Study measures fire risk, reality
Research focuses on 2019 assessment vs. Troublesome’s destruction
A study comparing a 2019 wildfire risk assessment to the aftermath of the East Troublesome Fire has shown mitigation work may have helped save properties.
The Columbine Lake neighborhood near Grand Lake provided a unique opportunity to compare wildfire risk assessments taken in 2019 with the destruction of the wildfire that moved through the area in October.
In partnership with the Grand County Wildfire Council and other local groups, the Wildfire Research Center conducted a number of rapid wildfire risk assessments in Grand County. These quick appraisals highlighted wildfire risk factors apparent on a given property, including those in the Columbine Lake area.
James Meldrum, a research economist with the US Geological Survey, presented the results of the assessment and compared that to what homes were lost in the fire at a Grand County Wildfire Council meeting last week.
“This is actually the first time we’ve had the unfortunate opportunity to look at how the (risk assessment) stands up against the fire,” Meldrum said.
In Columbine Lake, 26 of the 461 assessed structures were destroyed. Within the official fire perimeter, 24 of the 130 structures were lost. Meldrum used statistical modeling that isolates factors to see if a certain attribute determined whether a structure was lost.
“We’re trying to say, is it the roof or the defensible space in this individual property that made the difference?” he said, throwing out a couple examples.
According to the analysis, four main factors seemed to make the biggest difference within the fire perimeter: defensible space, other combustibles near the structure, posted and visible addresses, and the distance to the nearest structure.
Homes closer to overgrown, dense or unmaintained vegetation were five to seven times more likely to be destroyed in the fire.
“It’s that story that we’ve heard for quite a while, that defensible space near the home makes a difference,” Meldrum said. “It affects the fire behavior. It affects response.”
Combustibles other than vegetation around the house also played into whether a structure was lost.
Address visibility — meaning homes displaying their address at the end of the driveway with reflective material — also influenced homes that stayed standing within the fire perimeter. Outside the fire perimeter, this effect was even stronger.
With how dark it was and firefighters not necessarily being familiar with the area, reflective and well-placed address numbers likely helped the responders to identify where those structures were.
Distance to the nearest structure was not assessed in the risk survey but was easy to determine, according to Meldrum. The study found that the odds of losing a building decreased by 0.6 for every 10 feet farther away it was from the nearest structure.
“What this tells me is that homes affect each other,” Meldrum said. “Neighbors affect each other, so there’s this interdependence of risk between different homes.”
Other factors surveyed by the assessment, like the materials a home was made of or access to alternative roads to the house, didn’t seem to change whether a home was destroyed in this particular fire.
Meldrum did emphasize that a lack of variation between properties, the small and imperfect data set, and the fact that every fire event is different meant that these results should not be taken as absolute. While valuable, this analysis is also not meant to imply residents who lost their homes did anything wrong.
“I don’t want anyone to walk away from this thinking we’re pointing fingers at homes that were lost in that sense,” Meldrum said. “There’s so many other factors going on. That said, there is this relationship with higher risk places overall, which does tell us that there is meaningful information.”
While the calculated probability of a loss correlated weakly with the actual outcome, there were houses with a small overall risk that were still destroyed. Because so much influences the outcome of a fire, wildfire risk is just one factor.
Meldrum said that the data showed the little things a homeowner can do to make their house more wildfire safe do have an impact. He added that preventing structure loss needs to be a combination of efforts.
“These things feed off of each other,” Meldrum said. “The mitigation efforts a homeowner can make on their individual properties before an event happens — before there’s smoke in the air — those things can really make a difference and increase the effectiveness of the suppression resources.”
For homeowners interested in improving the wildfire risks around their own property, the Grand County Wildfire Council provides a wildfire home assessment and checklist at bewildfireready.org. Reflective address signs are also for sale.
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