Gauteng’s changing urban footprint 1990-2013

This map of the month series provides an image of Gauteng’s urban footprint and some indications of future growth using the most recently available data (see previous GCRO map of the month on urban spatial change here). Map 1 presents urban land cover across the wider Gauteng City-Region at two points in time. The parts of the map shaded black indicate urban land cover that existed in 1990. The yellow shading represents urban land cover that came into being between 1990 and 2013.

This map shows that much of the growth since 1990 looks like a fringe around the older settlement pattern (with the exception of some sections of the 1990 urban perimeter which have not expanded in part because of physical geography). This is an expected pattern of urban growth for the simple reason that available land is on the urban fringes, and owners of such land capitalise on increasing land values caused by rising demand.

The image also confirms what many residents of Gauteng have noticed over the last quarter of a century: whereas Pretoria was separate from Johannesburg in 1990, a bridge of relatively unbroken urban land now exists as a result of development in Midrand and Centurian (also see Map 3). Map 1 also shows urban land use change in the provinces adjacent to Gauteng. Platinum related growth in Rustenburg is particularly noticeable.

Map 1, based on 30m resolution satellite imagery, cannot give a sense of the type of land use, and it is important to remember that the expansion of the urban footprint has taken different forms. The fringe to the north and west of Johannesburg and Midrand is largely cluster housing development, office parks and retail. By contrast the growth south of Thokoza represents a combination of informal settlement and low cost housing.

Map 2 focuses in on the boundaries of Gauteng, and combines the urban footprint data of Map 1 with township establishment planning applications and planned mega human settlements. Township establishment applications refer to the process by which agricultural land is converted to urban for a variety of uses, including gated communities, suburbs, low cost housing, or economic activities. The red shading indicates township establishment applications which were approved between 2005 and 2013. The blue shading indicates township establishment applications which were under consideration in 2013. In other words, not all of the blue areas will be given planning approval but this indicates, nevertheless, a desire by owners of this land to have the right to construct urban developments of various kinds. The white outlines are of the mega human settlements announced by the Gauteng provincial government in April 2015.

An interesting trend is that the mining belt, which showed little urban land in 1990, has had some development over the last two decades and land owners have applied for permission to carry out further development. This is in-fill development which has taken place closer to residual mining structures and dumps, and on rehabilitated land. Another interesting feature is that some potential development is on very large plots of land, such as the privately owned Protea Glen Ext 22 and the proposed mega human settlement of Syferfontein (Map 4). By contrast, in Midrand the urban landscape (Map 3) has expanded, and is likely to continue growing, through the aggregation of smaller scale cluster housing, offices, and related uses.

Notes on interpretation

1. Note that these layers do not represent the same kinds of data. The urban land use layers of 1990 and to 2013 were both digitised by GeoTerra Image (GTI) using Landsat TM (1990 and 2000) and Landsat 8 satellite (2013) images. This satellite imagery is in the form of pixels (30x30 meter raster cells). The layer of township establishment applications, by contrast, shows parcels of land in the form of polygons of various sizes, shaped according to land ownership registration. The implication is that these outlines do not translate straight-forwardly into future urban land cover. For example, a land owner may have sought or may currently be seeking approval to develop their land, but may not eventually do so across the entire parcel of land even if they are given approval.
2. We have defined urban land use classes as built-up, commercial, village, school sports grounds, golf courses, townships, residential, industrial, mine buildings and informal. Smallholdings were excluded from the urban land use shading.
3. Planning approvals listed in the Gauteng Provincial Gazette from 2005 until 2013 are represented by the maps. To produce the maps, applications were filtered to depict all township establishment applications (submitted and approved) only, and therefore other applications such as for rezoning are not shown here.
4. Some of the past urban expansion did not take place following successful development applications. Notably, informal settlements occur irrespective of planning processes.
5. By nature the map does not show development on the existing urban footprint in which a great deal of densification has occurred through sub-division and, in some places, vertical construction. We intend to explore this kind of density in future maps.