| 摘要: | 有關水利及生態理論間之量化平台，是水利工程規劃設計時要解決的問題，本研究，利用台灣淡水及河口魚類誌中所記錄之魚類調查資料、中央研究院生物多樣性中心所架構之台灣魚類資料庫及相關國內外文獻，依據臺灣本島魚類棲息之五個動物地理分區，以各分區中淡水特有魚種之生存適合性作為評估河川生態的標準，制訂各分區上、中、下游河段之四種棲地適合度曲線（流速、水深、底質及水質棲地適合度曲線）。所繪的五區共60幅棲地適合度曲線圖，亦應用於筏子溪的不同型態河槽棲地分析及臺灣本島河川生態寬度及彎曲量化分析，共有以下結論： 1.由筏子溪不同型態河槽棲地分析結果發現，設計的河川寬度與型態皆能影響棲地面積數量。拓寬河道可增加河川棲地，傳統使用的複式斷面仍具有保持棲地之優勢。設計河槽型態愈彎曲複雜，某些流量下魚類適合的棲地愈多，當流量至Q50 之較大值後，河水已漫溢出岸邊，所有淹水區域成為魚類最佳棲地。這也呈現平常在颱風時期，臺灣常有民眾在大洪水時在岸邊捕魚景象之具體說明。 2.經分析全臺灣本島32個河段棲地型態，建議於營造改善已存在堤線之河川環境時，應至少保留設原計畫河寬的百分之七十作為河川生態寬度（Be），維持其原有河川地貌及地形，不予改變。另對於需新建河川防洪構造物河段，建議儘量採用計畫河寬計算公式所得之最大值（Max計畫河寬），作為治理計畫線寬度（Bp），並以Be=0.1324* Bp1.1931 之公式，求取治理河段需維持自然狀態的最小寬度。 3.在河川彎曲量化分析方面，從分析32河段中的11處蜿蜒河段，發現，Lepold and Wolman(1960)所獲得的蜿蜒河槽幾合特性中，彎頂距（λ）的公式尚可於臺灣適用，但彎槽擺幅與彎曲半徑公式則顯得並不適合。另河川彎曲處的凸岸區腹地，在水位溢槽時皆為優良棲地，在河川管理時，應列為水利用地保持自然狀態。 4.本研究在適合度曲線現地觀測試驗方面，發現前人繪製的適合度曲線，有僅針對單一目標魚種及受限於人工作業限制等缺憾。未來利用水中攝影長期藉由電腦記錄影像資料，分析適合度曲線應為經濟可行的方式之一。 5.本研究所研析的結果，可作為目前政府部門已展開之大規模水利建設計畫，如國土復育計畫及易淹水地區水患治理計畫之規劃參考，讓水利工程師更藉重生態學界的智慧，使未來所營造河川之環境更符合生態理念。 With the aim to resolve problems in quantifying ecological and hydrological aspects of water works engineering and design, this study applies data on fish species from the “Freshwater and estuarine fishes of Taiwan”, “The Fish Database of Taiwan “ from the Center for Biodiversity, Academia Sinica, and international scientific literature to fit four different habitat suitability curve regimes (flow velocity, water depth, bed material and water quality) of the upstream, midstream and downstream sections of rivers in five different geographical zones in Taiwan. In total, 60 habitat suitability curves for local endemic freshwater water species were drawn and used as the standard to assess river habitat ecology. This methodology was applied for different river channel types in Fatze River and a quantitative analysis was carried out for ecological width and sinuosity typical of rivers in Taiwan. The conclusions derived from our study can be summarized as follows: 1.The analysis on different river channel types in Fatze River shows that river width and channel form design both affect habitat area. Widening the river channel will increase river habitat area and traditionally methods in designing a complex cross-sectional relief are most efficient in maintaining habitat area. The more complex the design of the river channel sinuosity also increases habitat area for endemic fish species under certain discharge velocities. Once discharge exceeds Q50, the floodwater top the riverbanks and create optimal habitat conditions for the freshwater fish species. This conclusion is also visually corroborated by the presence of fishermen up and down the river coasts once a typhoon passes. 2.Following the analysis of 32 river sections and their habitat types in Taiwan, we concluded that for the future construction and amelioration of river embankments a minimum of 70% of the original channel width must be reserved for river ecology (Be). The landscape and topographical relief of the river must remain untouched. Additionally, for river sections in need of new floodworks construction, our study recommends that the largest value of the river width equation be used for regulating the project width (Bp). Furthermore, the relationship between Be and Bp should be established at Be=0.1324* Bp1.1931 to calculate the requisite minimum width of the river to maintain base ecology. 3.The analysis of the river sinuosity in 11 meanderings of the 32 rivers has confirmed that of the hydraulic geometric relationships obtained by Leopold and Wolman (1960), the equation for the distance between two meanders（λ）is applicable to Taiwan while the equations for amplitude and radius of the meander are not. The region outside of the river bend is a suitable habitat area during floods and, as such, by river management guidelines should be protected and preserved. 4.In situ observation and application of habitat suitability curves from previous studies targeted a single fish species and were constrained by physical limitations. In the future, the use of underwater long-term video cameras and datalinks for immediate computer analysis is recommended for field trials. 5.The results achieved in this study can used as a reference by government bodies involved in large-scale water works engineering projects (e.g. the Homeland Restoration Project and the Regulation of Flood-Prone Areas Project). It can be a functional tool in eco-engineering, and facilitate the implementation of ecological concepts in engineering and construction work. |
