圖書典藏及影音數位平台

為能明瞭石岡壩魚道內目前生態狀況，及上下游河道水域生態資源的變化，本計畫工作以每月採集所得的魚蝦類種類與數量，經由豐度、歧異度與均勻度及環境因子相關性等統計分析，除瞭解利用石岡壩魚道的生物種類、利用時機，與石岡壩對洄游生物的影響之外，並探討有何種生物利用魚道進行洄游，與生物利用魚道的季節，提出魚道本體之檢討。另對於在長庚橋與埤豐橋間，石岡壩對河川生物的阻隔作用情形，以及副壩與埤豐橋上游100公尺處的天然落差對河川生物之洄游所產生阻隔作用，提出改善方法與對策。 因此，本計畫進行石岡壩上下游水域生物監測、歷年水理與水質之蒐集等工作，再經由統計分析及水理分析，以瞭解水域生態資源變化，並探討與魚類生態之間關聯性及上下游生態廊道之通暢性，提出魚道改善設計規劃。其工作項目包括：(ㄧ)長庚橋至埤豐橋（含魚道）水域生態及洄游生物監測調查與統計分析。(二)建立石岡壩上下游和魚道之水域生物物種名錄。(三)蒐集分析長庚橋與埤豐橋間歷年水文水理(流量、流速)與水質狀況。(四)魚道水理分析與其系統改善規劃設計，包含：1.本體結構物（土木、閘門操作）、流量流速、魚道內部結構物布置等檢討分析以及2.魚道(入口、出口、本體）具體改善方案與圖說、工程費工期估算以及相關配合措施等。(五)工作報告及成果報告編撰印製等。

In order to understand the ecosystem of Shih-Kang Dam, this project was performed to do field investigation from Pifeng Bridge, which is 1 km downstream the dam, to Changgeng Bridge, which is 2 km upstream the dam. The estimation of the influence of habitat fragmentation to freshwater creatures due to the Shih-Kang Dam and groundsill works of Pifeng Bridge was also performed. The final purpose of the project is to bring out the improvement plan of Shih-Kang Dam fishway. Among all the 7 sampling spots, 24 species of fish, 3 species of crustacean, 20 families of aquatic insects and 7 species of plankton was recorded. The area around Shih-Kang Dam is rich in freshwater eco-resources. Not only catadromous fishes, Anguilla japonica and Anguilla marmorata, but also clean water indicator species Onychostoma barbatulum, and protected wild animals - Sinogastromyzon puliensis and Liobagrus formosanus has been found. It is believed that the ecosystem will be better after the function of fishway in Shih-Kang Dam is improved. In comparison to history records, some exotic species such as Spinibarbus hollandi, Onychostoma alticorpus, Ctenopharyngodon idella, Cirrhinus molitorella and Channa striata are new records. They reveal the invasion of exotic species in this area. In the results of the analysis of biodiversity indicator, there are two hot spots of biodiversity: Changgeng Bridge and Shih-Kang Dam fishway. Furthermore, slightly changes of biodiversity indicator among the 6 times of field investigations showed that the environment in these two sampling spots was stable. The 3D simulation of Shih-Kang Dam and fishway demonstrated close to the real water flow situation. It indicates that the water flow in the fishway is suitable to fishes. It shows there is no problem in fishway’s main body construction either. But the main systematic problem of fishway is the exit of fishway has too strong velocity and the sharp falls is too high for fish in downstream of Shih-Kang Dam. These two problems are two bottle necks for fish migration in this area. An extra pipe-type fishway install on the exit of fishway and another lower structure fishway install on the downstream of Shih-Kang Dam should be built in order to improve the ability of fish migration. After these improvement works are done, the field investigation of the river ecosystem shall be taken continuously to monitor the effect of these works.