What does a GIS do?

  1. collect, store, organize, and distribute data
    common to see data files in the 10-100 megabyte range, up to gigabytes of remote sensing data, for example…..
    USGS National Map (discover and download these data)
    USGS Earth Explorer (discover and download)
    USDA Food Environment Atlas (discover and download)
  2. allows exploration of  relationships among data layers
    “…high yield forage grass is most common on which rock types?”
    “…how does population density relate to water quality?”
  3. criteria matching
    “I need to find a place for an outdoor recreation specialist at the Forest Service that is…
    on public land
    with gentle slope
    with permeable soils (for the the privy!)
    possessing nice views of the Blue Ridge
    amongst shade trees
    and within 50 m of a canoe-able river…
    so that she can plan a campsite there.”
  4. allows scenario testing
    …if we moved the landfill, would it be farther from most domestic water wells?
    ” Would it be more visible?”
    “how about moving it to here?… or here?…”
    For example, commercially available ArcGIS extensions to test land use scenarios CommunityViz or Envision Tomorrow
  5. serves as a data handler for other analyses
    e.g., passing geologic and topographic data to an erosion model of the Appalachians, or passing water quality and groundwater levels to a groundwater flow model
    these are typically written in other languages (C++, Fortran, etc) that can access the GIS.

    1. flood inundation model (GIS holds the data couples with hydrologic model, and displays results)
    2. Smoke Dispersion modeling predicts the maximum downwind distance a PM2.5 (fine particle) concentration is predicted to occur.
  6. aids visualization
    • which improves understanding and pattern recognition
    • & facilitates public participation in alternative scenarios
    • & coordinates group decision making
  7. models environmental processes and outcomes
    forward modeling – input known conditions to predict outcomes
    inverse modeling – input known outcomes or conditions to understand causes
    See for example Geostatistical modeling in ArcGIS Pro help

This page has 1000 examples (yes, one thousand). http://gisgeography.com/gis-applications-uses/