JoAnne Skelly, a community educator with the University of Nevada Cooperative Extension, was among officials recently who warned residents of the risk of floods and mudslides due to rain and snowmelt. Disaster hasn't struck, but winter's far from over, and we're not yet out of the woods.
How has July's Waterfall fire contributed to the flood risk now?
In areas burned by forest and brush fires, a lower threshold of precipitation may initiate landslides/debris flow.
Slopes have been greatly destabilized due to vegetation loss. Soil absorption ability may have been impaired on some intense fire locations.
We are subject to two kinds of flooding: major winter floods and summer flash floods. A flash flood is a local flood of great volume and short duration. We will not always have a warning that these deadly, sudden floods are coming. So if someone lives in areas prone to flash floods, plan now to protect family and property.
We are very concerned about debris-flow incidents. Debris flows, sometimes referred to as mudslides or mudflows, are common types of fast-moving landslides. These flows generally occur during periods of intense rainfall or rapid snow melt. They usually start on steep hillsides as shallow landslides that liquefy then accelerate to speeds that are typically about 10 mph, but can exceed 35 mph.
The consistency of debris flows ranges from watery mud to thick, rocky mud that can carry large items such as boulders, trees and cars. When the flows reach flatter ground, the debris spreads over a broad area, sometimes accumulating in thick deposits that can wreak havoc in developed areas.
What areas of the city and outlying areas are most at risk?
The Burned Area Emergency Response report indicates neighborhoods at the foot of burned canyons at risk of debris-flow damage. Ash, Vicee and North Kings canyons are believed to be at greatest risk.
What can residents in high-risk areas do to best prepare for a mudslide this winter?
Develop a family disaster plan. Develop landslide-specific planning. Learn about landslide risk in your area. Contact local officials, state geological surveys or departments of natural resources, and university departments of geology. Landslides occur where they have before and in identifiable hazard locations.
Ask for information on landslides in your area, specific information on areas vulnerable to landslides and request a professional referral for a very detailed site analysis of your property and corrective measures you can take, if necessary.
If you are at risk from landslides, talk to your insurance agent. Debris flow may be covered by flood insurance policies from the National Flood Insurance Program.
Develop an evacuation plan. You should know where to go if you have to leave. Trying to make plans at the last minute can be upsetting and create confusion. Discuss landslides and debris flow with your family. Everyone should know what to do, in case all family members are not together.
What is the city doing to prepare for a flash flood or a mudslide?
Carson City has a flood-and-evacuation plan in place. The city has been working hard to stabilize slopes in the burned areas through seeding and mulching.
The city has been enlarging the detention basin at the foot of Vicee Canyon, and has plans to route floodwaters down city streets to the storm drainage system and then to the Carson River. They have cement barriers purchased for this purpose. They have also purchased a sand bag-filling machine that can fill 2,000 bags per hour. Sandbags are available at the corporate yard, 3505 Butti Way.
What should residents do if the National Weather service issues a flash flood warning?
If a flood warning is issued, a flood is imminent and residents close to the foot of burned canyons should evacuate. There is generally little time to respond, and the direction of the danger may be uncertain.
Residents should have alternate evacuation routes in case their main route has been blocked. In the event of a landslide, quickly move out of the path of the landslide or debris flow. Moving away from the path of the flow to a stable area will reduce your risk.
If escape is not possible, curl into a tight ball and protect your head. A tight ball will provide the best protection for your body.
For more information, call the UNR Cooperative Extension office at 887-2252.