by Richard C. McCrea
In 2015, CoreLogic conducted a study of wildfire hazards and risks, titled “CoreLogic® Wildfire Hazard Risk Report, Residential Wildfire Exposure Estimates for the Western United States, 2015,” by Howard Botts, Ph.d, et al.
This report examines the potential risk to residential properties from wildfire, with an evaluation of the total number and value of properties effected, at individual risk levels. The report tabulates property risk for a 13-state region in the western US, with an additional assessment for each individual state, selective metropolitan areas, with several actual examples from historic fires.
The report states: “Recent wildfire trends have shown us that wildfire risk is real and immediate threat to many homes in the western U.S. The number of homes exposed to the risk and the amount of damage realized each year will continue to increase. Preparing for and mitigating the hazard begins with understanding all of the essential, relevant conditions that contribute to residential wildfire risk exposure.”
The report illuminates the fact out that homes will continue to be constructed in the wildland-urban interface (WUI), with a growing number of structures at risk each year. In addition wildland fires have shown a pattern of growing larger particularly in the last decade. New homes builds often are located on the edge of urban development known as the WUI where dense vegetation leads to increased wildfire risk exposure.
Statistics from the Blue Ribbon Panel Report on Wildland Urban Interface Fire in 2008 (referenced in the Corelogic report) give an overview of structure loss from wildfire 1960 to 2007 which are listed below:
- 1960’s an average of 209 structures lost to wildfire each year.
- 1970’s an average of 405 structures lost to wildfire each year.
- 1980’s an average of 670 structures lost to wildfire each year.
- 1990’s an average of 932 structures lost to wildfire each year.
- 2000’s an average of 2726 structures lost to wildfire per year for the first 8 years of this decade.
The basic methodology of the CoreLogic study was to collect information on individual homes or properties that could be exposed to risk from wildland fire. An analysis was then conducted of the wildland fuels and terrain and then wildfire risk categories for those properties were defined, which include low, moderate, high, and very high.
The second part of this analysis was to determine a wildfire risk score, to take into account the homes at risk outside the WUI where wildland fuels are essentially absent (e.g. urban areas), but there still is a chance of ignition, mainly due to fire brands carried downwind. The wildfire risk score is determined by combining the risk category with a distance measurement from each property to the nearest high-risk area located outside the property boundary. A risk score from 1-100 was then calculated.
Trends in numbers of wildfires, large fire occurrence and acres burned were also evaluated and described in the report, which I feel is very important. Wildfire is described in general terms to give the reader a better understanding fuels, topography and fire behavior including how a fire spreads.
The results of this Corelogic analysis are quite staggering, showing there are nearly 900,000 residential properties that are at a high or very high wildfire-risk category, with an estimated reconstruction value of $238 billion. When taking into consideration the higher numeric risk scores of 81-100 for properties that combine WUI and adjacent areas which may be impacted by ember wash, this number skyrockets to 1.1 million homes with a reconstruction value of $268 billion. The number of properties and their value is immense.
I feel this is a very good report that succinctly outlines the problems and challenges with wildfire in the WUI and adjacent areas. The CoreLogic report is a wakeup call to land managers and wildland fire organizations, home owners and insurance companies. The risk to properties is huge and increases every year.
There are significant areas of Federal and state lands adjacent to private lands and structures and these agencies need to continue to manage wildland fuels, through thinning trees, chipping and prescribed burning. However public funding of hazardous fuels programs will probably never be adequate to keep up with the needs. This puts even more pressure on home owners and insurance companies to deal with this issue.
I think the real solution is for homeowners in the WUI and directly adjacent to it, to make their structures fire safe by clearing back burnable vegetation/materials an appropriate distance, and that homes are constructed with materials that resist ignition. This type of preventive work is the only way to make sure structures are safe because suppressing wildfires in these areas is hugely expensive and generally very dangerous for firefighters.
The CoreLogic report identifies significant risks to many homes in the western US, and these risks proved true in the losses of homes in Washington, Oregon, California and beyond in the burning summer of 2015. Mitigating these hazards depends on understanding the environmental conditions which includes fuel, weather and topography, that contribute to residential wildfire risk exposure. The Corelogic report does a good job of analyzing the risks and hazards and describing the situation in the WUI.
As the wildfire problem in the WUI grows the issues of protecting public and firefighter safety will increase. I feel the first and foremost objective in fighting fire in the WUI is the safety of the general public and firefighters, and saving structures must come after that, no matter what the value is of those properties.
A copy of the report can be downloaded at Core Logic.