台灣南部地區雨量集中於豐水時期，而枯水期的用水必須仰賴水資源系統管理，近年來受到氣候變遷的影響，台灣極端降雨及乾旱事件頻繁，本文研究台南地區氣候變遷對水資源系統之衝擊，並分析採行不同調適措施對降低氣候變遷衝擊的效能。 研究方法包含使用氣象合成模式將歷史的雨量及溫度資料進行繁衍，模擬近未來(2020~2039)200組資料，再透過水文模式(GWLF)進而求得台南區域未來的流量資料。藉由水資源系統動力軟體(VENSIM)去建構研究區域水資源系統，將上述台南地區相關資料匯入系統動力模式中便可求得該區域供需水情形，以探討氣候變遷下台南地區水資源系統狀況。本文以DPD (Deficit Percent Day)作為公共缺水指標、ASI (Agriculture Shortage Index)作為農業缺水指標探討台南地區水資源系統之衝擊。 氣候情境改變下缺水指標與流量的關係相當密切，當枯水期流量減少往往會造成缺水的風險上升，平均DPD變化倍數最高為3.03，而考慮公共需水成長的情況下最大倍數達30.7，結果表示公共需水成長為造成DPD上升的主因，未來情境公共需水成長假設下顯示研究區域水資源乘載力不足，現有淨水場供水能力與未來需水量兩者差距為108.7(萬噸/旬);各調適措施包括:一期作休耕、降低公共需水、擴建淨水廠，其中成效以擴建淨水廠最好，DPD平均值可下降最低至1786.2(%-day)，而休耕DPD平均值最低值為7483.2(%-day)。 ;The impact of climate change increases extreme rainfall and drought events in Taiwan recent years. Rainfall in southern Taiwan is usually concentrated in wet period. Therefore, water supply relies on adequate water resources system management in the dry season. This paper investigates the impact of climate change in Tainan water resources systems and the potential improvement measures in different ways. Daily weather data was derived from weather generator and subsequently flow was simulated with the hydrological model, namely, GWLF model. Regional water system was constructed with the system dynamics model, namely, VENSIM. The results of the water supply and demand simulation runs, represented as Deficit Percent Day (DPD) and Agriculture Shortage Index (ASI), were analyzed to investigate the impact on Tainan water resources system. Significant correlations among DPD, ASI and flow were identified, under different future scenarios. Lack of water resources carrying capacity in Tainan is concluded, given public water demand growth scenarios. Among three adaptation measures, namely water treatment plant expansion, public water demand reduction, and dry season fallow enforcement, the most effective is treatment plant expansion.
