綠屋頂降雨截水能力分析與模式發展

Abstract

為改善都市水泥化及綠地不足等問題，國際上正積極推廣綠屋頂，國內亦正在起步中， 由於綠屋頂的植物及土壤基質均可截留雨水，因而可降低逕流減少洪峰及雨水系統的負載。然 而綠屋頂之截水能力會因不同的設置條件而有所差異，唯目前國內外尚未有太多相關研究成果 可供推估綠屋頂的截水能力。本研究因而將探討不同綠屋頂斜度、降雨型式及基質厚度與特性 等因子對於綠屋頂截水能力之影響，分析綠屋頂在降雨期間之底部滲流與表面逕流隨時間變化 之情況。為了有效率的模擬綠屋頂之截水能力，本研究設計了一套特殊的綠屋頂實驗座台，以 期分析不同環境及設置條件下綠屋頂之降雨截水功能，實驗座台除了鋪設植物及基質，並針對 逕流及滲流水設計收集槽及適用的流量測量器，且將依據所得結果及相關理論試著建立一個模 式供評估台灣綠屋頂在不同條件下的降雨截水效益，以作為台灣推廣綠屋頂相關決策的重要依 據。此外，由於預期研究期間自然降雨事件數量有限，亦將試著建立一套適用的人工降雨器， 以期針對各種不同降雨模擬分析綠屋頂的截水能力及驗證所建立的模式。

Urbanization increases the area of impervious surfaces and the probability of flooding. Green roof (GR) is a potential technology to alleviate these problems. The plants and substrates of green roofs can retain precipitation, and both the runoff from rainfall events and the loading to storm sewers can be thus reduced. The rainfall detention capability of a GR is affected by various environmental and GR installation factors. No model is currently available to assess the GR rainfall detention capability in Taiwan. This study is therefore initiated to develop an appropriate model to assess the effect of roof slope, rainfall intensity, and substrate depth on the detention capability. For effectively simulating the runoff reduction of a GR, a special GR platform is designed to evaluate the detention effects under various environmental and installation conditions. During rainfall events, the temporal changes of percolated water and surface runoff are to be simultaneously measured by a particular water collection and measuring system designed by this study. Based on the results from a series of simulations, a GR rainfall detention model is to be established. The model can be also used to facilitate various GR planning and decision analyses. Furthermore, a rainfall simulator is to be established for simulating various rainfall events for developing and verifying the model.