Analysis And Assessment Of Precipitation And Runoff Water Quality In The Southeast Of Beijing Urban Area

Beijing is facing the serious problem of water scarcity. The quantity of waterresources per capita and year is less than 300m3. This amounts to 1/8 of the nationalaverage and 1/30 of the international average. With the development of urbanizationand the improvement of the people's living standard, the contradiction against watersupply and water demand is becoming more and more serious. Besides water shortage,Beijing is also seriously affected by local floods. In recent years, available waterresource capacity reduces year and year, but still the storm water in large amount havenot been effectively controlled and reasonably used. The development of urbanizationincreased the storm flood peak, burdened the flood protection pressure. In order toalleviate water resources shortage and to reduce flooding, and to give more attentionon the rainwater use has great and practical meaning. In the present study, the precipitation at Beijing city was studied during theperiod from June 2002 to September 2003. 416 samples were collected at BeijingUniversity of Technology which is an urban area in the SE of the city with no majorindustrial activities and minimum traffic density. Sixteen times of chemical tests wereconducted for the natural precipitation, runoff from house roofs, runoff from trafficroads, and runoff from greenbelts etc. According to the environmental qualitystandards for surface water (GB3838-2002), 20 items of water quality indexes weremeasured. The results show that the water quality in runoff from different soilsurfaces changes litter during initial raining period, then the water polluted extentbefore is much heavier than that after. Strom water runoff collected from roofs ofBeijing city zone has been polluted to a rather severe degree. Road surface runoff ispolluted seriously. Pollutants concentrations in road surface runoff are significantlyhigher than those in roof and lawn runoff. Major pollutants of runoff are organicsubstance and suspend solids. Although the concentration of the pollutants changedalong with the surface runoff process, the variety tendency of concentration of thepollutants is higher in the initial stage of runoff. As the precipitation time go last withtime by, the concentration of the pollutants drop gradually. The concentrations ofpollutants at final stages, except organic pollutants, belong to the group â…¢ accordingto the environmental quality standards for surface water (GB3838-2002).