Dynamics of land use/cover changes and landscape fragmentation analysis in Rustenburg area, South Africa (original) (raw)
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Land-use/Cover Mapping and Change Detection in the Rustenburg Mining Region using Landsat Images
IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium, 2008
Several decades of intensive mining have taken place in the Rustenburg region, located in the North West Province of South Africa. The platinum boom of the late 90s has seen new surface and underground operations opening up in this area. To assess land-use/cover and environmental impacts, remotely sensed data in the form of Landsat images were analysed. The post-classification change detection method was used to detect landuse/cover changes in the various images. Landsat ETM + 2002 was used as the reference image. Significant and extensive changes in the land-use/cover patterns occurred in the last three decades: vegetation has undergone a general decrease, and woodland and grassland have been changed to cultivated land. Open mining areas increased due to expansion of mining activities. High urban expansion due to influx of job seekers has lead to an increase in the built up area, formal and informal. Consequently, the landscape became highly disturbed due to increased mining, agriculture and urban development.
South African Journal of Science
Rural landscapes in South Africa experience high conversion rates due to intense land use; however, the changes are site specific and depend on the socio-economic and political history of the area. Land cover change (LCC) was assessed in response to socio-economic and political factors in uThukela Municipal District, KwaZulu-Natal, using Landsat imagery from 1984 to 2014, while making comparisons to other studies in South Africa. Socio-economic/political data were used to gain insights into the observed LCC patterns. Land cover was classified using a random forest classifier, and accuracies ranging from 87% to 92% were achieved. Systematic and intensity analysis methods were used to describe patterns, rates, and transitions of LCC in Imbabazane (ILM) and Okhahlamba (OLM) local municipalities. The results showed a reduced rate of change intensity from 3.4% to 0.9% in ILM and from 3.1% to 1.1% in OLM between 1984 and 2014. Grassland was persistent, covering over 70% in both local muni...
2012
Land use/cover trends in the Keiskamma catchment were investigated using Multi-temporal Landsat satellite imagery from 1972 to 2006. Object-oriented post-classification comparison and fragmentation analyses were performed; and the Landscape-Function analysis was used to assess the current rangeland condition of proximal hillslopes and the riparian zone. Temporal land use/cover analyses revealed that intact vegetation has undergone a significant decline from 1972 to 2006. Increases in degraded vegetation and fragmentation, as well as in bare eroded soil, were identified - particularly in the communal villages of the central Keiskamma catchment. The Landscape Organisation Index revealed very low vegetation connectivity in the communal rangelands that have weak local traditional institutions. Fragmentation analyses on the riparian and proximal hillslopes revealed evidence of increasing vegetation fragmentation from 1972 to 2006. Given the worsening degradation trends in the communal ar...
Geosciences, 2017
Land cover change analysis was performed for three catchments in the rural Eastern Cape, South Africa, for two time steps (2000 and 2014), to characterize landscape conversion trajectories for sustained landscape health. Land cover maps were derived: (1) from existing data (2000); and (2) through object-based image analysis (2014) of Landsat 8 imagery. Land cover change analysis was facilitated using land cover labels developed to identify landscape change trajectories. Land cover labels assigned to each intersection of the land cover maps at the two time steps provide a thematic representation of the spatial distribution of change. While land use patterns are characterized by high persistence (77%), the expansion of urban areas and agriculture has occurred predominantly at the expense of grassland. The persistence and intensification of natural or invaded wooded areas were identified as a degradation gradient within the landscape, which amounted to almost 10% of the study area. The challenge remains to determine significant signals in the landscape that are not artefacts of error in the underlying input data or scale of analysis. Systematic change analysis and accurate uncertainty reporting can potentially address these issues to produce authentic output for further modelling.
Simple algebraic change detection techniques viz. image difference and image ratio were applied to the South African national land use / cover (NLC) datasets of years 2000 and 2014, prepared in grid format covering the Klerksdorp-Orkney-Stilfontein-Hartebeestfontein (KOSH) region in order to assess land use/land cover changes. Both the 2000 and 2014 NLC datasets were generated from Landsat images using different classification schemes and the code values & attributes of the land cover classes of the two datasets were different/not comparable. In order to make these datasets comparable for change detection, the NLC2000 dataset was examined in ArcView GIS by superimposing it onto the NLC2014 dataset and similarities and differences were identified. For each cover type of the NLC2000 dataset, comparable cover type of the 2014 dataset was identified by making a query to the NLC2000 dataset and after viewing the spatial distributions of selected units in respect of the NLC2014 dataset. Suitable code values of NLC2014 dataset were identified for the NLC2000 dataset and it was later reclassified. The land use / cover change detection study reveals that increase in areas were observed for the cover types: Cultivated common fields (low), Cultivated common fields (med), Mines 2 semi-bare, Wetlands, Urban commercial and Plantations/woodlots mature. The Grassland, Thicket/dense bush, Urban residential (dense trees/bush), Mines 1 bare, and Cultivated common pivots (high) showed a decrease in places. During the 14 years, Grassland had decreased from 2,132.47 km2 (77.35% of the total area) to 1,629.78 km2 (59.11% of the total area) owing to landscape transformation to other land covers (e.g. Cultivated common fields and Urban residential) due to human activities. The percentage increase in areas observed for the Cultivated common fields (low and medium) were 8.21% and 2.96% while the Mines 2 semi-bare, Wetlands, Urban commercial, Plantations/woodlots mature showed increases of 0.67%, 0.32%, 0.28% and 0.23% respectively. The area of Thicket/dense bush decreased from 108.15 km2 to 56.71 km2 (change of 1.87%). Maps of land use/land cover changes and statistics obtained for the changed areas are very useful for identifying various changes occurring in different classes and for monitoring land use dynamics.
