異向含水層部分貫穿井溶質傳輸分析; Analysis of solute transport toward a partially penetrating extraction well in an anisotropic aquifer

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Title:	異向含水層部分貫穿井溶質傳輸分析;Analysis of solute transport toward a partially penetrating extraction well in an anisotropic aquifer
Authors:	吳嘉倫;Chia-Lun Wu
Contributors:	應用地質研究所
Keywords:	捕集區;縱向延散度;水力傳導係數異向比;部分貫穿井;longitudinal dispersivity;capture zone;partially penetrating well;hydraulic conductivity anisotropy ratio
Date:	2008-07-03
Issue Date:	2009-09-22 10:00:13 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	抽出處理法為傳統含水層整治技術，其方法為抽出含水層中受污染的地下水，降低其污染濃度至達到整治標準，有效的抽出處理系統設計應收集全部的污染物，並抽取最小量鄰近污染物的乾淨地下水。現地實務上，含水層只有部分垂直厚度受污染時，此時整治系統可以考慮採用部分貫穿井作為設計依據。本研究發展異向受壓含水層部份貫穿井溶質傳輸之數學模式，首先求解部分貫穿井抽水的穩態洩降解，利用洩降解可計算孔隙流速於水平與垂直方向之分量，所得流速可以建立二維圓柱座標移流-延散傳輸方程式，藉由Laplace轉換有限差分法求解，可得含水層中的溶質濃度分布；所得模式將用以分析井篩長度、含水層水力傳導係數異向比、縱向延散度及含水層延散度異向比等對溶質傳輸之影響，模擬結果顯示在含水層水力傳導係數異向比越大，縱向延散度越小的情況，將顯著影響部分貫穿井整治效率，其與全層貫穿井達到整治標準所需之時間差至2.5倍。本研究所發展之模式可作為部分貫穿井用於含水層整治系統設計之工具。 Pump-and-treat techniques are often applied to extract the polluted groundwater and to reduce the concentration of the contaminants to an acceptable level. The design of an effective and efficient pump-and-treat system requires that the recovery wells collect the contaminant and withdraws the minimum amount of clean water adjacent to the contaminant plume. The installation of a partially penetrating well in which only a portion of the well casing is screened is becoming more common because it is very often the case that only a portion of the vertical thickness of the aquifer is contaminated. In this study, a novel mathematical model describing the solute transport around a partially penetrating well is presented. To build the new model, the radial and vertical components of the pore water velocity are first computed using an analytical solution for the steady-state drawdown distribution near a partially penetrating well. Next, the obtained radial and vertical components of the pore water velocity are incorporated into a two-dimensional advection-dispersion equation in cylindrical coordinates from which the solute transport equation is derived. The developed model is used to investigate the effects of the site-specific aquifer parameters on solute transport near a partially penetrating well. Results demonstrate that the effect of the partially penetrating well on solute transport is significant when there is a large hydraulic conductivity anisotropy ratio and small longitudinal dispersivity. The mathematical model presented herein provides a useful tool for designing an effective and efficient pump-and-treat system for partially penetrating well.
Appears in Collections:	[應用地質研究所] 博碩士論文

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