CAREER: The role of multiscale fracture-matrix exchange and flow channelization on solute and colloid transport in fractured rock

Fractures in underground rock formations significantly influence how water, solutes, and colloids move through the subsurface. These processes are crucial to addressing real-world challenges such as ensuring drinking water quality; providing sufficient water quantity for consumption, agriculture, and industrial purposes; and managing geothermal energy, carbon dioxide, hydrogen, and natural gas storage resources.

However, the complexity of fractured rock systems makes them difficult to study and represent with mathematical models. This project will use multi-scale advanced imaging and geophysical monitoring technology to "see through" rocks and quantify how fluids and colloids move through fractures. These rich datasets will enable the development of simpler, more efficient models for predicting flow and transport in fractured rocks and thus enable scientists and engineers to better manage subsurface water resources.

In addition to advancing science, this project prioritizes education and outreach. A major objective of the educational plan is improving STEM education in rural Wisconsin. Through a partnership with a nature-based learning center, hydrology modules will be developed for middle school summer camps, high school field trips, and community visitor events.

Collectively, the education plan objectives of this project are anticipated to improve hydrogeology education across different educational levels, enhance participation from underrepresented rural communities in central Wisconsin, and broaden student recruitment and participation in geoscience and hydroscience.

The research objectives of this project are focused on how fracture-matrix exchange and fluid flow channelization impact solute and colloid transport in fractured rocks. The specific objectives are to 1) experimentally quantify flow channelization and fracture-matrix exchange in fractured rock cores using positron emission tomography, 2) measure and model differences between solute and colloidal channelization behavior and the role of colloidal attachment on flow channelization in fracture cores, and 3) upscale reduced physics flow and transport models using observational data from experimentally generated mesoscale fracture networks.

Multiscale laboratory data will provide spatially and temporally-resolved observations of channelization and fracture-matrix transport in different rock lithologies. This unique observational data will be used to develop and parameterize reduced physics graph-based models that capture the minimum physics necessary to describe essential characteristics of flow and transport in fractured rocks.

This contribution will be significant because field application of these computationally efficient models requires an understanding of how model properties vary in different lithologies and fracture geometries across spatial scales while accounting for subsurface uncertainty.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.