instituteurbanization and spatial connectivity in ethiopia: urban growth analysis using gis
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The 4th ESRI-Eastern Africa Conference, Addis Ababa, September 25, 2009TRANSCRIPT
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Urbanization and Spatial
Connectivity in Ethiopia:
Urban Growth Analysis Using GIS
Mekamu Kedir and Emily Schmidt
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Introduction
The Rural Urban Landscape in Ethiopia
• Of the estimated 73 million people living in Ethiopia (2007),
• 84% live in rural areas and with primarily income from agriculture
• 16% live in urban areas
• These are mostly located in the highland areas that comprise approximately 35% of Ethiopia‟s territory
• Urbanization rates differ according to methodologies and the database utilized:
• United Nations: 14.9% urban
• World Development Report:10.9% urban
• Central Statistical Agency of Ethiopia: 16% urban
• By comparison, the SSA average is 30% urban
• Ethiopia‟s non-agricultural sectors are also small relative to other countries in SSA
• In 2006/07 output of non-agricultural sectors contributed 54 % to GDP
• Non-agricultural sectors contributed 85 percent to GDP in SSA (and 75 percent of GDP in low income countries in SSA)
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• The Central Statistical Agency defines urban areas as:• Localities greater than 2000 inhabitants
• Administrative capitals of regions, zones, and woredas
• Localities with at least 1000 people doing non-agricultural activities, and / or areas where the administrative official declares the locality to be urban
• Given these definitions, urban areas do not remain constant between census years
• With this study we provide a consistent definition of urban areas which can be compared over time, across countries and within national boundaries
Introduction
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• In order to standardize urbanization measurements, we use
methodology developed by Uchida and Nelson (2009) which
incorporates a series of GIS data and analyses including:
• Travel time rasters,
• Population density
• Proximity to cities greater than 50,000
• We identify urban areas spatially using specific thresholds:
• A population density greater than 150 people per km2;
• Populations located within 1 hour travel time to a city of at
least 50,000 people.
• City centers of at least 50,000 people
Introduction
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This study uses:
• GIS road network data from each Ethiopian census year (1984,1994,2007)
• Population data from each Ethiopian census year
• Population density grids:
• Landscan
• GRUMP (Global Rural and Urban Mapping Project, Columbia University)
• Other biophysical data to create a travel time grid:
• land cover, rivers, water bodies and elevation and slope
Data and Methods
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In order to measure travel time to a major city:
Estimation of Travel Times
• A series of GIS layers are merged into a „friction layer‟ which represents the time required to cross each pixel
• Road type and class• Paved – all weather
• Paved – dry weather
• Gravel – all weather
• Gravel – dry weather
• Earth
• Waterbodies
• Landcover
• Slope
Data and Methods
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Road network
Rivers and lakesLand cover
Slope
Cities
Data and Methods: data reclassification
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Travel time
This friction layer is then used as an input into the “Cost
Distance” function in ArcGIS 9.2 in order to compute the
travel time in minutes from each pixel to the nearest
designated populated place.
In our study we analyzed travel time to cities of 50,000
people or more.
Road investments in Ethiopia greatly reduced travel time
between 1984 and 2007, especially in the highlands
Data and Methods
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Travel time 1984
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Travel time 1994
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Travel time 2007
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Once travel time is calculated to each major city for each census year, we are able to incorporate the cost distance raster into an agglomeration index measurement:
Urban population is determined using the criteria:
• Within an area of a population density of at least 150 people per square kilometer (calculated GRUMP and LandScan population density grids and adjusting for population growth
• Within a city of 50,000 people or within one hour travel time to a city of at least 50,000 people
Agglomeration Index
Data and Methods
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GRUMP population density grid
GRUMP (Global Rural-
Urban Mapping Project)
human settlement data is
available and applying UN
growth rates, population
was estimated for 2000
Data and Methods: Population Density
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LandScan population density grid
LandScan estimates the
large area population
density and spatially
allocates these data to key
infrastructure while
controlling for topography
Data and Methods: Population Density
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Average of GRUMP and LandScan
Following the Uchida
and Nelson (2008)
methodology, we
average the population
density grids for
GRUMP and
Landscan in order to
take into account
specific features such
as urban areas and
road infrastructure.
