FireLineTM: Pinpointing Losses in California Wildfires

Catastrophic wildfires ravaged Southern California in October and November of 2008. How successful was ISO’s FireLineTM model in identifying the actual homes and commercial properties affected by the wildfires in San Diego and San Bernardino Counties? The California wildfires of 2008 offered a unique opportunity to test the validity of FireLine, and this publication describes the important results.

Solution
The geographic correlation between FireLine fuels (for example, forested areas, brush, and tall grasses) and areas that actually burned in the recent wildfires is very high. FireLine classified 97.5 percent of the geographic area that burned as fuels. And FireLine identified 95.7 percent of the homes and commercial properties affected by the fires as exposed to the wildfire hazard. ISO field research also revealed that wind-borne burning embers carried outside the actual wildland fuels area caused 295 of the property ignitions studied in the fires. The FireLine Special Hazard Interface Area model proved effective in identifying 67 percent of those properties. A fuels dataset alone would not have detected them.

Techniques
The success of FireLine lies in the high quality of its databases and its componential assessment of the wildfire hazard. Rather than relying on a more simplistic, fuels-only approach, FireLine combines fuels with slope, road-access, and climate assessment of a risk’s inclusion in hazardous interface areas to determine the real exposure to wildfire hazard.

The slope of a property’s immediate terrain plays a significant role in determining a property’s wildfire exposure. Less than 24 percent of all policies written throughout the state of California are in areas with moderate or steep slope, but almost 70 percent of the burned properties were in such areas. Road-access problems — the extent to which the roads themselves impede firefighting equipment and thus deter efforts to save a property — are also a major hazard factor. Only 2 percent of California policyholders live in areas with access problems, while 17.5 percent of the burned structures were in such areas.

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The 2008 California Tea Fire: FireLine Accurately Identifies Burned Properties

The 2007 California Wildfires: FireLine Identifies Affected Properties

FireLine: Pinpointing Losses in the Wildfires of 2003

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