本研究探討曾文水庫受氣候變遷影響下，對水文及水資源所造成之衝擊。以台灣西南部的曾文水庫集水區為研究區域，該集水區氣候乾溼分明，85%的年雨量集中在溼季(5至10月)。因此亟需仰賴水庫調節，蓄存溼季時期的豐沛流量以確保乾季時期供水穩定，但在氣候變遷影響下，水文情況的改變勢必對水資源的分配與規劃利用產生影響及衝擊。
　　因此，本研究整合氣象繁衍模式、水文模式和水庫系統等模式，分析水資源系統之可供水量。其中，氣象繁衍模式結合全球環流模式模擬未來氣候變遷情境A1B、A2、B1下的溫度及雨量序列，溫度及雨量序列將作為後續水文模式之輸入值，模擬集水區未來可能的情境流量，接著藉由水庫系統模式模擬水庫操作下的可供水量，根據各標的需水量及可供水量模擬值計算水資源系統評估指標。本研究有別於以往僅以缺水率作為區分水資源乾旱等級之單一型指標，採用複合型水資源指標－可綜合評估缺水情況之缺水強度、缺水延時及缺水事件數，並透過指標之單調特性測試選出修正型乾旱風險指標作為本研究之水資源評估指標，且經過歷史乾旱紀錄驗證，足以作為乾旱事件之評判標準，最後以修正型乾旱風險指標探討氣候變遷對曾文水庫水源供給及缺水風險所帶來的衝擊。
　　研究結果指出：與基期相比，A1B情境下2020至2039年，缺水最嚴重之情況在未經人為乾旱管理操作下，其公共給水發生乾旱情況之總時間增加至2.2倍，發生乾旱等級二級狀況之總時間增加至2.34倍；農業給水發生乾旱情況之總時間增加至1.8倍，發生乾旱等級一級狀況之總時間增加至1.93倍。整體來說，水資源乾旱情況之發生期間及嚴重程度增加，缺水風險升高。

　　This study aims to assess the impact of climate change on the hydrology and water resource. In this study, the selected study area, Tseng-Wen Reservoir catchment locates in the southwestern Taiwan in which the precipitation between May and October contributes about 85% of the total water flux of a year. Hence, this reservoir plays an important role to provide functions on flood mitigation and water supply. Under the climate change, however, the change of hydrology would impact on the water allocation and management of reservoir storage.
　　Applications of weather generator, hydrological model, and reservoir system model are necessary to develop an assessment model of the water resource system. By integrating general circulation models, weather generator can simulate projected changes in temperature and precipitation under climate change scenarios. The projected data generated from weather generator would be the input data of the hydrological model to simulate the scenario streamflows. Then, the scenario streamflows were put into the reservoir system model to simulate the water supply. Aparts from previous studies using shortage rate as the level of water shortage hazard, this study attempts to develop a compound water resource indicator which is capable of multi-aspect description of water shortage, including duration of shortage, events of shortage and amount of water shortage. By analysis of monotonic behavior of indicator, this study chose the Preferable Drought Risk Index as performance index to estimate the risk of water shortage. The index is validated by the historical drought and is capable to be the criterion of drought.
　　With results of research on the risk of water shortage, under the most difficult situation in the A1B scenario whose projected period is 2020~2039yr, the drought period for public water supply is up to 2.2 times and for agriculture water supply is up to 1.93 times. Generally speaking, the drought period is longer and the water shortage increases, so the risk of water shortage would raise.

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