By Matthew Heller, National Geographic Maps

Arizona's Maricopa County Department of Emergency Management (MCDEM) provides communitywide education, planning, coordination, and continuity of government to protect lives, property, and the environment in the event of a major emergency.

In addition, the Maricopa County Emergency Operation Center, the Technical Operations Center of the Arizona Radiation Regulatory Agency (ARRA), and "REAT Forward" (ARRA's field location) are the major command and control centers during an "event" at Palo Verde Nuclear Generating Station, 45 miles west of Phoenix.

An event could range from an accident to a terrorist attack. "Decision makers and field-workers need to have continuity in the maps they are using," says Michael Philp, GIS programmer/analyst with MCDEM.

The Maricopa County Emergency Operations Center uses GIS to manage any incident in near real time. "GIS plays a major role in emergency management in Maricopa County," Philp says. "GIS is used in planning for emergencies, mitigating the effects of disasters, managing emergencies as they happen, and recovering from disasters after they have occurred."

Maricopa County maintains a comprehensive database of vector GIS data. The County also has a library of georeferenced aerial photography, which is updated on a regular basis. United States Geological Survey (USGS) digital line graphs are also used as raster backdrops, which are stored in an image catalog.

"In general, the County uses a mix of in-house data collection, commercially available data, and shared data from local, state, and federal government agencies," says Philp.

The agency has been using GIS to create emergency response maps for about five years, but "We needed a nice-looking basemap that would standardize the maps used in the Maricopa County Emergency Operations Center with the maps that the Arizona Radiation Regulatory Agency's field teams use," says Philp.

Drawing on ArcView 3.2a with ArcView Spatial Analyst and ArcPress, ArcGIS 8.1 with ArcView Spatial Analyst, ArcView 3D Analyst, and StreetMap USA extensions and National Geographic's TOPO! Image Support for ArcGIS extensions, the agency has been able to produce a series of maps from small handheld maps for field teams to large wall maps used for reference.

To update a map centered on the power plant, Philp used data from the TOPO! Arizona CD-ROM. "This solution gave MCDEM a standard basemap with integrated shaded relief to enable all of the field-workers and the command and control centers to use the same maps," says Philp.

To create the map, Philp started with a detailed, seamless topographic basemap for an area 10 miles around the plant. He used the extension to import the necessary 1:24,000 scale USGS "quad" maps from the Arizona CD-ROM, along with a corresponding grayscale hillshade created from the USGS 30 meter national elevation data set and stored them on a local hard drive as a single seamless JPEG image. In conjunction with ArcGIS 8.1 the extension automated the traditional process of locating the maps, clipping the collars, edgematching adjacent quads together, adding the hillshade, and reprojecting the images to match other data in the project.

Once in ArcGIS, Philp overlaid a sector system on top of the topographic basemap with concentric rings marked off every mile. Spokes from the center further segment the concentric circles, with each radius representing a sector. Sector A is at zero degrees, directly north of the plant. E is at 90 degrees, J is at 180, and N is at 270.

"Each person who lives around the plant knows the sector they're in. If you're in N-6, for example, you know exactly where you are in terms of direction and distance from the plant," says Philp.

The finished maps are used both digitally and displayed in hard-copy format at MCDEM's Emergency Operations Center, ARRA's Technical Operations Center, and ARRA's REAT Forward field location to assist in a coordinated government response.

Before this extension was available, MCDEM would use any one of several raster images as backdrops, which did and still does work quite well. However, "Small mines, remote landing strips, and the smaller washes don't show up on the imagery that is out there," says Philp. "There are no maps that show them and the data is not in our GIS."

"Field teams have mentioned that it is easier to find their way with the enhanced topographical data that the extension has provided. Obscure landmarks that show up on the TOPO! basemap help the field teams navigate in the remote desert area around the plant. ARRA has also mentioned that having the TOPO! data on the maps will aid in predicting where a radioactive plume would be likely to travel if a release were to take place."

Visit www.maricopa.gov/emerg_mgt/default.asp to learn more about Arizona's Maricopa County Department of Emergency Management. To learn more about National Geographic's TOPO! Image Support for ArcGIS extension, contact Matt Heller (tel.: 415-558-8700, ext. 100; e-mail: mheller@ngs.org; Web: www.nationalgeographic.com/topo).