圖書典藏及影音數位平台

石門水庫原設計並無水力防淤專用設施，經既有設施更新改善工程及未來石門水庫防淤隧道工程完成後，將提升水庫防淤功能及減緩水庫淤積，延長水庫壽命。爰此，為了解石門水庫排洪減淤操作對下游生態環境影響之程度及追蹤觀察排砂隧道及中庄調整池操作後淤泥回歸河道之影響，俾作為未來增設防淤隧道完工後之排洪減淤操作參考，研擬減輕下游河道生態衝擊之操作策略。研究之時間尺度從汛期前背景資料建立，到汛期中與後，特別是石門水庫操作排洪減淤及中庄調整池後，各項環境與生物指標反應之比較，整合分析評估對下游河道生態之影響時間，沖淤影響部份持續進行資料蒐集、現地監測及相關數值模擬分析，將有助於了解水庫放淤操作對下游河道泥砂濃度變化、底床沖淤情形及提早評估出高泥沙量或超量沖淤之河段，研擬相關因應對策。

Within Shihmen Reservoir watershed, the water quality in the reach between Chongyang Bridge and Guandu Bridge often classified as moderately to heavily polluted this year. However, flows with high-concentration sediment were rarely monitored, and emptying work operated at YuanShan weir has only been conducted once. We can inference that the relationship between water quality and sediment discharge in Shihmen Reservoir is insignificant. Compared to last two years, the quantity and diversity of calm in the river have been found increasing. This result suggests direct effectiveness of clam growth to mandatory clam releasing. Thus, we might consider using the species of fish with higher population as the environmental indicator. In addition, the oxidation-reduction potential might be directly related to the clam’s habitat. However more studies are needed to support this findings. The public concerns were focused on turbid water releases during typhoons in the past year. Only one typhoon named Maria struck and cause damages to Taiwan this year, but public tended to put more concerns on the operation and construction situation of Zhongzhuang retention basin and Amuping sediment sluicing tunnel. A great amount of fish death draws public attention as well. Such incidents seem to occur more often in summers. Dissolved oxygen of water bodies is also below the standard value in summers. More investigation should be conducted to clarify causes of the results. This Project used CCHE model to analysis the influence of river channel change. The first result showed that the growth of Wazihwei sand spit during typhoon was caused by backflow. Besides, the secondary sediment release could discharge about 1.33 million tons of sediment. Moreover, if the sediment release operations correspond with tide period cycles, it could reduce sediment deposition in the channel and take sediment farther even to the ocean. Take two typhoons struck in 2016 as an example, the amount of sediment release from Shihmen Reservoir is less than from Xindian River. Therefore, to overall evaluate the influence of upstream sediment release to the downstream channel beds, the sediment yield and release contributed to the whole basin of the Xindian River and Keelong River should be taken into account. In Shihmen Reservoir sustainable development have positive meaning by operation of sediment discharge inflow sediment to the downstream. For typhoon Maria(2018) as an example, Dahan River and others tributary inflow the amount of sediment discharge is less than Xindian River.