Remote sensing land-cover change in Port Elizabeth during South Africa’s democratic transition

John Odindi,Paidamwoyo Mhangara,Vincent Kakembo

doi:10.4102/sajs.v108i5/6.886

Abstract

Urban population increase has caused significant urban landscape transformation globally. Before 1994, South Africa’s highly regulated urban growth was shaped by the restrictive Prevention of Illegal Squatters Act of 1951. After the abolishment of the act in the 1980s, the period of transition to democracy in the 1990s was characterised by an unprecedented urban population influx that caused a myriad of socio-economic and environmental challenges. These challenges have consequently compounded the need to monitor urban growth for the planning and optimisation of urban spaces. The limitations of traditional mapping methods, such as surveying and photogrammetry, in urban mapping are well documented. In the recent past, satellite remote sensing has emerged as one of the most viable urban mapping tools. Using post-classification comparisons, we sought to monitor major land use and land cover (LULC) changes in the city of Port Elizabeth during South Africa’s democratic transition (1990–2000). Images for 1990, 1995 and 2000 were acquired, geo-rectified and atmospherically corrected. An iterative self-organising data analysis (ISODATA) was then used to generate existing LULCs. Classes generated using ISODATA were then amalgamated to the city’s major LULCs and resultant classes were validated using aerial photographs and field visits. Results showed that ‘Built-up’ and ‘Bare surface’ LULC classes had the highest increase and decrease, respectively. There was no change in the ‘Beach or dune’ LULC, whereas ‘Green vegetation’ and ‘Water’ classes had minimal changes. This study illustrates the efficacy of remote sensing in monitoring urban change and the potential of remote sensing to aid decision-making in rapidly changing urban landscapes.

Highlights

There have recently been unprecedented increases in the concentration of the population in cities, which have led to rapid urban landscape transformations
From 1991 to 1996, the population of Black South Africans in urban areas increased by about 27%15 and South Africa’s urban population grew by 4.3% to 56% between 1996 and 2001.17
Like many other urban areas in South Africa, the dynamic urban landscape is directly attributed to pre-1994 laws and the new government’s policies on the provision of social and physical infrastructure

Summary

Introduction

There have recently been unprecedented increases in the concentration of the population in cities, which have led to rapid urban landscape transformations. These transformations are often characterised by diverse biophysical and socio-economic processes related to the conversion of nonurban to urban lands and the resultant landscape heterogeneity.[1,2,3] Recent studies have shown that over 50% of the global human population resides in urban areas.[4,5] According to Montgomery and Hewett[6], the highest rates of urbanisation and its related spatial landscape changes are expected in developing countries. In sub-Saharan Africa for instance, urban population grew from 15% in the 1950s to 32% in the 1990s. By 2030 it is projected that 54% – 60% of the subSaharan population will live in urban areas.[5]

Objectives

Methods

Conclusion