Final Lab

        One of the major factors that affect the expansion of a wildfire is the topography of the surrounding terrain. The slope of a hill can give indications as to how fast a fire will spread as well as telling direction. Elevation can also be very significant in telling where different fuels for the wildfire are located, wether grass or trees. As can be seen in my project, the behavior of fire greatly depends upon changes in elevation, and fire tends to spread more quickly uphill. This information is very useful because it allows for more accurate prediction of fire spread. 

        In the case of the Station Fire in 2009, one of the primary and most obvious reasons for the fire spreading uphill is the fact that it started at the base of the Angeles National Forest. Looking at my reference map, it is clear that the fire started at a low elevation and somewhat close to a local road, which is a clue that the fire was possibly started by man. What is more important that can be inferred from the elevation of the initial fire is that it's direction can be predicted. Because plant life located at a higher elevation on the same slope of a fire gets dried out faster because of the rising heat, the fire will be able to use that fuel much more quickly than plant life below it, causing it to spread faster uphill (Fitzgerald). Due to the characteristics of fire and heat transfer, fires starting at lower elevations have a tendency to move to higher elevations.

        Another factor that had a great impact on the spread of the station fire, and all fires in general, is slope of terrain. There is a direct relationship between the slope of a hill and the rate of fire spread (Rothermel 24). The greater the slope of a hill is, the faster a fire will spread up that slope (Ntaimo 491). This phenomena can be clearly seen on the digital elevation model provided above. When comparing the fire perimeter on August 29 to the perimeter of August 30, the greatest expansion occurs where there is the greatest change in elevation, where the slope of the terrain is greatest. The same can also be seen when comparing the perimeter of August 30 to September 2. The most rapid expansion of the fire perimeter occurs when elevation is increasing.

        Slope and elevation are also critical in determining which fuels are available to be burned and how that effects the spread of the fire. When a slope is very steep it prohibits the growth of long-lasting fuel sources like pine trees but not fast igniting sources like sage brush. When a slope exceeds 60% incline, there is much less available fuel to burn (Mermoz 2709). This allows fire to spread very quickly up steep slopes but also means that an area will not remain on fire for a long time due to lack of fuel. The type of fuel that can be burned also depends on elevation. When reaching a certain elevation and the type of fuel changes from a fast igniting material like grasses to a slow igniting and burning material like pine, the rate of expansion will slow (McKelvey). The type of fuel that can be burned is very dependent on the slope and elevation of the fire area. 

        Topography is one of the primary factors that determine how a fire will burn. The expansion of the fire perimeter can be more predictable when considering the elevation and slope of the terrain, as well as what types of fuel the topography allows. Although other factors like wind speed and direction are much more variable and difficult to predict, knowing the topography of a fire region can greatly increase accuracy when predicting its expansion.

References

Fitzgerald, Stephen. "The Effects of Topography, Weather, and Fuel on Fire Behavior."      oregonstate.edu. Oregon State University, n.d. Web. 21 Mar 2013. <http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/19402/pnw618zappendixb.pdf?sequence=30>.

McKelvey, Kevin, and Kelly Busse. United States. United States Department of the Interior.Twentieth-Century Fire Patterns on Forest Service Lands. Davis: University of California Davis, 1997. Print.

Mermoz, Monica, Thomas Kitzberger, and Thomas Veblen. "Landscape Influences on Occurrence and   Spread of Wildfires in Patagonian Forests and Shrublands."Ecology. 86.10 (2005): 2705-2715. Print.

Ntaimo, Lewis, Bernard Zeigler, Maria Vasconcelos, and Bithika Khargharia. "Forest Fire Spread and Suppression in DEVs." Simulation. 80.10 (2004): 479-500. Print.

Rothermel, Richard. United States. United States Department of Agriculture. Mathematical Model for Predicting Fire Spread in Wildland Fuels. Ogden: , 1972. Print.