在過去，臺北盆地依賴地下水做為重要水資源之一，然而大量抽取地下水造成了地下水位逐年下降，進而導致嚴重的地層下陷問題。自1958年起實施的地下水管制措施有效減緩了地下水位的下降和地層下陷，但隨著地下水位回升，過高的地下水位將使工程施工成本增加並增加施工風險，且可能提高土壤液化潛勢。地質材料的空間分布、地質模型架構，以及地下水流場之動態特性，為評估地層下陷與土壤液化之基礎。因此，本研究建立異質性水文地質模型，以產製未調查區域的水文地質資料，並應用MODFLOW程式進行地下水數值模擬，以提供無觀測區域的地下水資訊。
臺北盆地由古新店溪、大漢溪、基隆河堆積而成，沉積層分布呈現相當大的空間變異性。本研究將臺北盆地內第四紀地層，依照水文地質特性劃分為較低透水性之松山層以及其下方由透水性較佳之礫石、砂組成之主要含水層；並篩選地質鑽探資料，應用轉移機率－馬可夫鏈法，計算各材料之空間連續性與建立松山層異質性水文地質模型。
研究結果顯示，臺北盆地中南北向地質材料的空間連續性優於東西向；而後挑選具長期觀測區間之地下水位結合水文地質模型，透過地下水模擬系統（Groundwater Modeling System, GMS）中的MODFLOW程式，建立臺北盆地地下水數值模式並進行穩態模式率定。模式水位與地下水位觀測資料相比，第一分層和第二分層的決定係數(R2)分別為0.95和0.83，而均方根誤差(RMSE)則分別為0.56及0.60公尺。在增加或減少一成之抽水量案例模擬中，其水位變化保持在一公尺之內，代表臺北盆地有潛力提供更多的水資源。本研究成果將可提供臺北盆地地下水資源管理之參考，使現有地下水資源得以妥善運用。

In the past, a large amount of pumping led to a continuous decrease in the groundwater level in the Taipei Basin, resulting in severe land subsidence. Subsequently, the implementation of a policy prohibiting groundwater pumping led to an increase in the groundwater level. However, this caused engineering problems, such as soil liquefaction. The spatial distribution of geological materials, the geology structure, and the groundwater level are essential for evaluating land subsidence and soil liquefaction. This study develops a heterogeneous hydrogeological model and applies the MODFLOW module for assessing the groundwater level.
Initially, a three-dimensional heterogeneous hydrogeological model in the study area was constructed. Non-consolidated sediment in the Taipei Basin is divided into two main layers. The first layer is the Songshan formation, primarily formed of fine grain materials, such as sand and clay. The second layer is a confined gravel layer below the Songshan formation. Transition probability - Markov chain approach was adopted to analyze the borehole data and generate realizations of the heterogeneous hydrogeological model in the first layer. The results show that the north-south spatial continuity of geological materials in the Taipei Basin is superior to the east-west direction. Furthermore, the hydrogeological model showed a 0.76% consistency with the borehole data.
Subsequently, the hydrogeological model was combined with the groundwater observation data for calibration to the steady-state groundwater level through MODFLOW packages in the Groundwater Modeling System (GMS) software. Compared to observed groundwater level, the coefficients of determination (R²) for the first and second layers were 0.95 and 0.83, respectively, while the root mean square errors (RMSE) were 0.56 and 0.60 meters. Water level changes remained within one meter when pumping volumes were increased or decreased by ten percent, indicating the potential of the Taipei Basin to provide additional water resources. The results provide a reliable assessment for groundwater resource management in the Taipei Basin in the future.

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