U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th Street, Corvallis, OR, 97333, USA.
U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th Street, Corvallis, OR, 97333, USA.
J Environ Manage. 2021 Jan 1;277:111418. doi: 10.1016/j.jenvman.2020.111418. Epub 2020 Oct 17.
Green roofs are among the most popular type of green infrastructure implemented in highly urbanized watersheds due to their low cost and efficient utilization of unused or under-used space. In this study, we examined the effectiveness of green roofs to attenuate stormwater runoff across a large metropolitan area in the Pacific Northwest, United States. We utilized a spatially explicit ecohydrological watershed model called Visualizing Ecosystem Land Management Assessments (VELMA) to simulate the resulting stormwater hydrology of implementing green roofs over 25%, 50%, 75%, and 100% of existing buildings within four urban watersheds in Seattle, Washington, United States. We simulated the effects of two types of green roofs: extensive green roofs, which are characterized by shallow soil profiles and short vegetative cover, and intensive green roofs, which are characterized by deeper soil profiles and can support larger vegetation. While buildings only comprise approximately 10% of the total area within each of the four watersheds, our simulations showed that 100% implementation of green roofs on these buildings can achieve approximately 10-15% and 20-25% mean annual runoff reductions for extensive and intensive green roofs, respectively, over a 28-year simulation. These results provide an upper limit for volume reductions achievable by green roofs in these urban watersheds. We also showed that stormwater runoff reductions are proportionately smaller during higher flow regimes caused by increased precipitation, likely due to the limited storage capacity of saturated green roofs. In general, green roofs can be effective at reducing stormwater runoff, and their effectiveness is limited by both their areal extent and storage capacity. Our results showed that green roof implementation can be an effective stormwater management tool in highly urban areas, and we demonstrated that our modeling approach can be used to assess the watershed-scale hydrologic impacts of the widespread adoption of green roofs across large metropolitan areas.
绿色屋顶是在高度城市化的流域中实施的最受欢迎的绿色基础设施类型之一，因为它们成本低，能够有效利用未使用或未充分利用的空间。在本研究中，我们研究了绿色屋顶在美国太平洋西北地区一个大都市地区减缓雨水径流的有效性。我们利用一种名为可视化生态系统土地管理评估（VELMA）的空间显式生态水文学流域模型，模拟在美国华盛顿州西雅图的四个城市流域内，将绿色屋顶分别覆盖现有建筑物的 25%、50%、75%和 100%时，所产生的雨水水文变化。我们模拟了两种类型的绿色屋顶的效果：扩展型绿色屋顶，其特点是浅层土壤剖面和短的植被覆盖；密集型绿色屋顶，其特点是较深的土壤剖面，可以支持更大的植被。虽然建筑物仅占四个流域总面积的 10%左右，但我们的模拟结果表明，在这些建筑物上 100%实施绿色屋顶，可以分别实现扩展型和密集型绿色屋顶的年平均径流量减少 10-15%和 20-25%，模拟时间为 28 年。这些结果提供了这些城市流域中绿色屋顶可实现的体积减少的上限。我们还表明，由于降水增加导致的更高流量模式下，雨水径流量减少的比例较小，这可能是由于饱和绿色屋顶的储存能力有限。一般来说，绿色屋顶可以有效地减少雨水径流，其有效性受到其面积和储存能力的限制。我们的结果表明，绿色屋顶的实施可以成为高度城市化地区有效的雨水管理工具，并且我们证明了我们的建模方法可用于评估在大型大都市区广泛采用绿色屋顶对流域尺度水文的影响。
