Browsing by Subject "GIS"

Now showing 1 - 5 of 5
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    Analysing the road reserve encroachment in Maseru Lesotho using remote sensing and image analysis
    (2021) Ralitsoele, Teboho; Sithole, George
    The increasing rate of urbanization and the problem of road reserve encroachment mean that there is no space for road expansion and sometimes for maintenance and road furniture, these and other problems have exposed the problem of road reserve encroachment. The main aim of this study was to investigate methods of finding the road reserve encroachment in Maseru Lesotho using aerial photos. The study used single image analysis and multiple image analysis methods. In single image analysis, the study used three methods of image classifications to find objects that are in the road reserve. Under classification, the study used both supervised and unsupervised image classifications. For supervised classification, the study used the direct image classification method where the aim was to look for every object found in the road reserve. For the indirect approach, the study looked for the ground to find objects in the road reserve. For unsupervised image classification, the study assumed that small clusters are encroachment. In multiple images analysis, the study used the 2015 and 2017 images to determine permanent objects found to have encroached road reserves. Here the assumption was that encroachment does not change over time, which means that unchanged objects during the change detection have encroached on the road reserve. The confusion matrix was used to tell the best performing method and the results show that the indirect method, both in Qoaling and Maqalika performed best. All the methods showed that there was an encroachment on a road reserve, and found that permanent objects were; houses, shops, and shopping centers. The study recommended the use of images with higher resolution and more bands, also that images be taken frequently.
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    Characterising South Africa’s major dust sources
    (2019) Bekiswa, Sisanda Ongeziwe; Eckardt, Frank
    The study investigates the surface controls of major dust emissions and determines the patial distribution of major dust source in South Africa. This study follows a multi-disciplinary approach where primary and secondary data were used. The main objective of the study is to determine the spatial distribution of South Africa's Major Dust Sources. Meteosat Second Generation (MSG) satellite imagery, land use and land cover maps were used to achieve the first and the second objectives of the study. Primary data involved sampling 30 soil samples in the field in order to achieve the third objective of the study. The crust, soil moisture, soil texture and grain size are all controls of dust emission. This investigation is however focused predominantly on grain size characteristics. GIS methods were also used to determine soil type from the African soil map. Soil samples in both provinces were then collected to assess the Particle Size Distribution (PSD) of the soils. The particle size was determined based on a sieve analysis for grain sizes that were greater than 2mm and laser diffractometry, MasterSizer (Malvern) was used to achieve this. The results from the Malvern were later put to R Statistics where they were clustered into eight clusters to determine similarities and difference of the grain size. Because there is no uniqueness in the soil types found in the study area, there were no solid conclusions made based in them. The results show that the soil types are found across South Africa but not the same amount of dust activity was detected in the other parts of the country. Previous studies show that global significant dust sources are natural sources such as lakes, pans and depressions. However, results demonstrate that South African dust sources are anthropogenic sources resulting from commercial agriculture in semi-arid regions. This study has demonstrated that surface sediments suitable for dust production are a mixture of fine material, silt (50µm) and coarse material, sand (2000µm) and it appears that all clusters in this study all contained both mixtures and all have potential to emit dust.
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    Children’s route choice during active transportation to school: difference between shortest and actual route
    (2016) Dessing, Dirk; de Vries, Sanne I; Hegeman, Geertje; Verhagen, Evert; van Mechelen, Willem; Pierik, Frank H
    BackgroundThe purpose of this study is to increase our understanding of environmental correlates that are associated with route choice during active transportation to school (ATS) by comparing characteristics of actual walking and cycling routes between home and school with the shortest possible route to school.MethodsChildren (n = 184; 86 boys, 98 girls; age range: 8–12 years) from seven schools in suburban municipalities in the Netherlands participated in the study. Actual walking and cycling routes to school were measured with a GPS-device that children wore during an entire school week. Measurements were conducted in the period April–June 2014. Route characteristics for both actual and shortest routes between home and school were determined for a buffer of 25m from the routes and divided into four categories: Land use (residential, commercial, recreational, traffic areas), Aesthetics (presence of greenery/natural water ways along route), Traffic (safety measures such as traffic lights, zebra crossings, speed bumps) and Type of street (pedestrian, cycling, residential streets, arterial roads). Comparison of characteristics of shortest and actual routes was performed with conditional logistic regression models.ResultsMedian distance of the actual walking routes was 390.1m, whereas median distance of actual cycling routes was 673.9m. Actual walking and cycling routes were not significantly longer than the shortest possible routes. Children mainly traveled through residential areas on their way to school (>80% of the route). Traffic lights were found to be positively associated with route choice during ATS. Zebra crossings were less often present along the actual routes (walking: OR = 0.17, 95 % CI = 0.05–0.58; cycling: OR = 0.31, 95 % CI = 0.14–0.67), and streets with a high occurrence of accidents were less often used during cycling to school (OR = 0.57, 95% CI = 0.43–0.76). Moreover, percentage of visible surface water along the actual route was higher compared to the shortest routes (walking: OR = 1.04, 95 % CI = 1.01–1.07; cycling: OR = 1.03, 95 % CI = 1.01–1.05).DiscussionThis study showed a novel approach to examine built environmental exposure during active transport to school. Most of the results of the study suggest that children avoid to walk or cycle along busy roads on their way to school.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-016-0373-y) contains supplementary material, which is available to authorized users.
