Debris flow advisories and warnings

CURRENT FLOOD WATCHES, DEBRIS FLOW ALERTS, FLOOD WARNINGS AND ADVISORIES FOR OREGON ISSUED BY THE NATIONAL WEATHER SERVICE CAN BE FOUND ONLINE AT: http://www.weather.gov/alerts/or.html

Landslide Hazards in Oregon Fact Sheet (1266 KB PDF)

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DEBRIS FLOWS IN OREGON

Debris flows are rapidly moving landslides that can destroy everything in their paths. They can easily travel a mile or more, depending on the terrain. They typically contain boulders and logs transported in a fast-moving soil and water slurry down steep hillsides and through narrow canyons. A debris flow moves faster than a person can run.

Throughout the rainy season, the National Weather Service will highlight the potential for debris flows and landslides as part of a flood watch, for areas included in the flood watch. The flood watch will include this language: "LANDSLIDES AND DEBRIS FLOWS ARE POSSIBLE DURING THIS FLOOD EVENT. PEOPLE... STRUCTURES AND ROADS LOCATED BELOW STEEP SLOPES... IN CANYONS AND NEAR THE MOUTHS OF CANYONS… MAY BE AT SERIOUS RISK FROM RAPIDLY MOVING LANDSLIDES" (National Weather Service).

WHAT TO DO

Homes and roads at the base of steep slopes in or near canyon outlets are in the most hazardous locations. People living or traveling roads in such areas should stay clear of steep stream channels and steep canyon walls. People living in these types of locations should have a safe place to go when a warning is issued. Motorists should avoid all but emergency travel on roads below hazardous areas during warning periods.

"People want to know what they should do when they hear there is a hazard of landslides in the area," says James Roddey, Earth Science Information Officer for the Oregon Department of Geology and Mineral Industries (DOGAMI). "Some areas are more hazardous than others when the danger of landslides is high. People know that if there's a flood warning, they should stay away from the river. We also want them to start thinking about staying away from steep slopes during intense rainstorms. Knowing ahead of time where the danger areas around your home for potential landslides might be is the first step in being prepared," explains Roddey.

He recommends several steps:

Stay alert. Listen to the radio, TV, or a weather radio, and if told to evacuate, do so immediately.
Listen for unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together. A trickle of falling mud or debris may precede larger landslides.
If you think there is danger of a landslide, leave immediately.
If water in a river or stream suddenly turns muddy or the amount of water flowing suddenly decreases or increases, this is a warning that the flow has been affected upstream. You should immediately leave the area because a debris flow may soon be coming downstream.
Assume highways are not safe. Be alert when driving, especially at night. Don't overdrive your headlights. Embankments along roadsides may fail, sending rock and debris onto the road.
Landowners and road managers should check road drainage systems and conduct needed maintenance in case the predicted heavy precipitation does occur.

Road maintenance personnel should also take heed of this increased hazard level and move out of the hazardous area along routes that avoid steep slopes if possible.

Cleaning up after landslides can also be hazardous. "When it's this wet outside, people need to be careful when they're cleaning up the mess. A small mudslide can actually be part of a larger landslide," explains Roddey. "Cleanup should not be done until after the storm."

WHERE TO FIND OUT ABOUT WARNINGS

Once the potential for debris flow hazards is issued as part of the NWS flood watch, the National Weather Service relays this information through its emergency management alert and information network. The National Oceanic and Atmospheric Administration (NOAA) Weather Radio and OEM's communication systems are part of the network.

DOGAMI will provide additional technical information in response to media or public questions. For more information contact James Roddey at (971) 673-1555.

Current Flood Watches, Debris Flow Alerts, Flood Warnings and Advisories for Oregon issued by the National Weather Service can be found online at: http://www.weather.gov/alerts/or.html

NOAA Weather Radio Frequencies:
162.400, 162.425, 162.450, 162.475, 162.500,162.550.

Office of Emergency Management Duty Officer: (503) 378-6377

Oregon Department of Geology and Mineral Industries: (971) 673-1555

Local radio and TV stations (not out-of-state cable TV)

Debris flow warnings