06/15/2023
The COMET Program has published a new training resource on post-wildfire environments. Wildfires are an increasing danger, especially in the Western U.S., and burn scars elevate the danger with a risk of flash flooding and debris flows. Burned soil no longer absorbs water well - the vegetation and organic matter burned hot, changing the structure of the soil and coating it with water-repellent material. Plus, the roots and networks of fungi and bacteria that normally hold healthy soils together were burned away. As a result, even a small amount of rainfall can put vast amounts of ash, burned vegetation, and soil into motion. Operational forecasters, emergency managers, department of transportation personnel, and other NWS partners can view a model simulation of how these factors combined in 2021 along Glenwood Canyon in Colorado to produce devastating impacts to Interstate 70.
National and international operational forecasters can go even deeper into the factors conducive for debris flows by taking the 45-minute lesson, "Monitoring for Potential Flash Flood & Debris Flow Threats.” The lesson immerses learners in assessing the potential for flooding and debris flow events following the 2018 Spring Creek Fire in Colorado. The learner takes on the role of a forecaster exploring the potential impact of rainfall events on three Values at Risk in the area. The lesson provides geological, hydrological and meteorological data, including three-dimensional models of the topography, soil burn severity, and drainages, that are used to evaluate hazards. The learner is supported by feedback from the Burned Area Response Team, Service Hydrologist and operational forecaster colleague to illustrate the contributions that each professional makes in assessing the potential for flash flood and debris flow events in a post-wildfire burn area.