 Subjects -> GEOGRAPHY (Total: 493 journals)
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- Temporal Characterization of Land Use Change and Land-scape Processes in
Informal Settlements in the City of Cape Town, South Africa
Authors: Perpetua I Okoye, Jörg Lalk
Pages: 214 - 235
Abstract: This study conducted a Land Use Change (LUC) analysis on informal settlements in Cape Town, South Africa, using bi-temporal steps, S1 (2010) and S2 (2016), to characterize land use (LU) conversions and landscape processes for informed policymaking. Utilizing the 2011 national land cover dataset and post-classification methods, two LU datasets and maps, D1 for S1 and D2 for S2, were derived. These classifications achieved an overall accuracy exceeding 95%, with Kappa coefficients above 0.9. The analysis employed change trajectories and conversion labels to evaluate LU changes and landscape dynamics, providing a thematic representation of LUC within informal settlements. Landscape reclamation processes, including abandonment, urban development, and RDP (Reconstruction and Development Programme) development, constituted approximately five percent of the total LU conversions, while degradation processes like persistence and intensification dominated, affecting approximately 93% of the area. Partial reclamation, notably through interspersed RDP (RDPi), accounted for about two percent of conversions. These findings highlight the importance of accurate and timely LUC data reporting in informal settlements to address socioeconomic challenges effectively and support policy decisions to enhance these communities' physical and socioeconomic infrastructure.
PubDate: 2024-07-10
DOI: 10.4314/sajg.v13i2.1
Issue No: Vol. 13, No. 2 (2024)
- Error Analysis in Multibeam Hydrographic Survey System
Authors: Basil Daniel Devote
Pages: 236 - 250
Abstract: Hydrographic surveying involves the integration of a depth-measuring sonar (Sound navigation and ranging) with a positioning system or Global Navigation Satellite System (GNSS); a motion sensor or Inertia Measuring Unit (IMU); and an azimuth sensor (gyroscope). The various sensors acquire data in terms of their respective reference frame and time. The challenge lies in integrating the various sensor frames and time, and in transforming the vessel frame coordinate system into a terrestrial reference frame. The integration of the various sensor frames and time is necessary to minimize systematic errors in the bathymetric data that result from latency, and calibration uncertainty. The focus of this research is to model the systematic bias associated with the integration of the various sensor reference frames. In so doing, the quality of the acquired data is enhanced, and error budgeting and uncertainty prediction can be effectively carried out during the preparation, acquisition, and processing stages of the bathymetric exercise. As such, the required project specification and hydrographic standards, as defined by the International Hydrographic Organization (IHO), are met.
PubDate: 2024-07-10
DOI: 10.4314/sajg.v13i2.2
Issue No: Vol. 13, No. 2 (2024)
- Characterising the evolution of the urban form of zones that accommodate
warehousing clusters in the City of Cape Town municipality
Authors: Masilonyane Mokhele, Brian Fisher-Holloway
Pages: 251 - 268
Abstract: Modern economies are characterised by increasing globalisation, e-commerce, and a growing number of logistics facilities. Despite insightful research on the changing locational patterns of logistics facilities epitomised by logistics sprawl, there is a lack of literature analysing changes in the urban form of areas that accommodate warehousing clusters. The paper, therefore, aims to analyse changes in the urban form of zones that accommodate warehousing clusters in the City of Cape Town municipality. The study was based on three main types of secondary data: georeferenced 1:50 000 topographical maps from 1942 to 2010, current and historical spatial planning policy applicable to the City of Cape Town, and historical literature on the spatial economic characteristics of the zones that accommodate warehousing clusters. The topographical maps were loaded onto ArcGIS 3.10, after which large buildings were traced to ascertain changes in the urban form of the warehousing cluster areas over the respective decades. The study found that changes in the urban form of the contemporary warehousing cluster areas were linked to the growth of industrial zones and the transport infrastructure. However, the spatial policy for the time under consideration, although cementing the growth of industrial zones in the municipality, did not explicitly consider the placement of warehousing facilities. In light of the findings, the City of Cape Town municipality is urged to anticipate and plan for the growth of warehousing relative to the industrial zones and transport infrastructure. To ensure efficient and sustainable land utilisation, derelict industrial buildings in accessible areas could be redeveloped to accommodate warehousing facilities.
