| The paper takes the hydrological data in Xifeng district Qingyang city as a foundation, has analysed and designed the urban rainwater collection and utilization system. First using the urban hardening collection surface, the pipe net layout and the Tianhu lake in the end of pipe network gathers the rain water, then through irrigation, afforestation, environmental sanitation, ground water recharge, traveling landscape, cultivation and so on takes full use of the water resources. By testing and studying on the runoff yield, water surface evaporation, water quality in the process of the rainwater collection and running scheduling of lake water in the process of rainwater using, obtained the following conclusions:(1) The relation equation between practical production flow and rainfall of per unit area of rainwater catching field was Q ' = 0.104P?0.382, R 2 =0.993; The relation equation between practical rainwater collection efficiency and rainfall was RCE = 0 .262ln( P) +0.002, R 2 =0.866.(2) The general trend of water surface evaporation increases gradually from January to August, and decreases form August to December. The water surface evaporation is the largest in August and the smallest in December. The water surface evaporation of experimental observation only occupies the theoretical value 55.4%, and the monthly distribution proportion of water surface actual Evaporation is smaller than the theoretical value from January to March, other months of this value is bigger than the theoretical value.(3) In monitor 12 indexes, pH, the chloride, the copper, the zinc, the nitrate, the sulfate and the lead meets "Surface Water Environment Quality Standard" I; the total phosphorus, the chemical oxygen demand and the five day biochemical oxygen demand and the escherichia coli meets "Surface water Environment quality Standard"â…¢; Only the total nitrogen has not achieved "Surface water Environment quality Standard" V, which is the lowest requirements.(4)It was feasible to infiltrate and recharge groundwater by using artificial wetland; There was great limitation to recirculate groundwater by small scale filling well which waits for further improvement in present's test project.(5) The paper obtains the agricultural irrigation water consumption and surplus water which the Tianhu lake can provide by the storage capacity adjustment computation, respectively is 90,000 cubic meters and 64,700 cubic meters, under the prerequisite condition of definiting the environmental sanitation, afforested and loss water volume. The irrigation water consumption accounts for the annual duplication water Storage capacity 24%, the surplus water accounts for the annual duplication water Storage capacity 17%. The irrigated area is 1500 Chinese acres which is the biggest, at this moment.(6) Environmental Impact Assessment: The project'planning, construction and operation of lake rainwater collection system don't have the conditionality environmental effect, besides waste of land resources caused by submerge, this project is reasonable.(7) The implementation and operation of rainwater collection in project area can prevent soil erosion about 117.4ha annual. It has controlled project area soil erosion phenomenon effectively. (8) The urban rainwater collection and utilization is a comprehensive ecology hydraulic engineering that integrates agriculture irrigation, the environmental sanitation afforests, soil and water conservation, the tourist landscape, the urban flood control and so on into one system. The urban rainwater collection and utilization system which takes the artificial lake as the carrier founds the new pattern for the large rainfall city highly efficient use of the rain water, and has the considerable benefits of society, economy and the potential benefit of ecology. |
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