在沿海地區，地下水資源自然會遇到與海水共存的問題，一旦海水過度入侵，會導致土壤鹽化、地表植被或耕作毀損等問題產生，因此需要透過觀測資料與數值模型了解海淡水的交界分布範圍，以及其受潮汐影響所造成的變化。水文地質數值模式模擬工作首重地質概念模型之建立，建構符合現地條件之地質模型可有效降低推估結果之不確定性，並提升水資源計算與評估之精準度。本研究以國立中央大學TaiCOAST臨海工作站為目標，進行水文地質調查工作，包括岩心鑽探與地質材料判識、地下水文觀測、水文地質特徵參數等，以GemPy開源地質建模套件建置三維地質概念模型，結合FloPy進行沿海地區流場模擬。本研究將場址內岩心分成兩部分，一部分用於建立地質模型，另一部份用於比對結果；流場模型則使用兩至三個月平均地下水頭做為建模依據，並透過海淡水的水頭變化進行模式驗證，最後藉由觀察流場模型探討潮汐變化對於沿海地區的影響。本研究能夠更有效率的藉由開源軟體建立三維水文地質模型，並串連python語言之水流數值模式套件進行地下水流場分析，以使用場址內三口岩心資料，藉由GemPy進行插植計算完成場址內三維地質模型並討論，以及利用地質模型所得之材料分布推估水力傳導係數導入Flopy程式內建立流場模擬。本研究期望透過大量岩心資料降低地質模型不確定性，提升地下水流流場推估之準確性，研究結果也能提供水文地質建模可行方案的參考依據。本研究結果顯示在TaiCOAST測站內之地下水鹽度隨潮汐之變化，地下水鹽度隨深度之變化主要受到地質分層結果影響，在高程-30m以上，水力傳導係數值較大，鹽度較容易隨潮汐變化；在高程-30m以下，水力傳導係數值較小，鹽度較不易隨潮汐變化。

Coastal groundwater resource is a potential alternative water resource to bridge the gap of increasing water demands. An accurate hydrogeological model could reduce the uncertainty of the flow and transport estimations in coastal aquifers. The study aims to develop a framework that integrates the open-source GemPy and FloPy for modeling seawater and freshwater interactions in the coastal aquifer in Taoyuan, Taiwan. The GemPy is a geological modeling suite based on implicit interpolation algorithms and is employed to build the 3D geological model for the coastal aquifer. The FloPy allows the users to simulate MODFLOW and the relevant modeling packages for aquifer systems. In the study, a series of field works were conducted to acquire site-specific information, including core drilling and identification of geological materials, groundwater level observation, and hydraulic tests. The geological model uses data obtained from the core samples to map the stratigraphic distribution of the coastal aquifer. The groundwater flow model was then calibrated and validated based on long-term observation at the site. The submarine groundwater discharge at the site was systematically assessed and the parameter heterogeneous induced uncertainty was evaluated. The results of this study indicate that groundwater salinity within the TaiCOAST station varies with tides. The variation of groundwater salinity with depth is primarily influenced by the geological stratification. Above an elevation of -30m, where hydraulic conductivity values are higher, salinity is more susceptible to tidal fluctuations. Below an elevation of -30m, where hydraulic conductivity values are lower, salinity is less likely to change with tides.

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