應用系統動力學於多元化水資源策略模擬與分析-以台中地區為例

Abstract

本研究應用系統動力學建立多元化水資源策略分析模型，以台中地區大甲溪與大安溪流域作為研究區域，分析各種供水策略並探討缺水量與成本之間相互影響。首先藉由「問題定義」、「系統描述」、「因果回饋圖」以及「可能策略研擬」等建模步驟來建置系統動態模型。並驗證此系統的合理性，在模型檢定無誤後，即進行策略之情境模擬。並以缺水指數與花費程度指標進行各策略模擬結果的衝突分析。 本研究以1975年至2001年實際入流量分別模擬台中地區現有地表水系統供應民國110年中成長與高成長之不同需水量下，所得SI值(缺水指數)中成長為0.98與高成長為5.98，因此對高成長而言需擴增其他供水來源如農移用水、淨水廠擴充、廢污水回收與人工湖等。本研究另針對不同系統容量擴張策略進行分析，結果顯示在高成長需求下系統若只進行單一項目改善以淨水廠擴充最能有效降低缺水風險，但所需成本亦是單一型項目改善策略中最高。反之同時進行廢污水回收、人工湖建置及農移用水則最能減少缺水風險，且總成本亦最低，因此合理的複合型改善策略較只改善單一項目，應為較佳的選擇，本研究建置的多元化水源整體調配系統動態模式，除了已完成之各種改善方案的模擬外，後續更可做為其他可能方案的分析平台。

This study uses the system dynamic method (SD) to develop a regional water resources strategy planning model. The proposed model can evaluate the total cost and the potential risk of water deficit for variant capacity expansion strategies. The total cost includes the cost of facility expansion or installation and the water deficit risk is surrogated by the shortage index (SI). The model was applied to examine the water resources problem in Taichung area at central parts of Taiwan. The water demand in Taichung has increased significantly in recent years owing to the development of industry and increasing living standards. Therefore, appropriate strategies to reduce the risk of water deficit in the future are urgent. However, for financial reasons, only limited capacity expansion for existing facilities or intervention for new facilities is possible in the area. The study for Taichung area used the hydrology data from 1975 to 2001 and simulated the outcome of variant strategies for water demands predicted by the low or high economic growth rates at the target year 2069. For the existing system, the SI values were 0.98 and 5.98 for the low and high growth rate demands respectively, and demonstrated that the area has high water deficit risk for high economic growth. Evaluation for the variant capacity expansion strategies showed that simultaneously improving multiple system items including waste water reuse, constructed lake and reallocating agriculture water use was most effective. The study shows that the proposed model is a valuable platform for strategy assessment and intervention.