| China’s urbanization has maintained a high growth rate for many years.The proportion of urban population and the area of urban built-up areas have increased exponentially.However,the extensive development method also brings huge hidden dangers.The hardening of urban built-up areas The impervious area has rapidly increased,the properties of the underlying surface of the city have changed,the permeable area of green areas and lakes has been reduced,the time of runoff confluence during rainfall has been shortened,the flood peak has been raised and advanced,and the city is prone to waterlogging in the rainy season,which has seriously affected the residents’ health.Health level of life.In this context,my country issued the sponge city policy in 2014,and selected 30 cities with different geomorphological environmental characteristics as pilot projects in two batches across the country.In the past five years,my country’s sponge city construction has advanced by leaps and bounds,but at the same time it has been exposed.Based on the existing part of the research,this paper identifies the construction benefits of the roof rainwater runoff reuse system,an important part of the sponge city construction,and uses the "Sponge City Construction Performance Evaluation and Assessment" The Measures are based on actual and demand identification and selection of four aspects:water ecology,water environment,water resources,and water security,using the quantitative evaluation method of environmental resources to quantitatively evaluate the construction benefits of roof rainwater runoff reuse system.Research indicates:(1)Through experiments,the rainwater runoff coefficient of building roofs in Xi’an area is determined to be 0.778,and the variation law of roof rainwater runoff water quality over time is combined with the runoff-rainfall process diagram,and it is found that the accumulated roof rainwater runoff collected over time The pollution concentration gradually decreased and eventually stabilized.(2)The study analyzed the differences in the final collected runoff water quality and volume of the three collection methods:no abandonment,runoff 5min before abandonment,and runoff 10min before abandonment.Whether long-term rainfall or abandonment of flow has little impact on water quality and quantity.Whether the runoff is abandoned or not has a significant impact on short-term rainfall.The runoff 10min before the abandonment can reduce the water quality indicators of the final collected rainwater runoff by 3.3%to 2.1%,but at the same time the final collected water volume has also decreased by 4.5%.(3)The simulation researched the influence of different roof materials and designs on the roof runoff coefficient,and found that the tile roof has a more obvious effect on the reduction of runoff compared with the cement roof,and the dryness of the roof has a certain influence on the roof runoff coefficient.The runoff coefficient of cement roofs is higher between 0.81 and 0.91.The impact of cement houses with different slope designs on runoff is reflected in both runoff and runoff peaks.Roofs with higher slopes have a larger runoff coefficient and generate more runoff.More,and roofs with lower slopes will have larger runoff peaks.(4)Taking Fengxi New City in Xixian New District as a research case,the proportion of roof coverage in Fengxi New City area is determined to be 18%by manual marking method,with an area of about 44.8km2,which can generate about 1.18-1.35 million tons of roof runoff each year.Using the quantitative evaluation method of the benefits of the roof rainwater runoff reuse system,the potential benefit of the construction of Fengxi New City is estimated to be 3,398,300 to 3,759,400 yuan per year.The potential benefits of roof rainwater runoff reuse system perform well and have high investment value. |
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