Collaborative Research: A Systematic of Solute Transport Influenced by Preferential Flow Paths at the Decimeter and Smaller Scales

在密西西比州哥伦布市的大弥散实验(MADE)现场最近的研究表明，含水层在分米(Dm)和更小尺度上的非均质性所产生的优先流动路径似乎对羽流尺度的溶质迁移具有主导作用。这项合作研究回应了在Made现场观察到的dm尺度非均质性对羽流尺度溶质传输的影响的普遍缺乏的研究。我们的目的是系统地研究dm尺度优先流动路径对溶质传输特性的影响，并严格检验双域传质方法可以有效地表示这种特性的假设。(1)生成dm尺度的河流沉积河道的三维地质合理网络，并模拟此类系统中的详细输运。(2)评估双域传质模型，以及可能的其他替代模型，描述溶质传输的关键特征的能力。(3)进行了一系列大直径塔板实验，测量了不同非均质构型和流速下的传质模型参数值。(4)在现场进行示踪剂试验，利用染料示踪、土壤取芯和图像分析等方法获得传质模型参数值，为优先流动路径提供直接的现场证据。我们将尝试将岩性特征与示踪剂试验获得的传质模型参数联系起来。

0003914GorelickRecent studies at the Macrodispersion Experiment (MADE) site in Columbus, Mississippi have indicated that the preferential flow paths resulting from aquifer heterogeneities at decimeter (dm) and smaller scales appear to have a dominant effect on plume-scale solute transport. This collaborative research responds to the general lack of studies on the effect of dm-scale heterogeneities on plume-scale solute transport as observed at the MADE site. Our intent is to systematically study the characteristics of solute transport influenced by dm-scale preferential flow paths, and rigorously test the hypothesis that a dual-domain mass transfer approach can provide an effective representation of such characteristics.Four specific elements are integrated into the proposed research. (1) Generate 3-D geologically plausible networks of dm-scale fluvially deposited channels and simulate detailed transport in such systems. (2) Assess the ability of the dual-domain mass transfer model, and possibly other alternative models, to represent the key characteristics of solute transport. (3) Conduct a series of large-diameter column experiments to measure the mass transfer model parameter values under different heterogeneity configurations and flow rates. (4) Conduct tracer tests at the MADE site to obtain the mass transfer model parameter values, using dye-tracing, soil coring and image analysis aimed at providing direct field evidence of preferential flow paths. We will attempt to relate the lithologic characteristics to the mass transfer model parameters obtained from the tracer tests.