摘 要 本研究主要以碎形理論(fractal theory)探討烏溪中上游河川棲地分佈之研究。彙整國內外生態棲地結構量化之文獻，利用HEC-RAS 3.0及RHABSIM 2.2進行演算分析，河段模擬流量從5cms?180cms，並運用網格計數法(box counting algorithm)分析四種棲地型態(深潭、淺瀨、深流、緩流)的碎形維度，再以平均碎形維度(mean fractal dimension)表示河川棲地內全部嵌塊體的複雜程度，將碎形維度與潭瀨所佔面積、所佔面積百分比或歧異度等做一系列關係之探討，亦討論潭瀨棲地隨時間、空間之動態變化情形，並定義衡量棲地環境優劣的棲地指標，以此指標量化河川棲地之優劣，得1987?2001年河川棲地環境優劣之變化趨勢，結果得知淺瀨、深流、緩流這三種棲地型態之碎形維度皆介於2.0?2.6之間，此結果可以將棲地邊緣的複雜程度表現出來。綜而言之，運用碎形維度(fractal dimension)、棲地歧異度(habitat diversity)等方法，可以分析研究河段在不同年份下的棲地環境之變化，以及因時空變化後棲地環境之相對優劣程度。本研究對於未來生態保育以及生態工程施作上，亦提供一種有效的分析方式。 ABSTRACT In this study, fractal theory is applied to discuss the habitat distribution in the upstream Wu River. Collecting references were addressed on quantifying the ecological habitat. The habitat is analyzed by two model, HEC-RAS 3.0 and RHABSIM 2.2, simulating flow between 5cms and 180cms. This research makes use of box counting algorithm to analyze fractal dimension of pool, riffle, run and glide. Moreover, mean fractal dimension is estimated to represent the complexity of all patches in riverine habitat. This research discusses fractal dimension, the areas of habitat in river, diversity, and their temporal and spatial variety. Finally, in this study proposes the habitat index (HI) to determine the condition of riverine habitat from 1987 to 2001. The result shows that the fractal dimension is between 2.0 and 2.6, which represents the complexity of edge of habitats. In a word, this research approach is proven to be feasible to apply fractal dimension and habitat diversity to analyze the variety of habitat in the different years. This method provides an efficient way to address ecological condition in natural rivers.
