Geographic Information Systems: What is GIS?

"A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on earth. GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps."

GIS is a rapidly growing technological field that can assess real world problems, such as prioritizing sensitive species habitat or determining the effects of future development on the environment, through incorporating graphical features with tabular data. GIS is a tool to aid in decision making and provide an intuitive visual "explanation" of phenomenon.

GIS is a computer-based data collection, input, storage, analysis, and cartographic visualization technology that integrates data from diverse sources into a geographic database. Typical data sources include existing maps, aerial photographs, satellite imagery, text files, statistical data, and in situ measurements (e.g. water quality monitoring in the field).

What is now the GIS field began in 1960, with the discovery that maps could be programmed and stored in the computer allowing for necessary future changes. This technology replaced the era of hand cartography, where even small changes meant the map would have to be completely re-drawn. What Can GIS Do?
  • GIS is a tool that allows water quality experts and interested public members to:
  1. Explore and organize water quality data and information
  2. Comprehend complex geographic relationships
  3. Present data in an understandable manner
  4. Enhance the analysis of available options
  5. Streamline the decision-making process
  6. Make more informed decisions
  7. Plan for the future based on an accurate digital picture of the past and present
  8. Effectively communicate with citizens
  • An important characteristic of a GIS is that it retains the geographic location or spatial integrity of real world features. Spatial (geographic) information is special because:
  1. It is a representation of an infinitely complex earth
  2. It is multi-dimensional, i.e., it includes data about time and location as it applies to the earth
  3. Almost all human activities and decisions involve a geographic component
  4. It is essential to watershed analysis
Real World Uses of GIS
Given the capacity of a GIS to help in answering many types of questions, it is not surprising that it has become a powerful tool for decision makers in government agencies at all levels. A review of geospatial data created by jurisdictions in San Diego County highlights the potential for more than a hundred applications, including those of interest to water quality professionals as well as members of the public who wish to participate in watershed management. Team 1 group photo

Winning Team 1, at San Diego State University
Geography Department's GPS Treasure Hunt

Careers in GIS
GIS presentation by Dr. Tsou Those wishing to pursue careers in professions involving GIS applications need look no further than the universities and colleges in San Diego County, one of the core areas of GIS education and research in the United States. Foremost among the GIS programs in the local area are the geographic information science curricula offered by the Department of Geography at San Diego State University ( Geospatial Job Information (from
Presentation at San Diego State University GIS Day by Dr. Ming Tsou

GIS Careers typically include positions such as:

  • Cartographic designer
  • Computer programmer
  • Database administrator
  • Project manager
  • System administrator

GIS jobs range from part-time posts in small towns to full-time posts in large cities, so the average salary varies widely. The salary range is typically between $31,387 for an entry level GIS analyst to $83,333 for a GIS supervisor.