Research Articles (Geography and Environmental Studies)

Permanent URI for this collection

https://scholar.sun.ac.za/handle/10019.1/613

Browse

Now showing 1 - 20 of 120

Addressing the need for improved land cover map products for policy support
(Elsevier, 2020-10) Szantoi, Zoltan; Geller, Gary N.; Tsendbazar, Nandin-Erdene; See, Linda; Griffiths, Patrick; Fritz, Steffen; Gong, Peng; Herold, Martin; Morah, Brice; Obregon, Andre
The continued increase of anthropogenic pressure on the Earth’s ecosystems is degrading the natural environment and then decreasing the services it provides to humans. The type, quantity, and quality of many of those services are directly connected to land cover, yet competing demands for land continue to drive rapid land cover change, affecting ecosystem services. Accurate and updated land cover information is thus more important than ever, however, despite its importance, the needs of many users remain only partially attended. A key underlying reason for this is that user needs vary widely, since most current products – and there are many available – are produced for a specific type of end user, for example the climate modelling community. With this in mind we focus on the need for flexible, automated processing approaches that support on-demand, customized land cover products at various scales. Although land cover processing systems are gradually evolving in this direction there is much more to do and several important challenges must be addressed, including high quality reference data for training and validation and even better access to satellite data. Here, we 1) present a generic system architecture that we suggest land cover production systems evolve towards, 2) discuss the challenges involved, and 3) propose a step forward. Flexible systems that can generate on-demand products that match users’ specific needs would fundamentally change the relationship between users and land cover products – requiring more government support to make these systems a reality.
Advances in optical earth observation for geological mapping : a Review
(CONSAS Conference, 2016) Ngcofe, Luncedo Dalithemba; Van Niekerk, Adriaan
Recent increases in the availability of earth observation (EO) data and the advances made in its processing have opened up new opportunities for earth monitoring studies. This article reviews recent advances in EO, specifically in the optical domain, and comments on their potential for geological investigations. A review of the literature revealed that much work has been done on the use of multispectral to hyperspectral EO data for geological investigations, but that relatively little emphasis has been placed on the value of high spatial resolution in geological studies. From the literature it was found that geographic object based image analysis (GEOBIA) is a relatively new paradigm in remote sensing that has been shown to reduce the intra-class spectral variability in high spatial resolution imagery, thereby increasing image classification accuracies. It has been used for many applications, but relatively little research has been done on the application of GEOBIA for geological investigations. Another finding of this review is that the power of EO data increases substantially when different types of data are used (fused) together. Data fusion seizes the advantages of the capabilities of each sensor while reducing its limitations. By its nature, GEOBIA offers the ability to fuse disparate data sources and the review concludes that more research is required on the use of GEOBIA and data fusion of high resolution EO data for geological mapping.
An ‘age-regation’ process as theoretical understanding of the gated retirement village
(SUN MeDIA Bloemfontein, 2012-04) Goldhaber, Ravit; Donaldson, Ronnie
Gating the elderly appears to be a common and inevitable part of international urban life. In our study we have used the structure-agency relationship to identify and analyse the salient elements of the process of gating. In order to emphasise the dichotomy of the process in which aging people congregate together and, simultaneously, segregate themselves from urban life, we coined the term “age-regation”. We provide a comprehensive and logically structured theoretical framework, in which the theoretical bases of the gated retirement village are discussed within two overarching constructs, namely age (identity, lifestyle) and the congregation/segregation enclave (physical, social, psychological, political, economic, mobility, racial).
Aircraft noise management through controlled-area demarcation in South Africa : its application at Cape Town International airport
(Academy of Science for South Africa, 2005) Van der Merwe, J. H.; Von Holdt, D. S.
Aircraft noise is a growing social, technical, economic and environmental problem, especially in developing countries like South Africa. It arises from the growth in air traffic, urbanization, uncoordinated planning around airports, and open-window living that makes physical insulation an ineffective mitigating solution. Cape Town International airport is a typical South African example of the phenomenon. Air traffic volume is steadily increasing and an additional runway has been proposed for the airport's efficient operation. The changing noise pattern requires the demarcation of a 'noise-controlled area' around the airport as the planning framework that is legally prescribed to manage this type of environmental nuisance. This paper reports the application of geographic Information system (GIS) technology to define a control zone using various spatial demarcation techniques. Each alternative zone has different spatial characteristics that define and incorporate the adjacent residential communities affected as well as vulnerable land in the vicinity. An aircraft noise generation model was used to map noise intensity contours. Different spatial noise footprints for six optional demarcation criteria were used to identify affected areas around the airport. The GIS methods were then compared and evaluated to select the optimum planning approach under South African conditions.
