Information from SANSA
South Africa is rapidly urbanising and that puts pressure on adequate and effective urban planning. The growth of cities also results in degradation of natural habitats, changes in species composition, cities’ micro-climate, energy flows and subsequently creating urban heat islands. There is an urgent need for effective and sustainable urban planning and development management, supported by adequate and up-to-date geospatial information. This article demonstrates how remote sensing technologies support urban spatial planning and human settlements development policies.
In the 2016 State of the Province Address (SOPA), the Premier of Gauteng, David Makhura stated that the Gauteng Province is faced with various problems related to rapid urbanisation. The Gauteng Premier estimates that about 1-million people migrated to Gauteng between 2011 and 2016. This has major implications on the spatial planning imperatives relating to service delivery, housing, health, education, and infrastructure. Moreover, in 2015, the United Nations estimated that 71,3% of South Africa’s population will live in urban areas by 2030 and almost 80% by 2050. Furthermore, South Africa’s urban population is becoming larger and younger with two-thirds of South African youth living in urban areas. Polokwane, Rustenburg, Vanderbijlpark, Nelspruit and Ekurhuleni are the five fastest-growing urban areas, with average annual population growth rates of between 1,6% and 2,9% over the last decade, compared to Cape Town with a rate of 1,4%. Gauteng province, the country’s geographically smallest but economically busiest province, has both the biggest and the fastest growing population, according to census 2011, with 12,2-million people counted in 2011 – a 33,7% increase over 2001 and more than double the national average increase .
Recent urbanisation in South Africa is not unique, since the African continent is also rapidly urbanising from 15% in 1960 to 40% in 2010, and the population of urban dwellers is projected to reach approximately 60% in 2050 [2,3]. Whereas these high urban growth rates are associated with rising economic prosperity, urbanisation in Africa has resulted in a proliferation of slums, service delivery problems, pressure on basic social amenities, poverty and widening levels of inequality. South Africa, widely recognised as one of the emerging economies globally, is confronted with similar problems emanating from urbanisation.
The most important reasons behind rapid urbanising in South Africa are rural-urban migration and natural population growth that result in the proliferation of informal settlements. It is estimated that at least 1,2-million households reside in shacks in at least 2700 shack areas nationwide . The proliferation of slums due to urbanisation in South Africa’s economic hubs such as Cape Town, Johannesburg and eThekwini increasingly present not only a challenge to urban spatial planning, but leads to increased poverty and inequality levels in urban centres, as shown by their city Gini coefficients of 0,67, 0,75 and 0,72 respectively.
Rapid urbanisation as seen in South Africa and other regions has made cities the most dramatic manifestations of human activities on the surface of the Earth . Moreover, cities degrade natural habitats, simplify species composition, disrupt hydrological systems, and modify energy flow and nutrient cycling, leading to urban heat islands . Without adequate geospatial information, it is difficult to plan and develop housing or human settlements infrastructure, utilities and services, or to protect and manage the environment, assign appropriate titles and tenure to land and property parcels; or to effectively assess and collect property revenue.
This article describes how remote sensing technologies support urban spatial planning and human settlements development policies, and demonstrates how the use of satellite-based geospatial information has helped to improve urban planning and decision making.
Responding to rapid urbanisation in South Africa
In response to rapid urbanisation, the South African government is developing and implementing new integrated spatial planning and land use management policy aimed at providing sustainable human settlements infrastructure development. Since the introduction of the Integrated Development Planning (IDP) and subsequent sectoral instruments such as the Spatial Development Frameworks (SDF), at least, 5,6-million formal houses were built since 1994 . The Spatial Planning and Land Use Management Act 16 of 2013 (SPLUMA) came into effect on 1 July 2015, to provide a fundamental framework for integrated spatial planning and land use management. The act calls for a coherent and planned approach to urban and rural spatial development planning and land use management. In a sense, SPLUMA seeks to regulate urbanisation by promoting sustainable land development that limits urban sprawl and protects prime and unique agricultural land from urbanisation through a planned approach.
