Anyone who’s lived on the West coast over the last few years remembers the harsh realities wildfires have brought each summer. Communities in California, Oregon, and Washington have been devastated by wildfires that have consumed acres of public and private land and destroyed entire towns. During wildfire season, even if you live hundreds of miles away, the smoggy air can make it hard to breathe.
 
But, did you know one of the biggest problems that wildfires can leave behind in their aftermaths? Flooding. And flooding can lead to mudslides.
 
For example, in 2017, southern California was hit by the Thomas Fire, which was the largest fire in California history to-date. It was also one of the most expensive, costing more than $1.8 billion. But it wasn’t until January 2018 when the rain created devastating mudslides, which tore through the small town of Montecito, killed 23 people, and destroyed dozens of homes.
 

The “Fire-Flood Erosion Sequence”

While it sounds counterintuitive that wildfires would cause flooding, consider what gets destroyed in a powerful fire: trees, plants, and groundcover are all essential for keeping rainwater manageable, and without them, forests get transformed into areas fraught with flood conditions.
 
In fact, wildfires have created so many floods that scientists have dubbed the phenomenon “the fire-flood erosion sequence,” noting that post-wildfire flooding creates “catastrophic erosion.”
 

Waterproofing the soil with fire

In another seeming paradox, the heat of a wildfire can render the ground impermeable to water. When plant material burns under intense heat, it can form a waxy substance that penetrates and coats the topsoil, making it hydrophobic, or water-repellant. Water can flow twice as fast across hydrophobic soil, making floods more likely and more intense.
 

Wildfire scars feed the perfect storm

Wildfires leave behind burned, bare land which can drive the formation of thunderstorms, sometimes long after the flames have gone out. Vegetation can take three to five years to return. In the meantime, the ground is dry and dark, with an increased propensity to absorb heat from the sun. This creates hot spots of rising warm air that suck cooler, more humid air underneath. The convection currents can build into intense thunderstorm systems.
 
Powerful thunderstorms, water-repellant soil, and a lack of vegetation to slow the flow of water – this is the recipe for a flood. Fast-flowing flood water, especially moving down a steep slope that has been stripped of vegetation by a wildfire, may carry loose soil with it to become a mudflow.
 

Mudflows vs. Mudslides

FEMA’s definition of a mudflow also describes what is not a mudflow:  
 
A river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water. Other earth movements, such as landslide, slope failure or a saturated soil mass moving by liquidity down a slope, are not mudflows.  
 
Although people tend to use the terms “mudflow” and “mudslide” interchangeably, mudflows are a peril of floods and mudslides are a peril of landslides. Thus, damage caused by mudslides is not covered by a flood policy. For example, a rain-saturated embankment that destabilizes, collapses, and slides down a hill – although potentially devastating – may be considered a mudslide and not covered under an NFIP or EZ Flood policy.

The 2018 Montecito Mudslides that followed the 2017 Thomas Fire incurred $421MM in insurance claims. Ultimately, California’s Insurance Commissioner instructed that anyone with fire insurance should be covered, as the wildfire was the proximate cause of the mudslides.
 

Are your clients protected?

A wildfire alone is a traumatic event. Add to that the devastation of a flood and your client could be facing a one-two punch from which anyone would struggle to recover. If they live in an area prone to wildfires, think about having a conversation about how they can also help protect themselves with a flood insurance policy.
 
Want to learn more? Watch our webinar on Flooding After Fire.
 
^{This article is provided for general informational purposes only and is not intended to provide individualized advice. All descriptions, summaries or highlights of coverage are for general informational purposes only and do not amend, alter or modify the actual terms or conditions of any insurance policy. Coverage is governed only by the terms and conditions of the relevant policy.}