The wildland–urban interface in the United States based on 125 million building locations

Abstract

The wildland-urban interface (WUI) is the focus of many important land management issues, such as wildfire, habitat fragmentation, invasive species, and human-wildlife conflicts. Wildfire is an especially critical issue, because housing growth in the WUI increases wildfire ignitions and the number of homes at risk. Identifying the WUI is important for assessing and mitigating impacts of development on wildlands and for protecting homes from natural hazards, but data on housing development for large areas are often coarse. We created new WUI maps for the conterminous United States based on 125 million individual building locations, offering higher spatial precision compared to existing maps based on U.S. census housing data. Building point locations were based on a building footprint data set from Microsoft. We classified WUI across the conterminous United States at 30-m resolution using a circular neighborhood mapping algorithm with a variable radius to determine thresholds of housing density and vegetation cover. We used our maps to (1) determine the total area of the WUI and number of buildings included, (2) assess the sensitivity of WUI area included and spatial pattern of WUI maps to choice of neighborhood size,(3) assess regional differences between building-based WUI maps and censusbased WUI maps, and (4) determine how building location accuracy affected WUI map accuracy. Our building-based WUI maps identified 5.6%-18.8% of the conterminous United States as being in the WUI, with larger neighborhoods increasing WUI area but excluding isolated building clusters. Building-based maps identified more WUI area relative to census-based maps for all but the smallest neighborhoods, particularly in the north-central states, and large differences were attributable to high numbers of non-housing structures in rural areas. Overall WUI classification accuracy was 98.0%. For wildfire risk mapping and for general purposes, WUI maps based on the 500-m neighborhood represent the original Federal Register definition of the WUI; these maps include clusters of buildings in and adjacent to wildlands and exclude remote, isolated buildings. Our approach for mapping the WUI offers flexibility and high spatial detail and can be widely applied to take advantage of the growing availability of high-resolution building footprint data sets and classification methods.

The global wildland–urban interface

“…Although the WUI is defined in different ways for different regions and applications [19][20][21][22][23][24][51][52][53][54] , we used the conceptual WUI definition of the US Federal Register 53 , first operationalized by ref. 1, which is the most widely used WUI definition in the United States and many other countries 1,[19][20][21]54 .…”

Towards an Integrated Approach to Wildfire Risk Assessment: When, Where, What and How May the Landscapes Burn

“…WUI maps typically use a set of predefined rules and parameters to identify where human settlements adjoin or intermingle with flammable vegetation, to highlight locations of potential fire exposure across landscapes. To date, there are multiple WUI mapping approaches [51,53,54], and these methods have been applied in many regions and at spatial scales ranging from local to global [50,55]. Information derived from these maps allowed policy makers and land managers to direct management efforts to reduce potential exposure to wildfires via the prioritization of fuel treatments around exposed areas.…”

Determination of Soil Contamination at the Wildland-Urban Interface after the 2021 Marshall Fire in Colorado, USA

“…Wildfire risk at the wildland-urban interface (WUI) is expected to increase in the future due to expansion of the WUI and increased wildfire activity. , The WUI, defined as the area where houses meet or intermingle with undeveloped wildland vegetation, is expanding in many regions across the globe. This expansion is particularly evident in the United States, where home construction from 1990 to 2010 increased the WUI area from 581,000 km 2 to 770,000 km 2 and increased the number of houses at the WUI from 30.8 million to 43.4 million .…”