Areas of the U.S. wildland-urban interface threatened by wildfire during the 2001-2010 decade

The wildland-urban interface (WUI) is defined in terms of housing density and proximity to wildlands, yet its relevance seems to be only in conjunction with wildland fire threats. The objective of this paper is to (1) identify the WUI areas threatened from wildfire during the 2000's and (2) quantify the values that were threatened. We use 1 km fire detection data generated using MODIS satellite imagery over a 10-year period combined with population densities to identify threatened areas of the WUI. We then use data on structures, structure content, and population to identify the people and property threatened from identified fires within the WUI. We find that 6.3 % of the U.S. population (17.5 million) resided within these areas and that 2.1 % of the population lived in WUI areas where more than one fire has occurred. However, we find that only a third of the affected population was threatened during daytime hours, as most leave the threatened portion of the WUI during peak ignition hours. The threatened area comprised 4.1 % of the coterminous USA and 44.9 % of the WUI. Within these areas were 7.8 million residential, commercial, industrial, governmental, religious, and educational structures, with a building and building content value estimated at $1.9 trillion. Overall, 7.3 % of residential structures in the USA were found within the WUI with wildfire activity; however, for some states, this number was as high as 25.4 %.