Erosion dynamics of viscous flows over granular substrates

Erosion and deposition are naturally occurring processes that, at equilibrium, can benefit an ecosystem. Consequences of excessive erosion and deposition include a reduction in reservoir storage capacity, river pollution due to moving sediment containing nutrients, damage to infrastructure, and landslides. Erosion and landslide mitigation are important in protecting many ecosystems. In this project, we investigated questions about landscape erosion using experiments, numerical tools, and mathematical modeling. Our experiments involve laying a bed of sand on an inclined plane and releasing a flow of viscous fluid over the bed. Images taken from the top view and side view of these experiments are analyzed to track the front position of the erosion, the height of the bed of sand, and concentration over time. We used numerical tools to analyze the images from each experiment and extract quantitative information. In our results, we compare the angle of inclination to the rate of erosion of the bed and the percentage of erosion that occurs. From the experiments, we also found the critical angle that induces landslides. The models we use are derived from particle-laden lubrication theory that describes the flow of particles mixed in a fluid. We used the data from our experiments to test simplified mathematical models for the erosion concentration and the height of the block.