Collaborative Research: Solute Transport in Aquifers Containing Connected High-Conductivity Networks: Theory Founded on Laboratory and Field Data

合作研究：含有连通高电导率网络的含水层中的溶质输运：基于实验室和现场数据的理论

• 批准号: 0537668
• 负责人: Steven Gorelick
• 金额: $ 13.72万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0537668&HistoricalAwards=false
• 关键词: Collaborative; Research; Solute; Transport; Aquifers

05-38011Chunmiao Zheng. .05-37668Steven M. GorelickAfter many years of research, it is evident that the prevalent, advection-dispersion model (ADM) does not adequately describe solute behavior in media with even modest heterogeneity. The ADM is based on the premise that groundwater velocity variations are due to heterogeneity in hydraulic conductivity, K, which is assumed to be correlated but otherwise random. From a geologic perspective, this premise is often unjustified because connectedness rather than randomness is expected in heterogeneous aquifers. Although a growing body of field evidence now points to the critical importance of mass transfer controlled by connected conduits in low-K matrix, there has been no systematic evaluation of non-ADM alternative models. The goal of this project is to investigate alternative transport model formulations that are based on the mass-transfer concept, and determine the best means to obtain the parameter values controlling rate-limited migration of solutes between relative aquifer conduits and the surrounding matrix. A comprehensive set of laboratory experiments and field tests at the Macro-Dispersion Experiment (MADE) site in Mississippi will be conducted to assess and contrast alternative theoretical models of solute transport in aquifers containing connected high-K networks. The research project will address four important questions: (1) What is the nature, geometry, and scale of connected high-K preferential flow channel networks in a heterogeneous fluvial aquifer? (2) How are such flow channel networks (and flow barriers) related to the texture, structure and grain-size distribution of fluvial sediments? (3) Without specific knowledge of conduit-network geometry or model calibration, can a previous theoretical relation determining the value of the mass-transfer coefficient in the embedded network systems be verified in the laboratory and field? (4) What is the most appropriate model to represent solute transport in aquifers containing small-scale connected high-K networks, and how can the parameters for that model be obtained from readily available field and laboratory data?The proposed project will allow us to establish a comprehensive, sound conceptual and modeling framework that is useful in practice to account for the controlling effects of connected high-K networks. In hydrogeology, this is important to the accurate prediction of contaminant transport, management of groundwater quality, and understanding of the migration and distribution of solutes in natural environments. This work is relevant to other areas of hydrology and to other areas of science. The topic of transport and mass transfer involving preferential pathways has important cross-over value to other disciplines, such as botany and animal physiology where systems of highly conductive networks embedded in less conductive matrix are commonplace. In hydrology, the mechanism of slow mass transfer occurs when dendritic networks of surface water interact with groundwater in deltas and estuaries. In plant and animal tissue, delivery of nutrients and drugs involves analogous mass-transfer processes, albeit at different scales.

05-38011郑春苗 .05-37668Steven M. Gorelick 经过多年的研究，很明显，流行的平流弥散模型 (ADM) 并不能充分描述即使具有适度异质性的介质中的溶质行为。 ADM 的前提是地下水流速的变化是由于导水率 K 的不均匀性造成的，假设 K 是相关的，但在其他情况下是随机的。从地质角度来看，这个前提通常是不合理的，因为异质含水层中预期的是连通性而不是随机性。尽管现在越来越多的现场证据表明低 K 矩阵中连接管道控制的传质至关重要，但尚未对非 ADM 替代模型进行系统评估。该项目的目标是研究基于传质概念的替代输运模型公式，并确定获得控制相对含水层管道和周围基质之间溶质限速迁移的参数值的最佳方法。将在密西西比州的宏观分散实验（MADE）地点进行一套全面的实验室实验和现场测试，以评估和对比包含相连的高 K 网络的含水层中溶质传输的替代理论模型。该研究项目将解决四个重要问题：（1）异质河流含水层中连接的高K优先水流通道网络的性质、几何形状和规模是什么？ (2) 这些水流通道网络（和水流屏障）与河流沉积物的质地、结构和粒度分布有何关系？ (3) 在没有管道网络几何或模型校准的具体知识的情况下，是否可以在实验室和现场验证先前确定嵌入式网络系统中传质系数值的理论关系？ (4) 代表包含小规模连接的高 K 网络的含水层中溶质迁移的最合适的模型是什么，以及如何从现成的现场和实验室数据中获得该模型的参数？拟议的项目将使我们能够建立一个全面、完善的概念和建模框架，该框架在实践中很有用，可以解释连接的高 K 网络的控制效果。在水文地质学中，这对于准确预测污染物迁移、地下水质量管理以及了解自然环境中溶质的迁移和分布非常重要。这项工作与水文学的其他领域和科学的其他领域相关。涉及优先路径的运输和质量传递主题对其他学科具有重要的交叉价值，例如植物学和动物生理学，其中嵌入不太导电的基质中的高导电网络系统很常见。在水文学中，当地表水的树枝状网络与三角洲和河口的地下水相互作用时，就会发生缓慢的传质机制。在植物和动物组织中，营养物质和药物的输送涉及类似的传质过程，尽管规模不同。