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A Case Study of a Community Affected by the Witch and Guejito Fires (NIST TN 1635)



Alexander Maranghides, William E. Mell


The National Institute of Standards and Technology (NIST) has a Reduced Risk of Fire Spread in Wildland-Urban Interface (WUI) Communities research program. The program objective is to develop, by the end of FY2013 first generation tools for improved risk assessment and risk mitigation in WUI (wildland-urban interface) communities at risk from wildfires. These tools will be developed and tested through a coordinated effort that includes laboratory and field measurements, physics-based fire behavior models, and economic cost analysis models. The NIST WUI Team was invited by CAL FIRE to collect post incident data from the California October 2007 fires. Early on, the NIST WUI Team initiated a case study within the Witch Fire perimeter. The case study is focused on The Trails development at Rancho Bernardo, north of the City of San Diego. There were 274 homes in The Trails, with 245 within the fire perimeter 74 homes were completely destroyed and 16 were partly damaged. Field measurements included structure particulars, specifically roof type, proximity of combustibles to the structure, and damage to wildland and residential vegetation. Documentation included over 11,000 pictures. The data collected and the data analysis to be conducted are divided into three initial papers. This paper will address primarily the event timeline reconstruction and general fire behavior observations. The second paper will investigate the impacts of structure attributes, landscaping characteristics, topographical features and wildland fire exposure on structure survivability. Lastly, the third paper will investigate the use computer modeling as a tool to understand fire behavior at the WUI.
Technical Note (NIST TN) - 1635
Report Number


Wildland Urban Interface, WUI, fire behavior, community, Witch fire, Guejito fire


Maranghides, A. and Mell, W. (2009), A Case Study of a Community Affected by the Witch and Guejito Fires (NIST TN 1635), Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed June 13, 2024)


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Created April 30, 2009, Updated November 10, 2018