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Using GIS for Analysis: Queries Re-classification Map overlay Real world Land use Elevation Parcels Streets Retail A sample of approaches:

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Presentation on theme: "Using GIS for Analysis: Queries Re-classification Map overlay Real world Land use Elevation Parcels Streets Retail A sample of approaches:"— Presentation transcript:

1 Using GIS for Analysis: Queries Re-classification Map overlay Real world Land use Elevation Parcels Streets Retail A sample of approaches:

2 Queries Aspatial Questions about attributes How many ___ are there? Which is the oldest? Which has the greatest land value? Could be answered with database software alone Spatial Questions about location, size, shape, distances, etc. Where is ___ ? Which is the longest US route within the county? Which is the most isolated golf course? Require a map – or GIS

3 Combination Queries Some queries involve 2 or more criteria (spatial or aspatial) For these, use Boolean operators: AND, OR, NOT

4 Combination Queries Which golf courses are in Mesa AND have 36 holes? In Mesa 36 holes

5 Combination Queries Which golf courses are in Mesa OR have 36 holes? In Mesa 36 holes

6 Combination Queries Which 36-hole golf courses are NOT in Mesa? In Mesa 36 holes

7 Using GIS for Analysis Queries Re-classification Map overlay

8 Reclassification Result of query is a new data layer Which land in Maricopa County is federally managed? BIA BLM BOR DOD FS FWS NPS

9 Query approach: Which land is managed by BIA OR BLM OR BOR OR FS OR FWS OR NPS? BIA BLM BOR DOD FS FWS NPS

10 Reclassification Approach: a New Data Layer Federally managed Other

11 Reclassification approach cellOwnership A1BLM A2BLM A3FS A4Non-fed CellOwnership A1Fed A2Fed A3Fed A4Non-fed Reclassification is often a step to get data ready for overlay analysis Data Table Before Reclassification Data Table After Reclassification

12 Using GIS for Analysis Queries Re-classification Map overlay

13 Map Overlay Ian McHarg (“Design with Nature”) – pre-computer advocate of map overlay

14 Map Overlay vs. Combination Query “Which Golf Courses are in Mesa AND have 36 holes?” Map overlay produces a new data layer

15 Map Overlay vs. Reclassification Which land in Maricopa County is Federally managed? BIA BLM BOR DOD FS FWS NPS Map overlay involves data from two or more layers

16 An example of a GIS analysis… GIS as a tool in fire management: Sequoia-Kings Canyon National Park

17 GIS as a tool in fire management: Sequoia-Kings Canyon National Park Question: “Where should we do controlled burns, in order to best reduce the risk of severe out-of-control wildfires?” Several aspects to consider: Ecological need (natural fire interval) Human value: Infrastructure, human life & safety Hazard: ability to control a fire, once started Risk: based on historic record of wildfire occurrence

18 Analysis to determine ecological need Data available: Vegetation ClassificationRI max 1 - Ponderosa Mixed Conifer6 2 - White Fir Mixed Conifer16 3 - Red Fir Mixed Conifer50 4 - Lodgepole Pine Forest163 5 - Xeric Pine Forest50 6 - Subalpine Conifer508 7 - Foothills Hardwood & Grassland17 8 - Foothills Chaparral60 Maximum average interval for fire occurrence 1.Natural Occurrence of fire, by species, based on analysis of tree rings

19 Analysis to determine ecological need Data available: Ponderosa forest 2.Vegetation map

20 Data available: Analysis to determine ecological need 3.Historical fires

21 Analysis steps: Departure from natural fire interval Vegetation types Reclassify Overlay Fire return interval Date of last fire Reclassify Years since last fire FRI TSLF Analysis to determine ecological need

22 Analysis steps: Departure from natural fire interval Reclassify Ecological need for burn Departure index Need to burn <-5Extreme -5 to -2High -2 to 0Moderate > 0Low Analysis to determine ecological need

23 Map of ecological burn need

24 Additional steps …. Where to do controlled burns Ecological burn need Ability to control burn Vegetation types Types of fuel slope elevation Date of last fire

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26 Where to do controlled burns Ecological burn need Ability to control burn Vegetation types Types of fuel slope elevation Date of last fire Infrastructure & Safety issues Risk of wildfire Additional steps ….

27 Today’s Challenges Environmental, Social, Political, Economic … Local, National, Global Information is an essential tool to address these issues Geographic technology can help to answer more complex questions covering larger geographic extents than ever before

28 Geographic information Involves a specification of location on the earth’s surface (WHERE) Also involves WHAT is at that location Goal is to uncover WHY something is located where it is


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