Ants, altitude and change in the northern Cape Floristic Region
(Blackwell publishing Ltd, 2006) Botes, A.; McGeoch, M. A.; Robertson, H. G.; Van Niekerk, Adriaan; Davids, H. P.; Chown, S. L.; 0000-0002-5631-0206
Aim: Climate-modelling exercises have demonstrated that the Cape Floristic Region is highly sensitive to climate change and will apparently lose much of its northern limits over the next few decades. Because there is little monitoring of diversity in this area, ant assemblage structure was investigated within the main vegetation types in the Greater Cederberg Biodiversity Corridor. In particular, we sought to determine how ant assemblage structure differs between the main vegetation types, how restricted ants – and in particular the major myrmecochores – are to the major vegetation types, and which environmental variables might underlie differences in the ant assemblages and in the specificity of species to particular areas. Location: Northern Cape Floristic Region, Western Cape, South Africa. Methods: Sampling was undertaken during October 2002 and March 2003 across an altitudinal gradient ranging from sea level (Lambert’s Bay) to c. 2000 m a.s.l. (Sneeukop, Cederberg) and down again to 500 m a.s.l. (Wupperthal) in the Western Cape, South Africa. Pitfall traps were used to sample ants at 17 altitudinal bands, stretching over three vegetation types (Strandveld, Mountain Fynbos and Succulent Karoo). Biotic and abiotic environmental variables were collected at each sampling site. Generalized linear models were used to determine the relationships between species richness, density, abundance and the abundance of the major myrmecochores, and the environmental variables. Redundancy analysis was used to determine the relationship between ant assemblage structure and the environmental variables. The Indicator Value Method was used to identify characteristic ant species for each vegetation type and altitudinal site. Results: Temperature explained significant proportions of the variation in species density and abundance, and, together with area and several vegetation variables, contributed significantly to the separation of the assemblages in the major vegetation types and biomes. Four major myrmecochores were identified [Anoplolepis sp. (cf. custodiens), Anoplolepis sp. (cf. steinergroeveri), Camponotus niveosetosus, Tetramorium quadrispinosum]. The abundances of the two Anoplolepis species were related to vegetation variables, while the abundance of the other two species showed opposite relationships with temperature variables. Fourteen ant species were characteristic of certain vegetation types and altitudes. Several of these species contributed to the differences between the assemblages. Main conclusions: There are likely to be substantial and complex changes to ant assemblages as climates change in the northern Cape Floristic Region. Moreover, the importance of ants for ecosystem functioning suggests that these responses are not only likely to be a response solely to vegetation changes, but might also precipitate vegetation changes. The changes that are predicted to take place in the next 50 years in the Cape Floristic Region could be substantially exacerbated by such synergistic effects, which have major implications for long-term conservation plans. Ongoing monitoring of this transect will reveal the nature and pace of the change as it unfolds.
The application of an Urban Sprawl Index : comparing towns and cities in the Western Cape Province, South Africa
(CONSAS, 2018) Horn, Anele; Van Eeden, Amanda
The incidence and effects of urban sprawl have been the subject of a great many academic research mainly as a result of the challenges posed by continued urbanisation, especially in developing countries (see inter alia Jenks, Kozak and Takkanon 2008; Mander, Brebbia and Tiezzi 2006; Jenks and Burgess 2000; and Soja 2000). South Africa witnessed a proliferation of legislation and spatial policies to limit urban sprawl and contain the physical expansion and development of urban areas during the last two decades in response to exponential post-apartheid urbanization. In 2005, the Provincial Spatial Development Framework of the Western Cape Province, South Africa stated that “an Urban Edge shall be drawn around all villages, towns and cities in the province with the primary function to contain outward growth of urban settlements” (City of Cape Town, 2009) and in parallel the Provincial Department of Environmental Affairs and Development Planning published the Western Cape Urban Edge Guideline document assisting all municipalities in the province to delineate urban edges to be included in municipal Spatial Development Frameworks (SDF) thereby illustrating intent on maintaining urban footprints that are compact and limit developments that could be considered urban sprawl. Subsequently municipal urban edges have been delineated and are presently reflected in most municipal Spatial Development Frameworks in the province. This paper presents an Urban Sprawl Index as a tool to comparatively analyse the extent of urban sprawl between cities and towns of different sizes, making use of cadastre, land use and population data over time. The Urban Sprawl Index (USI) for the Western Cape put forward by this research will enable the comparative measurement of the extent of urban sprawl proportionately between the Metropolitan and local municipalities in the province and thereby aid in understanding the impact of planning instruments such as urban edges in the context of development dynamics and pressures experienced by individual cities.
