Vegetation maps of the Santa Monica Mountains produced from a NASA airborne sensor, taken before and after the 1996 Calabasas/Malibu brush fire, are helping scientists improve predictions of fire hazards in the area and may one day reduce the risk of catastrophic fires.
The maps of chaparral vegetation were created with advanced measurements from NASA's Airborne Visible and Infra-Red Imaging Spectrometer (AVIRIS), which was developed and is managed by the Jet Propulsion Laboratory. The images were taken on October 17 and October 23. The fire started in Calabasas on October 21 and, eventually, burned more than 12,000 acres.
"With AVIRIS, we've been working on techniques to use the spectral information measured by the instrument to map different vegetation communities in the Santa Monica Mountains," said Dr. Dar Roberts of the University of California, Santa Barbara. "This information should improve our ability to assess fire risk and predict fire behavior, and perhaps could provide more effective information for planners and agencies concerned with fire prevention. We can also predict moisture content in the foliage, which helps us understand how different areas will burn."
The AVIRIS instrument flies aboard a NASA ER-2 airplane. While being carried 20 kilometers (12 miles) above sea level at a speed of 730 kilometers per hour (450 miles per hour), the instrument can take approximately 7,000 measurements per second. Earth scientists use AVIRIS to conduct research and applications across a range of scientific disciplines, including ecology, geology, mineral hazards, snow and ice, coastal and inland waters, and wild fires.
"This technique of imaging spectroscopy implemented with AVIRIS represents a fundamental new way of studying the Earth. We are measuring in detail how light is absorbed or reflected by various materials on the Earth's surface. In the case of the Santa Monica Mountains, we are measuring the presence of molecules such as chlorophyll, leaf water and cellulose. By measuring these molecules we can map different vegetation types, vegetation moisture and the overall amount of vegetation, all of which play a role in predicting wild fire hazards," said Robert Green, the AVIRIS experiment scientist at JPL.
"The value in repeated flights is that if we have sufficient information over time, we can presumably build up a very complete understanding of the links between vegetation patterns and fire behavior," said Dr. John Gamon, associate professor of biology and microbiology at California State University, Los Angeles. "This issue will not go away with a single fire, but will come back repeatedly to haunt us, as demonstrated by the most recent burn. It is important to remember that fire is an integral part of the Southern California ecosystem and is here to stay."
Scientists and fire agencies will use the AVIRIS vegetation maps and measurements they have taken on the ground to produce computer models to forecast how and where a fire would burn in the area. Such information could assist firefighters to prepare for future fires that reach across both wildland and urban areas.
"An accurate fire model could be very useful in allowing us to strategize by staying one or two steps ahead of an actual fire as it burns, allowing more efficient deployment of resources during an emergency. The AVIRIS information can tell us what kinds of fuel are present and that could help us plan safe and effective 'prescribed' burns," said Herb Spitzer, assistant fire chief at the Forestry Division of the Los Angeles County Fire Department. "If we could burn the vegetation more frequently and in small patches, then it would reduce the risk of catastrophic fires."
The AVIRIS program is managed by JPL for NASA's Office of Mission to Planet Earth, Washington, D.C. The Mission to Planet Earth program oversees a long-term, coordinated effort to study Earth's air, water, land and life as a global environmental system.
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