拆除石岡壩及替代水源方案以回復大甲溪河相自然演變

Shigang Dam Removal and Water Storage Alternatives to Restore the Dajia River Morphological Natural Evolution

陳樹群(Su-Chin Chen) ； 張豐年(Feng-Nan Chang) ； 邱彥瑜(Yen-Yu Chiu) ； 鄭皓元(Hao-Yuan Cheng)

《中華水土保持學報》 53卷1期 (2022/03) Pp. 1-12

https://doi.org/10.29417/JCSWC.202203_53(1).0001

摘要

石岡壩經集集地震抬升，壩址處成為河道不連續之遷急點，下游河段因土砂受攔阻，缺乏砂源，沿河構造物頻繁受損，修復工程從未間斷；上游庫區則因嚴重淤積喪失蓄水功能，僅能調節發電尾水。雖然藉由固床工等橫向結構物及庫區疏濬以維護石岡壩穩定供水，但仍無法阻止河床持續刷深之趨勢。藉由一維動床數模可知，若維持現況，未來沖淤不平衡之情形將持續擴大，然若將石岡壩拆除則可使下游河段逐漸回淤，河道連續性將復原。因此，建議政府啟動石岡壩拆除及替代水源規劃以恢復大甲溪自然河相。

關鍵字

石岡壩 ； 拆壩 ； 河相演變 ； 大甲溪

並列摘要

After the 1999 Chichi earthquake, the site of the Shigang Dam became a knickpoint in the discontinuous riverbed profile. Sediment became blocked by the dam, causing a lack of sediment supply that led to frequent damage to the structures along the river downstream, followed by a series of engineering repairs. For several years, transverse structures such as groundsills were used, and regular reservoir dredging was performed to maintain the water supply function. However, the river still appears unbalanced, with sediment deposition in the upstream and degradation downstream of the dam. One-dimensional sediment transport simulation indicates that with the current layout the imbalance will likely continue into the future; however, if Shigang Dam is removed, the downstream deposits will gradually return and the continuity of the river will be restored. Therefore, we suggest that administrators should start planning for the removal of Shigang Dam to restore the morphology of the Da-Jia River to a natural state and arranging for an alternative water supply.

並列關鍵字

Shigang Dam ； dam removal ； river morphology evolution ； Dajia River

參考文獻

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