Transcript GIS AND CENSUS MAPPING IN ST. LUCIA Presented by Sherma Lawrence Central Statistical Office, St.

GIS AND CENSUS MAPPING
IN ST. LUCIA
Presented by Sherma Lawrence
Central Statistical Office, St. Lucia
October 2007
GIS and Census Mapping in St. Lucia
Census History - Dissemination
• The previous dissemination of census results had been
limited to tables and reports.
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GIS and Census Mapping in St. Lucia
Census History - Maps
• In 1980 aerial photographs were used to guide the
enumerators along their designated Enumeration
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Districts (ED).
1991 the aerial photographs were used in collaboration
with hand drawn maps.
Subdivision of island into Enumeration Districts
(approximately 100 households per unit)
Delineation project by Statistics Department to identify
areas previously left out
New EDs hand drawn to scale from 1:2500 topographic
map sheets.
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GIS and Census Mapping in St. Lucia
Introduction of GIS
• Reasons for the introduction of GIS at the
Statistics Department:
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Preparation for 2001 census
Increasing demand for updated maps
Technological initiatives
Development of human and physical
resources
GIS and Census Mapping in St. Lucia
GIS Software
• Arcview 3.0 was
chosen as the first GIS
software package of
the Statistics
Department
– Simple User Interface
– Great functionality
• Upgrading from 3.0
through to 3.2
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GIS and Census Mapping in St. Lucia
GIS Software
• Arcview uses prior to
2001
– Digitize topographic
map sheets using
heads-down digitizing
– Subdividing of digital
map in to
Enumeration Districts
using heads up
digitizing
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GIS and Census Mapping in St. Lucia
GIS Software
• Creating multiple ED
layouts within one
project
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GIS and Census Mapping in St. Lucia
GIS Software
• Creating dot density map
to represent population
distribution at District
level
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GIS and Census Mapping in St. Lucia
Arcview
ArcGIS
ARC MAP
ARC TOOLBOX
(Floating Toolbar in Arc Map)
ARC CATALOG
ArcReader
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ArcEditor
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Global Positioning Systems (GPS)
Why GPS?......
• Topographical maps were out dated
• Inaccuracy in ED maps
• Rate of national development
• Need for regular updating and
maintaining of Enumeration Districts.
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ED Development with GPS
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GPS used to update roads, footpaths and buildings.
Differential correction done with pathfinder office
Base files from Cable and Wireless Base Station
New files exported as shapefiles
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GIS and Census Mapping in St. Lucia
Mobile GIS
• Upgrade to Trimble Geo XM GPS unit
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Functionality of a PDA with a high-tech GPS system
1-2 meter accuracy
Microsoft Windows CE operating system
Terrasync Software
• Arcpad software
– Import Arcview project unto the unit
– Realtime editing
– Easy transfer from desktop to mobile unit
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GIS and Census Mapping in St. Lucia
Updating EDs using Aerial Photos
• 2004 aerial photos obtained from the Survey and
Mapping Section of the Ministry of Physical
Development\
• Individual images were used because of the size
of the file
• Inserted into Arcview as graphic
• Used as a back drop for updating EDs
• Too many trees in certain areas obstructed the
view of houses and parts of the road
• Ground truthing field trips.
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GIS and Census Mapping in St. Lucia
Developing Settlements
• During the 2001 census each building was numbered
sequentially and given a unique identifier comprising
the 5-digit ED number and three digit number from 001999.
– e.g. 14705042 would be ED number 14705 and building number
042
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Creating Settlement Boundaries
• Buildings with the same address were grouped
together using the select by attributes feature in
Arcview
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GIS and Census Mapping in St. Lucia
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Generating Settlement Codes
• A unique 9 digit settlement code was developed
– 2 digit district code (standard)
– 3 digit main settlement number
– 2 digit sub settlement number
– 2 digit sub-sub settlement number
e.g. Sans Souci in La Borne is 120330403
Gros Islet – Monchy - La Borne - Sans Souci
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Generating Settlement Codes
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GIS Applications
• Settlement boundaries have
revolutionized the dissemination of
census data within the Statistics
Department.
• Statistical information can now be
mapped relative to the administrative
boundaries used by an agency such as
Health Regions, Education Districts,
Political Constituencies, etc
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GIS Application…..Demographics
Dot Density ……
• is a simple
application where the
value of the variable
is represented by dots
• In the case of St.
Lucia, used to
represent population
count where
1 dot =200 persons
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GIS Application…..Demographics
Population By
Settlement …..
• It is easier to disseminate
demographic information
at the settlement level
• A Settlement map can
now be provided to
accompany the
information
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GIS Application…..Health
Heath…..
• Undefined boundaries
• Heath Regions were
developed by combining
the settlement catered to
by the Health Centres
and Hospitals in the
Regions
• Reported case of Diabetes
relative to the location of
Health facilities by
settlements
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GIS Application…..Health
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GIS Application…..Crime
Crime….
• A K-mean Cluster Classification Analysis was performed using the
results of the 2001 census to determine areas most prone to crime
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GIS Application…..Crime
GIS Application…..Economy
Economy….
• Combined average income per household
• Useful for poverty assessment, feasibility studies
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GIS Application…..Elections
General Elections…..
• Redefining and re-digitizing of Electoral Boundaries
prior to the 2001 National Elections
• Subdividing or Electoral Constituencies into Poling
Divisions
• Providing maps for National Voter registration project
• Displaying Election Results on Statistics website:
http://www.stats.gov.lc/election.htm
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GIS Application…..General Elections
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GIS Application…..Industry
Industry….
• Data entry of 2001 census visitation records
• Classification based on the United Nations
“International Standard Industrial Classification of All
Economic Activities”
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Type of Business
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GIS Applications….Industry
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GIS Applications….Web Maps
http://www.stats.gov.lc/mapping_page/map_index.htm
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Conclusion
• The applications mentioned above are a
mere demonstration of capabilities of GIS
• GIS is a valuable investment and has
proven to be an asset at the St. Lucia
Statistics Department
• GIS has positively affected the way we
collect, analyze and use data
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The end
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