Study On The Runoff Control Technology Of Gridded Vegetation Measures In Green Building And Community

Urbanization process, with the water shortages and environment damage of urban water resources, coupled with the increased in impervious surface change the regional water cycle andincreased the load on urban drainage systems, "drought" and "floods" became a growing problem. With the "sponge city" campaign carried out, a series of stormwater management technologies have been proposed and utilized. Green building and community occupied 20~32% of the urban construction land.It significant to use rainwater management measures and optimize their combined operation in the building and community.Based on the technical characteristics of the individual stormwater management measures and the urban grid management concept, a gridded vegetation runoff control technology is proposed in green building and community. The runoff control effectiveness of the individual stormwater management measures was been system evaluated. The green roof runoff control technology was monitoring and analysis for three consecutive years. Finally, the gridded vegetation runoff control technology was assessd by SWMM software. The main conclusions are as follows:(1)Individual stormwater management measureshavedifferent structure, function and design methods. Permeable paving improves the water penetration performance of impervious surfaces. Grass ditch has a good runoff transmission and pretreatment effect. Bioretention facilities can control runoff pollution to a greater extent.Individual stormwater management measures should be exerted and integrated, so as to achieve optimal control of rainwater runoff in green building and community.(2)The research of green roofs runoff control ingridded vegetation measures, the results are as followsf:1) Increasing the substrate thickness of green roofs can enhance the SS, TN and NH3-N control effect, but can not enhance the TP control effect. Organic matters get the best control effect with the substrate thickness of 150 mm. The modifier recycled brick can strengthen the control effect of organic matter and prelates can strengthen the control effect of phosphorus. By adding recycled brick and prelates, green roofs were able to improve on TN and NH3-N removal, but SS concentration would rise. Japonicus were more adaptable than Yulong grass in test environment, its runoff quality was better than Yulong gras in addition to TP.2) In the runoff of green roofs, SS and NH3-N decreased year by year, NO3-N increased year by year, TN interannual remained stable, COD and TP interannual change was not significant.3) In addition to SS index slightly higher, the improved roof(substrate thickness of 150 mm, garden soil: perlite: vermiculite = 8: 1: 1, vegetation select japonicus) runoff quality includes COD, NH3-N, TN and TP was better than garden soil roof and bare roof. In the improved roof runoff, the EMC values of SS, COD, NH3-N, NO3-N, TN and TP in improved roof runoff were(14.43~53.19),(13.51~36.74),(0.340~0.543),(0.456~0.859),(0.964~1.452) and(0.034~0.173) mg/L, the EMCs values were 36.79, 23.67, 0.441, 0.632, 1.131 and 0.079 mg/L, the pollutants removal rate were-145.21%~-0.91%,-110.67%~-33.10%,-7.72%~61.28%,-385.93%~5.02%,-30.96%~59.38% and 1.60%~27.44%. The water runoff control of improved roof was better than garden soil roof and bare roof. In the improved roof runoff, the runoff delay time was 16~26 min, the peak delay time was 27~51 min, the peak reduction rate was 50.0%~80.6%, the runoff control rate was 18.0%~45.4%.4) With the extension of the time runoff, the NH3-N content increased, NO3-N content decreased and TN content was substantially unchanged.(2)The runoff of community usd gridded vegetation measures was simulated by SWMM. In return period of 1a, 2a and 5a rainfall event, peak runoff extend time was 15 min, 10 min and 10 min. The peak reduction rate was 74.96%?72.23% and 67.58%. The runoff volume reduction rate was 63.30%?60.63% and 58.57%.The total runoff pollutant reduction rate(SS) was 71.99%?61.22% and 45.44%. The total runoff pollutant reduction rate(COD) was 69.61%?53.24% and 34.46%. The total runoff pollutant reduction rate(TN) was 53.82%?42.59% and 21.21%. The total runoff pollutant reduction rate(TP) was 55.33%?45.79% and 32.40%.In green building and community, using gridded vegetation runoff control technology could fully demonstrate the technological advantages of each individual stormwater management measures. It was help for achieving effective control of rainwater runoff, which was important for the stormwater management in city.