Application of geospatial technology for gap analysis in tourism planning for the Western Cape
(Academy of Science of South Africa, 2013) Van der Merwe, Johannes H.; Van Niekerk, Adriaan
ENGLISH ABSTRACT: We report on the use of modern spatial computing technology in the development of spatial tourism policy and planning in the context of a bounded resource base. We refer briefly to provincial tourism development policy, expand on the tourism marketing framework and use the express tourist preferences to determine suitability indicators or attraction features for a spatial tourism resource base, paying special attention to the conceptual foundations of attraction and the mapping of tourism potential variables. We applied the methodology to a combination of tourism products in the Western Cape Province of South Africa in an approach that involved applying the spatial multiple criteria evaluation through the weighted linear combination of spatial factor layers as images in a geographical information system. We performed an analysis of the gap between tourism potential and tourism resource provision at a spatial resolution of individual towns’ spheres of influence, as represented by Thiessen polygons. The outcome in map format demonstrates the applicability of the technique to the Western Cape. The fine-scale spatial result was analysed for its strategic planning implications. Our results are useful for entrepreneurial and regulatory planning and can be replicated in different spatial locations if the appropriate database can be constructed.
Applying the water-energy-food nexus to farm profitability in the Middle Breede catchment, South Africa
(Academy of Science of South Africa, 2018) Seeliger, Leanne; De Clercq, Willem P.; Hoffman, Willem; Cullis, James D. S.; Horn, Annabel M.; De Witt, Marlene
The water-energy-food nexus has emerged as a useful concept to understand the multiple interdependencies that exist between the water, energy and food sectors. The nexus is an ambitious attempt to work across disciplines and scales to understand the workings of these complex systems. It is, however, criticised for being more of a general framework than a practical methodology because of the vast amount of data it would need to make real-life contributions to sustainable development. We show how the nexus approach, when used within a farm budget model, can transform the problem focus in water governance. By changing the relationship among water, energy and food production of a farm, profitability is significantly changed. The water-energy-food nexus debate is discussed within the context of the South African water sector, particularly the Breede River Catchment. Working from within the farm budget model, we demonstrate the impact of moving from an irrigation canal system that requires electricity for pumping, to a gravity-fed piped irrigation system in the Middle Breede River. The finding is that the water-energy-food nexus has the potential to unlock groundbreaking solutions to complex problems in agricultural water management when used in appropriate modelling systems.
Architecture in Southern African informal settlements : a contextually appropriate intervention
(Urbanistični inštitut RS, 2019) Perold, Rudolf; Donaldson, Ronnie; Devisch, Oswald
Architectural professionals can contribute to efforts at achieving sustainable urbanism. However, the realm of professional discourse is extremely limited. Grounded architectural practice (GAP) is developed as a conceptual framework to explore an emergent form of contextually appropriate architectural practice in the context of a resident-driven in situ informal settlement upgrading project. The exploration takes the form of a descriptive narrative. Each challenge that arose during the descriptive narrative was mapped according to Engeström’s activity system model, an analytical tool emanating from cultural-historical activity theory (CHAT). By participating in live projects in informal settlements and analysing these projects by means of CHAT, the authors explored the highly improvising and generative everyday practices of the urban majority. Architectural practice in such a context requires a multi-disciplinary approach which extends beyond conventional professional boundaries, and attention must be paid to building the capacity of all participants to function in such uncharted territory.
Are the walls giving way to fences? Is racial integration within Kwadukuza municipality leading to income-based class segregation?
(CONSAS, 2017-10) Singh, Vishanth; Van Eeden, Amanda
The racial and development imbalances created by apartheid have made a profound impact on the urban and social landscape in South Africa. Despite it being 20 years into the dawn of a new South Africa, many parts of society are still bearing the brunt of the harsh impacts of apartheid. The first democratic elections in 1994 heralded a new era of hope and optimism for a better life in a racially integrated country. However 20 years into democracy, it is essential to monitor changes in integration. Literature suggests that, in the absence of legally enforced segregation as with apartheid, society will segregate itself on class or other factors. The purpose of this study is to measure whether the changes in racial integration are leading to class-based segregation in KwaDukuza, South Africa. The Neighbourhood Diversity Index was used to investigate how the racial patterns changed over the years and a Geographic Weighted Regression (GWR) model was used to determine if there is a relationship between racial integration and income that could explain transference from racial to classed-based segregation. The study found that low levels of racial integration have taken place but certain areas of the municipality have become increasingly segregated. The GWR model found a positive relationship between income and racial segregation in certain areas. This study further highlights that politicians, decision makers, and town and social planners face a long and socially demanding challenge in redressing past imbalances and promoting integration by breaking down the current trend of class-based segregation.
