由氫氧同位素組成顯示南投烏溪上游集水區之水文及環境的意涵

Abstract

本研究分析台灣中部南投地區烏溪上游集水區內包括雨水、地表溪水及地下水各季之氫、氧穩定同位素組成，其目的在瞭解本研究區天水之水文同位素特徵，進而鑑別地下水之補注來源與型態。由各季雨水之同位素特徵比較顯示，因雨量效應的影響，導致夏季雨期雨水之氫、氧同位素組成之平均值較冬季旱期之值為輕。比較雨水與各流域地表水及各地下水區之同位素特徵顯示，地表水及地下水主要源自夏季雨期之降水。統計比較地下水與地表水之同位素特徵顯示，埔里盆地之地下水約有90％以上來自其南側山區之集水區；在貓羅溪流域，地下水來自濁水溪之水源貢獻量約為其東側山區之集水區的二分之一。 Seasonal samples of rain, surface, and gorund- waters were collected and analyzed to determine hydrogen and oxygen isotope compositions in order to better define their isotope characteristics and to differentiate groundwater origin and recharge in the watersheds of the Wuchi system, Nantou. The results showed that maritime airmass is the dominate source of local precipitation. The isotope signals of summer precipitation are relatively depleted compared with those of winter, primarily due to the effect of the precipitation amount. Isotope evidence also indicated the surface waters mainly orginate during rainy seasons. A statistical comparison of isotope characteristics between surface and ground-waters showed that 90% of the groundwater in the Puli Basin is derived from the south side of its watershed. As for the Maolouchi river basin, it swa estimated that water from the Choshuichi contribute to the groundwater system with about half the total amount deriving from the eastern side of its watershed.