河川棲地模式PHABSIM之水理計算敏感度分析

本研究針對河川棲地模式PHABSIM之水理計算進行敏感度分析。PHABSIM模式包含水理演算與棲地模擬兩部份，水理模式之主要目的在計算各種流量之斷面水深與流速分布，以便進一步透過棲地模式中標的物種之棲地適合度曲線找出斷面之流速與水深所對應之棲地適合度指數，求得河溪中可使用之棲地面積。PHABSIM之水理模式中提供三種方法建立水位與流量之關係，根據本研究各種案例探討之結果發現對數－對數迴歸法（L-L法）適用於水深與流量呈線性關係之渠道，渠道輸送法（C-C法）及步推迴水法（S-B法）則適用於曼寧n値較爲固定之渠道。另外本研究亦針對組合棲地適合度（CSF）之計算方式進行比較，結果顯示PHABSIM模式提供之四種CSF法雖然在計算之棲地面積大小方面有所差異，但在棲地面積與流量關係之整體變化上則具有一致之趨勢。

關鍵字

棲地模式；水理計算；水位－流量關係；棲地適合度指數；權重可使用棲地面積；組合棲地適合度

並列摘要

A sensitivity analysis on the hydraulic calculation of the riverine habitat model PHABSIM is presented. PHABSIM system consists of two simulation modules, namely, hydraulic and habitat models. The hydraulic model is mainly to simulate the flow depth and cross-sectional velocity distribution. The hydraulic data are further incorporated with the target species criteria curves to determine the habitat suitability indices. The habitat model uses these indices to calculate the weighted usable area of a stream reach. PHABSIM supports three methods for establishing the stage-discharge relationship. The results of case studies indicate that log-log regression (L-L) method is suitable for the channels having linear stage-discharge relationship; whereas channel-conveyance (C-C) and step-backwater (S-B) methods are applicable to the channels of constant roughness (Manning's n value). Four formulas for estimating the combined suitability factor (CSF) are also compared. It is revealed that the habitat areas calculated with various CSF are different in magnitude, however, the overall trend for the variation of habitat area with discharge is consistent.

並列關鍵字

Habitat model ； Hydraulic calculation ； Stage-discharge relationship ； Habitat suitability index ； Weighted usable area ； Combined suitability factor

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