PubDate: 2024-07-10
DOI: 10.4314/sajg.v13i2.3
Issue No: Vol. 13, No. 2 (2024)
- Classification of 3D Sonar Point Clouds derived Underwater using Machine
and Deep Learning (CANUPO and RandLA-Net) Approaches
Authors: Simiso Ntuli, Mulemwa Akombelwa, Angus Forbes, Mayshree Singh
Pages: 269 - 287
Abstract: The techniques of point cloud classification in aquatic environments have various applications such as landslide hazard mapping, recovery of lost objects, underwater infrastructure inspection, exploration of mineral resources on the seabed, underwater cultural heritage documentation, environmental preservation and conservation purposes. This study combines acoustic (Sonar) and laser-based (Lidar) remote sensing technologies in an aquatic environment with two machine and deep learning approaches to illustrate the techniques to identify submerged objects. Firstly, the relative accuracy of the underwater imaging system, the BlueView BV5000 Mechanical Scanning Sonar, is evaluated at close range. Secondly, the supervised CANUPO and RandLA-Net classification approaches are used to classify submerged sonar point clouds. Common objects of interest, namely tyres and chairs, were selected for classification. Relative accuracy measurement results showed a centimetre-level root mean square error (RMSE) value, with good accuracies recorded when the scanner is positioned close to objects. The best results were achieved when the target objects were placed at a minimum distance of 2 m from the acoustic scanner. Subsequently, the results of point cloud classification were satisfactory for both approaches. An overall accuracy of 79.81% and an F1 score of 79.80% were achieved using the CANUPO classification approach. On the other hand, an 80.72% overall accuracy and an 80.63% F1 score were obtained using a RandLA-Net approach. These analyses provide a reasonable framework for the parameters that can be used when applying these techniques in natural aquatic environments.
PubDate: 2024-07-12
DOI: 10.4314/sajg.v13i2.4
Issue No: Vol. 13, No. 2 (2024)
- A holistic categorisation of address purposes as an analytical entry point
to finding solutions for addressing governance in South Africa
Authors: Sharthi Laldaparsad, Serena Coetzee, Nerhene Davis
Pages: 288 - 303
Abstract: An address is structured information allowing one to locate a building or other feature in the physical world; yet, in large parts of the world, including South Africa, many people must get by without such a utility. Although addresses are being rolled out, there is still no clarity concerning stakeholder responsibilities in the governance of addresses and address data in South Africa. In this paper, we present a categorisation of address purposes based on a holistic analysis of the many purposes of an address found in literature. Supported by this categorisation, stakeholders who could or should be involved in addressing governance in South Africa are identified. This first hierarchical categorisation of address purposes can be extended with additional levels of categorisation of new and diverse uses and purposes of addresses as they emerge. The categorisation confirms the significant value of addresses to society, governance, and the economy, sanctioning the need for investments for implementing an effective addressing infrastructure. The study serves as the analytical entry point to finding solutions for more coherent policy formulation and governance.
PubDate: 2024-08-06
Issue No: Vol. 13, No. 2 (2024)
- Impact of Landuse change on Urban Thermal Variance in Umuahia Urban,
Nigeria: a Remote Sensing-based Approach
Authors: Felix Ike, Victor U Nkemdirim, Innocent; C Eneogwe
Pages: 304 - 320
Abstract: Urbanization is directly related to changes in land surface temperature (LST). However, little is known about the spatial and temporal impact of urbanization on Urban Thermal Variance (UTV) in Umuahia. To this end, we quantified the spatiotemporal associations of UTV intensity between 1986 and 2017. We calculated LST change by using a land-use change map and computed the level of vegetation coverage based on the Normalized Difference Vegetation Index (NDVI), and the Urban Thermal Field Variance Index (UTFVI). In so doing, we could determine the ecological index from multi-temporal Landsat data. Results showed that, at the expense of other types of land cover, the built-up portions of the study area were progressively increasing in surface area with a concomitant increase in temperature. The transfer matrix developed in this study reveals that within the 31-year period there was a transformation of about 59.88% and 8.23% from vegetation and bareland, respectively, to built-up cover. The spatio-temporal distribution of surface temperature showed that the built-up areas recorded the highest annual mean temperatures of 21.50oC in 1986, 22.20oC in 2001, and 26.01oC in 2017. Results of the UTFVI showed that more areas were undergoing deteriorating ecological change and imbalances, thus leading to an increase in the area affected by the strong heat island phenomenon, which accounted for 0.065% of the total study area in 1986, 1.02% in 2000, and 32.91% in 2017. We concluded that urbanization has increased the overall surface temperature of the city. However, owing to the re-location of the city’s main market, there has been a decline in UTFV in the vicinity of the city centre. The research findings indicate that the implementations of effective plans to mitigate the heat island effects are imperative for the promotion of sustainable urban development.