The South African land reform policy under the democratic government (after 1994) was designed to redress the inequality of land ownership aiming to reverse the land ownership injustice that had occurred in the past era as a deliberate act of policy by the colonial and the apartheid government. This study aimed at investigating the effects of the South African land reform policy on land use and land cover change on a land restitution project in Makotopong, Limpopo province, South Africa. To determine land cover dynamics, 1994 and 2007 Landsat images were used. A maximum likelihood classification for each image was computed for identification of land cover variables. Trends in land cover change depict a decline in post-transfer activities with agricultural cropland decreasing from 78.04 ha in 1994 to 20.43 ha in 2007. Inadvertently, land under fallow and shrubs increased by 6% and 30%, respectively. This accelerated decline of agricultural activity is mainly attributable to change of land ownership and management skills from the commercial farmers to the inexperienced land claimants. Results suggest that quantification of the changes in land use and land cover types can be very useful in assessing environmental and social condition of the land reform project. The study recommends that spatial data analysis through remote sensing procedures should form the information base in monitoring and evaluating the land reform projects to ensure productivity and management.
Environmental Monitoring and Assessment
In semi-arid regions, interactions between biophysical and socio-economic variables are complex. Such interactions and their respective variables significantly alter land use and land cover, degrade landscape’s structure, and impede the efficacy of the adopted land management interventions. This scenario is particularly prevalent in communal land tenure system or areas managed by a hybrid of traditional and state led institutions. Hence, this study sought to investigate the impacts of land use and land cover changes (LULCCs) on land degradation (LD) under communal rural districts, and the key drivers of habitat fragmentation in the Greater Sekhukhune District Municipality (GSDM), South Africa. The study used the wet and dry season multi-temporal remotely sensed image data, key-informant interviews, and workshop with tribal council to determine the major drivers of LULCC and LD. Results revealed that mines and quarries, subsistence and commercial cultivation, and thicket/dense bush L...
The Race for Space: Tracking Land-Cover Transformation in a Socio-ecological Landscape, South Africa
Environmental Management, 2013
Biosphere Reserves attempt to align existing biodiversity conservation with sustainable resource use, specifically for improving socioeconomic circumstances of resident communities. Typically, the Biosphere Reserve model is applied to an established landscape mosaic of existing land uses; these are often socio-ecological systems where strict environmental protection and community livelihoods are in conflict, and environmental degradation frequently accompanies ''use''. This raises challenges for successful implementation of the model, as the reality of the existing land-use mosaic undermines the theoretical aspirations of the Biosphere concept. This study focuses on the Kruger to Canyons Biosphere Reserve (K2C), South Africa; a socio-ecological landscape where formal conservation is juxtaposed against extensive impoverished rural communities. We focus on land-cover changes of the existing land-use mosaic (1993-2006), specifically selected land-cover classes identified as important for biodiversity conservation and local-level resource utilization. We discuss the implications of transformation for conservation, sustainable resource-use, and K2C's functioning as a ''Biosphere Reserve''. Spatially, changes radiated outward from the settlement expanse, with little regard for the theoretical land-use zonation of the Biosphere Reserve. Settlement growth tracked transport routes, transforming cohesive areas of communal-use rangelands. Given the interdependencies between the settlement population and local environmental resources, the Impacted Vegetation class expanded accordingly, fragmenting the Intact Vegetation class, and merging rangelands. This has serious implications for sustainability of communal harvesting areas, and further transformation of intact habitat. The distribution and magnitude of Intact Vegetation losses raise concerns around connectivity and edge effects, with longterm consequences for ecological integrity of remnant habitat, and K2C's existing network of protected areas.
After independence, Zimbabwe adopted two major land reform programmes to address the racially skewed land ownership. Due to the perceived failure of these programmes, the country embarked on a highly politicised and forceful acquisition and redistribution of white owned commercial farms under the Fast Track Land Reform Programme (FTLRP). Whereas a large number of Zimbabweans have been allocated land under the programme, there has been a significant decline in agricultural productivity and an increase in degradation of land and associated resources. Popular opinion has even suggested the country's current socioeconomic challenges are linked to the programme. Mitigating land degradation, enhancing agricultural productivity and promoting natural resources sustainability requires an objective understanding and determination landscape transformation within relevant administrative decision making spatial extents. In this study, we adopted multi-temporal remotely sensed imagery to determine landscape transformation after the implementation of the FTLRP in Chipinge administrative district, characterised by heterogeneous land usage and natural resources. Major land-use-land-cover types were determined using the Support Vector Machine classification algorithm and accuracy established using field survey and ancillary data. Results show significant landscape transformation after the implementation of the FTLRP. Specifically, there was a decline in plantations, small farms, water bodies and forests and an increase in bare areas and settlements. This study demonstrates the value of remotely data in monitoring landscape transformation arising from a shift in policy. Furthermore, these results provide an insight into multi-temporal spatial changes in cultivated, natural and degraded lands, valuable for designing measures to improve landscape productivity and to adopt relevant rehabilitation measures. Understanding multi-temporal landscape change within an administrative boundary is particularly valuable for area specific planning, policy formulation and adoption of desired mitigation measures.