Abstract
Past studies reported a drastic growth in the wildland-urban interfaces
(WUI), the locations where man-made structures meet or overlap wildland
vegetation. There is a perception that damages due to wildfires are
mainly located at the WUI. However, there is no clear evidence that
wildfire intensity and frequency are highest in these regions. In this
work, we have reported the actual occurrences of wildfires with respect
to WUI and how much of the WUI are on complex topography in California
(CA), the state with the highest burned area and risk of wildfires. We
calculated the overlap of the burned area from previous wildfire events
in California in the last ten years with the WUI perimeters. Two
currently existing WUI definitions are used for this purpose.
Furthermore, we also calculated the number of fire ignition points that
lie within the WUI perimeters. We found that a very small percentage of
wildfire ignitions actually occurred in the WUI areas. Moreover, the
overlap between the wildfire burned area and WUI areas was also found to
be small. To find out if the wildfires burned in the vicinity of WUI
areas, we created buffers around both the WUI areas and the wildfire
perimeters separately and computed the impact of buffer distance on the
overlap. This behavior has been connected to the importance of firebrand
ignition from spot fires in the WUI. Moreover, a majority of WUI areas
in CA was found to be situated on complex topography. Therefore, we
conclude that in CA, wildfires are not limited to WUI regions only, but
their main fire fronts burn farther away from the WUI and are mostly
located on complex topography, where controlling large wildfires is more
difficult and fire behavior is more complex. Results from this study
will give direction for remapping the existing WUI definitions, will be
helpful for wildfire management and will benefit policymakers and land
managers at the state and local level to focus on the factors that
determine the high-risk prone areas for future wildfires.