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What does a GIS do

Publié par elharrak mardi 8 avril 2014



  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.
    USGS National Map or download National Atlas data files
  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 build a campsite there."
  4. allows scenario testing
    ...if we raised the smokestack to 990 ft, would the effluent bypass the inversion layer?"  
    "how about moving it to here?... or here?..."
    CommunityViz a commercial ArcGIS extension to test land use scenarios 
  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. A flood inundation model (HEC-RAS flow model coupled with GIS layer of watershed)
    2. A forest fire plume model
  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 

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