溪流狀況指數(ISC)之水文次指數應用於上游河溪生態棲地之評估

Abstract

溪流生態棲地之評估方式繁多，隨著地區不同會有不同的選擇，本研究以流量變化劇烈、河溪生命周期短、生態復育潛力相對豐富之上游野溪作為研究對象。選擇工程人員較易使用、兼具物理性、化學性及生物量化指標—由澳洲維多利亞省所發展之溪流狀況指數(Index of Stream Condition, ISC)評估模式。其中，針對水文次指數作修正，以雨量變異作為生態狀況變化之指標。 本研究根據河溪生態水文評估方式選擇適合臺灣上游野溪之評估方式，依溪流魚類調查相關文獻及現地調查之限制來分析指標魚類之調查項目，並進行統計分析。統計分析結果顯示雨量變異與生態因子關係顯著，利用雨量變異推估生態因子狀況，並將原本使用流量計算之水文次指數修正為使用雨量資料計算之水文次指數。 本研究用修正之水文次指數算法對於尖石錦梅橋上游區域進行評分，藉由與原始水文次指數之比較，本研究修正後水文次指數明顯於較符合生態之變化情況，並反映出溪流環境之優劣。且本研究修正之水文次指數在算法、資料合適性、資料取得效率與實際運用等幾個面向上，皆較舊有水文次指數適用於臺灣上游野溪之狀況。

There are many kinds of assessments on ecological habitat of stream due to the different regions and localities. This study targeted at torrents, which have less contamination and more ecological potential restoration comparing with downstream ones and chose Index of Stream Condition, developed by the State of Victoria in Austria, which is included in physical, chemical and botanical indexes and easier use for engineers, especially. In which, the hydrology sub-index is modified by this study and is represented by rainfall variation. This study selects the habitat methods which is applicable to the upstream torrents of Taiwan from a variety of instream flow methods, analyzes the research factors of fishes by the references of ecologic surveying and the limit of field investigation. The statistic analysis showed that the relation between rainfall variation and the ecological factors are significant. The ecological factor is estimated by rainfall variation, and the hydrology sub-index used to calculate by flow variation is modified by calculating by rainfall variation. This study applies modified factor to access the upstream watershed from Chinmei bridge of Chienshih. Comparing with Tsai’s model, the modified model of this study significantly represents the better result on the variation of ecological environment. Moreover, the model of this study shows more feasible in calculating method, data appropriateness, the efficiency of data collection or application for upstream torrents in Taiwan.