Prototype Scale Evaluation of Non-Newtonian Algorithms in HEC-RAS: Mud and Debris Flow Case Studies of Santa Barbara and Brumadinho

The Santa Barbara post-wildfire debris flows and the Brumadinho tailing-dam failure were two of most catastrophic flood events late 2010s. Both these carried so much solid-phase material, that classic, clear-water, risk approaches cannot replicate them, or forecast other like them. This case study applied new non-Newtonian features in HEC-RAS 6.1 to events, testing widely used model on common mud flow hazards (post-wildfire floods mine tailing dam failures). reproduced inundation boundaries event timing (where available) for both events. ratio between largest clasts channel size, parametric trade-offs, “convex” alluvial plain topography, stochasticity introduced by urban infrastructure made modeling more difficult less precise than Brumadinho. Despite challenges, results provide prototype scale validation verification tools this model.