Mechanisms controlling green roof peak flow rate attenuation
| Autor: | Andrew W. Sims, C. C. Smart, Denis M. O'Carroll, Clare Robinson |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
010504 meteorology & atmospheric sciences
Attenuation Stormwater Flow (psychology) Green roof 0207 environmental engineering Soil science 02 engineering and technology 01 natural sciences 6. Clean water Volumetric flow rate 13. Climate action Environmental science Richards equation 020701 environmental engineering Surface runoff Intensity (heat transfer) 0105 earth and related environmental sciences Water Science and Technology |
| Zdroj: | Journal of Hydrology. 577:123972 |
| ISSN: | 0022-1694 |
| Popis: | Stormwater flow rate attenuation is an important component of stormwater management but the mechanisms governing peak flowrate attenuation have received limited attention in the green roof community. Previous green roof literature studies that have reported peak flow rate attenuation have focused on comparing the peak precipitation intensity with the peak drainage rate over a given storm event. However peak drainage rates do not necessarily correspond with peak precipitation intensity if peak precipitation intensity occurs before field capacity is achieved. As such use of event based flow rate attenuation does not facilitate investigation of the mechanisms governing peak flow rate attenuation. This study combines field data collected on a 200 m2 green roof with a Richards based numerical model to quantify and provide new insights into the mechanisms governing flow rate attenuation. The average peak flow rate attenuation from all measured drainage events was 58% (n = 121 distinct rainfall peaks) and the average peak delay was 12.8 min. Field capacity was found to be a statistically significant point where attenuation performance decreases. Peak stormwater flow rate attenuation below field capacity was found to be significantly higher than after field capacity is reached with capillary storage the dominant attenuation mechanism before field capacity is reached and routing and gravity storage important attenuation mechanisms after field capacity is reached. The Richards equation based numerical model yielded very good predictions of observed peak flow rates using laboratory derived model parameters and without the need for model calibration. This study suggests that green roofs have considerable potential to attenuate stormwater flow rate, thus helping to mitigate damage due to urban runoff and providing some protection against storm intensification associated with climate change. The validated numerical model is a valuable tool for the prediction of stormwater flow rate attenuation in different climates and can therefore be used in green roof design and by regulators to better evaluate the potential benefits of green roofs. |
| Databáze: | OpenAIRE |
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