BACKGROUND: The Santa Monica Mountain Range, located just north of Los Angeles, is one of the most fire-prone regions in Southern California. To help fire managers identify the best locations for site treatments in that region, a University of Wisconsin, Madison team of scientists developed a map that incorporates both environmental and human factors to pinpoint where the most devastating wildfires are likely to start.
MODEL BEHAVIOR: In collaboration with the US Forest Service's Northern Research Station in Evanston, Illinois, the researchers generated computer models based on a variety of data for the Santa Monica Mountain region, including what starts fires, and how much area is burned by fires, as well as the locations of homes, roads, trails, local climate, and terrain. They found that the vast majority of wildfires begin near human infrastructure or along roads that serve as an interface between wild land and urban areas. However, the area burned by a fire depends more on such factors as the type of terrain, climate or vegetation. By combining the data on where fires are likely to start with where fires are most likely to spread, the UWM researchers were able to map out areas where the most destructive fires are likely to start.
RUNNING WILD: Weather is a key factor in starting and spreading wildfires -- particularly drought, which dries out vegetation. Trees, underbrush, dry grassy fields, pine needles, dry leaves and twigs can all cause and spread forest fires because they burn faster, like kindling, than large logs or stumps. The more fuel that is present, the more intensely the fire will burn and the faster it will spread. When the fuel is very dry, such as after a long drought, it is consumed much faster, and the fire is much more difficult to contain. As the fire spreads, it generates heat that evaporates the moisture in potential fuel materials just beyond it, making it easier for those to ignite. Wind can also help spread a forest fire, and is the most unpredictable factor. Winds supply the fire with extra oxygen and push it across the land at a faster rate. Because the wind generally flows uphill, fires also travel faster up a slope than downhill. Wildfires can even generate their own winds, called fire whirls, which resemble tornados. They arise from the vortices created by the fire's heat, and can be so strong they have been known to hurl flaming logs and burning debris over long distances.
The American Geophysical Union contributed to the information contained in the TV portion of this report.