Assessing the influence of DEM source on derived streamline and catchment boundary accuracy
(South African Water Research Commission, 2019) Mashimbye, Zama Eric; De Clercq, Willem Petrus; Van Niekerk, Adriaan
Accurate DEM-derived streamlines and catchment boundaries are essential for hydrological modelling. Due to the popularity of hydrological parameters derived mainly from free DEMs, it is essential to investigate the accuracy of these parameters. This study compared the spatial accuracy of streamlines and catchment boundaries derived from available digital elevation models in South Africa. Two versions of Stellenbosch University DEMs (SUDEM5 and DEMSA2), the second version of the 30 m advanced spaceborne thermal emission and reflection radiometer global digital elevation model (ASTER GDEM2), the 30 and 90 m shuttle radar topography mission (SRTM30 and SRTM90 DEM), and the 90 m Water Research Commission DEM (WRC DEM) were considered. As a reference, a 1 m GEOEYE DEM was generated from GeoEye stereo images. Catchment boundaries and streamlines were extracted from the DEMs using the Arc Hydro module. A reference catchment boundary was generated from the GEOEYE DEM and verified during field visits. Reference streamlines were digitised at a scale of 1:10 000 from the 1 m orthorectified GeoEye images. Visual inspection, as well as quantitative measures such as correctness index, mean absolute error, root mean squares error and figure of merit index were used to validate the results. The study affirmed that high resolution (<30 m) DEMs produce more accurate parameters and that DEM source and resampling techniques also play a role. However, if high resolution DEMs are not available, the 30 m SRTM DEM is recommended as its vertical accuracy was relatively high and the quality of the streamlines and catchment boundary was good. In addition, it was found that the novel Euclidean distance-based MAE and RMSE proposed in this study to compare reference and DEM-extracted raster datasets of different resolutions is a more reliable indicator of geometrical accuracy than the correctness and figure of merit indices.
Assessment of accuracy : systematic reduction of training points for maximum likelihood classification and mixture discriminant analysis (Gaussian and t-distribution)
(CONSAS Conference, 2018-09) Ritchie, Michaela; Debba, Pravesh; Luck-Vogel, Melanie; Goodall, Victoria
Remote sensing provides a valuable tool for monitoring land cover across large areas of land. A simple yet popular method for land cover classification is Maximum Likelihood Classification (MLC), which assumes a single normal distribution of the samples per class in the feature space. Mixture Discriminant Analysis (MDA) is a natural extension of MLC which can be used with varying distributions and multiple distributions per class, which simplifies the classification process tremendously. We compare the accuracies of MLC and MDA (using a Gaussian and t-distribution) as the number of training points are systematically reduced in order to simulate varying reference data availability conditions. The results show that the more robust t-distribution MDA performs comparatively with the Gaussian MDA and that both outperform MLC when sufficient training points are available. As the number of training points increases the MDA accuracies increase while the MLC accuracy stagnates. At very low numbers of training samples (ranging from 22 to 169 dependent on the class), there is more variability in terms of which method performs best.
A biodiversity monitoring framework for South Africa : progress and directions
(Academy of Science of South Africa, 2007) Reyers, Belinda; McGeoch, Melodie A.
Global declines in biodiversity, and the associated impacts on human wellbeing, have triggered national and international agreements to reduce or halt these trends. The Convention on Biological Diversity's 2002 commitment, 'to achieve, by 2010, a significant reduction in the current rate of biodiversity loss....', is an often cited example and has caused a flurry of activity in the development of biodiversity monitoring systems. At a national scale, South Africa's National Environmental Management: Biodiversity Act and associated legislation have highlighted the need for a national biodiversity monitoring framework. The National Biodiversity Strategy and Action Plan makes a significant contribution to the development of this framework. As South Africa begins to implement the action plan, a review of existing national monitoring programmes in terms of global and national biodiversity monitoring requirements is important. This paper presents the results of a review of these national programmes, to provide a broad overview, assess alignment with national and global requirements, evaluate gaps and discuss a way forward in the devising of a national biodiversity monitoring framework. We find that the National Biodiversity Strategy and Action Plan aligns well with the Convention on Biological Diversity's 2010 target objectives, but differs in terms of the indicators proposed. Existing national biodiversity monitoring programmes also exhibit these indicator differences and show several gaps in indicator development and data collation. These gaps raise concern around the country's ability to report on the Convention on Biological Diversity's 2010 target, but together with the sound platform provided by the National Biodiversity Strategy and Action Plan, provide a good indication of national priorities and a way forward through a combination of short-term achievable tasks and longer-term development of programmes.
