RUI: Predicting Transport Through Heterogeneous Facies Assemblages: Geostatistical Anatomy of Buried-Valley Aquifiers, II

RUI：通过非均质相组合预测输运：埋谷含水层的地统计解剖学，II

• 批准号: 9628299
• 负责人: Robert Ritzi
• 金额: $ 6.61万
• 依托单位: Wright State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 1998-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9628299&HistoricalAwards=false
• 关键词: RUI; Predicting; Transport; Through; Heterogeneous

9628299 Ritzi Contaminant problems have created the need to understand how hydraulic conductivity (K) is distributed in aquifer systems. Extreme-value pathways exert a dominant physical control on contaminant transport, and thus the boundary between high-K and low-K materials (hydrofacies) must be quantified. Although the exact geometry of the hydrofacies can only be determined by a prohibitive amount of subsurface information, stochastic methods such as conditional indicator simulation provide a way to compute a number of realizations of hydrofacies distributions that honor available data at their locations, with specified functions for the principal directions of spatial correlation of the hydrofacies, the scale of correlation in these directions, and the proportions. Running transport simulations using a large number of these realizations and examining the central tendency and variance of simulated contaminant travel times, or the simulated contaminant pathways, can give insight into how contaminants will move through the real system. These simulations can also be incorporated into a formal decision-analysis framework. However, the field data at a specific site commonly are insufficient for the purpose of defining the spatial correlation and proportions of the hydrofacies directly. Therefore, analog sites that are data rich need to be studied in order to find models for spatial correlation and proportions of hydrofacies that, on the basis of similar geology, can be transferred to data-poor sites. Indeed, one of the research needs identified by the National Research Council in Alternatives for Ground Water Cleanup, is the development of statistical models representing common geologic environments, which can be used to assess the variability of aquifer properties and thereby improve the success of aquifer restoration (NRC, 1994, p. 73). The proposed research will develop statistical models for aquifer properties in buried-valley aquifers, which occur across the central a nd western glaciated plains of North America and are vital to the water resources of the region. In such glacially derived aquifers, it is common to have low-K facies (e.g., till or lacustrine clay) juxtaposed with high-K facies (e.g., sand and gravel outwash). This is a renewal proposal. In the prior phase, several locations were studied in a buried-valley aquifer system located in Ohio, with the successful development of models for the hydrofacies distribution, proportions, principal directions of spatial correlation, and correlation scale in these directions. These statistical models were linked to the deposition processes that created the aquifer system, and therefore are likely to be applicable to other locations in the aquifer, and to other aquifer systems where similar depositional processes have operated. However, hydrofacies models are most useful when based on the features of numerous well-studied examples. The generality and usefulness of quantitative geostatistical models will likewise increase with their numbers, if more data-rich analogs are examined. One goal of this renewal proposal is to develop new geostatistical models for a buried-valley aquifer system in Indiana. However, the main focus of this work will be to critically evaluate methods of linking spatial correction of hydrologic parameters and geologic structure. The transition probability has been shown to be an even more interpretable representation of spatial correlation than the variography used in the prior phase. Thus the transition probability may provide a new tool for linking spatial correlation and deposition processes. The innovative aspect of this work is that it will provide a way to test the hypothesis that generic hydrofacies models can be developed for a specific class of aquifers. This will be the first comparison of spatial correlation of hydrogeologic parameters among aquifers, and is part of the longer-term goal of developing a catalogue of quantitative hydrofacies. ??

9628299 Ritzi 污染物问题需要了解水力传导率 (K) 在含水层系统中的分布情况。 极值路径对污染物迁移发挥主要的物理控制作用，因此必须量化高 K 和低 K 材料（水相）之间的边界。 尽管水相的精确几何形状只能通过大量的地下信息来确定，但条件指示符模拟等随机方法提供了一种计算水相分布的多种实现方式的方法，这些实现遵循其位置上的可用数据，并具有指定的函数水相空间相关性的主要方向、这些方向上的相关性规模以及比例。 使用大量这些实现来运行运输模拟并检查模拟污染物传播时间或模拟污染物路径的集中趋势和方差，可以深入了解污染物如何在真实系统中移动。 这些模拟也可以纳入正式的决策分析框架中。 然而，特定地点的现场数据通常不足以直接定义水相的空间相关性和比例。 因此，需要研究数据丰富的模拟站点，以便找到空间相关性和水相比例的模型，这些模型可以在相似的地质基础上转移到数据贫乏的站点。 事实上，国家研究委员会在地下水净化替代方案中确定的研究需求之一是开发代表常见地质环境的统计模型，该模型可用于评估含水层特性的可变性，从而提高含水层​​恢复的成功率（NRC，1994 年，第 73 页）。 拟议的研究将开发潜谷含水层含水层特性的统计模型，这些含水层遍布北美中部和西部冰川平原，对该地区的水资源至关重要。 在此类冰川衍生的含水层中，通常同​​时存在低 K 相（例如，耕土或湖相粘土）与高 K 相（例如，砂砾石冲刷）。 这是一项更新提案。 前期对俄亥俄州潜谷含水层系统的多个位置进行了研究，成功开发了水相分布、比例、空间相关主方向以及这些方向的相关尺度模型。 这些统计模型与创建含水层系统的沉积过程相关，因此可能适用于含水层的其他位置，以及发生类似沉积过程的其他含水层系统。 然而，当基于大量经过充分研究的例子的特征时，水相模型是最有用的。 如果检查更多数据丰富的类比，定量地质统计模型的通用性和实用性同样会随着模型数量的增加而增加。 这项更新提案的目标之一是为印第安纳州的潜谷含水层系统开发新的地质统计模型。 然而，这项工作的主要重点将是批判性地评估将水文参数空间校正与地质结构联系起来的方法。 转移概率已被证明是比前一阶段使用的变异分析更容易解释的空间相关性表示。 因此，转移概率可以提供一种连接空间相关性和沉积过程的新工具。 这项工作的创新之处在于，它将提供一种方法来检验可以为特定类别的含水层开发通用水相模型的假设。 这将是含水层之间水文地质参数空间相关性的首次比较，也是开发定量水相目录的长期目标的一部分。 ??