Mapping Wildfire Damage


Case Study

Determining the extent of vegetation damage in New Mexico Wildfire

Landsat 7 ETM+ (Source: USGS EROS) image over the Cerro Grande wildfire in New Mexico with Genie Pro derived feature classification

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Background

In May of 2000, a wildfire swept through Cerro Grande and the surrounding area near Los Alamos, New Mexico. The fire was started as a controlled burn on May 4th but resources were underestimated and quickly went out of control until containment on May 19th. Critical elements to the spread of the fire were 1) the fact that the area had received drought level rainfall for the past 3 years, 2) high winds and 3) that there was high levels of forest fuel buildup. In the two weeks prior, four other fires in the area had gotten out of control in the Bandelier National Monument area adjacent to Cerro Grande.

A total of almost 48,000 acres were burned including the destruction of about 280 homes with over 400 families displaced. The total fire damage cost was estimated at $1 billion.(Source: US GAO/T-RCED-00-257)

Determining the Extent of Damage

Using Landsat 7 ETM + imagery over three different time periods, one prior to the fire in April (Image 1), one while the fire was in progress on May 9, 2000 (Image 3) and a third after the fire had been extinguished in July 2000 (Image 5), Genie Pro is used to analyze, monitor and map the progression of the wildfire. For this study, the April (before) image was trained using 8 feature classes that included grasslands, forest, sparse vegetation, clouds, mostly rock, mostly dirt and several other mixed catelgories that represent the surface materials in the area (Image 2). After the fire began, Genie Pro was trained using 2 feature classes, the fire damaged area and background (Images 4 and 6). In both images Genie Pro was able to easily map the fire progression and deliver a final assesment of total area and location of the damage created by the out of control fire. The area damaged by fire is represented in red in all images.

Images

Image 1 - Cerro Grande area near Los Alamos, NM prior to the wildfire (April 14, 2000).

Image 2 - Land Cover classification of the pre-wildfire Landsat 7 image (14APR00). A solution was generated using 9 feature classes including grasslands, forest, sparse vegetation, clouds, snow, mostly rock, and several other mixed categories that represent the surface materials in the area.

Image 3 - This May 09, 2000 Landsat image shows the encroachment of the wildfire towards Los Alamos, NM. The wildfire spread out of control from May 4th through May 19, 2000.

Image 4 - The two feature class solution developed over the affected area shows the impacted forest areas as of May 09, 2000.

Image 5 - Post wildfire Landsat image. July 2000

Image 6 - The burn area was determined using two feature classes to develop the solution, a "fire damaged" and a "background" class that included everything else. The solution was then applied to the image with the fire damaged area represent in red. The mapped extent of the affected area was exported as shapefiles for further evaluation.

Source: GAO/T-RCED-00-257 Cerro Grande Fire - United States General Accounting Office
Source: Landsat 7+ETM SlC-on - USGS EROS Center