the changing rule of hydrological and water quality characteristics of greening roof under different rain intensity under different substrate thickness and different matrix design structure.The cutting efficiency of green house in face of Rain Water can reach 28.46% and 48.85%,and the reduction rate of Rain Water in hierarchical matrix design is11.88% higher than that in uniform matrix design,The removal efficiency of COD?TN?TP?TSS was 50.2%-69.1%?40.7%-56.6%?38.5%-61.8%?45.9%-82.8%respectively.The hierarchical matrix design was more uniform for COD?TN?TP?TSS increased by 8.48%?13.69%?10.60%?19.20%.(4)Research area status and greening roof simulation based on SWMM.Based on the data collected on the spot,the regional model for the study was established to simulate the current situation and the greening roof development,and the variation law of hydrological and water quality characteristics under the current conditions of the study area and after the greening roof development was obtained.At the same time,it was concluded that the reduction efficiency of the greening roof was limited.When the rainfall intensity was low,the effect on the hydrological and water quality of the study area was obvious,with the rainfall increasing.The improvement efficiency of hydrology and water quality decreases sharply with the increase of degree.There are 46 papers,31 tables and 51 references in this paper.