屋頂綠化結合雨水利用系統容量優化設計

Optimized Capacity Design of Rainwater Harvesting Systems for Green Roof Irrigation

全球都市化造成環境惡化，最近已有研究指出屋頂綠化可有效改善都市水環境。然而，儘管屋頂綠化可改善都市水環境，但在熱帶和亞熱帶地區其灌溉用水仍受限制，這不僅增加了水資源負擔，也消耗抽水所需之電力。採用雨水灌溉之屋頂綠化系統與傳統雨水利用系統設計有很大不同。本研究探討屋頂綠化結合雨水利用設計因素，並建立數學模擬模型，闡明貯集容量與系統性能之間的相關性。過去研究以沖廁用水為研究對象，所需水量對於計算系統為固定，而屋頂綠化則受澆灌需求、土壤和植被的影響。此外，屋頂綠化逕流係數隨降雨事件、土壤厚度、植物及屋頂坡度的變化而不同。本研究模擬計算屋頂綠化結合與水利用貯集容量設計，並根據案例研究提出替代水率最佳容量設計。結果顯示，本研究所提出之屋頂綠化結合雨水利用之容量設計及最佳化之方法，在提高替代水率及經濟上皆為可行。

 

Rapid urbanization had worsened urban environments worldwide. Recent research had identified green roof as an effective approach to adapt stormwater. However, despite various efforts to promote green roof, a major limitation of these systems in tropical and subtropical regions was that involved irrigation depend on potable water, which not only increased the burdens of scarce water resources but consumed municipal pumping electricity. Some researchers focused on determining how to use rainwater as an innovative irrigation water source and design storage tank size. However, specific design factors related to RHSs that incorporate green roof irrigation systems differ considerably from traditional RHSs designs. Previous studies had recommended using rainwater to address these concerns, although further research is required to develop a suitable design method. In this study, the major design factors for RHSs for green roof was examined, and a simulation-based mathematical model was established to elucidate the correlation between tank size and system performance. The majority of previous studies had focused on water source for toilets, which is constant for calculating system. For green roof irrigation that support plant life, water demand is subject to variations based on climate, soil, and vegetation. Moreover, the runoff coefficient of green roof differed in conjunction with variations in rainfall events, hydrological pro-exponential factors, soil thickness, plant selection, and roof slope. In this study, the tank size was determined with a simulation-based RHSs design method for green roof irrigation systems, and the optimal tank size was proposed based on the case study. The optimal system design of the potable water replacement rate was also discussed based on a case study of a university building in Keelung, Taiwan. The results show that simulation-based RHSs design method for green roof irrigation systems provides the optimize tank size and economic performance is feasible. Therefore, the RHSs design method of green roof is a useful tool for reducing irrigation water.