Lab 8

          In 2009, the city of Los Angeles suffered its most destructive fire in history known as the Station Fire named for its origin nearing the Angeles Crest Fire Station in the Angeles National Forest (Mittal 11). Started by arson on August 26th, the Station Fire was not fully contained until October 16 (Mital 1). During its rampage, 160,577 acres of land was burned, 89 homes were destroyed, and two firefighters' lives were lost (Mittal 1). Costing about $95 million to suppress, the Station Fire was also the most expensive fire in the history of United States (Mittal 1). The reference map below illustrates the extent and growth pattern of the fire as well as land use of the areas around the fire.

          From the above reference map it is apparent that the southern parameter of the fire reached high density residential areas, thus resulting in the destruction of civilian houses, closing of schools, and mandatory evacuation from cities such as La Canada Flintridge, Altadena, Glendale, and La Crescenta (O'Connor). Additionally, major roads such as California State Route 2 were cut off due to the extent of fire. From the map, one might notice that the growth of the fire, especially when it first started, seems to progress mainly in a northward direction. This can be explained by the tendency of fire burning uphill faster than downhill. Since flames and heated air always move upward, areas above a fire are not only more prone to be lit on fire but also are heated by hot air from below, making them drier and more suitable for fire. As the Angeles National Forest has a steep slope facing south, it would be natural for the fire to rapidly grow northward.

          With 25% of its land burned, the city of Los Angeles faced yet another threat even after the fire was extinguished. Without plants to buffer the rainfall and roots to stabilize and hold together the soil, the bare land after a wildfire is extremely vulnerable to erosion. Also, due to the effect of hydrophobicity, a process through which the chemicals released from the combustion of plants condense to form a waxy coating on the ground, soil becomes repellent to water and rate of water runoff is thus increased (Moench & Fusaro). Erosion not only posits a problem for agriculture due to soil loss, but also causes great danger to lives and properties of people in the form of landslides. Since the Station Fire took place on a landscape with steep slope, the possibility of landslides was very high. To make things worse, the threat was imminent because the fire ended right before winter season. To gauge the potential and threat of erosion and landslides after the fire, I created a thematic map showing the distribution of different levels of post-fire erosion potential across the county.

          The post-fire erosion potential level is calculated based on the Revised Universal Soil Loss Equation. The equation follows roughly as: A= R * K * L * S * C * P, where A is soil loss in tons per acre per year; R is the rainfall erositivity factor measured for each area; K stands for soil erodibility which is dependent on the composition of soil at a given area; L and S are the topographic length-slope factors that measure steepness; C is the factor of soil coverage; and P takes erosion preventive practices into account (Jones and Kowalski and Shaw). From the map, it is apparent that the area where the Station Fire took place has very high erosion potential as predicted. Moreover, the mountain range with the highest post-fire erosion potential seems to be directly adjacent to residential areas, causing the situation to be even more threatening. 

          As countermeasures for landslides, the Los Angeles county government deployed a number of methods and treatments. Damaged and hazardous trees were fell to ensure safety and slow water runoff (Station Fire Burned-Area Report 13). Sandbags and k-rails were used to block overland flow and protect assets. Additionally, a design combining k-rail and chainlink fencing called rock fall catch fences were used to further minimize damage to people or properties (Station Fire Burned-Area Report 13). Woodstraw mulches were applied to increase soil stability (Station Fire Burned-Area Report 13). Additionally, contour log terraces could be placed to stabilize soil and stop water runoff (Moench and Fusaro). Since an ecosystem is extremely vulnerable to exotic or invasive plants immediately after a stand replacing fire, the prevention of weed growth is also important for both erosion prevention and ecosystem protection. Since weeds do not have strong roots capable of stabilizing the soil, their growth is not only useless but also harmful to the process of restoration as they hinder the regrowth of native plants. 

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References

Jones, David S., David G. Kowalski, and Robert B. Shaw. "Calculating Revised Universal Soil Loss Equation (RUSLE) Estimates on Department of Defense Lands: A Review of RUSLE Factors and U.S. Army Land Condition-Trend Analysis (LCTA) Data Gaps." Http://www.cemml.colostate.edu. Center for Ecological Management of Military Lands, n.d. Web. 22 Mar. 2013. <http://www.cemml.colostate.edu/assets/pdf/tps-96-8.pdf>.

Moench, R., and J. Fusaro. "Soil Erosion Control after Wildfire." Soil Erosion Control after Wildfire. Colorado State University, 3 Aug. 2012. Web. 22 Mar. 2013. <http://www.ext.colostate.edu/pubs/natres/06308.html>.

O'Connor, Robert. "CFN - CALIFORNIA FIRE NEWS - CAL FIRE NEWS : Station Fire Evacuations: Mandatory Evacuation Orders." Web log post. Station Fire Evacuations: Mandatory Evacuation Orders. CALIFORNIA FIRE NEWS, 30 Aug. 2009. Web. 22 Mar. 2013. <http://calfire.blogspot.com/2009/08/station-fire-evacuations-mandatory.html>.

United States. Department of Agriculture. Station Fire Burned-Area Report. USDA Forest Service, 23 Sept. 2009. Web. 19 Mar. 2013. <http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5245056.pdf>.

United States. Government Accountability Office. STATION FIRE Forest Service’s Response Offers Potential Lessons for Future Wildland Fire Management. By Anu K. Mittal. United States Government Accountability Office, 16 Dec. 2011. Web. 18 Mar. 2013. <http://www.gao.gov/assets/590/587075.pdf>.