Ian Bourg, assistant professor of civil and environmental engineering and the Princeton Environmental Institute, has received a five-year, $400,000 CAREER award from the National Science Foundation to study the hydrology and mechanics of fine-grained soils and sedimentary rocks.
Fine-grained, clay-rich rocks such as shale and mudstone constitute roughly two-thirds of Earth’s sedimentary rock mass, yet they remain a sparsely charted frontier in groundwater-hydrology research. These rocks cover, contain or produce many sources of subsurface water, carbon and energy such as natural gas. Clay-rich rocks have the distinct properties of ultra-low permeability, as well as the capability to swell, shrink and crack, all of which can be used to control subsurface fluid flow. As a result, these rocks can be used for hydrocarbon extraction, carbon capture and storage, high-level radioactive waste storage, and sourcing and storing groundwater.
For this project, Bourg will develop a general theory of the hydrologic properties of fine-grained soils and sedimentary rocks with the goal of understanding their hydrologic, mechanical and chemical properties from the nanometer scale to the tens and hundreds of meters. His research will rely on simulations and rigorous experimentation for each scale. He also will develop the use of molecular-dynamics simulations as an educational tool that could illustrate important scientific concepts and phenomena in an intuitive, hands-on manner. This tool will be developed for the first year of the Princeton course, ENV 301: “Introduction to Environmental Engineering,” and as a web-based interface that will enable the broader community — particularly high-school students and teachers — to visualize and explore simulation results stored on the high-performance data-storage systems at the National Energy Research Scientific Computing Center.
The NSF project ties into research on the physics of soil carbon storage that Bourg conducted through PEI's Carbon Mitigation Initiative. His CAREER-grant work could explain empirical observations that fine-grained soils tend to accumulate more organic carbon.