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    Towards universal health coverage: a mixed-method study mapping the development of the faith-based non-profit sector in the Ghanaian health system
    (BioMed Central, 2018-10-05) Grieve, Annabel; Olivier, Jill
    Background Faith-based non-profit (FBNP) providers have had a long-standing role as non-state, non-profit providers in the Ghanaian health system. They have historically been considered to be important in addressing the inequitable geographical distribution of health services and towards the achievement of universal health coverage (UHC), but in changing contexts, this contribution is being questioned. However, any assessment of contribution is hampered by the lack of basic information about their comparative presence and coverage in the Ghanaian health system. In response, since the 1950s, there have been repeated calls for the ‘mapping’ of faith-based health assets. Methods A historically-focused mixed-methods study was conducted, collecting qualitative and quantitative data and combining geospatial mapping with varied documentary resources (secondary and primary, current and archival). Geospatial maps were developed, providing a visual representation of changes in the spatial footprint of the Ghanaian FBNP health sector. Results The geospatial maps show that FBNPs were originally located in rural remote areas of the country but that this service footprint has evolved over time, in line with changing social, political and economic contexts. Conclusion FBNPs have had a long-standing role in the provision of health services and remain a valuable asset within national health systems in Ghana and sub-Saharan Africa more broadly. Collaboration between the public sector and such non-state providers, drawing on the comparative strengths and resources of FBNPs and focusing on whole system strengthening, is essential for the achievement of UHC.
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    Unlocking the potential of remote sensing for kelp biomass estimation in South African Kelp Concession Areas
    (2024) Searle, Lauren Jane; Bolton, John; Rothman, Mark; Bray, Kate
    The use of high-resolution imagery (HRI) has the potential to improve the accuracy of kelp biomass estimates, ensuring the implementation of sustainable harvesting. However, definitive research on the potential of HRI in this application is lacking in the current literature. An accurate estimation of kelp biomass is crucial to calculate maximum sustainable yield (MSY) in South African kelp Concessions. This study seeks to fill the knowledge gap by exploring the effectiveness of HRI for estimating the biomass of kelp along a specific stretch of coastline. The study aim is achieved by analysing HRI of Concession Area 6 taken from an aircraft. Maps quantifying kelp extent are derived from image classification methods applied to the HRI. A total biomass figure is then determined using the product of the calculated kelp extent and an average biomass figure of 14.5 kg/m-2 , taken from the literature. A total biomass of 40527.9 tonnes wet weight was calculated for Concession Area 6. The classification of HRI provided an overall accuracy of 95%, which is relatively high when compared to Sentinel-2 satellite imagery which resulted in an overall accuracy of 75%. When compared to the kelp extent measured in previous studies, HRI-derived maps had consistently less kelp coverage than maps from other imagery, suggesting that other imagery overestimates kelp extent (likely due to resolution). However, this was confounded given different imagery used at different times and so it was not possible to rule out change in kelp coverage over time. The results demonstrate the value of HRI in the mapping of kelp extent, which can ultimately be used to produce more accurate MSY assessments and support sustainable harvesting practices. However, before HRI can be integrated into MSY assessments, it is imperative to calculate more accurate biomass figures that are specific to the Concession Area, rather than relying on region wide estimates. Additionally, it's important to acknowledge that while HRI excels in precision, other imagery may be more suitable for large-scale estimates where accuracy is not a primary concern and due to its cost-effectiveness.