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 - 37668史蒂文·M. Gorelick经过多年的研究，很明显，流行的对流-弥散模型（ADM）不能充分描述介质中的溶质行为，即使是适度的非均匀性。ADM是基于这样的前提下，地下水速度的变化是由于在水力传导率，K，这是假定为相关的，但在其他方面随机的不均匀性。从地质学的角度来看，这一前提往往是不合理的，因为在非均匀含水层中，预期的是连通性而不是随机性。虽然越来越多的现场证据表明，在低K矩阵连接导管控制的传质至关重要，一直没有系统的评价非ADM替代模型。本项目的目标是调查替代运输模型配方的基础上的质量转移的概念，并确定最佳的手段来获得控制相对含水层管道和周围的矩阵之间的溶质的速率限制迁移的参数值。将在密西西比的宏观弥散实验（MADE）现场进行一系列全面的实验室实验和现场测试，以评估和对比含有连接的高K网络的含水层中溶质运移的替代理论模型。研究项目将解决四个重要问题：（1）在异质河流含水层中，连通的高K优先流通道网络的性质、几何形状和规模是什么？(2)这种流动通道网络（和流动障碍物）与河流沉积物的结构、构造和粒度分布有何关系？(3)在没有嵌入式网络几何学或模型校准的具体知识的情况下，确定嵌入式网络系统中的传质系数值的先前理论关系能否在实验室和现场得到验证？(4)什么是最合适的模型来代表溶质运移含水层包含小规模连接高K网络，以及如何可以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的，健全的概念和建模框架，在实践中是有用的，以考虑连接的高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运移、管理地下水质量以及了解自然环境中溶质的迁移和分布具有重要意义。这项工作与水文学的其他领域和其他科学领域有关。涉及优先途径的运输和质量传递的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，其中嵌入导电性较低的基质中的高导电网络系统是常见的。在水文学中，当三角洲和河口的地表水树枝状网络与地下水相互作用时，就会发生缓慢的质量转移机制。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。