| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 107 === Green roofs have many different benefits, and the ability to reduce runoff is one of the important benefits. The green roof''s soil layer provides a temporary retention of rainfall, so the green roof releases moisture more slowly to reduce peak flow than the impervious roof.
In the past studies on rainfall retention, researchers have studied factors such as environmental conditions, irrigation methods, and soil thickness or vegetation characteristics. The results of these studies can clearly identify the projects affecting runoff, but compare the different combinations of green roofs. However, there are not many studies comparing different combinations of green roofs.
This study explored the differences in rainfall retention, peak attenuation and delay by peak-to-peak of different combinations of green roofs. The platform of National Taiwan University were chosen as the study site. This study designed three combinations of green roofs, each of which is a no-maintenance managed extensive green roof (10cm), a low-maintenance managed extensive green roof (15cm), a high-maintenance managed intensive green roof (30cm), and divides rainfall events by rain depth. Small rainfall events (less than 5mm), medium-sized rainfall events (5~19mm), and large rainfall events (greater than 19mm).
The results show that for small and medium-sized rainfall events, the three combined green roofs have an average rainfall retention and peak attenuation of more than 85.73%, but for large rainfall events, the extensive green roof (10cm) and the extensive green roof(15cm) only retention of 35.91% and 46.13%, while the peak attenuation fell to 48.68% and 64.22%. The 30cm combination can keep the rainfall retention at 80.7% and peak attenuation at 93.52%. The results show that the intensive green roof of the high-dimensional tube is better than the other two combinations in the case of daily irrigation, the rainfall retention and the peak attenuation.
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