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An Analysis of Utilizing Time Domain Reflectometry and Numerical Simulation to Characterize Hydraulic Properties and Mass Transport Process in the Unsaturated Zone
|Contributors: ||NTOU:Institute of Applied Geosciences|
unsaturated zone;mass transport;TDR;soil water content;hysteresis;modeling;model calibration
|Issue Date: ||2013-10-07T02:34:04Z
|Abstract: ||隨著人口日益增加的同時也造成了地球水資源匱乏的壓力，自然資源的永續利用及環 境問題的探討將成為許多專家學者的首要任務，其中水資源方面，最為貼近人類活動 之未飽和層尤其受到重視。過去數十年，許多研究工作針對未飽和層土壤流體與污染 物傳輸進行探討，完成許多室內試驗，然而因實驗尺度之關係，室內結果往往無法完 整呈現野外現地之真實狀況。近年來，時域反射儀（TDR）不僅成功的應用於現地土 壤含水量之量測，污染物濃度分佈之現地量測也開始漸漸受到重視。因此，本研究驥 望藉由室內砂箱實驗與野外現地TDR 量測，針對未飽和層水頭張力、土壤含水量、水 力傳導係數等水文地質參數，分析其在時間與空間之變化並探討遲滯效應對量測結果 之影響，同時於室內與現地進行污染物傳輸之實驗，分析其濃度分佈、傳輸途徑及遲 滯效應對於污染物濃度之影響。藉由室內與現地TDR 之量測數據，建立未飽和層流體 與污染物傳輸數值模型，利用數值模型優化之技巧，找尋最佳水文與污染物參數，確 保數值模型之正確性。經由本專題計畫，驥望可發展出一套TDR 現地量測污染物濃度 之標準流程並建立一正確且適用之未飽和層數學模式，提供往後未飽和層污染物傳輸 分析與污染物整治可行性評估之參考指引。|
As an ever expanding population puts more and more pressure on the Earth’s water resources, research on substantial use of natural resources and environmental problem undoubtedly will remain a high priority issue for many years to come. Of particularly importance is the fundamental and applied research on the subsurface flow and mass transport, especially within the unsaturated zone. Although many research focused on the unsaturated flow and transport in laboratory soil columns in the last decades, the results could not completely represent the real situation on the field scale. Accordingly, some researchers started to develop the field-scale techniques to monitor and predict the unsaturated flow and transport. Among these innovative techniques, recently developed time domain reflectormetry (TDR) enables us to simultaneously obtain the soil water content and contaminant concentration using a single probe without disturbing soil in the field. Therefore, in order to study the spatial and temporal distributions of suction heads, soil water contents, and contaminant concentrations in the unsaturated zone, the TDR technique and the sandbox experiment will be conducted and compared with each other in this study. Based on the laboratory experiments and field tests, a standard procedure for measuring soil water contents and contaminant concentrations using the TDR technique in the field will be established. Besides, the effects of hysteresis, scale, and heterogeneity on the properties of unsaturated flow and transport will be addressed in detail. Coupled unsaturated flow and transport models will be developed by using the data collected from TDR and sandbox experiments. The sensitivity analysis and automated parameter estimation method will be conducted on the model calibration. The standard measuring procedure of TDR technique and calibrated unsaturated flow and transport models can provide as reference tools for contaminant site investigation and remediation assessment in the future.
|Appears in Collections:||[應用地球科學研究所] 研究計畫|
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