| 摘要: | 為解決近年來台灣水資源之枯旱現象，地下水成為抗旱之關鍵水資源。而如何描繪與評估地下水流場為水資源開發領域之重要關鍵議題之一。本研究主要目的是評估場址尺度，在同時受到潮汐之劇烈影響下，利用多種現地水力試驗，結合創新的觀測方式，和正逆推數值模式等方法推估水文地質參數空間分布與建構地下水流場時空動態特徵進行參數分析，以降低傳統場址評估流程所消耗之相關成本。本研究以國立中央大學TaiCOAST臨海工作站地下水觀測井場作為主要研究場域，共包含6口觀測井，進行相關試驗，包含複井、分層定量抽水及觀測、多深度分層微水試驗及水力剖面掃描。同時參考現地岩心材料分佈配合VSAFT2逆推水平向水力傳導係數之二維空間分布。本研究將使用數值模式融合水力試驗獲得之含水層特徵參數空間分布，並對各試驗之空間代表性及其逆推結果，進行參數空間分布不確定性分析。此模式將用於研析本場址地下水與海水交互作用之反應特性，同時探討不同試驗尺度代表性，對於水力剖面掃描逆推結果不確定性，以評估水力試驗尺度效應之影響。
本研究在現地場址使用了跨孔分層定量抽水，搭配分層觀測這項技術，可以在有限的井位內，創造複數觀測點。結合複井定量抽水試驗結果和跨孔定量分層抽水試驗結果，可發現將潮汐影響排除和未將潮汐影響排除，對於水力參數推估將會有一個數量級(order)的差別。綜合初步岩心判釋，可發現此地由淺至深大致呈現礫石夾中砂和砂泥互層；而排除潮汐影響，同時結合不同尺度之試驗資料所推得之K值，結果顯示該現地場址之K值變異程度很小，且各項試驗所推得之K值介於0.188至4.23m/day之間，符合合理範圍內，與岩心鑽探資料相符合。研究結果顯示在資料點數量許可下，結合抽水試驗之結果並搭配水力傳導係數逆推，能大致描繪含水層異質性的分布狀況。
;To address the recent drought phenomenon in Taiwan, groundwater has emerged as a crucial water resource for drought resilience. The depic-tion and assessment of the groundwater flow field are among the key issues in the field of water resource development. The primary objective of this study is to evaluate site-scale hydrogeological parameter analysis, consid-ering the significant influence of tidal fluctuations. This is achieved through the utilization of various in-situ hydraulic tests, innovative observation methods, hydrogeological tests, forward and inverse numerical modeling techniques, aiming to estimate the spatial distribution of hydrogeological parameters and construct the spatiotemporal dynamic characteristics of the groundwater flow field. The ultimate goal is to reduce the costs associated with traditional site assessment processes. The study focuses on the groundwater observation well site at the TaiCOAST Coastal Research Sta-tion, National Central University, comprising 6five monitoring wells. The conducted hydraulic profiling tests include slug tests, stratified quantified pumping and monitoring, and tracer tests. Additionally, the distribution of in-situ rock core materials is considered in conjunction with the VSAFT2 inverse modeling approach to estimate the two-dimensional spatial distri-bution of horizontal hydraulic conductivity. The study incorporates the spatial distribution of hydrogeological parameter characteristics obtained from hydraulic tests into numerical models and performs uncertainty analysis of parameter spatial distribution for each test, taking into account spatial representativeness and the results of inverse estimation. This model is then employed to analyze the response characteristics of groundwa-ter-seawater interaction at the study site and investigate the representative-ness of different test scales, thereby assessing the impact of the hydraulic profiling scale effects on the uncertainty of inversion results.
In this study, cross-hole stratified quantified pumping coupled with layered observations was employed at the field site to create multiple ob-servation points within a limited number of wells. By combining the results of quantified pumping tests in multiple wells and cross-hole quantified layered pumping tests, it was found that excluding or including tidal in-fluences would result in an order of magnitude difference in the estimation of hydraulic parameters. Integrating preliminary core interpretations, the site was observed to exhibit a general sequence from shallow to deep, charac-terized by gravel interbedded with sand and sandy mud layers. Excluding tidal influences and combining K values derived from tests of different scales, the results indicated minimal variation in K values at the field site. The K values obtained from various tests ranged from 0.188 to 4.23 m/day, falling within a reasonable range and consistent with core drilling data. The study results demonstrate that with an acceptable number of data points, integrating pumping test results and utilizing inverse estimation of hydraulic conductivity can effectively depict the distribution of aquifer heterogenei-ty. |
