臺灣處於熱帶及副熱帶季風氣候區，降雨量豐沛，但因降雨時空分布不均，河川坡陡流急，水資源的使用效率不高。其他新興水源例如海岸水庫及地下水庫，將成為替代方案之一。若未來臺灣推動興建海岸水庫，則需選定適當場址，足夠的水源以及確保水庫的永續性相當重要，因此流量與輸砂變化趨勢的分析是必要參考的因素。本研究採用TCCIP提供之網格化觀測雨量以及AR6全球氣候模式降尺度資料中5個GCM模式之SSP2-4.5中間路線情境資料，以美國陸軍工兵團發展之HEC-HMS降雨逕流模式進行逕流量模擬，並且結合美國墾務局發展之SRH-2D水理輸砂模式進行河道輸砂量模擬，模擬分析二仁溪河口歷史基期30年(1992~2021年)以及未來世紀中(2046~2065年)和世紀末(2081~2100年)之逕流量和輸砂量。以Mann-Kendall趨勢分析與Theil-Sen斜率檢定計算基期30年之趨勢變化以及變化率，同時將1992-2021年作為基期，計算世紀中和世紀末逕流量與輸砂量的改變量，以評估氣候變遷的對逕流量和輸砂量的影響。
研究結果顯示，基期歷年平均日逕流量與輸砂量均為上升趨勢，上升速率分別為2.08萬立方公尺/日和6.35噸/日，在月季尺度中較顯著變化為8月份之逕流量與輸砂量，預計每年上升12.41萬立方公尺/日和47.49噸/日。在世紀中和世紀末年平均日逕流量預計將分別增加0.36%和5.73%，歷年平均日輸砂量預計將分別增加52.99%和72.31%，顯示輸砂量增加量較逕流量增加量更多。在豐水期，世紀中和世紀末平均日逕流量預計將增加1.34%和6.28%，平均日輸砂量預計增加60.22%和79.55%，在枯水期平均日逕流量將分別減少65.26%和32.00%，平均日輸砂量將分別減少34.89%和15.95%。

The water resources in Taiwan are limited for having steep slopes and uneven distributions of precipitation over space and time in river catchments. Therefore, the analyses of streamflow and sediment yields have become a crucial task to ensure the capacity and sustainability of reservoirs under the impact of climate change. In this study, we utilized the Rainfall-Runoff Model (HEC-HMS) developed by the U.S. Army Corps of Engineers to simulate the streamflow and the Sedimentation and River Hydraulics Model (SRH-2D) developed by the U.S. Bureau of Reclamation to simulate the sediment yields in Erren River for three periods of time, including the base period (1992~2021), the near-future period (2046~2065), and the far-future period (2081~2100). The Mann-Kendall trend test and Theil-Sen slope test were used to quantify the trends of daily streamflow and sediment yields. The results showed, in the base period, the annual average daily streamflow and sediment yields in Erren River have increased by 20,800 cubic meters and 7.09 metric tons per year, respectively. In the wet seasons, the streamflow have increased most significantly by 43,809 cubic meters per year. In the near-future and far-future periods, the annual average daily streamflow is expected to increase by 0.34% and 5.71%, while the annual average daily sediment yields are expected to increase by 52.99% and 72.31%, respectively. However, in the dry seasons, the annual average daily streamflow is expected to decrease by 11.42% and 1.14%, while the annual average daily sediment yields are expected to decrease by 34.89% and 15.95% in the near-future and far-future periods, respectively.

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