In my previous post, I explained that flash floods and landslides pose the greatest threat to human life and property in the rainy seasons after an unnatural crown fire. This risk may persist for several years, depending on several factors. First, the intensity of the crown fire determines how damaged everything is to begin with. A more intense crown fire usually correlates with larger soil issues and greater vegetative destruction. Second, the extent of the hydrophobic (water-repelling) soils will determine how much soil is at risk of sheet erosion. Third, the slope of an area is a huge factor in floods and landslides, with steeper slopes posing a greater risk. Fourth, the intensity of the post-fire rains are the hammer driving the rest of these factors.
With so many conditions in play determining the outcome of your property and possibly your life, you need a way to protect yourself. That said, I will not pretend to be an expert on emergency preparedness or response. I am leaning heavily on research-driven sources which I will provide links for.
So how do you protect yourself?
Act with Discernment: The National Weather Service states “If you can look uphill from where you are and see a burnt-out area, you are at risk.” Have your bags and vehicle packed and ready so you can leave at a moment’s notice. You may be in danger before emergency systems are triggered. Per the NWS: “The important point is that for any burn area it will take much less rainfall to result in flash flooding than it would have before the wildfire occurred. In fact, thunderstorms that develop over burn areas can produce flash flooding and debris flows nearly as fast as National Weather Service radar can detect the rainfall. If heavy rainfall is observed even for a very short time there is the potential for Flash Flooding and/or Debris Flows.” The NWS also states that as a general rule, half an inch of rainfall in less than an hour is enough to trigger a flash flood in a burn-scarred area; however, if you are in an area of steep slopes and severe soil damage even light rains can trigger these events. Lastly: “In the event of moderate to heavy rainfall, do not wait for a flash flood warning in order to take steps to protect life and property. Thunderstorms that develop over the burned area may begin to produce flash flooding and debris flows before a warning can be issued.”
Burned Area Emergency Response (BAER): Burned Area Emergency Response, or BAER, is a series of actions taken by government agencies to reduce the risk of post-fire catastrophes on public land. These include treating hydrophobic soils to help them absorb water again as well as treating the land to divert and disrupt potential water flows. Anything that can be done to slow the water and increase absorption will reduce the risk, and government agencies cooperate to make this happen. One important caveat: If you are in an area that recently burned, it is unlikely BAER will be completed before the rains come. You can see if BAER is being done in your area here.
After fires, government agencies offer fire remediation services on properties that have been burned down or otherwise damaged by the fire. If this is offered to you, do not refuse this. No matter how you feel about the government or how much paperwork you need to struggle through, this is crucial. Firstly, you want to remove soil toxins that develop when things in your home (like lead or asbestos for older homes) that aren’t designed to burn, do burn. Secondly, their treatments help break up the hydrophobic soils and will prevent erosion, at least on your land. This won’t stop a flood or mudslide that has already cut loose higher up, but it can prevent your house from starting or contributing to one. You can maximize your impact and minimize your risk by talking to your neighbors affected by the fires, resulting in a greater sphere of protection around your property.
Treat Your Own Land: You don’t have to wait for disaster response teams to help you. There are steps you can take to protect your property. As with any heavy rain event, sand-bagging your home is always a good idea. In terms of hydrophobic soils, the University of Idaho has several suggestions:
1. “Place fallen logs or fallen trees across slopes to slow runoff and intercept sediment.”
2. “On level or gentle slopes, rake or hoe the upper few inches of soil to break up water repellent layers, allowing water to infiltrate soils for seed germination and root growth.”
3. “On gentle to steep slopes, scatter straw mulch to protect soils from erosion. If possible, anchor straw to hold it in place.”
4. “Use seeding, straw bale check dams, silt fences, and other practices that control erosion and reduce runoff.”
I would imagine home improvement stores like Lowe’s or Home Depot would be willing to offer these free or at reduced cost if you explain your situation.
Please share this information with anyone who needs it. If you have been affected, please consider these remediations. At the very least, know when to “get out of Dodge”. Our communities have suffered too much.
The wildfire series will continue after things calm down a bit.
Sources and Further Information:
Brooks, Randy. After the Fires: Hydrophobic Soils. University of Idaho Cooperative Extension. https://www.uidaho.edu/-/media/UIdaho-Responsive/Files/Extension/forestry/F5-After-the-Fires-Hydrophobic-Soils.pdf
Federal Emergency Management Agency. How to Prepare for a Flood. https://www.fema.gov/media-library-data/1409002852888-3c5d1f64f12df02aa801901cc7c311ca/how_to_prepare_flood_033014_508.pdf
National Interagency Fire Center. Post Wildfire Recovery. 2018. https://www.nifc.gov/BAER/
National Weather Service/National Oceanic and Atmospheric Association. Burn Scars Have an Increased Risk of Flash Flooding and Debris Flows. https://www.weather.gov/riw/burn_scar_flooding
National Wildfire Coordinating Group. Inciweb – Incident Information System. 2018. https://inciweb.nwcg.gov/
US Department of Agriculture, National Resources Conservation Service. Soil Quality Resource Concerns: Hydrophobicity. 2000. https://web.archive.org/web/20040726160247/http://lamar.colostate.edu/~rmoench/hydrophobic.pdf