臺灣集集攔河堰的興建對濁水溪流域水文環境影響之研究

Hydrologic Alterations Caused by Chi-Chi Diversion Weir in Jhuoshuei River Basin, Taiwan

曹鈞(Jyun Tsao) ； 葉信富(Hsin-Fu Yeh)

《臺灣鑛業》 70卷2期 (2018/06) Pp. 18-29

摘要

臺灣需要建造水庫及攔河壩堰，來提供足夠用水及防洪目的，但人工構造物會影響河川生態及流量。集集攔河堰建造目的主要為供給下游地區穩定的水源，並減少抽用地下水，減緩濁水溪下游地區地層下陷的情況。本研究利用統計分析方法比較河川流量、基流及雨量趨勢，並使用雙累積曲線探討趨勢發生改變的時間，來評估集集攔河堰的興建對濁水溪流域帶來水文環境改變。研究結果顯示，流域長年年雨量變化不甚顯著，而年流量卻有17.02%的下降趨勢，經斜率分析發現，雙累積曲線分析之轉折點為2001年，此時間亦為集集攔河堰完工時間。故進一步以2001年為分界，前後年平均流量減少了8%，而年平均基流量減少26.5%。本研究所探討之結果，可以提供日後水資源管理規劃之參考。

關鍵字

集集攔河堰 ； 基流 ； 趨勢分析 ； 雙累積曲線

並列摘要

Taiwan has many hydraulic structures such as reservoirs and weirs to store water and prevent flooding. These artificial structures may affect the biological environment and the hydrologic regimes of the rivers they are constructed to control. The main purpose in constructing the Chi-Chi diversion weir was to supply sufficient water for the Jhuoshuei River’s lower reaches while reducing the use of groundwater to mitigate the subsidence problem in the river’s downstream regions. . In this study, we used several statistical analysis methods to determine trends and slope magnitudes of streamflow, base flow, and precipitation in the Jhuoshuei River. Double Mass Curves (DMC) were also used to find the change point of the hydrologic data to evaluate changes before and after weir construction. The results showed no obvious long-term precipitation data trends, but streamflow displayed a downward trend (-17.02%). Furthermore, DMC indicated a breakpoint occurring in 2001, which is exactly the time the Chi-Chi diversion weir was built. A comparing of the average flows before and after 2001 showed that annual streamflow declined 8% and the annual base flow declined 26.5%. This study’s findings may serve as a reference for the management and regulation of water resources in the future.

並列關鍵字

Chi-Chi diversion weir ； base flow ； trend analysis ； Double mass curve