Assessing wildfire-related risk to people, property and the environment: A spatial analysis of California's wildland urban interface

Population deconcentration has resulted in rapid development in the outlying fringe of metropolitan and rural areas. This demographic change has increased the size of the wildland-urban interface (WUI), the area where structures and development meet or intermingle with the undeveloped wildland. Expansion of the WUI in recent decades has created an environment in which fire can readily move between structural and vegetative fuels. This expansion has increased the likelihood that wildfires will threaten people, property and the environment, which has significant health, planning, and policy implications. The aim of this analysis was to: 1) identify areas at high risk for wildfires, 2) explore historic and projected housing development, and 3) provide policy recommendations to reduce wildfire-related risk in California. ArcGIS was used to manage, process, and analyze spatial patterns between variables of interest. Results show wildfire risk is greatest in southern California due to the types of vegetative fuels and their rapid rotation. High-density housing helps contributes to the fire threat by providing fuel as well as a place where people and property are at risk. This risk may increase as projected development is slated for high-wildfire risk areas, especially in Riverside and San Diego counties. Planners should consider mitigation policies, such as regulating current or prohibiting new housing development in areas at high-wildfire risk. Regulations could include fuel reduction techniques, such as the creation of defensible space around property with low or non-fire fuels, and building ordinances, which require fire-resistant materials, to reduce the potential of spot fire development.