OECD/SWAC Africapolis with green space indicators
Date modified: 21 December 2024
Product Overview
Background
OECD Sahel and West Africa Club created Africapolis to provide a much needed standardised geospatial database on urbanisation dynamics in Africa, with the aim of making urban data in Africa comparable across countries and across time. Africapolis defines an urban agglomeration using two criteria, a boundary encompasses an area where there is a population of 10 000 people or more and where buildings are less than 200 metres apart. The 2015 version of Africapolis is the first time where data for all 54 countries is available, which was then updated in 2020. Africapolis closes one major data gap by integrating smaller cities, i.e., those under 500 000 people.
Africapolis boundaries can be combined with other data sources to track sustainability and inclusivity. For example, as seen here, to track the availability of green spaces in cities. Africapolis boundaries are combined with the ESA World Cover database. The % of green space is available for each of the boundaries in 2015 and 2020 identified by Africapolis.
Specifications
Spatial and temporal coverage
Africapolis utilizes polygon vector data to map the spatial extent of urban settlements, with each polygon’s size representing the settled area. Population figures are linked as attributes to these polygons, providing insights into the demographic characteristics of each urban agglomeration.
There are two layers available: africapolis_2015 and africapolis_2020.
Table 1: Africapolis data specifications
Specification |
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Product name |
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Coordinate reference system |
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Spatial Coverage |
Africa |
Africa |
Temporal range |
2015 |
2020 |
Data Format |
Vector |
Vector |
Figure 1: The geographic extent of Africapolis data
Processing
The boundaries of Africapolis are based on a large inventory of housing and population censuses, electoral registers and other official population sources, in some cases dating back to the beginning of the 20th century. While essential for building any database, the regularity, the detail and the reliability of these sources vary from country to country, and from period to period. Census data or official population records are often more than 10 years old and, in certain cases, go back 30 or more years. Given the pace of demographic and urban change, these are significant periods.
Satellite and aerial images are then used to fill in and complete the gaps and inconsistencies in official records, by capturing the physical evidence on the ground, that is the built-up area and the precise location of settlements. Other official cartographic resources, such as administrative boundaries, are also used to link population data to observed information on the built-up areas.
The OECD Sahel and West Africa Club and e-Geopolis have worked for years to build the Africapolis database, learning during the process, adding new sources and improving on the tools and methodology used to make the data as precise as possible.
The green space indicators Climate – Mapping Africa Transformations for the 2015 and 2020 Africapolis boundaries are defined using ESA World Cover database 2020 and 2021. The total area of three landcover classes are related to – grasslands, trees, and shrublands – are then divided by the total footprint of the Africapolis boundary to estimate the % of green space available in given year in the functional urban area.
References
Sahel and West Africa Club (SWAC)
Africa’s Urbanisation Dynamics 2020: Africapolis, Mapping a New Urban Geography
Boosting African cities’ resilience to climate change | OECD
License
The Africapolis is provided free of charge, without restriction of use. For the full license information see the Creative Commons Attribution 4.0 International License.
Acknowledgements
Africapolis is produced by the Sahel and West Africa Club (SWAC) in collaboration with e-Geopolis.org.
Data Acess
OGC Web Services (OWS)
The Africapolis product africapolis_2015, africapolis_2020 are available through the Digital Earth Africa’s geosever.
Table 4: Geoserver data access details.
OWS details |
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Name |
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Web Map Services (WFS) URL |
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Layer name |
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