By JoAnne Castagna
Out-of-control wildfires swept across southern California this past fall, leaving in their path death and destruction. Twenty raging brush fires were fanned by strong winds that quickly spread to seven counties. Homes were burned to the ground, hundreds of acres of forest were destroyed, and thousands of people were left homeless. A precise method was needed to help in locating and assisting displaced people.
In response, the Federal Emergency Management Agency (FEMA) sought the U.S. Army Corps of Engineers’ Geographic Information System (GIS) expertise and capability. The Corps had used its GIS expertise on several past missions, including during Hurricane Katrina and on 9/11 at the World Trade Center. The maps helped FEMA to identify territories in the scorched counties affected and to help locate displaced people requiring assistance, such as temporary trailers, and to protect the state from potential safety hazards that can result from these fires in the future. The mission continued to move forward in December with the help of these GIS maps, which cover the 500,000 acres of land that were burned.
GIS map depicting where damaged structures are located in San Diego County. (Photo by Chad Markin, Geographer/GIS Coordinator, USACE, Rock Island District.)
Stephen McDevitt, GIS expert with the Army Corps’ New York District, is one of the national action officers responsible for deploying and managing GIS teams throughout southern California to assist FEMA and other federal, state, and volunteer organizations. “GIS is a computer-based information system and tool for analysis of spatial data,” said McDevitt. “The GIS takes data from various sources, such as aerial photographs, drawings, and electronic geographic data, and combines these layers of information in various ways as overlays to perform spatial analysis and produce an electronic map that depicts the results of that analysis.”
Chad Markin, geographer/GIS coordinator with the Army Corps’ Rock Island District, deployed to California in support of the mission. “We used a lot of different data from a lot of different sources to perform analyses and create GIS mapping products,” said Markin. “This included aerial photography pre- and post-event, satellite imagery, commercial data sources, and vector data from varying sources in the field that include things like fire perimeters, ignition points, and burn intensity data.”
TYPES OF GIS MAPS
County and damaged structure maps. These maps identified counties that were adversely affected and identified damaged homes and businesses. The information shows FEMA where to set up Disaster Recovery Centers (DRC) to enable residents to obtain FEMA assistance applications. Maps of the DRC locations were also created to direct the public to the nearest DRC. When FEMA receives assistance applications from residents, it contacts them to ascertain where their damaged home is located. FEMA then looks up the location on the Corps’ GIS maps and verifies that the county they live in was badly burned and that structures where damaged.
FEMA individual assistance application maps. These maps are used to locate where residents are submitting applications for FEMA assistance. “FEMA plots these maps with dots to show where clusters of residents are filling in applications,” said John D. Ennis, geographer/GIS with the Army Corps’ Chicago District, who also deployed to California to create maps. These dots also show FEMA where damage may have occurred and where a DRC may need to be set up.
Demographic maps. These maps are used to determine the locations of economically challenged individuals who do not have transportation to get to their nearest DRC. Once identified, FEMA sends a mobile DRC to the area.
Flood plain maps. For FEMA to set up temporary trailer parks for residents, it needs to know where flood plains are located. Flood plains are areas of land that border rivers that are prone to flooding. FEMA doesn’t set up trailers in those areas.
Soil burn severity maps. Even after southern California gets back to normal, safety hazards can result from these fires. These maps show where the fires burned the valley the most and where there is the most soil erosion. This is important for FEMA to know, because when fire “cooks” the soil, it eventually breaks it up, leaving chunks of soil “like pottery.” When the rainy season comes, this soil washes down like “chunks of tire.” These large pieces of hard earth can cause mudslides down hills, injuring people and damaging property.
“In the 2003 fires in California, many people were killed by mudslides. There was heavy rain, and the mudslides buried and killed people,” said Ennis.
“Besides FEMA, Corps maps are being used by different groups for different reasons,” said Ennis. “For example, the Environmental Protection Agency wants to see the burned areas to see what environmental impacts have occurred, and emergency responders want to see them so they know from which areas to evacuate people.”
JoAnne Castagna, Ed.d., is a technical writer-editor for the U.S. Army Corps of Engineers, New York District.