█ K. LEE LERNER
GIS is the common abbreviation for Geographic Information Systems, a powerful and widely used computer database and software program that allows scientists to link geographically referenced information related to any number of variables to a map of a geographical area. GIS allows its users to analyze and display data using digitized maps. In addition, GIS can generate maps and tables useful to a wide-range of applications involving planning and decision-making. GIS programs allow the rapid storage, manipulation, and correlation of geographically referenced data (i.e., data tied to a particular point or latitude and longitude intersection on a map).
In addition to scientific studies, by 2003, GIS programs were in wide use in a number of emergency support agencies and systems (e.g., the Federal Emergency Management Agency (FEMA)).
GIS programs allow scientists to layer information so that different combinations of data plots can be assigned to the same defined area. GIS also allows users to manipulate data plots to predict changes or to interpret the evolution of historical data.
GIS maps are able to convey the same information as conventional maps, including the locations of rivers, roads, topographical features, and geopolitical information (e.g., location of cites, political boundaries, etc.). In addition, to conventional map features, GIS offers geologists, geographers, and other scholars the opportunity to selectively overlay data tied to geographic position. By overlaying different sets of data, scientists can look for points or patterns of correspondence. For example, rainfall data can be layered over another data layer describing terrain features. Over these layers, another layer data representing soil contamination data might be used to identify sources of pollution. In many cases, the identification of data correspondence spurs additional study for potential causal relationships.
GIS software data plots (e.g., sets of data describing roads, elevations, stream beds, etc.) are arranged in layers that can be selectively turned on or turned off.
NASA engineers and teams of other scientists—including researchers and undergraduates from Stephen F. Austin University in Nacogdoches, Texas—employed GIS mapping to map remains found after the break up of the space shuttle Columbia in January 2003. Debris field maps helped narrow search patterns and—by linking the location of debris—allowed engineers and investigators to reconstruct critical elements of the disaster sequence. GPS data were used to construct the debris maps and to provide accurate representations of the retrogressive pattern of debris impacts.
GIS technology can also aid epidemiologists in tracking diseases and would be instrumental in the early identification of patterns of disease that could reveal a bioterrorist attack.
█ FURTHER READING:
Rigaux, P. et al. Spatial Databases: With Application to GIS. Morgan Kaufmann, 2001.
Steede-Terry, K. Integrating GIS and the Global Positioning System. ESRI Press, 2000.