Introduction to Geographic Information Systems (GIS)

1. Introduction to Geographic Information Systems (GIS)

2. Organization of presentation • Basics of GIS • GIS data at the New Jersey Department of Environmental Protection

3. Basics of GIS

4. Geographic Information Systems (GIS) • GIS facilitates visualization and analysis of spatial data • Spatial data are stored in map layers

5. Coordinate Systems • Spatial data are referenced to locations on the earth’s surface using coordinate systems • Ensure all map layers share a common coordinate system • Recognized global coordinate systems consist of: • A Spheriod: a mathematical description of the earth’s shape • A Map Projection: a mathematical conversion from spherical to planar coordinates

6. Map Projection

7. Map Projection

8. Scale • Tells how map distance relates to real world distance • Map Scale: ratio of map distance to actual ground distance • 1:10,000 (1 map cm = 10,000 real cm) • Small scale (1:100) vs. large scale (1:10) • Scale Bar: graphic display of map scale

9. Resolution • The accuracy with which a given map scale can depict the location and shape of map features • Larger the map scale, the higher the resolution • As map scale decreases, resolution diminishes and feature boundaries are smoothed, simplified, or not shown at all. • Rule of thumb: error = 2% of map scale • Resolution plays a large role in GIS, especially in raster-based modeling

10. Raster-based GIS • Data stored in a ‘regularized grid of cells covering an area’ • Grid cells called picture elements or ‘pixels’ • Nodes, Arcs, Areas

11. Vector-based GIS • Image and data stored separately • Data: attribute table • Image: points, lines, polygons

12. Summary • GIS facilitates visualization and analysis of spatial data • Spatial data are stored in map layers • Most GIS programs are raster- or vector- based • Raster - data and image stored together in regularized grid made of pixels • Vector - data and image stored separately; points, lines and polygons

13. GIS and Water Quality data at the New Jersey Department of Environmental Protection http://www.nj.gov/dep/

14. NJDEP - GIS The NJDEP – GIS Department (http://www.nj.gov/dep/gis/) provides GIS files for state administrative areas, hydrology, geology, land use, etc., such as: • Counties • Digital Elevation Grid • Hydrography • Watersheds • Water Quality Monitoring Stations

15. NJDEP - Water Monitoring & Standards The NJDEP Office of Water Monitoring & Standards (http://www.state.nj.us/dep/wmm/) oversees the Bureau of Fresh Water and Biological Monitoring . This bureau is in charge of monitoring the ambient conditions of the state's fresh and ground water resources. This monitoring includes : • regular sampling through a statewide network consisting of 115 surface water monitoring stations, • 820 benthic macroinvertebrate biological stream monitoring stations, • 100 fish assemblage biological stream monitoring stations, and • 150 ground water stations.

16. ESRI arcGIS at UNC UNC GIS software includes ESRI arcGIS version 9.0, 9.1 , 9.2 , 9.3 Getting Started: http://www.lib.unc.edu/reference/gis/getting_started.html Technical support research@unc.edu (919) 962-HELP Data Sources: http://www.lib.unc.edu/reference/gis/ Amanda C. Henley, GIS Librarian amanda.henley@unc.edu (919) 962-1151