CSU Voices and Views

On the track of wildfires

CSU experts drawn to science of flaming landscapes
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By Sean Kearns,
CSU Science Communications Advisor

A fire burns outside of Cal Poly San Luis Obispo's Swanton Racific Ranch.

Photo courtesy Swanton Pacific Ranch

Just what is “spreading like wildfire”?

It can be a multi-story wall of flames racing uphill at 40 miles an hour, burning at 400 degrees F – or much hotter.  It can be a blaze that roars across the top of a vegetative canopy – and then returns to ignite what was left underneath.  It can be a searing rage that leaps into the sky and, with its back to the wind, lands on a distant untouched stretch of land – and torches it.

Sometimes it seems to stay put, burning hotly in a bowl of chaparral under the heavy atmospheric lid of an inversion layer, with the fast-rising pressure intensifying the heat – until the fire blows up like a ruptured pressure cooker, unleashing an incendiary rain.

If something’s spreading like wildfire, be very careful.

RECENT HISTORY

Each year in the United States since 2000, between 63,000 and 97,000 wildfires burned, annually combining to consume between 3.5 million to 9.9 million acres.

A year ago, the Station Fire in the Angeles National Forest, east of Pasadena, burned officially for about 50 days, consuming 160,577 acres, destroying 91 structures and claiming two human lives.  It was the tenth largest wildfire in California history.

Three years ago, on Oct. 21, 2007, the Harris Fire started at 9:30 a.m. near the U.S.-Mexico border east of San Diego. Later it jumped over a mountain and exploded the home of geologist Tom Varshock, an alumnus of San Diego State University.  He became the first of the fire’s five fatalities.  Eventually more than 90,000 acres burned and more than 550 buildings (including 253 homes) were destroyed.

About two hours after the Harris Fire started and about 35 miles north, power lines ignited the Witch Fire near San Diego and it began to spread.  By the time it was fully contained more than two weeks later, the Witch Fire had become the fifth-largest fire in state history.  It burned nearly 200,000 acres, destroyed roughly a thousand homes and 500 other buildings, injured 40 firefighters and claimed two civilian lives.

Over the next two days in San Diego County, nature and humans unleashed other wildfires, including the 9,000-acre Rice Fire near Fallbrook; the 49,000-acre Poomach Fire, to which the Witch connected; the 250-acre Coronado Hills Fire, burning just south of CSU San Marcos; and the Ammo Fire, scarring 21,000 acres of Camp Pendleton.

To date, no wildfire in California history has spread quite like the Cedar Fire in October 2003, burning across 280,000 acres, destroying 2,820 structures and killing 15 people. 

CSU CONNECTIONS

With such dramatic, far-reaching impacts, wildfire attracts the attention of researchers at California State University campuses throughout the state.

At San Diego State University, whose Sky Oaks Biological Field Station was destroyed by the Coyote Fire in July 2003, researchers have detailed fires’ economic impacts and developed the San Diego Wildfires Education Project.  About 800 miles north, researchers at Humboldt State University’s Wildland Fire Laboratory have tracked the fire history of redwood forests.

In between are the Southern California Wildfire Hazard Center at CSU Long Beach; the Fire Protection Administration and Technology Program at Cal State L.A.; the Swanton Pacific Ranch field site (itself devastated by a 2008 fire) and the new Fire Protection Engineering master’s program at Cal Poly San Luis Obispo; the Big Chico Creek Ecological Reserve near Chico State; and numerous scientists focused on wildfire ecology, behavior, prevention, policies and impacts.

For example, CSU Chico geographer Don Hankins has examined how California’s ancient indigenous populations used prescribed fires as a conservation tool.

INFERNO BEHAVIOR

Ray Shackelford certainly knows fires.  Author of “Fire Behavior and Combustion Processes” (in its ninth edition) and a past president of the San Bernardino County Fire Chiefs, he has taught at Cal State L.A. since 1978.

“For years and years,” he said, “fires would burn in and out of jurisdictions before the jurisdictions could get their incident commands set up.”  He recalled one from decades ago:  “It started in Monrovia, swept into Arcadia, then into some (Los Angeles) county area, then to Sierra Madre, and into Pasadena.  And all before noon.”

According to Shackelford, fire behavior is driven by three key factors:  weather, topography and fuel.

He outlined a repeated scenario:  “If we’ve had a long, hot dry spell without a lot of rain, and then we get Santa Ana winds, coming in from the northeast drying out the fuel even more…  The fuel is preheated and pre-dried, and once you get ignition, you’re really asking for disaster.”