Biogeographical patterns of endemic terrestrial Afrotropical birds
(Wiley-Blackwell, 2002) De Klerk, Helen Margaret; Crowe, T. M.; Fjeldsa, J.; Burgess, N. D.
Biogeographical zones are described for terrestrial bird species endemic to the Afrotropics using up-to-date distributional data and multivariate statistical techniques. This provides an objective basis for a hierarchy of subregions, provinces and districts, based on a set of rules. Results are compared to previous studies at continental and regional scales. Biogeographical zones for passerines and non-passerines are compared and found to be similar. Peaks of species richness and narrow endemism are described for the six major subdivisions (subregions) identified by the cluster analysis. Coincidence of peaks of species richness and narrow endemism is found to be low, such that areas selected to represent high species richness tallies will often fail to represent narrow endemics. Strong regionalization of Afrotropical birds indicates the need to use a biogeographical framework in conservation priority setting exercises to ensure that unique, but species-poor, avifaunas are not neglected.
Business clustering along the M1-N3-N1 corridor between Johannesburg and Pretoria, South Africa
(CONSAS Conference, 2016) Pillay, Xaven; Geyer, H. S.
As a communication axis between Pretoria and Johannesburg the Old Pretoria Main Road always served as a linear force of attraction of urban development. This force was subsequently strengthened, first by the construction of the M1 and N1 motorways and later by the N3. Anecdotal evidence points to these sections of the motorways being one of the fastest-growing urban corridors in South Africa. Using available aerial photography, together with the information from zoning and cadastral data, footprints of buildings within a 500 metre buffer from the centre line of the corridor were established. These footprints were used to identify 15 areas in which significant clusters of industry, commerce and services occur. A survey, combining different sources of information was subsequently conducted to distinguish between different groups of businesses along the corridor. Based on this information the types and rates of business clustering along these sections of the corridor from 2001 to 2012 were determined.
Catering for large numbers of tourists : the McDonaldization of casual dining in Kruger National Park
(Uniwersytet Mikołaja Kopernika w Toruniu, 2016) Ferreira, Sanette L. A.; Van Zyl, Gesina W.
Since 2002 Kruger National Park (KNP) has subjected to a commercialisation strategy. Regarding income generation, SANParks (1) sees KNP as the goose that lays the golden eggs. As part of SANParks’ commercialisation strategy and in response to providing services that are efficient, predictable and calculable for a large number of tourists, SANParks has allowed well-known branded restaurants to be established in certain rest camps in KNP. This innovation has raised a range of different concerns and opinions among the public. This paper investigates the what and the where of casual dining experiences in KNP; describes how the catering services have evolved over the last 70 years; and evaluates current visitor perceptions of the introduction of franchised restaurants in the park. The main research instrument was a questionnaire survey. Survey findings confirmed that restaurant managers, park managers and visitors recognise franchised restaurants as positive contributors to the unique KNP experience. Park managers appraised the franchised restaurants as mechanisms for funding conservation.
Change detection of bare areas in the Xolobeni region, South Africa using Landsat NDVI
(CONSAS Conference, 2015-06) Kemp, Jaco; Singh, Rebekah Gereldene; Engelbrecht, Jeanine
Identification and protection of areas that are vulnerable to erosion is essential for the conservation of the sensitive wetlands and estuarine ecosystems along the Xolobeni coastal strip. The forecasting of these erosion susceptible areas requires an understanding of the inter- relationships of the critical factors that have influenced erosion potential over time. Vegetation and bare areas are some of the contributing factors that have influenced erosion at Xolobeni. This study used remote sensing as a tool to provide some information on the inter-relationship between vegetated classes and bare areas. Normalised Difference Vegetation Index (NDVI) data derived from multi-temporal Landsat 5 imagery has formed the baseline information for this study. A density slicing approach was adopted to classify the region into four vegetation structure classes of predominant land cover types. Post classification change detection data has provided an understanding of the relative susceptibility of the different vegetated classes to being degraded to bare areas. The results suggest that poorly vegetated regions were most susceptible to further degradation and an elevated susceptibility to erosion. On the other hand, moderately and densely vegetated regions were less susceptible to land degradation. The information can be used to identify measures to mitigate the effects of land degradation in vulnerable areas.
