Collaborative Research: High-resolution Dynamic Characterization of Transport Pathways: Providing New Insights into Subsurface Processes

Michigan State University, East Lansing MI

Investigators

Abstract

Project Title: High-Resolution Dynamic Characterization of Transport Pathways: Providing New Insights into Subsurface Processes Team 1 Proposal 07-38955 Principal Investigators: James Butler, Geoffrey Bohling, and Gaisheng Liu Institution: Univ. of Kansas Team 2 Proposal 07-38938 Principal Investigators: David Hyndman and Remke Van Dam Institution: Michigan State Univ. Team 3 Proposal 07-38960 Principal Investigator: Chunmiao Zheng Institution: Univ. of Alabama Project Abstract A large body of theoretical and experimental research has identified the spatial distribution of hydraulic conductivity (K) as the most significant factor controlling subsurface solute transport. Previous work has shown that detailed characterization of heterogeneous aquifers is necessary to develop predictive models and improve our understanding of transport behavior. Although numerous studies have demonstrated that classic advection-dispersion models can reasonably describe field-scale solute transport in mildly heterogeneous aquifers, efforts to develop predictive transport models in highly heterogeneous aquifers have not met with success. Recent modeling studies have indicated that small-scale variations in hydraulic conductivity may be the primary cause of the highly asymmetric tracer plumes that have been observed in such aquifers. However, the current generation of field methods is not capable of characterizing these variations at the level of detail required for predictive transport modeling. In this project, we will develop new methods to characterize and simulate transport through heterogeneous aquifers. By combining a new direct-push profiling method with novel "full-resolution" 3D ground-penetrating radar methods, we will describe the spatial distribution of K at previously unattainable vertical and lateral resolutions. We will apply our approach at the extensively studied MADE site and demonstrate the value of such detailed characterization by predictively simulating saline tracer tests monitored with time-lapse geophysics, and through reassessment of a previously performed large-scale tracer test. The high-resolution 3D K description of the MADE site will be used to evaluate alternative solute-transport modeling approaches, and to develop new insights into transport processes in highly heterogeneous aquifers. We will demonstrate the broad applicability of the developed techniques and principles at additional sites in the United States and Germany. The project will have significant broader impacts in the areas of science, practice, and education. The unprecedented level of characterization of hydraulic conductivity at the MADE site will provide the necessary detail to address a suite of fundamental questions concerning solute transport in highly heterogeneous formations. These data sets will improve our conceptual understanding of, and modeling capabilities for, solute transport through such systems. The insights and methods developed in this research will also be of great value for applied hydrogeology; their incorporation into practical investigations should dramatically improve the quality of predictive models, leading to more reliable risk assessments and more efficient allocation of resources for site characterization and remediation activities. We will develop high-resolution immersive visualizations of our results to provide practitioners, researchers, and students with an ability to explore subsurface transport phenomena in a highly heterogeneous environment.