近年來，全球氣候變遷導致氣候異常，世界各地降水特徵逐漸發生變化，加上台灣特殊的地理形態，山區陡坡地形，造成大部分水資源流入海洋的時間相當短。除了台灣的降雨模式外，長期降雨分佈也不均勻且不易利用。綠色屋頂可以使屋頂具有擋水的功能，亦可以緩衝暴雨和充分水資源再利用，還有助於控制緩和城市洪水。因此，在當前水資源有限的狀態下，如何使粗放式屋頂綠化達到穩定的水平衡是本研究的主要課題。本研究通過不同種類植物的蒸散量實驗，歸納驗證得出了各類薄層綠屋頂植物的實際需水量。為了驗證薄層綠屋頂植物需水量水平衡估算參數，採用水文和氣象數據進行蒸散發實驗，在大面積綠色屋頂區域內估算供水和需水量，並進行分析和驗證。據此，建立基於雨水利用率的水平衡評價方法，為實際薄層綠屋頂實務提供設計依據參考。

Global warming has led to abnormal climate and characteristic rainfall changed gradually in recent years. Coupled with Taiwan's special landform with steep slope terrain, the majority of water resources flow into the ocean with quite short term. In addition to rainfall patterns in Taiwan, long-term rainfall distribution is uneven and unavailable. Green roof can make the roof have the function of retaining water, which can buffer the rainstorm and water usage. It can also be helpful to control of urban flood. Therefore, in the current state of limited water resources, how to make the extensive green roof reach a stable water balance is the main issue of this research. Through different kinds of plant evapotranspiration experiment was obtained the actual amount of water requirement. In order to validate the estimation parameters of water balance, hydrometric and weather data are adopted to evapotranspiration experiment. The water supply and demand are estimated within an area of extensive green roof, and are analyzed and verified. As a results, a water balance evaluation method is established by the rainwater utilization ratio to provide a basis reference for practical implementation.