綠屋頂對雨水保留與洪峰減緩影響之研究

綠屋頂具有很多不同的效益，其中減少逕流的能力為其中一項重要效益。綠屋頂的介質層提供了暫時吸收雨水的滯留空間，因此相較於不透水屋頂，綠屋頂更能緩慢釋出水分以減輕峰值流量。在過去雨水保留的相關研究中，已有研究人員針對環境條件、澆灌方法、介質厚度或植被特徵等因子進行研究，這些研究的結果可明確得知影響逕流量的項目，但比較不同維護管理類型的綠屋頂之研究並不多。本研究探討不同維護管理類型綠屋頂的雨水保留與洪峰減緩能力之差異，於國立臺灣大學造園館三樓頂屋進行現地模擬實驗。本研究設計三種組合的綠屋頂，分別為10cm零維護管理綠屋頂、15cm低維護管理綠屋頂、30cm高維護管理綠屋頂，並依降雨量將降雨事件劃分成小型降雨事件(小於5mm)、中型降雨事件(5~19mm)、大型降雨事件(大於19mm)。研究結果顯示，對於小型與中型降雨事件，三種組合的綠屋頂都有超過85.73%的平均雨水保留率與洪峰削減率，但對於大型降雨事件，10cm組合與15cm組合只平均保留35.91%與46.13%的雨量，而平均洪峰削減率降至48.68%與64.22%，30cm組合則能將雨水保留率持續在80.7%，平均洪峰削減率持續在93.52%。結果證明高維管精緻型綠屋頂在每天澆灌的情況下，雨水保留率與洪峰削減率皆優於另兩種組合。

關鍵字

綠屋頂；逕流；雨水保留；洪峰削減；洪峰延遲

並列摘要

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.