防砂工程与河川物理栖地复育探讨——以石门水库苏乐溪及匹亚溪为例

Influence of the River Engineering on the Restoration of River Physical Habitat——A Case in Sule and Pia River in Shihmen Reservoir Watershed

过往河川经历土砂灾害后,往往采用人为工程控制土砂,一方面保护下游水库库容,另一方面则快速达到集水区土砂稳定;但兴建工程方式在近年逐渐出现破坏河川栖地之反对声音。以石门水库集水区两条土砂灾害严重之河川(包括苏乐溪及匹亚溪)进行探讨,由长期监测及河川物理栖地调查,说明防砂工程对河川复育之选择性及必要性,并强调防砂工程兴建需因应土砂量变化而进行长期调整概念,作为防砂工程与栖地复育相互依存参考。

The study proceeded long-term observation of the river physical habitat in Sule and Pia river watershed in Shihmen reservoir watershed.The result of long-term observation indicates that the engineering must be established in the river watersheds with much sediment yields to achieve the stable sediment.The study proposes the river engineering assessment procedure to decide to establish,adjust or remove the engineering based on the integrated analysis of the protected objects,the debris flow or flood events,and the discharge and suspended load of the river.The assessment can be a reference for the establishment,adjustment or removal of the river engineering in the future.