USGS Western Ecological Research Center

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Every year, wildfires devastate the landscapes of Southern California from Los Angeles to San Diego. Why do some communities burn, and some don't? USGS is analyzing fire patterns at the wildland-urban interface (WUI) for clues to help cities balance their management of fire hazards and natural resources.

The wildland-urban interface of Southern California. --Photographer: Jon Keeley/USGS


The overall goal of the Wildfire Risk Scenario Project is to inform the balanced management of fire hazards and natural resources. To do so, project researchers are studying several components of a wildfire’s path towards landscape damage and destruction:

  1. What factors determine when and where fires start?
  2. How do fires reach housing from the wildland?
  3. What factors lead to home and structure loss once fires reach an urban area?
  4. What fire management and wildfire factors lead to biodiversity change and natural resource impact?

To understand and model this hazardous equation and to share these findings, researchers are making the following efforts:

Collecting Wildfire Damage Data Through Satellite Imagery
Aerial photos and public records provide key data on human structures pre- and post-fires, such as housing arrangement/density, landscaping, proximity to wildlands, wind direction. Using satellite images and remote sensing data, the team has digitized data on >36,000 homes and structures in Santa Monica Mountains and >687,000 in San Diego County and identified structures damaged or destroyed since 2001.

Identifying Landscape Factors Contributing to Wildfire Risk
Published findings suggest loss of human structures is related to housing density/arrangement, historic fire frequency and location on the landscape. Researchers are examining additional factors such as presence of powerlines, hill slope, and topographic relationship to ridgelines, creeks/drainages and Santa Ana winds.

Identifying Home Factors Leading to Wildfire Damage
Southern California fires are mainly spread by wind-blown embers, and ornamental trees and other landscaping may be key conduits for fire spread even across disconnected neighborhoods. Researchers are also examining variables such as urban vegetation/structures, home age, duration of ownership, plot size and local roads access.

Dissecting the Efficacy of Traditional Fire Suppression
How well do existing fire management instruments work? The team is analyzing traditional concepts such as fire breaks, wildland fuels management and “defensible space” to determine how and how well each method actually minimize fire risk to communities.

Measuring Impact on Biodiversity and Habitats
Altered fire regimes also impact the ecosystem. The team is measuring the changes in species diversity and vegetative habitat types after repeat fires, and examining whether fire suppression treatments themselves may impact wildlife and habitat connectivity.

Public Outreach of Wildfire Risk Factors
Throughout the course of the project, new findings, maps and other products will be shared with managers at state, local and federal offices, as well as public and private stakeholders.

Updated 2012.05.10

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