PubDate: 2024-08-06
Issue No: Vol. 13, No. 2 (2024)
- Mapping smallholder maize farm distribution using multi-temporal
Sentinel-1 data integrated with Sentinel-2, DEM and CHIRPS precipitation
data in Google Earth Engine
Authors: Colette de Villiers, Cilence Munghemezulu, Solomon G. Tesfamichael, Zinhle Mashaba-Munghemezulu, George J. Chirima
Pages: 321 - 351
Abstract: Mapping smallholder maize farms in complex and uneven rural terrain is a major barrier to accurately documenting the spatial representation of the farming units. Remote sensing technologies rely on various satellite products for differentiating maize cropland cover from other land cover types. The potential for multi-temporal Sentinel-1 synthetic aperture radar (SAR), Sentinel-2, digital elevation model (DEM) and precipitation data obtained from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) version 2.0 was investigated for mapping maize crop distributions during the growing seasons, 2015–2021, in the Sekhukhune municipal area of Limpopo, a province in South Africa. Sentinel-1 variables, including monthly VH, VV, VV+VH (V = vertical, H = horizontal) polarization band data and data issuing from the principal component analysis of VH polarization were integrated with Sentinel-2-derived normalized difference vegetation index (NDVI), DEM terrain, and precipitation data. The random forest (RF) algorithm was applied to distinguish maize crops from four other land cover types, including bare soil, natural vegetation, built-up area, and water. The findings indicated that the models that used only Sentinel-1 data as input data had overall accuracies below 71%. The best performing models producing overall accuracies above 83% for 2015–2021 were those where Sentinel-1 (VV+VH) data were integrated with all the ancillary data. Overall, the McNemar test indicated enhanced performance for models where all other ancillary input data had been incorporated. The results of our study show considerable temporal variation in maize area estimates, with 59 240.84 ha in the 2018/2019 growing season compared to 18 462.51 ha in the 2020/2021 growing season. The spatial information gathered through these models proved to be valuable and is essential for addressing food security, one of the objectives of the Sustainable Development Goals.
PubDate: 2024-08-06
Issue No: Vol. 13, No. 2 (2024)
- Assessing the Impact of Spatial Planning on the Spread of COVID-19 within
Kampala City
Authors: Brendah Nagula, Ronald Ssengendo, Fredrick Omolo Okalebo, Ivan Bamweyana
Pages: 352 - 364
Abstract: Spatial planning has previously had an impact on the dynamics of pandemics. However, its influence on the spread of COVID-19 has not been explored. This research therefore focused on assessing the impact of spatial planning on the spread of COVID-19 in Kampala City. The research was based on the confirmed COVID-19 cases registered between 21 March 2020 and 27 March 2021 and was conducted in conjunction with the spatial analytical methods of the Global Moran’s Index, Anselin’s Local Indicator of Spatial Association (LISA) and the Geographically Weighted Regression model (GWR). Global Moran’s I and Anselin’s LISA were used to determine the spatial distribution of COVID-19 cases. The GWR was used to model the relationship between conformance to spatial planning and the spatial distribution of COVID-19 cases. Results attained through these methods showed a random distribution of cases, with LISA results indicating parishes located in the Central Division as major disease risk sites of COVID-19. Furthermore, results from the GWR revealed a negative relationship, with an R2 value of 0.51, between spatial planning and the spatial distribution of Covid-19. This means that variations in spatial planning initiatives could explain 51 per cent of the variations in COVID-19 cases in Kampala City. Therefore, to change Kampala into a pandemic-resilient city, there is a need to develop appropriate compact spatial planning designs, especially in the parishes of Nakasero 1, Nakasero 11, Nakasero III, and Kagugube.
PubDate: 2024-08-06
Issue No: Vol. 13, No. 2 (2024)
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