South African Journal of Geomatics https://www.ajol.info/index.php/sajg <p>The South African Journal of Geomatics (SAJG) publishes peer-reviewed original papers within the broad discipline of Geomatics (including surveying techniques, technology and applications, mine surveying, hydrographic surveying, cadastral systems, land tenure, development planning, GIS, photogrammetry and remote sensing). The journal is designed to serve as a source reference and archive of advancements in these disciplines. The focus is on papers relevant to the South African and African context, but is not restricted to these areas. This includes both technological developments as well as social adaptations appropriate to the needs of Geomatics in Africa.</p> <p>Other websites associated with this journal:&nbsp;<a title="http://www.sajg.org.za" href="http://www.sajg.org.za" target="_blank" rel="noopener">www.sajg.org.za</a></p> en-US <p>Authors who submit papers to this journal agree to the following terms:</p><p>a) Authors retain copyright over their work, while allowing the journal to place this work on the journal website under a Creative Commons Attribution License, which allows others to freely access, use, and share the work, with an acknowledgment of the work's authorship and its initial publication in this journal.</p><p>b) Authors are able to waive the terms of the CC license and enter into separate, additional contractual arrangements for the non-exclusive distribution and subsequent publication of this work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal.</p><p>c) In addition, authors are encouraged to post and share their work online (e.g., in institutional repositories or on their website) at any point after publication on the journal website.</p> Julian.Smit@uct.ac.za (Prof Julian Smit) president@sagi.co.za (SAGI Ex-Officio Member of Management Committee) Tue, 16 Jan 2024 16:58:39 +0000 OJS 3.3.0.11 http://blogs.law.harvard.edu/tech/rss 60 Multicriteria decision method for renewable energy production: siting solar, wind and small hydropower plants in Zimbabwe https://www.ajol.info/index.php/sajg/article/view/262690 <p class="SAJGAbstract"><span lang="EN-GB">Energy development in Zimbabwe has not been coincident with the rising demand for energy, thus placing a large strain on existing resources. The National Renewable Energy Policy states that by 2030, Zimbabwe should to some extent be driven by clean and sustainable energy sources. In support of this initiative, this study sought to identify suitable locations for renewable energy production plants (solar, wind and small hydropower) in Zimbabwe. The Analytic Hierarchy Process (AHP) was used to evaluate the decision criteria. A raster-based suitability model was constructed using the decision criteria, and areas showing suitable sites to install wind, solar and small hydropower (SHP) plants were identified. The results showed that suitable sites for small-scale wind turbines are in the Beitbridge rural district covering a land area of approximately 12&nbsp;719 km<sup>2</sup>. Hwange rural was found to be the district with a large potential for siting solar power plants with a land area of approximately 26&nbsp;974 km<sup>2</sup>. Several river channels distributed throughout the country were identified as potential sites for establishing SHP plants. The main contributions of this paper are the identification of the evaluation criteria and suitable sites for wind, solar and SHP plants in Zimbabwe.</span></p> Grace Ngwenya, Simon Antony Hull Copyright (c) 2024 https://www.ajol.info/index.php/sajg/article/view/262690 Tue, 16 Jan 2024 00:00:00 +0000 Evaluation of the Performance of the Water Cloud Model and Modified Water Cloud Model in Estimating Soil Moisture. A case study of Kiruuli Village https://www.ajol.info/index.php/sajg/article/view/265359 <p>In Uganda, crop yields have been constrained by recurrent droughts and reliance on rain-fed agriculture. As a straightforward measure, irrigation farming has been adopted by the government through its rehabilitation of old schemes and its assistance to farmers in the setting up of micro-irrigation farms. Of consequence is the fact that the maximization of crop yields through irrigation necessitates soil moisture data for irrigation scheduling. Both ground-based measurements and remote sensing techniques can be used to access this information, with the latter holding the advantage of gathering more information over a wider area. Because of its ability to account for vegetation cover, the Water Cloud Model (WCM) ─ a remote sensing-based model ─ has been widely used in earlier studies to estimate soil moisture content over vegetated areas. However, the accuracy of the model is limited by the assumption that vegetation is a homogenous scatterer. Thus, the Modified Water Cloud Model (MWCM) was developed in accordance with the debate that by considering the heterogeneous scattering nature of the vegetation, it would perform better than the WCM. Using Kiruuli Village (in a coffee-growing area), this study compared the performance of the WCM and the Modified Water Cloud Model (MWCM) in estimating soil moisture. The models were implemented using Sentinel 1 and 2 images acquired on 05 September 2021 and 02 August&nbsp; 2021, respectively. Results showed that the MWCM performed slightly better than the WCM with Root Mean Square Errors (RMSEs) of 3.3346 and 3.7482, respectively. The marginality of the results can be attributed to a relatively high vegetation fraction at the time of image acquisition and a reasonably small area of comparison. Generally, more work can be carried out to compare the models across a larger area with a sparser vegetation cover.</p> Mark Mukomazi Buyungo, Ivan Bamweyana Copyright (c) 2024 https://www.ajol.info/index.php/sajg/article/view/265359 Wed, 21 Feb 2024 00:00:00 +0000 Validating Uav-Sfm Photogrammetry Heights for Highway Topographic Surveying in Tanzania https://www.ajol.info/index.php/sajg/article/view/264909 <p class="SAJGAbstract"><span lang="EN-GB">The demand for accurate topographic surveying data to support ever-growing infrastructural development such as highway construction is huge. Topographic surveying defines a point with X, Y, and Z relative values to create a 3D earth surface model. The Z values represent the vertical height of a point from the benchmark. Vertical heights can be obtained from conventional levelling and Digital Elevations Models (DEMs), as in the case of heights from unmanned aerial vehicle structures from motion photogrammetry (SfM-P) and global navigation satellite systems (GNSSs). </span></p> <p class="SAJGAbstract"><span lang="EN-GB">GNSS-Real Time Kinematics (RTK) is the most common method used but is sometimes outscored because of limitations in terms of time consumption and physically inaccessible surfaces. Recently, SfM-P surveys appear to have been quick and effective in accessing areas that would not have been possible when applying GNSS RTK methods. SfM-P surveys have recently been reorganized through cheap, rapid and elementary methods, but few research findings have been documented. Therefore, the study for validating SfM-P surveys in topographic surveys of highways in Tanzania has proved to be most opportune.</span></p> <p class="SAJGAbstract"><span lang="EN-GB">In this study, an evaluation was performed by comparing SfM-P survey method heights to GNSS RTK method heights for an area with 3km wide and 19 km long. A total of 39 ground control points was used. The standard deviation between the SfM-P method heights and the GNSS RTK method heights was ±1.4 cm. The samples of elevation data for the preliminary surveying of highways were determined at an 80% accuracy level. However, among the respective heights, only 20% produced a +/- two-centimetre (2 cm) relative precision ─- an extremely high precision level and most satisfactory for detailed topographic surveys. This study confirms that the SfM-P survey can be most helpful in preliminary highway surveys in Tanzania and in surveys of those areas, such as the Dodoma region, with a sparser vegetation cover. However, the SfM-P survey method cannot guarantee good performance to comply with the detailed highway topographic survey height requirements of Tanzania.</span></p> Nicholas Charles Batakanwa Copyright (c) 2024 https://www.ajol.info/index.php/sajg/article/view/264909 Thu, 15 Feb 2024 00:00:00 +0000