南台灣河川水質改善效益評估-以高雄市台南市為例

水利與環保單位採用各種河川整治工程與環保政策，以提昇台灣地區河川水體品質。這些工程的效益評估，主要根據水質參數改善的程度而定，然而各河川原本就具有特定的季節與長期水質變化趨勢，因此單獨的水質改善結果，無法客觀評估水質改善工程實際的影響時間範圍與效應。為解決此一問題，本研究採用經濟學上常用之累積和管制圖(Cumulative Sum, CUSUM)結構轉變檢定，結合時間序列分解技術，作為河川水質參數之時間序列轉折點偵測依據。為驗證可行性，本研究比對二仁溪4個水質測站(包括崇德橋測站、南雄橋測站、石安橋測站及南萣橋測站) 2007年至2017年之河川污染指數時間序列轉折點與相關整治工程及環保政策之相關性。結果發現，水質淨化場由於成效發揮時間較為集中，可在河川污染指數時間序列上產生轉折點。不同處理水量之水質淨化場其對於轉折點的影響也不同，處理水量較大之水質淨化場較容易產生轉折點。

關鍵字

CUSUM結構轉變檢定；時間序列分解；二仁溪；轉折點偵測；水質淨化場；水資源回收中心

並列摘要

Many river water quality improvement projects and environmental policies are implemented by authorities. The effectiveness of these projects and policies are evaluated by removal rate of water pollution. However, it is difficult to determine the period of influence. In this study, CUSUM (Cumulative Sum) test combined with seasonal trend decomposition methods were used to analyze changepoints in the long-term trend (2007–2017) of the river pollution index (RPI) of Erren River, Taiwan. Times when the river pollution index changes were compared with times when river water quality improvement projects and environmental policies were implemented. Results show that the period of influence of onsite treatment facilities can be identified by changepoints. The detecting of changepoints are affected by the volume of wastewater treated. However, the period of influence of wastewater treatment plants is not identified by changepoints for the low integral sewage treatment rate.