濁水溪中上游生態基流量之推估與應用

Abstract

本研究結合HEC-RAS 3.0水理模式與河川棲地模式RHABSIM(River Habitat Simulation Model)，探討河川水理條件與生物棲地之關係。以濁水溪中上游為研究樣區，並以埔里中華爬岩鰍、濁水溪中上游中表層活動之魚類及台灣石魚賓為標的魚種，推估該樣區之生態基流量。結果顯示在無任何水工結構物的低流量情況下，若採1cms已可滿足標的魚種生存的生態基流量。若考量天然流量下提供其他引水需求時，則生態放流量為18cms時，可獲致最大之棲地面積。本文亦分析設置水工結構物如橋樑及堰等後，所造成水深變化對棲地環境的影響，研究發現如名竹大橋與集集攔河堰等大型水工結構物造成水位的抬昇，對生態棲地面積則有相當程度的影響。

This study combines hydraulic model HEC-RAS 3.0 and River Habitat Simulation Model (RHABSIM) to probe into the relationship between the river hydraulic conditions and creature habitats. To estimate the ecological instream flows by using Sinogastromyzon puliensis, middle-surface layer fishes, and Acrossocheilus paradoxus as target species in the upstream and the midstream of the Cho-Shui River. The result shows that the discharge of 1cms have already satisfied the ecological instream flows of the fishes of target species in the condition of low flow without any hydraulic constructions. Considering the needs of providing other diversion under the natural flow, it can get maximum habitat areas when the ecological release flows is 18cms. It also analyses the influences of the habitat environment causing by thechange of water depth after setting up hydraulic constructions such as bridges and weirs. It indicates that the risen water-level caused by large hydraulic constructions such as Ming-Zhu Bridge and Chi-Chi retaining weir have fairly influence to ecological habitat areas.