Demonstration Study On Low Impact Development Technology In Green Building And Community

Long-term high strength development and construction and city disruptive led to a series of problems:the natural hydrological balance significantly broken,climate and environmental degradation,worsening waterlogging risk,loss of rainwater resources,serious storm runoff pollution,soil,water source partition,river base flow loss,city water body water quality deterioration and so on,and these conditions had been a wake-up call for urban development and infrastructure construction mode.In December2009,Shenzhen government decided to introduce the international advanced concept low-impact development of comprehensive utilization of rainwater and set guangming new district as a demonstration area for the comprehensive utilization of rainwater.This study carried out the demonstration coummunity in the first phase of shenzhen wanzhangpo relocation project.Based on early research and later site reconnaissance,data compilation,design and construct the demonstration community.To assess the impact efficiency of the low impact development technology on demonstration community runoff,monitor water quantity and quality of the low impact development technology outlet and the total demonstration community outlet.This study monitored the water quantity and quality of demonstration community,and selected three typical rainfall for effectiveness evaluation.The research focused on studying the influence of the green roof and green roof-bioretention facilities on rainfall runoff,the influence of low impact development facility for demonstration community on rainfall runoff and the influence in different return period under the model evaluation.The research results are as follows:?1?Study on the impact of green roof and green roof-biological retention facilities on rainfall runoff.1)Green roof and green roof-bioretention facility can obviously delay and the cut rainfall,the efficiency of the green roof-bioretention facility was slightly better than the green roof,which was not very significant.Green roof produced runoff lagged 8-28 min of the rainfall,and ended runoff lagged 18-38 min of the rainfall,the runoff peak lagged17 to 26 min,green roof-bioretention facility produced runoff lagged 15-39 min of the rainfall,and ended runoff lagged 16-37 min of the rainfall,the runoff peak lagged 8 to11 min.Compared to the ordinary roof runoff,the runoff volume reduction rate of green roof is 35.58%-84.16%,and the runoff volume reduction rate of the green roof-biological retention facility is 36.13%-85.41%.2)Green roof and green roof-bioretention facility can obviously reduce the EMC of SS and COD,and the effect of green roof-bioretention facility is better than that of green roof,but both can not remove TN,TP,NH₃-N stably.The green roof and green roof-bioretention facility has a significant effect on the load reduction of runoff,and the effect of green roof-bioretention facility is better than the green roof.Compared with ordinary roof flow,green roof can reduce the EMC of SS,COD,TN,TP,NH₃-N25.51%-45.02%,54.98%-67.39%,38.76%-64.39%,10.66%-9.59%,11.05%-38.88%respectively,green roof-bioretention facility can reduce the EMC of SS,COD,TN,TP,NH₃-N29.58%-51.02%,59.21%-70.44%,43.02%-59.87%,8.62%-59.87%,8.62%-33.68%respectively.Per unit SS,COD,TN,TP and NH₃-N load reduction of green roof was 56.82%-91.33%,76.5%-94.9%,71.9%-90.8%,41.8%-83.7%,59.7%-88.3%respectively,per unit SS,COD,TN,TP and NH₃-N load reduction of green roof-bioretention facility was 57.32%-93.06%,77.5%-95.7%,74.4%-91.4%,33.9%-84.3%,57.6%-89.3%respectively.?2?In the demonstration community,volume reduction rate of three corresponding rainfall was between 64.88%and 90.89%,compared with the traditional runoff volume,the coumunity with low impact development technologies reduced 41.57%to 86.42%.The concentration of SS,COD,TN,TP and NH₃-N was reduced by 56.55%-87.72%,72.04%-92.03%,71.85%-92.12%,51.58%-84.78%,48.00%-86.79%,respectively.?3?Simulated water runoff of demonstration project with and without low impact development technology in the green building and community model respectively,simulation results showed that:compared with the traditional community,under the interval period of 0.5,1,2,5a,runoff peak of the LID community delayed 7-8 min,3-6min,3-4 min,1-3 min respectively,the peak value was cut 30.00%-41.27%,30.00%-34.97%,20.27%-22.28%,20.27%-21.90%respectively,the total runoff volume was cut 48.16%,42.78%,36.74%and 42.78%,respectively.The total SS load of the LID community reduced 72.46%,71.67%,70.69%and 71.67%respectively,the total COD load reduced 71.43%,67.47%,64.46%and 67.47%respectively,the total TN load reduced 49.85%,46.64%,39.91%and 46.64%respectively,the total TP load reduced 40.67%,40.59%,39.99%and 40.59%respectively,the total NH₃-N reduced55.07%,52.92%,47.56%and 52.92%,respectively.Based on the study of the water quality and quantity from the greenroof,greenroof-biodetention facility and the total outlet in the demonstration community,it showed that sequencing and parallel LID faciliyies both had great effect in controlling runoff pollution,time delay of flood peak and cut water and had great significance in controlling the disaster of flood and source pollution reduction.We suggested that populize the application of low influence development rainfall utilization system in green buildings and communities.