USGS-landslides.20060216T194637 pgori@usgs.gov 20060216T194637.000Z Actual Alert Public en-US Geo Flash flood and debris flow Outlook for Sierra Fire Future Moderate Possible Susan Cannon Flash Flood and Debris Flow Outlook for Sierra Fire Watersheds burned by the Sierra Fire in Orange County are susceptible to flash floods and debris flows during rainstorms. Drainageways in Featherly Regional Park, stream crossings on State Highways 91 and 241 and Gypsum Canyon Road, and Santiago Reservoir could be impacted by these events. A short period of moderate rainfall on the burned watersheds can lead to flash floods and debris flows. Rainfall that is normally absorbed by vegetation can run off almost instantly. This causes creeks and drainage areas to flood much sooner during a storm, and with more water than is normal. In addition, the soils in a burn scar are highly erodible so flood waters can contain significant amounts of ash, mud, boulders, and vegetation. Within the burned area and downstream, the powerful force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and structures, and can cause injury or death if care is not taken. For information on what to do if you live near a recently burned area, and mmore information on post-fire debris flows: http://landslides.usgs.gov/research/wildfire/ http://www.usgs.gov/hazard_alert/alerts/landslides.rss Susan Cannon, cannon@usgs.gov Anahiem Hills, south of State Highway 91 and east of State Highway 214, Orange County, southern California