Using GIS
for Analysis:
Retail
A sample of
approaches:
Streets
Parcels
•
Queries
Elevation
•
Re-classification
Land use
•
Map overlay
Real world
Queries

Aspatial

Questions about
attributes





Spatial

How many ___ are there?
Which is the oldest?
Which has the greatest
land value?
Questions about
location, size, shape,
distances, etc.


Could be answered with
database software alone


Where is ___ ?
Which is the longest US
route within the county?
Which is the most
isolated golf course?
Require a map – or
GIS
Combination Queries
 Some
queries involve 2 or more
criteria (spatial or aspatial)
 For
these, use Boolean operators:
AND, OR, NOT
Combination Queries

Which golf courses are in Mesa AND have 36
holes?
In
36
Mesa holes
Combination Queries

Which golf courses are in Mesa OR have 36
holes?
In
36
Mesa holes
Combination Queries

Which 36-hole golf courses are NOT in
Mesa?
In
36
Mesa holes
Using GIS for Analysis

Queries

Re-classification

Map overlay
Reclassification

Result of query is a new data layer
Which land in Maricopa County is federally managed?
BIA
BLM
BOR
DOD
FS
FWS
NPS

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
Reclassification Approach:
a New Data Layer
Federally
managed
Other
Reclassification approach
Data Table Before Reclassification
cell
Ownership
A1
BLM
A2
BLM
A3
FS
A4
Non-fed
Reclassification is
often a step to get
data ready for overlay
analysis
Data Table After Reclassification
Cell
Ownership
A1
Fed
A2
Fed
A3
Fed
A4
Non-fed
Using GIS for Analysis

Queries

Re-classification

Map overlay
Map Overlay

Ian McHarg (“Design with
Nature”) – pre-computer
advocate of map overlay
Map Overlay vs. Combination Query
“Which Golf Courses are in Mesa AND have 36
holes?”
Map overlay produces a new data layer
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
An example of a GIS analysis…
GIS as a tool in fire
management:
Sequoia-Kings Canyon
National Park
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
Analysis to determine
ecological need

Data available:
1. Natural Occurrence of fire, by species,
based on analysis of tree rings
Vegetation Classification
1 - Ponderosa Mixed Conifer
2 - White Fir Mixed Conifer
3 - Red Fir Mixed Conifer
4 - Lodgepole Pine Forest
5 - Xeric Pine Forest
6 - Subalpine Conifer
7 - Foothills Hardwood & Grassland
8 - Foothills Chaparral
Maximum
average interval
for fire
occurrence
RImax
6
16
50
163
50
508
17
60
Analysis to determine
ecological need

Data available:
2. Vegetation map
Ponderosa forest
Analysis to determine
ecological need

Data available:
3. Historical fires
Analysis to determine
ecological need

Analysis steps:
Vegetation
types
Date of last
fire
Reclassify
Reclassify
FRI
Fire return
interval
Years since
last fire
TSLF
Overlay
Departure from
natural fire interval
Natural FRI - TSLF

Natural FRI
Analysis to determine
ecological need

Analysis steps:
Departure from
natural fire interval
Reclassify
Ecological
need for burn

Natural FRI - TSLF
Natural FRI
Departure
index
Need to
burn
<-5
Extreme
-5 to -2
High
-2 to 0
Moderate
>0
Low
Map of ecological burn need
Additional steps ….
Vegetation
types
Date of last
fire
Types of
fuel
Ecological
burn need
slope
elevation
Ability to control
burn
Where to do
controlled burns
Additional steps ….
Vegetation
types
Date of last
fire
Types of
fuel
Ecological
burn need
slope
elevation
Ability to control
burn
Infrastructure &
Safety issues
Risk of wildfire
Where to do
controlled burns
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
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