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 Chunmiao Zheng。 .05-37668STEVEN M. GORELICKAFTER多年来的研究，很明显，流行的，对流 - 分散模型（ADM）没有充分描述具有适度异质性的媒体中的溶质行为。 ADM基于这样的前提：地下水速度变化是由于液压电导率K的异质性K，假定相关但其他随机的。从地质的角度来看，这种前提通常是不合理的，因为在异质含水层中预计连接性而不是随机性。尽管越来越多的现场证据表明，低K矩阵中连接导管控制的传质的重要性至关重要，但没有对非ADM替代模型进行系统的评估。该项目的目的是研究基于质量转移概念的替代传输模型公式，并确定获得相对含水层管道和周围矩阵之间溶质的参数值的最佳手段。将在密西西比州的宏分散实验（制造）站点进行一组实验室实验和现场测试，以评估和对比含有含有连接的高K网络的含水层中溶质传输的替代理论模型。研究项目将解决四个重要问题：（1）在异质河流含水层中，连接的高-K优先流通信道网络的性质，几何形状和规模是什么？ （2）这种流通通道网络（和流动屏障）与河流沉积物的质地，结构和晶粒大小分布有何关系？ （3）如果没有特定的导管网络几何形状或模型校准，可以在实验室和现场中验证以前的理论关系来确定嵌入式网络系统中质量转移系数的值？ （4）在包含小规模连接的高K网络的含水层中代表溶质传输的最合适模型是什么？如何从易于使用的现场和实验室数据中获得该模型的参数？所提出的项目将使我们能够建立一个全面，合理的概念和建模框架，这些框架可在实践中有助于计算连接高的网络的控制效果。在水文地质学中，这对于准确预测污染物运输，地下水质量管理以及对自然环境中溶质的迁移和分布的理解很重要。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传质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，在植物学和动物生理学中，嵌入较低导电矩阵中的高电导性网络的系统很普遍。在水文学中，当地表水的树突状网络与三角洲和河口的地下水相互作用时，慢速传递的机理发生。在动植物组织中，养分和药物的递送涉及类似的质量转移过程，尽管在不同的尺度上。