Data and Methods: Population Density
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Agglomeration Index 1984Results
In 1984, Addis Ababa and other
larger cities were primarily
confined to its city administrative
boundaries.
There were only a few cities with
greater than 50,000 people
Limited road networks and more
dispersed population characterized
the demographic landscape.
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ResultsAgglomeration Index 1994
By 1994, Ethiopia‟s cities grew, and
the country‟s transportation network
expanded
Urban corridors were formed
between Sebeta in the southwest
and Bishoftu to the southeast, linking
to Nazareth
Population growth and improved
transportation infrastructure in
Shashamene and Awasa also
facilitated linkages to form an urban
network between Oromia and SNNP
regions.
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ResultsAgglomeration Index 2007By 2007, urban linkages were
clearly visible throughout Oromia,
SNNP, and Amhara regions.
Addis Ababa expanded to connect
Sebeta and Bishoftu, and Asela in
the South.
Addis Ababa also connected to
Ambo in the west, and Debre
Berhan in the east
Hosaena linked to Sodo and
Shashamene
Linkages between Arba Minch and
Sodo were also forming
Jimma had grown into a
southwestern hub with opportunities
to link with Nekemte to the north.
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• Since the previous census in 1994, new cities have been created, and economically viable cities have experienced large growth in population count and density
• Given that growth in the number of cities with at least 50,000 people mainly occurred in the four major regions, we find that increased urbanization rates are primarily confined to these regions
• The city administrative areas, of Addis Ababa and Dire Dawa, as well as Harari, a small urban region, experienced the greatest urbanization from 1984 to 1994.
• From 1994 to 2007, Addis Ababa and other urban areas expanded significantly into other regions.
• Given improved travel time between major cities, as well as increased population density on these corridors, urban areas in Ethiopia look more like networks in 2007 than the isolated communities typical of the 1984 urban landscape
Results
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Larger cities have emerged over the 3 census years, especially
in Oromia, Amhara and SNNP regions
Cities in 1984* Cities in 1994 Cities in 2007
Region Over 20,000 Over 50,000 Over 20,000 Over 50,000 Over 20,000 Over 50,000
Tigray 1 1 5 1 10 3
Oromia 7 3 17 4 32 8
Amhara 5 3 7 3 18 7
SNNP 4 0 7 1 18 5
Gambella 0 0 0 0 1 0
Benishangul -
Gumuz
0 0 0 0 1 0
Harari 1 1 1 1 1 1
Dire Dawa 1 1 1 1 1 1
Addis Ababa 1 1 1 1 1 1
Somali 1 0 4 1 5 1
Afar 0 0 0 0 0 0
Number of cities over 20 and 50 thousand people during the census years
Results
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Table 1: Agglomeration Index – Percent of people considered urban by region
Total Population
(thousands)
Percentage
Urban
Total Population
(thousands)
Percentage
Urban
Total Population
(thousands)
Percentage
Urban
Regions 1984 1994 2007
Addis Ababa 1,423 61.2 2,113 85.5 2,738 99.3
Afar 780 - 1,061 - 1,411 -
Amhara 10,686 2.0 13,834 3.7 17,214 7.5
Benishangul-Gumuz 351 - 460 - 671 -
Dire Dawa 158 20.3 252 58.2 343 66.3
Gambella 172 - 182 - 307 -
Harari 82 55.2 131 76.2 183 86.0
Oromia 14,016 1.7 18,733 4.6 27,158 9.2
SNNP 7,501 - 10,377 2.2 15,043 21.1
Somali 2,006 0.2 3,199 1.6 4,439 1.9
Tigray 2,692 2.0 3,136 3.8 4,314 8.0
Ethiopia 39,869 3.7 53,477 7.1 73,919 14.2
Results
• Addis Ababa (24%), Dire Dawa (38%) and Harari (21%) experienced the greatest urbanization from 1984 to 1994
