Technology Research And Demonstration For Urban Rainwater Utilization

The acceleration of urbanization makes the city underlying surface changed and the runoff time shortened makes the impervious area, the surface runoff, the peak discharge and the probability of flood produce increased. Moreover, most rainfall drains away in the form of surface runoff and lessens the groundwater recharge. But the resulting problems, such as the aggravation of rain-runoff pollution, the fall of ground water levels and the degradation of urban ecological environment, have restricted the sustainable development of the city. Therefore, the research on urban rainwater resources use has important academic significance and practical value to ease contradiction between water resources supply and demand, to conserve groundwater, to relieve urban rainfall flood load, to regulate the climate, to reduce non-point pollution that caused by urban storm water and runoff and to improve urban ecological environment.This study took the office area of Irrigation Center in Yellow River Institute of Hydraulic Research and the water-saving irrigation proving ground as the test areas, by targeting rain resource and through experimental investigation, analyzed the rain water availability and put forward the rain water use technology and approach, also with the engineering demonstration, obtained the following results:(1) By analysis different sessions of rainfall to runoff process, the runoff coefficient of roof, canopy and road surface were0.94,0.96and0.80;(2) By researching the change rule of water quality with rainfall and rainfall duration, the relativity relationship between water quality characteristic value and index, the relationship between SS and COD was the best, the synergistic effect was obvious.(3) According to the rainfall characteristics in Xinxiang city, the calculation method for urban rainwater utilization potential was determined. Taking the office area and proving ground as a case to analysis and the average annual rain water availability was1850m3.(4) Taking the office building roof as the water catchment area, the demonstration project of rainwater using was constructed. The project adopt the roof rainwater collected way and composed by down pipe, PVC tubing, open reservoir on ground, irrigation system, overflow port, water supplement system, and so on. The design recurrence interval of reservoir is5years, the duration of design storm is30minutes, the design rainfall intensity is193.41L/ (s·hm2), the design flow is27.54L/s, the volume is46.5m3, the gradient of collecting pipe is0.01, the roughness coefficient is0.009and the pipe specification is160mm. The available rain water collecting in demonstration is502.52m3. The research result can provide reference for rainwater use of water shortage city in northern river basin.