摘要 本研究以HEC-RAS3.0河川水理模式和RHABSIM2.2河川棲地模式模擬演算河川棲地，再利用歧異度與碎形維度加以描述棲地的多樣性與邊界複雜性，並且分析在研究河段中設置攔水壩對河川棲地分佈的影響，比較設置堰壩與否造成棲地的變化結果發現於歧異度部分，在流量小於70cms時設置堰壩會降低歧異度，而流量大於70cms則會增加。碎形維度部分，在流量小於90cms時設置堰壩維度較高但會隨著流量增加而遞減，而未設置堰壩則維度較低但會隨著流量增加而遞增。最後以歧異度與平均碎形維度定義一個棲地指標表示棲地的優劣程度，結果顯示在小於60cms未設置堰壩的棲地優於有設置堰壩的棲地，若流量在60?100cms之間則相反。 ABSTRACT This study applies hydraulic model HEC-RAS 3.0 and habitat model RHABSIM 2.2 to calculate the riverine habitat, and estimates diversity index and fractal dimension to describe the diversity and complexity of habitat. The Influences on the riverine habitat distribution from setting a weir in research area are analyzed. The result shows that setting a weir reduces habitat diversity in the cases when the flow is less than 70cms, but increases habitat diversity in the cases when the flow is great than 70cms. Given the flow being less than 90cms, the introducing of a weir makes that fractal dimension higher than that without a weir, but its dimention reduces when flow increases. Originally without a weir, fractal dimension in habitat becomes lower when flow increases. Finally, by combining with diversity and fractal dimension, a habitat index is defined to show the adequacy of riverine habitat environment. The result shows that in the cases while flow being less then 60cms, the riverine habitat with a weir is better then that without a weir. However, the situation reverses when the flow is between 60~100cms.