• From1994 to 2007 the change in urban share was less than the previous decade for Addis Ababa (14 %), Dire Dawa (8%) and Harari (10%)
• All other regions experienced greater urbanization from 1994 to 2007
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Population density and urban growth in 1994
Limited
urbanization (2.2%)
is present in SNNP
region in 1994
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Population density and urban growth in 2007
City growth, as well
as more networked
infrastructure
increased
urbanization rates
in SNNP almost
20%
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Percent population connected to a city of at least 50,000 people in 1994
Region Access < 1
hour
Access 1-3
hours
Access 3 - 5
hours
Access 5 - 10
hours
Access > 10
hours
Tigray 3.7 3.4 16.2 47.7 29.0
Afar - - - 5.6 94.4
Amhara 2.8 8.0 18.1 44.5 26.6
Oromia 5.3 7.7 20.6 36.7 29.8
Somali 8.0 - - 11.0 81.1
Benishangul-Gumuz - - - 11.2 88.8
SNNP 3.4 7.3 26.9 39.6 22.9
Gambella - - - - 100
Harari 100 - - - -
Addis Ababa 100 - - - -
Dire Dawa 100 - - - -
Ethiopia 8.4 6.4 18.2 36.0 31.0
Results
• In 1994, all of the inhabitants in Gambella region were more than 10 hours travel time to a city of at least 50,000 people
• Overall, 31% of the population in Ethiopia was more than 10 hours away from a major city
• In the four main regions, more than 50% of the population was over 5 hours travel time from a city
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Travel Time: Percent point change in access to a city from 1994 to 2007
Region Access < 1 hour
Access 1 - 3 hours
Access 3 - 5 hours
Access 5 -10 hours
Access > 10 hours
Tigray 7.13 12.01 (3.72) 5.98 (21.39)
Afar - - - 4.11 (5.89)
Amhara 2.23 14.68 18.94 (12.49) (23.35)
Oromia 3.74 10.40 15.84 (8.88) (21.10)
Somali - - - 2.62 (2.61)
Benishangul-Gumuz - - - 17.91 (17.91)
SNNP 9.17 45.37 (14.59) (21.56) (18.39)
Gambella - - - - -
Harari - - - - -
Addis Ababa - - - - -
Dire Dawa - - - - -
Ethiopia 4.10 17.12 7.54 (9.93) (18.83)
Results
• No improvement was experience in Gambella region between 1994 and 2007
• Population over 10 hours in the main four regions improved by at least 18%
• Only 2.6 percent of the population in Somali region decreased travel time to under 10 hours over the 13 year period.
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Difference in travel time to a city of at least 50,000 between 1994 and 2007
New gravel roads built between Kebri
Dehar and Gode; and Harar and Imi
eased access constraints in Somali
region considerably.
Although access has improved
considerably, populations remain very
remote (78 percent of the population
in Somali region is still further than 10
hours from a major city).
Extended evaluation of nascent
corridors between Jijiga and Kebri
Dehar, and between Harar – Imi –
Gode, could be undertaken to
understand the tradeoffs of investing
in these areas
Results
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• Ethiopia has placed a primary emphasis on rural and agricultural led development; nonetheless, the country continues to urbanize and agglomeration economies are beginning to link and form corridors of economic growth.
• Improved transport within Ethiopia has facilitated greater mobility of capital, goods, and people, and incentivized population clustering along major transportation routes
• Improvements in road infrastructure between large cities, as well as increases in population density along these corridors, have increased urbanization rates (agglomeration indices) from 3.7 to 14 percent over the last 2 decades
• This dramatic transformation in the economic landscape is likely to continue, with important implications for future economic growth and public investments in infrastructure.
Conclusions
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