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Geographic Information Systems

Geographic Information Systems

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Geographic Information Systems

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  1. Geographic Information Systems Geography 1050

  2. What is a GIS? A Geographic Information System (GIS) is a system of computer software, hardware and data, and personnel to help manipulate, analyze and present information that is tied to a spatial location. • Spatial location: usually a geographic location • System: linking software, hardware, and data • Personnel: a thinking explorer who is key to the power of a GIS

  3. What is a GIS? • A method to visualize, manipulate, analyze, and display spatial data • “Smart Maps” linking a database to a map

  4. Data for GIS Application • Digitized and scanned maps • Databases - table of data • Field sampling • Remote sensing and aerial photographs

  5. A database - not easy to interpret Population density in the US

  6. Visual analysis of data“Picture is worth a thousand words” Population density in the US

  7. Different data layers combine

  8. Maps and databases are “Interactive” GIS User: • asks questions • sorts and combines data • looks for patterns and connection

  9. Two ways to display spatial data • Raster - Grid • “pixels” • a location and value • satellite images and aerial photographs are in this format • Vector - Linear • points, lines, and polygons (shapes) • feature (house, road, lake, etc.) and attributes (size, type, length, etc.)

  10. Some ways Geographic Information Systems are used: • Emergency Services - Fire and Police • Environmental- monitoring and modeling • Business - site location, delivery systems • Industry - transportation, communications, mining, pipelines • Government - local, provincial, federal, military • Education - research, teaching tool, administration

  11. CASE STUDY- GIS and AquacultureSoft-Shell Clam Site Assessment, Burgeo, NL • evaluation of the viability of the soft-shell clam resource • GIS technology was applied to collected data to map and analyze: • physical site characteristics and landuse • water quality • the soft-shell clam resource.

  12. CASE STUDY- GIS and Aquaculture • study area divided in a series of 100 m x 100 m grid cells. • Field survey data included: • clam biology (length and width and weight) • hydrographic data (water depth, current speed and direction, bottom substrate, tidal data, rainfall), • water quality data (fecal coliform, salinity, temperature) • land use data (cottage locations).

  13. Study area, survey grid and water monitoring locations CASE STUDY- GIS and Aquaculture

  14. Water Quality CASE STUDY- GIS and Aquaculture • Contamination by fecal coliform a concern becaue of nearby cottages • If density exceeds 13.99MPN/100ml harvesting in the area is not permitted • During the majority of the sampling period the densities were at 1.9 MPN/100ml • Following extended rainfall event the fecal coliform densities ranged from 17 to 920 MPN/100ml

  15. CASE STUDY- GIS and AquacultureWater Quality: Time Series maps of fecal coliform

  16. CASE STUDY- GIS and Aquaculture Water Quality • Clams need salinities of at least 5 parts per thousand (ppt) to survive • Salinity in study area fell below 5ppt during rainfall event • Fecal coliform densities and salinities returned to normal more quickly in Big Barasway than in Indian Hole and Little Barasway • Big Barasway flushes faster and therefore this area could be seeded with clams from Indian Hole and Little Barasway

  17. CASE STUDY- GIS and Aquaculture Soft-Shell Clam Database and Aquaculture Management • Clam densities of different size classes for each grid cell were calculated and mapped • Recruit class (clams with a length between 50 and 63.5mm) represents the market clam population • A grid cell is economically viable only if the recruit clam density is $10/m sq.

  18. CASE STUDY- GIS and AquacultureSoft-Shell Clam Database

  19. CASE STUDY- GIS and Aquaculture Aquaculture Management • Mature clam densities of 161 to 269/m sq. are acceptable for good growth • Densities higher than 269/m sq. can impede growth because of competition for food and space • When the density of mature clams exceeds 269/m sq. the area should be culled

  20. CASE STUDY- GIS and Aquaculture Harvesting Plan • GIS is able to identify areas of no harvesting, harvesting only, culling only, and combined harvesting and culling. • Criteria for harvesting: • density of recruit clams > 10/m sq. • Criteria for culling: • density of mature clams > 269/m sq.

  21. CASE STUDY- GIS and Aquaculture Harvesting Plan