The Zaca Fire has been burning in the Santa Barbara backcountry since July 4th, and is currently the 2nd largest wildfire in the recorded history of the state of California at over 220,000 acres. The largest fire was the Cedar Fire in San Diego in 2003 at 273,000 acres. The Cedar Fire also consumed 4,847 structures and 15 people died; the Cedar Fire began in the San Diego backcountry but, due to high speed downslope winds, it transitioned through the wildland urban interface into neighborhoods of San Diego. In contrast, the Zaca Fire has only destroyed 1 ‘outbuilding,’ and there have been no fatalities. The winds have generally been low velocity westerly winds. The fuel moisture content this year in Los Angeles County, where monitoring is most extensive, is 49%, the lowest on record. Fire danger is considered extreme once fuel moisture drops below 60%. This may explain why the fire has grown so large, given the relatively neutral wind conditions.
Firefighters have been able to contain the southern extent of the fire from crossing the Santa Ynez River and coming over the Camino Cielo crest into Goleta and Santa Barbara. The only ramifications of the fire to the south coast area have been episodic ash fall events in the morning and generally poor air quality during the day, depending on prevailing wind direction.
Two web resources are particularly notable. The Santa Barbara Independent has teamed up with Ray Ford, author of the definitive SB area hiking books, to provide excellent coverage. Use Google News, and type in ‘zaca fire ray ford’. Of the government websites, InciWeb is useful for facts ), though their maps are nearly useless. The CDF website has wonderful maps available for download in PDF format at a much finer scale (http://cdfdata.fire.ca.gov/incidents/incidents_ details_maps?incident_id=190).
Fire related research in UCSB Geography is primarily concerned with mapping fuel amount, fuel condition, and fuel moisture content, as well as modeling future weather conditions and fire temperature retrieval. Additionally, a fire spread model has been developed at UCSB (Marco Morais’ Master’s Thesis, 2001: Comparing spatially explicit models of fire spread through chaparral fuels: a new algorithm based upon the Rothermel fire spread equation). Research is generally focused on fire in southern California (PhD candidates Ted Eckmann, Philip Schneider, and Seth Peterson), though fire fuels are also being studied in Yellowstone (Kerry Halligan, recent PhD), Yosemite, and Great Basin National Parks (PhD candidate Seth Peterson). Dr. Dar Roberts is the primary mentor for these students.
The graphic above is raw AVIRIS imagery (data are not geometrically or radiometrically processed) from the Zaca Fire 1430 PST 12 August 2007. The fire and the smoke plume are clearly visible in the center of the image. The spectral profile (bottom) shows smoke of different temperatures. The red line represents cool smoke, with temperature highest for the white line. As fire temperature increases, energy begins to be emitted into the short-wave infrared portion of the electromagnetic spectrum sensed by the AVIRIS instrument.
Article contributed by graduate student Seth Peterson. Seth is working on a dissertation titled “Relationships between ground-based vegetation amount and live fuel moisture measurements for fire fuels research and remotely sensed data of varying spatial resolution.” According to Seth, the research centers on the fact that different ecosystems have different drivers of fire risk. For chaparral ecosystems, the main driver is fuel moisture, insofar as a majority of the vegetation that burns is living and the water in the vegetation must be evaporated before it can combust. For forested ecosystems, the primary driver is fuel amount and continuity of fuels — both vertically and horizontally. Seth is attempting to measure these fuel properties, primarily with remotely sensed data. NB: Dylan Parenti contributed to the generation of the figure used above.