Fire moving uphill also preheats fuel in its path, and flames on an incline are closer to the uphill vegetation.  Sometimes fire rapidly moving uphill will burn the top of the brush but leave it unburned underneath.  Subsequently, it ignites bundles of vegetation and animals, torches that tumble down the slope, and ignite the fuel left behind.  “We call them ‘pineapples,'” said Shackelford.

Across Southern California, as an adaptation to long periods of drought, many plants die back 50 percent or more every year.  “That’s a lot of dead brush,” said Shackelford.

Oil-rich plants, such as creosote bush, manzanita and eucalyptus, provide even more BTUs, allowing the fire to burn quicker and faster.  Depending on weather, topography and fuel – and, of course, on the notorious wind to which they all contribute – fire may advance 10 miles an hour or race 40 miles an hour, said Shackelford.

And then Shackelford mentions “conflagration.”

“When the fire gets so large, it creates its own winds.  It sucks the moisture and the fuel itself.”

Sometimes, Shackelford said, a valley will catch fire under an inverse layer of high pressure.  It’s like having a lid on a pressure cooker, until it gets so hot inside that the heated air blasts through the layer in an eruption.  “Some people can get killed when that happens,” he said.

Shackelford cites the development of accurate fire models for making fire-fighting safer and more effective.  The models run a variety of existing data – such as vegetative patterns and topography – through algorithms with real-time observations to generate two-, four- and six-hour predictions of fire behavior.

TERROR-TRACKING TECHNOLOGY

Smoke rising from the Station Fire.

Smoke rising from the Station Fire.

At San Diego State University’s Visualization – or Viz – Center, scientists derive pictures of fire behavior and intensity from data collected by sensor networks, geospatial imagery, unmanned aircraft and other technologies.  Eric Frost, a professor in SDSU’s graduate program in homeland security, directs the Viz Center.  Tom Varshock, the geologist killed by the Harris Fire, had been one of his students.

According to Frost, critical aid in battling last year’s Station Fire (and most other fires in the U.S. and northern Baja California) came from two NASA satellites.  Each made a daily pass over the area, providing a fresh read on the fire’s thermal bands.  The result: Twice-daily maps that showed the presence of fire and its temperature across 150-mile-wide swaths of land. 

“Mapping the real fire presence was extremely helpful,” said Frost.  “You can see where the fire is and where it’s going – and you see that in 3-D.  Here’s where it’s hot, and here’s where it’s cooler.  You can overlay the winds and smoke, with temperatures.  And the fire becomes far more understandable than it is with a ‘burned-not burned’ fire-line map.”

Southern California wildfires, he said, generally burn at 300 to 350 degrees F, yet some parts of the recent Tea Fire near Santa Barbara exceeded 500 degrees.

During San Diego County’s fiery October 2007, scientists used a Predator – a technology-laden unmanned aerial vehicle from NASA and the U.S. Forest Service.  According to Frost, it looked “through the smoke” to generate accurate battlefield maps using specialized software built by Google Earth engineers.  The maps revealed a fire with fringes that ranged from very wide to very narrow.  In some areas, the Predator revealed a fire pattern more akin to a mine field in which fires leapt from spot to spot, hop-scotching over so-called lines.  Firefighters and commanders could see they were fighting a massive, moving 3-D phenomenon.

“From the maps and images together, people could see how the fires were actually going,” said Frost.  “And that was way scarier than we would have thought before.  It really makes you admire the courage of firefighters and appreciate the complexity of trying to stop fire storms in complex topography with hundreds of thousands of people involved.”

The Viz Lab has recently begun trying to take advantage of the public’s use of smartphones, which can be used to take and send photos, with precise time and location data.  Massive computing power combines the images into composite views.  The result:  “It is essentially a 3-D surround video of the fire from the public, built by the public and sent out to the public and decision-makers,” said Frost.

(In 2010, the Viz Center has also used similar approaches to map, almost in real time, conditions following the earthquake in Haiti and the oil spill in the Gulf of Mexico.)

Ultimately, a wildfire ceases to spread, is extinguished – or simply burns out – and dies, clearing an ecological stage for whatever comes next.  It may be rain and mudslides.  It may be a regeneration begun by pioneering plants and animals.  And, someday, it may be another fire.

A sampling of wildfire resources and reports from around the CSU:

Fire Protection Administration Program at Cal State L.A.

Animated maps comparing the spread of San Diego wildfires in 2003 and 2007  

The Fires Down Below: ‘Look-Down’ Technology

San Diego Wildfires Education Project

Southern California Wildfire Hazard Center

Wildland Fire Laboratory

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