An Object-Based Classification and Fragmentation Analysis of Land Use and Cover Change in the Keiskamma Catchment, Eastern Cape, South Africa (original) (raw)
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2018
Countries around the world are faced with land use and land cover (LULC) change due to various factors such as rapid population growth, increased demand for agricultural productivity, and change in climatic characteristics. Land cover change needs to be addressed through monitoring and management. Automated geographical analysis offers a powerful tool for monitoring and detecting LULC change over time and space. This study was conducted to assess LULC in the northern Keiskamma catchment of the Eastern Cape Province of South Africa. The study specifically aimed to quantify LULC dynamics in the area using Landsat imagery between the years 2000 and 2016. Five images were acquired at an interval of approximately four years. Six land cover classes were generated by classifying the multispectral and normalized difference vegetation indices (NDVIs) of each image using an unsupervised classification technique. Accuracy assessment of the classification based on the latest image was evaluated...
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.
African J. of Economic and Sustainable Development, 2015
Many factors contribute to rapid urban expansion and large-scale land use/land cover (LULC) changes. This paper analyses spatiotemporal patterns of LULC and quantifies landscape structures in the Rustenburg district, South Africa, locus of a platinum mining boom. Using multi-temporal Landsat images from 1973 to 2002, LULC changes are evaluated to derive transition matrices of patterns and rates of change of LULC classes. These matrices are integrated with landscape metrics to assess impacts of LULC changes on landscape fragmentation. Changes in LULC are coincident with expansion of mining; urban and mining categories increase at the expense of cultivated land, woodland and grassland. The landscape becomes highly fragmented with decreases in mean and largest patch size, and increases in patch density. The pre-existing natural land cover, grassland, shows a high degree of fragmentation. To ensure proper landscape planning for resource management, this study has implications for rapidly growing cities and mining regions.
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...
Physics and Chemistry of the Earth, Parts A/B/C, 2017
Land degradation as a result of inappropriate land use practices, such as overgrazing and cultivation on steep slopes, etc. is one of the major global environmental challenges. Specifically, land degradation threatens the productivity and sustainability of the natural environment, agriculture, and most importantly rural economies in most developing countries, particularly the sub-Saharan region. The main aim of this study was therefore, to assess the potential and strength of using the free or readily available Landsat series data in mapping degraded land areas at the King Sabata Dalindyebo local municipality in the Eastern Cape, South Africa (1984e2010). Data analysis was done using a robust non-parametric classification ensemble; Discriminant Analysis (DA). The results show that degraded areas vary over the years. For example, the results show that the year 1994 and 2004 incurred high degradation levels, when compared to the year 1984 and 2010. Moreover, the observed degradation significantly (a ¼ 0.05) varies with soil type. The chromic acrisols have the highest levels of erosion (approx. 80% in 1984), when compared to humic-umbric acrisols (less than 10% for the entire period under study). It can also be observed that considerable part of degradation occurred in the northern part of the municipal district. Overall, the findings of this research underlines the importance and efficacy of multispectral Landsat series data-set in mapping and monitoring levels of land degradation in data-scarce catchments.
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...
Woodlands and savannahs provide essential ecosystem functions and services to communities. On the African continent, they are widely utilized and converted to subsistence and intensive agriculture or urbanized. This study investigates changes in land cover over four administrative regions of North Eastern Namibia within the Kalahari woodland savannah biome, covering a total of 107,994 km 2. Land cover is mapped using multi-sensor Landsat imagery at decadal intervals from 1975 to 2014, with a post-classification change detection method. The dominant change observed was a reduction in the area of woodland savannah due to the expansion of agriculture, primarily in the form of small-scale cereal and pastoral production. More specifically, woodland savannah area decreased from 90% of the study area in 1975 to 83% in 2004, and then increased to 86% in 2014, while agricultural land increased from 6% to 12% between 1975 and 2014. We assess land cover changes in relation to towns, villages, rivers and roads and find most changes occurred in proximity to these. In addition, we find that most land cover changes occur within land designated as communally held, followed by state protected land. With widespread changes occurring across the African continent, this study provides important data for understanding drivers of change in the region and their impacts on the distribution of woodland savannahs.
South African Journal of Geomatics
The Jukskei River catchment is one of the urban catchments in the central part of Gauteng province covering a large part of City of Johannesburg Metropolitan Municipality and small part of Tshwane and Ekurhuleni Metropolitan Municipalities that have witnessed tremendous land use/land cover (LULC) change over time. Jukskei River catchment is one of the fastest growing catchments in terms of population and change in LULC over time. Therefore, it is very important to detect the nature and extent of these changes in order to identify the direction and future expansion of LULC within the catchment area. To accomplish that, multi-temporal satellite remotely sensed data acquired from Landsat-5 Thematic Mapper (TM) 1987, Landsat-5 Thematic Mapper (TM) 2001 and Landsat-8 Operational Land imager (OLI) 2015 were used to detect LULC change in Jukskei River catchment area. The Jukskei River catchment was classified into four major LULC classes including: Built-up area, bare surface, sparse veget...
Land Degradation & Development, 2019
Vegetation degradation has been identified as a serious environmental problem, around the communal villages of South Africa. An investigation of the relationship between vegetation condition and local grazing management systems was undertaken across the communal villages of the central Keiskamma Catchment, Eastern Cape Province. The hypothesis that "differences in grazing management strategies may explain the variations in vegetation condition within these communal villages" was tested. Landsat TM imagery of 1984 and 1999, in conjunction with SPOT-4 imagery of 2011, was used to assess the spatial and temporal trends in vegetation. Structured interviews were administered among communal village authorities to obtain information regarding the functionality of local grazing management structures. Using the logistic regression in IDRISI Selva remote sensing software, relationships between vegetation condition and grazing management systems were analysed. Spatial and temporal trends in vegetation cover revealed a drastic reduction in fair vegetation, an increase in extremely degraded vegetation and bare/eroded surfaces, particularly in villages with ineffective rangeland management practices. The hypothesis was accepted; a distinct relationship between the respective grazing practices and vegetation condition was identified. Variations in the functionality of local grazing management structures in the communal villages account for the vegetation condition disparities observed. A revitalisation of these structures is key in vegetation restoration endeavours.
Advances in Science, Technology and Engineering Systems Journal
The study revealed that the catchment has undergone drastic modifications in land use/cover in the past four decades. The results showed that agriculture, barren land, and built-up increased by 0.09 %, 63.95 %, and 34.19 %, while vegetation and water bodies drastically declined by 45.88 % and 60 % respectively. In conclusion, the Klip river catchment is at high risk of continuous flooding because of the rapid decrease in natural vegetation and water bodies. Therefore, the study recommends that government should give a greater focus on protecting, preserving, and regenerating natural vegetation as well as water bodies. This information will be useful to planners and policymakers in the planning and development of land use management strategies needed to reduce flooding in the study area.