Characteristics of zircon in placer deposits along the west coast of South Africa
(Academy of Science for South Africa, 1999) Philander, C.; Rozendaal, A.; De Meijer, R. J.
Mining along the west coast of South Africa is dominated by the exploitation of onshore and offshore diamond deposits. The relatively recent discovery of vast resources of heavy minerals in the area has resulted in the establishment of a major related industry. Today, Namakwa Sands is a 10-million-ton-per-year operation and significant producer of ilmenite, zircon and ruffle by world standards. Heavy minerals are widely distributed along the entire west coast and are mainly concentrated in Mesozoic fluvial, Cainozoic marine and Recent aeolian unconsolidated placers. Basement rocks form part of the middle to late Proterozoic Namaqualand Metamorphic Complex, Gariep Group and Palaeozoic Cape Supergroup. Their diverse lithologies are the source of the younger heavy-mineral concentrations. The present study focuses on the characteristics of zircon (ZrSiO4), the mineral with the highest intrinsic value of the entire heavy-mineral suite. Both the heavy-mineral fraction and zircon concentrates of a representative suite of samples along the west coast were investigated using analytical techniques that included: transmitted/reflected light microscopy, electron microprobe mineral analysis, ICP for rare earth element analyses, PIXE for single-grain analyses and cathodoluminescence. Their radiometric characteristics were determined using a hyper-pure germanium detector. All samples studied comprised a heterogeneous population of zircon grains with diverse physico-chemical properties. This was expressed by large differences in colour and trace element chemistry of single grains. The percentage of grains hosting inclusions, such as ilmenite, magnetite, monazite, quartz and fluids, varied for each sample. Zoned, metamict and grains with overgrowths and replacement textures contributed to the diverse characteristics of zircon samples. Concentrations of the various grain types differed among samples and contributed to the unique character of each population. Bulk chemistry and radiometric signature support this observation. This variation depends on the composition of the source rock and stage of sedimentological evolution of the sands. A high degree of heterogeneity of the zircon population will adversely affect beneficiation of these mineral deposits. As a result, its quantification is required to optimize mineral recovery.
Characterizing degradation gradients through land cover change analysis in rural Eastern Cape, South Africa
(MDPI, 2017) Munch, Zahn; Okoye, Perpetua I.; Gibson, Lesley; Mantel, Sukhmani; Palmer, Anthony
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.
Climate-based regionalization and inclusion of spectral indices for enhancing transboundary land-use/cover classification using deep learning and machine learning
(MDPI, 2021) Kavhu, Blessing; Mashimbye, Zama Eric; Luvuno, Linda
Accurate land use and cover data are essential for effective land-use planning, hydrological modeling, and policy development. Since the Okavango Delta is a transboundary Ramsar site, managing natural resources within the Okavango Basin is undoubtedly a complex issue. It is often difficult to accurately map land use and cover using remote sensing in heterogeneous landscapes. This study investigates the combined value of climate-based regionalization and integration of spectral bands with spectral indices to enhance the accuracy of multi-temporal land use/cover classification using deep learning and machine learning approaches. Two experiments were set up, the first entailing the integration of spectral bands with spectral indices and the second involving the combined integration of spectral indices and climate-based regionalization based on Koppen–Geiger climate zones. Landsat 5 TM and Landsat 8 OLI images, machine learning classifiers (random forest and extreme gradient boosting), and deep learning (neural network and deep neural network) classifiers were used in this study. Supervised classification using a total of 5140 samples was conducted for the years 1996, 2004, 2013, and 2020. Average overall accuracy and Kappa coefficients were used to validate the results. The study found that the integration of spectral bands with indices improves the accuracy of land use/cover classification using machine learning and deep learning. Post-feature selection combinations yield higher accuracies in comparison to combinations of bands and indices. A combined integration of spectral indices with bands and climate-based regionalization did not significantly improve the accuracy of land use/cover classification consistently for all the classifiers (p < 0.05). However, post-feature selection combinations and climate-based regionalization significantly improved the accuracy for all classifiers investigated in this study. Findings of this study will improve the reliability of land use/cover monitoring in complex heterogeneous TDBs.

Browse

Browsing Research Articles (Geography and Environmental Studies) by Title

Results Per Page

Sort Options