october 2007gis and census mapping in st. lucia gis and census mapping in st. lucia presented by...

October 2007 GIS and Census Mapping in St. Lucia

GIS AND CENSUS MAPPING IN ST. LUCIA

Presented by Sherma Lawrence

Central Statistical Office, St. Lucia


Census History - Dissemination

• The previous dissemination of census results had been limited to tables and reports.


Census History - Maps

• In 1980 aerial photographs were used to guide the enumerators along their designated

Enumeration 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.


Introduction of GIS

• Reasons for the introduction of GIS at the Statistics Department:– Preparation for 2001 census– Increasing demand for updated maps– Technological initiatives– Development of human and physical

resources


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


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


GIS Software

• Creating multiple ED layouts within one project


GIS Software• Creating dot density

map to represent population distribution at District level


ArcGIS

ARC CATALOG

ARC MAP

ARC TOOLBOX(Floating Toolbar in Arc Map)

Arcview

ArcReader


ArcEditor


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.


ED Development with GPS

• 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


Mobile GIS

• Upgrade to Trimble Geo XM GPS unit– 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


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.


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 001-999.– e.g. 14705042 would be ED number 14705 and

building number 042


Creating Settlement Boundaries

• Buildings with the same address were grouped together using the select by attributes feature in Arcview


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 numbere.g. Sans Souci in La Borne is 120330403

Gros Islet – Monchy - La Borne - Sans Souci

12 - 033 - 04 - 03


Generating Settlement Codes


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


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


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


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


GIS Application…..Health


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

GIS Application…..Crime


GIS Application…..EconomyEconomy….• Combined average income per household• Useful for poverty assessment, feasibility studies


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




GIS Application…..General Elections


GIS Application…..IndustryIndustry….• Data entry of 2001 census visitation records• Classification based on the United Nations

“International Standard Industrial Classification of All Economic Activities”

NUMBERS OF BUSINESS

0

10

20

30

40

50

60

70

80

Baker

y

Man

Of C

loth

ing

Man

of F

urnitu

re

Garag

e

Mar

ket/M

inim

art/S

uperm

arke

ts

Retai

l Sto

res

Other

Ret

ail S

tore

s

Other

Non S

tore

Ret

ail

Guest H

ouse/H

otels

Resta

urant &

Bar

s

Regula

tioon o

f Public

Ser

vice

Pre/P

rimar

y

Other

Ente

rtain

men

t Act

iviti

es

Beauty

Sal

on

Type of Business

Co

un

t


GIS Applications….Industry


GIS Applications….Web Maps

http://www.stats.gov.lc/mapping_page/map_index.htm


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


The end

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