Fires, ferns and squirrels: variability in the controls on nonlocal hillslope sediment transport

Hillslope processes are commonly modeled through diffusive frameworks relying on empirical calibration of long-term erosion rates or sediment fluxes. These models are fundamentally unequipped to capture variability in the relative rates of mechanistically distinct transport processes–or their varying responses to perturbation. Predicting how fluxes or landscapes will respond to rapidly changing Anthropocene conditions requires decoupling these process components from the diffusive paradigm. Probabilistic convolutional models capable of linking dynamic environmental variables to fluxes and landscape evolution under multiple processes have seen extensive theoretical development, but remain untested in real landscapes. A particularly promising feature of this model framework is its ability to capture long-distance or “nonlocal” particle fluxes, which are characteristic of steeplands and contribute to both elevated erosion rates and debris flows after wildfires. In this talk, I present experimental work on burned and vegetated hillslopes in the Oregon Coast Range, which took the first steps toward establishing a unified probabilistic representation of particle travel distances with connections to measurable physical controls. Ongoing work in California’s Central Coast Range incorporates this probabilistic representation in the first field test of a convolutional model to investigate the roles of biotic disturbance and vegetation regrowth in controlling post-fire steepland sediment fluxes.

Dr. Danica Roth is an assistant professor in the Department of Geology and Geological Engineering at the Colorado School of Mines. Prior to Mines, she completed an NSF postdoctoral fellowship at the University of Oregon, a Ph.D. in earth science at UC Santa Cruz and undergraduate degrees in physics and astronomy at UC Berkeley. Danica’s research interests center on understanding the coupling of surface processes with regional variables such as climate, biology and anthropogenic influences in order to better relate process mechanics to landscape form and evolution across scales. Common themes in her work include examining feedbacks and morphodynamics in complex Earth surface systems, and linking empirical observations, experiments, and analytical and geophysical techniques to the development of physically-based theory.

For the zoom information please contact Rey Garduño (rgarduno@stanford.edu)