花蓮溪流域鳳林地區地表地下水之氫、氧同位素時空分布特徵

The Spatial and Temporal Variation of Hydrogen and Oxygen Isotopes of the Surface Water-Groundwater System on Fon-lin Area in Hualien River Basin

高雨瑄(Yu-Hsuan Kao) ； 許少華(Shaohua Marko Hsu) ； 汪中和(Chung-Ho Wang) ； 彭宗仁(Tsung-Ren Peng)

《農業工程學報》 53卷2期 (2007/06) Pp. 22-30

https://doi.org/10.29974/JTAE.200706.0003

摘要

本研究利用氫、氧同位素針對花蓮溪上游鳳林開發區地下水及地表水水文特性進行分析，判斷該區域地下水的補注源及地表與地下水間的相互關係。分析結果顯示同位素示蹤法適合闡述本區域的水文特性。此外由分析氫、氧同位素的組成，可定性地說明該區重要的水文循環特性。配合豐枯水期地表水及地下水的同位素組成，可追溯地下水源，輔助對地下水流場的瞭解。經氫氧同位素組成的分析顯示，此區地下水有淺、中、深的分層現象。雨水對地下水的影響深度約40m左右的淺層含水層。中層是為封閉的含水層，深層地下水在枯水季有高山區域流達的水源。此外，研究區中馬鞍溪南岸附近有一明顯的地下水分區邊界。本區地下水於枯水季時主要由中央山脈的側流補注，豐水季時則主要由含水層上游的馬鞍溪補注。依據氫氧同位素組成的時序變化，可推測本研究區於豐枯水季有不同的地下水流場；豐水季由於含水層上游的馬鞍溪補注，地下水流向為西南南朝東北方向移動；枯水季則因中央山脈的側流補注使得地下水流由西南西朝東北方向流。本研究另外輔以地下水數值模式進行比對，結果可提供往後建構地下水概念模式的參考。

關鍵字

氫氧同位素 ； 模擬 ； 地下分水嶺 ； 水文循環

並列摘要

This study used water samples taken from Fon-lin region in Hualien river basin and analyzed their hydrogen and oxygen isotopes to investigate the possible sources and evolution processes of groundwater and river water flow. The spatial and temporal variations of such isotopes for groundwater and river provided sufficient information to qualitatively describe the processes of the hydrology cycle in Fon-Lin alluvium. Based on the avaliable isotope samples, we found that Fon-lin alluvium, groundwater can be conceptually divided into three layers. The infiltration due to rainfall is limited in top layer and is around the range up to 40m from ground surface. The middle layer can be considered as a semi-confined layer. According to our analysis, the third layer provides a pathway of groundwater source, which possibly collects water from high mountains during dry seasons. In addition, we found a obvious groundwater divide on the south side of Ma-An river. In dry seasons, water in aquifers is recharged from the west side of central mountain region. However, in wet seasons, the major source of groundwater is mainly from the groundwater divide on the south region near Ma-An river. In order to obtaind general insight into to regional flow patterns that are varied with dry and wet seasons, we employed MODFLOW associable with PEST models to simulate the groundwater flow in Fon-Lin area. Our numerical simulation also shows that the flow directions of groundwater is slight changed from dry seasons to wet seasons.

並列關鍵字

Hydrogen and Oxygen Isotopes ； Simulation ； Ground water divide ； Hydrological cycle