[Capacity of extensive green roof to retain rainwater runoff in hot and humid region]

Ying Yong Sheng Tai Xue Bao. 2017 Feb;28(2):620-626. doi: 10.13287/j.1001-9332.201702.038.
[Article in Chinese]

Abstract

The water logging has become the environmental problem of major cities with the sharp increase of impermeable urban pavement as the contributing cause. Abroad, the green roof has been widely used as a practical measure to intercept rainwater, yet the capacity of green roof to retain rainwater varies with climate conditions. As the hot and humid climate zone features high temperature, humidity and precipitation, it is meaningful to study the capacity of green roof to retain rainwater under such climatic condition. In this research, 3 plat forms were set up in Guangzhou in rainy and hot summer to test the capability of simple green roof to retain rainwater runoff, and the efficiency of green roof to retain rainwater under local climate conditions was worked out based on the meteorological observation and data measurement during the 13-month test period. The results showed that the simple green roof with a substrate thickness of 30, 50 and 70 mm could retain 27.2%, 30.9% and 32.1% of precipitation and reduce the average peak value by 18.9%, 26.2% and 27.7%, respectively. Given an urban built-up area of 1035.01 km2 in Guangzhou and a roof area percentage of approximately 37.3% and assuming the green roofs with 30 mm-thick substrate were applied within the area, the light, medium and heavy rain could be delayed at 72.8%, 22.6% and 17.4%, respectively. Accordingly, the rainwater retained could reach up to 14317×104 m3. It suggested the great potential of the simple green roof in retaining rainwater. The research could serve as reference for the hot and humid climate zone to alleviate water logging and visualize sponge city construction.

城市内涝是困扰各大城市的环境问题,其主观原因是来自迅速增加的城市不透水面.国外运用屋顶绿化作为截留雨水的措施得到广泛实践,而屋顶绿化滞留雨水能力随气候条件的变化而变化.湿热气候区具有气温高、湿度高、雨量大的气候特点,在此气候条件下探讨屋顶绿化截留雨水的效能具有重要意义.本研究以在夏季雨热同期的广州市为例,搭建3个简单式屋顶绿化测试平台,通过13个月试验期的气象观测和数据测定推算其截留雨水的效能.结果表明: 基质厚度30、50和70 mm简单式屋顶绿化的降雨滞留率分别为27.2%、30.9%和32.1%,平均峰值减少量为18.9%、26.2%和27.7%.广州市建成区面积1035.01 km2,屋顶面积约占37.3%,假设在此区域推行30 mm厚度基质的屋顶绿化,小、中、大雨的总迟滞比率分别为72.8%、22.6%和17.4%,以此推算得出可滞留雨水体积达14317×104 m3,说明简单式屋顶绿化的截留雨水效应具有巨大潜力.本研究结果可为湿热气候区城市缓解城市内涝、建设海绵城市的构想提供参考.

Keywords: Guangzhou; extensive green roof; hot and humid region; rainwater interceptionu.

MeSH terms

  • Cities
  • Climate
  • Conservation of Natural Resources*
  • Rain
  • Water Movements*