Noting that we were getting hundreds of search hits on a previous version of an info-brochure that we originally published in 2010, we decided to issue a new, updated version: HAZ-2021-01 Post-wildfire Hazards: Mud Slides :: Debris Flows. The subject is unfortunately very relevant given the exceptional drought conditions in the US West and elsewhere in the world exacerbating the threat of major wildfires. During the 2020 fire season, Colorado suffered three of its largest wildfires on record: Cameron Peak, East Troublesome, and Pine Gulch, totaling almost 450,000 acres (700 mi2, 1800 km2). Of course, if we don’t get any more rain, we don’t have to worry much about mud flows! But seriously, the problem of post-wildfire hazards is only going to get worse. If you or anyone you know lives in an area that has seen wildfire activity in the past decade, it’s best to become acquainted with the threat that these hazards pose to life, limb, and property. (ED: On a side note, coincidently, the New York Times just published an informative story on the effects of post-wildfire conditions on our water supply.) Post-wildfire mudslide blocking I-70 in Glenwood Canyon, in the area damaged by the 2020 Grizzly Creek fire, June 2021. Photo credit: CDOT. An alluvial fan with fire damage exiting Kroeger Canyon after the Missionary Ridge fire near Durango, September 2002. Photo credit: Dave Noe for the CGS. Denuded slope above houses on Red Ridge after the Missionary Ridge fire north of Durango, 2002. Photo credit: Dave Noe for the CGS. Burned area ripe for a mud flow, given some precipitation, Paradise Acres, Huerfano County, Colorado, August 2018. Photo credit: Kevin McCoy for the CGS. Tree trunk with up-stream face scoured by debris flow, Paradise Acres, Huerfano County, Colorado, September 2018. Photo credit: Jon Lovekin for the CGS. Post-wildfire debris flow deposit, Paradise Acres, Huerfano County, Colorado, August 2018. Photo credit: Kevin McCoy for the CGS. Post-wildfire debris flow deposited in burn area below a steep mountain grade, Paradise Acres, Huerfano County, Colorado, 2018. Photo credit: Kevin McCoy for the CGS. Some vegetation returning two months after wildfire, Paradise Acres, Huerfano County, Colorado, August 2018. Photo credit: Kevin McCoy for the CGS. Post-wildfire debris flow from the “1,000-year rain event” in September near Jamestown, Colorado, November 2013. Photo credit: Jon White for the CGS. Debris fan exiting from gulch, truncated by Left Hand Creek, Boulder County, November 2013. Photo credit: Jon White for the CGS. House destroyed by debris flow, after the “1,000-year rain event” in September near Jamestown, Colorado, November 2013. Photo credit: Jon White for the CGS. Related Publications
Citations Colorado Geological Survey. “HAZ-2021-01 Post-wildfire Hazards: Mudslides and Debris Flows.” Colorado Geological Survey, June 2021. https://coloradogeologicalsurvey.org/publications/post-wildfire-mud-slides-debris-flows/. Categories Hazards, Publications Tags 2020s, CGS, debris flow, digital, fire, free, hazards, landslide, mudslide, pdf, publication, RockTalk, water, wildfire