| 摘要: | 人類社會對於水資源的需求量持續增加，全球用水量增加的主要因城市擴張、農業活動增長、人口快速增長、經濟發展和生活水平提高，而地下水資源作為傳統水資源的替代來源，近年來更將沿海含水層補注至海洋之地下水視為潛在可用水資源來源，透過估算地下水通量及推估含水層參數，並討論沿海含水層之海淡水交互作用與潮汐變動特性，可提供地下水水資源管理之參考依據。本研究以中央大學TaiCOAST臨海工作站作為試驗區域，水文地質參數取得方法分為室內試驗與現地試驗，室內試驗為材料熱傳導試驗，測量飽和狀態下土壤材料熱傳導係數等參數，以此結果輔助辨識現地地質材料與地下水流通量。現地試驗為熱示蹤劑加熱試驗(單井加熱試驗)。針對井內垂直溫度分布進行高解析連續量測，利用地下水溫度變化、熱傳導係數與體積熱容量等參數，推估地下水通量並與現地鑽探岩心進行比對，以垂直剖面溫度變化圖評估地質分層及透水特徵區域。根據單井加熱試驗結果，其中高熱傳輸反應區段為深度17-19m、32-34m和42-47m，深度17-19m對應岩心材料為礫石夾砂土，深度32-34m對應岩心材料為礫石砂土互層，深度42-47m對應岩心材料為砂土黏土互層之砂土部分呈細砂狀；低熱傳輸反應區段為深度3-6m、6-11m和19-26m。根據地下水通量垂直分布圖，深度6-8m為低透水性區段，地下水通量約2.4m/day，此區段在加熱試驗中熱傳輸反應為相反。而深度19-26m處地下水通量約0.05 m/day，此區透水性應為較差，地下水流動速率較慢，與加熱試驗結果之熱傳輸反應相同。然加熱試驗結果可判釋潮汐對沿海含水層之影響，可證本研究區域受潮汐影響相當顯著，進一步探討沿海含水層潮汐變動特性之關係。;The increase in global water consumption is mainly owing to urbanization, growing agricultural activities, population growth, economic development, and improving living standards. Forcing the water resource authority concerned to seek new water resources to catch up with the gap of growing demand. Groundwater recharged from coastal aquifers to the ocean is a potential alternative water resource have drawn more attention in recent years. In this study, we aim to quantify the groundwater flux in coastal areas and the interaction between coastal aquifers and seawater intrusion and tidal variations, can provide valuable insights for groundwater resource management. The laboratory experiments include thermal analyzer to measure parameters such as the thermal conductivity of soil materials under saturated conditions, which help identify field geological materials and groundwater flux. The field tests involve heat tracer test (single-well). High-resolution continuous measurements of vertical temperature distribution in the wells are performed. According to the results of the heat tracer tests, the high thermal response zones are located at depths of 17-19m, 32-34m, and 42-47m. The depth range of 17-19m corresponds to gravel-sand mixture in the drilling core. The depth range of 32-34m corresponds to interbedded gravelly sand in the drilling core. The depth range of 42-47m corresponds to sand-silt mixture interbeds, with the sandy portion exhibiting a fine sand texture. The low thermal response zones are observed at depths of 3-6m, 6-11m, and 19-26m. The groundwater flux analysis revealed a low-permeability zone at 6-8m depth, with a flux of around 2.4m/day. Interestingly, heating tests exhibited contrasting heat transfer behavior in this zone. At depths of 19-26m, a slow groundwater flux of about 0.05 m/day and poor permeability aligned with the observed heat transfer reactions. However, the results clearly demonstrate the influence of tides on coastal aquifers, indicating a significant tidal effect in the study area. The relationship between tidal variations and the characteristics of coastal aquifers can be further explored. |