The role of implementing government programmes is usually cascaded to the provincial government and municipalities. The Gauteng Spatial Development Framework, Gauteng Growth Management Perspective, Gauteng Spatial Perspective (GSP) 2030 Concept Paper and Municipal Spatial Development Frameworks provide valuable insights on how the provinces and municipalities plan to implement the policy directives mandated by SPLUMA and the National Development Plan 2030 (NDP). The latter recognises the value of geospatial information in national spatial development and calls for the establishment of a national observatory for spatial data and analysis. Among other things, the NDP recognises reconfiguration of towns and cities into more efficient and equitable urban forms, including aspects spatial restructuring strategies and the creation of a robust set of indicators as part of a spatial governance evaluation framework. Satellite-based remote sensing has played a fundamental role in supporting urban spatial planning, existing policies, and in mapping and monitoring human settlements and urban growth in South Africa.
Satellite earth observation is vital in supporting the NDP which identified the need to restructure cities into equitable and efficient spaces by curbing urban sprawl through densification of housing on well-located land parcels in the inner cities and focussing urban development.
Moreover, the role that space-based earth observation technologies should play in providing workable solutions to improve a range of social and economic challenges facing the country was recognised by the Government of South Africa through the SANSA Act (2008) which provides for the “promotion and use of space and co-operation in space-related activities…”. The Act provides for satellite-based earth observation technologies and applications in support of several activities, including urban spatial planning and development in South Africa.
Geospatial information provided by satellite imagery is critical in planning and identifying suitable locations for human settlements and infrastructure development. The integration of satellite-based information with other socio-economic and field environmental datasets allows city planners to broaden their understanding of urban ecology necessary for them to design smart cities resilient to the impacts of climate change.
Approaches to mapping urban areas
Urban land surfaces are typically arranged in elaborate complex pictorial designs that are of unpredictable size, shape, and pattern. Satellite-based remote sensing data has been routinely used (since the 1970s and 1980s) to infer the impact of urban growth on the multiple dimensions of cities . However, satellite images have traditionally been too coarse to monitor complex and sometime fines-scale changes in urban land surfaces.
The last decade has seen the growth of high spatial resolution satellite sensors capable of differentiating up to sub-metre urban built-up infrastructure and landscape features. High spatial resolution sensors launched in recent times include SPOT 6/7 (1,5 m), Pleiades (0,7 m), Worldview 1, 2 and 3 (0,46 m), Quickbird (0,61 m), Ikonos (0,82 m), Kompsat 3 (0,5 m and 0,7 m) and Syksat 1 and 2 (0,9 m).
The emergence of these very high-resolution satellite sensors now provides new vistas in mapping and monitoring urban landscapes.
These sensors are capable of discerning individual buildings and transportation networks, making it feasible for urban planners to frequently update cadastral city maps and detect the rapid changes occurring due to urbanisation. Satellite imagery offers an accurate visual portrayal of the physical form and morphology of urban areas that is critical in accurately mapping the complex urban landscape. The repetitive nature of satellite image acquisitions makes it possible to monitor and detect rapid land developments in urban areas.
Spatial distribution of human settlements
The urban scene shows the spatial arrangement of different land cover types and the condition of the natural environment (Fig. 1). Interpretation of urban features from the satellite image show commercial areas, suburban areas, road networks, recreational areas, vegetation and other land use and land cover features around Pretoria. In this case, the understanding of the current spatial orientation of human settlement types is required by planners for site selection, zoning regulation, resource allocation, monitoring the state of the environment and urban growth management. This information is also vital in transforming the apartheid suburban spatial configurations that relegated the black majority from the mainstream urban economy to the urban peripheries.
Satellite-derived land use information is critical for spatial planning and urban development management. The classification map in Fig. 2 shows the spatial distribution of human settlement types around Johannesburg. The location of townships and informal settlements (pink) in urban fringes is evident. This information is necessary for improving road network infrastructure, and other services like schools and clinics in areas that are poorly serviced.
Urban growth and sprawl
The value of satellite imagery in monitoring and detecting urban growth and transformation is well established and has been demonstrated. Fig. 3 shows human settlement expansion around Pretoria that took place between 1990 and 2014. This information is used for planning service delivery to communities and assessing the environmental impacts of human settlement development. It is evident that such urban expansion as shown in Fig. 3 requires corresponding capacities to provide basic services such as water and sewerage systems, electrification, sanitation and waste management, transportation infrastructure, schools, hospitals, parks and recreation facilities and other social amenities.
