Abstract

Geospatial technologies play an important role in understanding and monitoring of land cover and land use change which is critical in achieving Sustainable Development Goal (SDG) 11 and related goals. In this study, we assessed SDG Indicator 11.3.1, Ratio of Land Consumption Rate to Population Growth Rate (LCRPGR) and other urban growth trends of four cities in South Africa using Landsat 5 TM and SPOT 2&5 satellite images and census data collected in 1996, 2001 and 2011. The 2011 built-up areas were mapped using South Africa’s SPOT 5 Global Human Settlements Layer (GHSL) system whereas the 1996 and 2001 built-up areas were extracted from Landsat 5 and SPOT 2 satellite imagery using a kNN object-based image analysis technique that uses textural and radiometric features. We used the built-up area layer to calculate the land consumption per capita and total urban change for each city, both of which have been identified as being important explanatory indicators for the ratio of LCRPGR. The assessment shows that the two major cities, Johannesburg and Tshwane, recorded a decline in the ratio of LCRPGR between the periods 1996–2001 and 2001–2011. In contrast, the LCRPGR ratios for secondary cities, Polokwane and Rustenburg increased during the same periods. The results further show that Tshwane recorded an increase in land consumption per capita between 1996 and 2001 followed by a decrease between 2001 and 2011. Over the same time, Johannesburg experienced a gradual decrease in land consumption per capita. On the other hand, Polokwane and Rustenburg recorded a unique growth trend, in which the overall increase in LCRPGR was accompanied by a decrease in land consumption per capita. In terms of land consumption, Tshwane experienced the highest urban growth rate between 1996 and 2001, whereas Johannesburg and Polokwane experienced the highest urban growth rates between 2001 and 2011. The information derived in this study shows the significance of Indicator 11.3.1 in understanding the urbanization trends in cities of different sizes in South Africa and creates a baseline for nationwide assessment of SDG 11.3.1.

Highlights

  • In 2015, world leaders adopted the 2030 Agenda for Sustainable Development, which included 17 Sustainable Development Goals (SDGs) aimed at ending poverty, hunger and inequality, taking action on climate change and the environment, improving access to health and education, building strong institutions and partnerships, among other actions [1]

  • This is evident through availability of global datasets such as the Global Human Settlement Layer (GHSL) developed and maintained by European Commission’s Joint Research Centre [12], the Global Urban Footprint (GUF) developed and maintained by Deutsches Zentrum für Luft- und Raumfahrt (DLR) [13], and the Atlas of Urban Expansion, developed by New York University [14]

  • This study assessed the ratio of land consumption rate to population growth rate (LCRPGR) and other associated urban growth trends in four cities in South Africa, comprising two major cities (Johannesburg and Tshwane) and two secondary cities (Rustenburg and Polokwane) using Landsat 5

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Summary

Introduction

In 2015, world leaders adopted the 2030 Agenda for Sustainable Development, which included 17 Sustainable Development Goals (SDGs) aimed at ending poverty, hunger and inequality, taking action on climate change and the environment, improving access to health and education, building strong institutions and partnerships, among other actions [1]. The availability of free and open earth observation data, robust algorithms and high performance computing systems are contributing to initiatives aimed at mapping and assessing human settlements or urban growth patterns at a global level. This is evident through availability of global datasets such as the Global Human Settlement Layer (GHSL) developed and maintained by European Commission’s Joint Research Centre [12], the Global Urban Footprint (GUF) developed and maintained by Deutsches Zentrum für Luft- und Raumfahrt (DLR) [13], and the Atlas of Urban Expansion, developed by New York University [14]. This study assessed the ratio of land consumption rate to population growth rate (LCRPGR) and other associated urban growth trends in four cities in South Africa, comprising two major cities (Johannesburg and Tshwane) and two secondary cities (Rustenburg and Polokwane) using Landsat 5

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City Definition Approach
Matching Population to Urban Areas
Results and Discussion
Image Classification
Urban Expansion and Population Growth Trends
Ratio of Land Consumption Rate to Population Growth Rate

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