EAR-PF Dynamics from drones: using high-resolution repeat topography and grain size to differentiate between physically-based models of debris creation and debris flow initiation

Barnhart Katherine R, Boulder CO

Investigators

Abstract

Dr. Katherine R. Barnhart has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at the University of Colorado and University of Kansas. The project seeks to assess the mechanisms responsible for initiating debris flows - water-laden slurries of soil and rock from landslides - that move rapidly through channels in steep landscapes and present hazards to human life, infrastructure and property. To benefit the public, the outcomes of this project will include a landscape evolution model incorporating processes responsible for the recharge of debris, and processes responsible for the actual debris flow initiation. This model will improve predictions and risk assessment in debris flow prone areas. For the education component of this project, Dr. Barnhart will develop a senior-undergraduate and first-year graduate student course focused on the philosophy of science as applied to the geosciences and an investigation into the ingredients of a good research question. Debris flows are among the most dangerous and frequent natural hazards; once initiated in a steep region, a debris flow can continue to travel over shallow terrain, greatly extending the hazard, frequently destroying houses and covering streets with mud, which is costly to remove. Models for debris flows that relate antecedent conditions (e.g., soil moisture) and external forcing (e.g., surface hydrodynamic stresses) provide an opportunity for mechanistic understanding and prediction of natural debris flows. However, the steep and difficult terrain in debris flow prone regions precludes the observation of initiation zones which, in turn, prevents attribution of debris recharge and flow initiation to specific mechanisms. The project will employ novel methods -including drone-based photography- to make observations within the steep terrain in debris-flow initiation zones. Maps of topography and sediment characteristics will be made from these images which will constrain numerical models for (1) the amount and size distribution of material delivered to the channel between debris flow events, (2) the timing and (3) mechanisms of debris flow initiation.