A New Method for Identification of Preferential Flow Paths at Sites of Groundwater Contamination

[903103]巴特勒水导率的空间分布对污染物在地下的运动有重要的控制作用。已经发展了许多理论，通过使用随机过程或分形表示来模拟电导率变化，来量化水力电导率的空间变化对污染物输送的影响。这正变得越来越明显；然而，对一个地点的电导率变化的建模不充分，可能会对由复杂岩性混合组成的单元产生重大限制。显然，需要在更大范围内对特定地点的水力传导率分布进行量化，以可靠地预测此类系统中的污染物运动。特别是，对于横向连续的高水力导电性区域（作为优先流动路径）的了解通常是至关重要的。然而，事实证明，在现场确定这些区域是困难的。常规的现场技术提供的信息是高度平均的，或者仅限于测试井附近。该研究为井间空间导流系数的估算提供了一种新的现场方法。虽然是为估计饱和地层中导电性变化的一般任务而开发的，但这对于确定优先流动路径是有效的。该方法包括三个主要要素：1)最近提出的水力层析成像方法，2)用于多级采样井中油管压降测量的低成本压力传感器，以及3)用于地层控制的地球物理调查数据。水力层析成像技术有可能比以前更详细地获得井间水力导电性分布的图像。泵送引起的水头变化的垂直变化的详细信息将从低成本压力传感器获得。利用井间探地雷达测量来约束反演过程，可以解决非唯一性问题。本研究的主要目的是对这一有前途的新方法进行彻底的理论和实地评估。将这些特征合并到一个地点模型中应该显著地提高模型预测的质量，从而导致更可靠的风险评估和更有效地分配地点特征和补救活动的资源。对地下水压导率变化的描述将具有前所未有的详细程度。此外，这些资料应有助于更好地将水力导电性变化与其地质起源联系起来，从而促进将地质资料纳入水文地质调查。[903103]巴特勒水导率的空间分布对污染物在地下的运动有重要的控制作用。已经发展了许多理论，通过使用随机过程或分形表示来模拟电导率变化，来量化水力电导率的空间变化对污染物输送的影响。这正变得越来越明显；然而，对一个地点的电导率变化的建模不充分，可能会对由复杂岩性混合组成的单元产生重大限制。显然，需要在更大范围内对特定地点的水力传导率分布进行量化，以可靠地预测此类系统中的污染物运动。特别是，对于横向连续的高水力导电性区域（作为优先流动路径）的了解通常是至关重要的。然而，事实证明，在现场确定这些区域是困难的。常规的现场技术提供的信息是高度平均的，或者仅限于测试井附近。该研究为井间空间导流系数的估算提供了一种新的现场方法。虽然是为估计饱和地层中导电性变化的一般任务而开发的，但这对于确定优先流动路径是有效的。该方法包括三个主要要素：1)最近提出的水力层析成像方法，2)用于多级采样井中油管压降测量的低成本压力传感器，以及3)用于地层控制的地球物理调查数据。水力层析成像技术有可能比以前更详细地获得井间水力导电性分布的图像。泵送引起的水头变化的垂直变化的详细信息将从低成本压力传感器获得。利用井间探地雷达测量来约束反演过程，可以解决非唯一性问题。本研究的主要目的是对这一有前途的新方法进行彻底的理论和实地评估。将这些特征合并到一个地点模型中应该显著地提高模型预测的质量，从而导致更可靠的风险评估和更有效地分配地点特征和补救活动的资源。对地下水压导率变化的描述将具有前所未有的详细程度。此外，这些资料应有助于更好地将水力导电性变化与其地质起源联系起来，从而促进将地质资料纳入水文地质调查。

9903103ButlerThe spatial distribution of hydraulic conductivity is a significant control on the movement of contaminants in the subsurface. A number of theories have been developed to quantify the influence of spatial variations of hydraulic conductivity on contaminant transport by using stochastic processes or fractal representations to model the conductivity variations. It is becoming increasingly apparent; however, that the modeling of the conductivity variations at a site be inadequate may have significant limitations in units composed of a complex mixture of lithologies. Clearly site-specific hydraulic conductivity distribution at a larger scale need to be quantified to reliably predicts contaminant movement in such systems. In particular, knowledge on laterally contiguous zones of high hydraulic conductivity, which serve as preferential flow paths, is often critical. The field identification of such zones, however, has proven difficult. Conventional field techniques provide information of a highly averaged nature or restricted to the vicinity of the test well. This research would develop a new field method for the estimation of spatial in hydraulic conductivity between wells. Although developed for the general task of estimation of hydraulic conductivity variations in saturated formations and this effective for the identify of preferential flow paths. This methodology involves three primary elements: 1) a recently proposed method for hydraulic tomography, 2) low-cost pressure sensors for drawdown measurements in the tubing used in multilevel sampling wells, and 3) geophysical survey data for stratigraphic control. Hydraulic tomography has the potential to produce images of the hydraulic conductivity distribution between wells at most detail than previously possible. Detailed information about vertical variations in pumping-induced head changes would be at obtained from the low-cost pressure sensors. Nonuniqueness would be addressed by using cross-hole ground-penetrating radar surveys to constrain the inversion process. The primary purpose of the research is a thorough theoretical and field assessment of this promising new methodology. The incorporation of such features into a site model should dramatically improve the quality of model predictions, thus leading to more reliable risk assessments and a more efficient allocation of resources for site characterization and remediation activities. The descriptions of hydraulic conductivity variations in the subsurface would have a level of detail that has not previously been possible. In addition, the information should help better relate hydraulic conductivity variations to their geologic origins and thus facilitate incorporation of geologic information into hydrogeologic investigations.9903103ButlerThe spatial distribution of hydraulic conductivity is a significant control on the movement of contaminants in the subsurface. A number of theories have been developed to quantify the influence of spatial variations of hydraulic conductivity on contaminant transport by using stochastic processes or fractal representations to model the conductivity variations. It is becoming increasingly apparent; however, that the modeling of the conductivity variations at a site be inadequate may have significant limitations in units composed of a complex mixture of lithologies. Clearly site-specific hydraulic conductivity distribution at a larger scale need to be quantified to reliably predicts contaminant movement in such systems. In particular, knowledge on laterally contiguous zones of high hydraulic conductivity, which serve as preferential flow paths, is often critical. The field identification of such zones, however, has proven difficult. Conventional field techniques provide information of a highly averaged nature or restricted to the vicinity of the test well. This research would develop a new field method for the estimation of spatial in hydraulic conductivity between wells. Although developed for the general task of estimation of hydraulic conductivity variations in saturated formations and this effective for the identify of preferential flow paths. This methodology involves three primary elements: 1) a recently proposed method for hydraulic tomography, 2) low-cost pressure sensors for drawdown measurements in the tubing used in multilevel sampling wells, and 3) geophysical survey data for stratigraphic control. Hydraulic tomography has the potential to produce images of the hydraulic conductivity distribution between wells at most detail than previously possible. Detailed information about vertical variations in pumping-induced head changes would be at obtained from the low-cost pressure sensors. Nonuniqueness would be addressed by using cross-hole ground-penetrating radar surveys to constrain the inversion process. The primary purpose of the research is a thorough theoretical and field assessment of this promising new methodology. The incorporation of such features into a site model should dramatically improve the quality of model predictions, thus leading to more reliable risk assessments and a more efficient allocation of resources for site characterization and remediation activities. The descriptions of hydraulic conductivity variations in the subsurface would have a level of detail that has not previously been possible. In addition, the information should help better relate hydraulic conductivity variations to their geologic origins and thus facilitate incorporation of geologic information into hydrogeologic investigations.