The results from this study show that the extent of urban areas in the City of Tshwane metro increased by over 80% between 1990 and 2014. Similar satellite image based urban change detection studies reveal comparable trends of 67% and 57% in urban expansion in Johannesburg and Ekhululeni since 1990.
The utilisation of satellite imagery is powerful in demarcating urban extents and its skeletal structure. Municipalities are often confronted with the mammoth task of controlling urban sprawl, which is exacerbated by the lack of timely spatial information on urban expansion rates. Satellite imagery can be used to provide accurate and up-to-date geospatial information on the spatial structure and boundaries of cities. Fig. 4 illustrates the urban footprint of Polokwane in Limpopo.
Timely information on urban expansion provided by satellite imagery is vital in ensuring integrated spatial planning and land use management as required by SPLUMA. Classification of the human settlements is useful in identifying vacant land parcels that are suitable for densification of human settlements as required by the NDP goals on human settlements, which are also incorporated in the Gauteng Growth Management Perspective.
Enumerating low-cost housing units
Very high spatial resolution satellite imagery has proven to be an indispensable tool in enumerating low-cost housing units implemented during the Upgrading of Informal Settlement Programme in the North-West Province. A collaborative study between SANSA and the Department of Human Settlements in 2014 demonstrated the value of satellite imagery in tracking and independently validating housing development within 45 municipalities across the country. The study revealed that informal settlements precincts increased by 191 between 2006 and 2011 despite the provision of low-cost housing by the government. It was evident from the study that government required timely and consistent spatial data to track government investment in the provision of low-cost housing and in monitoring the proliferation of informal settlements. Fig. 5 reveals that low-cost housing units are detectable from very high-resolution imagery.
Executing financial audits by municipalities is a challenging task that has to be performed. In 2013, SANSA in partnership with the North-West Department of Local Government and Human Settlements successfully conducted a satellite image-based study to verify the number of completed houses built during the implementation of the Tranche projects which were implemented between 1996 and 2008. The results of this study were used to support financial audits by municipalities during the implementation of the Tranche projects. Fig. 6 shows the transformation of informal settlement around Soshanguve, north of Pretoria between 2006 and 2016. The number of houses were quantified using very high-resolution satellite imagery.
Provision of services and other social amenities
Provision of services such as water, sewerage, electricity, roads and other social amenities is an integral component of all human settlement programmes in South Africa. Satellite imagery provides urban planners with a visual reference useful in optimising transmission routes for water, sewerage, telecommunication and electricity. Fig. 7 illustrates the value of satellite imagery in the planning of basic services such underground water pipes to communities. The image also shows encroachment of human settlements on servitudes.
Conclusion and recommendations
This article highlighted the important role that data and geospatial information derived from high resolution satellite-based remote sensing can play to support spatially explicit land use planning and management. Specific remote sensing applications have been presented to highlight the consistency that should be systematically devised in assessing human settlements at city level. The article has illustrated how remote sensing plays a central role in the implementation of the spatial elements of key legislative interventions such as SPLUMA and its contribution to the NDP.
The brief has shown that urban planners can monitor urbanisation growth rates, identify a suitable site for human settlements, conduct inventory dwelling units, map informal settlements and independently track government investment in the provision of low-cost houses using information derived from remotely sensed satellite imagery.
It is recommended that urban planners should integrate satellite technologies with other spatially orientated geographical information systems to track land use changes at an appropriate scale to meet the human settlements and urbanisation goals highlighted in the NDP.
It is also strongly recommended that satellite earth observation data should be used in conjunction with other socio-economic and environmental datasets, to improve key national regulations in particular the environmental impacts assessment (EIA) regulation of the National Environmental Management Act.
Whereas geospatial information is integral to urban planning, it is recommended that government should increasingly place emphasis on the use of remote sensing technology to fully exploit the underlying benefits that can be derived from satellite imaging technologies and spatial intelligence. This calls for a coordinated national programme to increase remote sensing skills and continue investment in high resolution space-borne imaging systems and advanced image processing capability.
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Contact Ndleleni Boyilane, SANSA, Tel 012 844-0321, firstname.lastname@example.org