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  1. Article: The Use of C-Band and X-Band SAR with Machine Learning for Detecting Small-Scale Mining

    Janse van Rensburg, Gabrielle / Kemp, Jaco

    Remote Sensing. 2022 Feb. 17, v. 14, no. 4

    2022  

    Abstract: Illicit small-scale mining occurs in many tropical regions and is both environmentally and socially hazardous. The aim of this study was to determine whether the classification of Synthetic Aperture Radar (SAR) imagery could detect and map small-scale ... ...

    Abstract Illicit small-scale mining occurs in many tropical regions and is both environmentally and socially hazardous. The aim of this study was to determine whether the classification of Synthetic Aperture Radar (SAR) imagery could detect and map small-scale mining in Ghana by analyzing multi-temporal filtering applied to three SAR datasets and testing five machine-learning classifiers. Using an object-based image analysis approach, we were successful in classifying water bodies associated with small-scale mining. The multi-temporally filtered Sentinel-1 dataset was the most reliable, with kappa coefficients at 0.65 and 0.82 for the multi-class classification scheme and binary-water classification scheme, respectively. The single-date Sentinel-1 dataset has the highest overall accuracy, at 90.93% for the binary water classification scheme. The KompSAT-5 dataset achieved the lowest accuracy at an overall accuracy of 80.61% and a kappa coefficient of 0.61 for a binary-water classification scheme. The experimental results demonstrated that it is possible to classify water as a proxy to identify illegal mining activities and that SAR is a potentially accurate and reliable solution for the detection of SSM in tropical regions such as Ghana. Therefore, using SAR can assist local governments in regulating small-scale mining activities by providing specific spatial information on the whereabouts of small-scale mining locations.
    Keywords artificial intelligence ; data collection ; image analysis ; spatial data ; synthetic aperture radar ; Ghana
    Language English
    Dates of publication 2022-0217
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2513863-7
    ISSN 2072-4292
    ISSN 2072-4292
    DOI 10.3390/rs14040977
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Phytomass and ecological significance of Chrysocoma ciliata L. within the Lets’eng-la-Letsie catchment area of Lesotho, southern Africa

    Smit, GN / Janse van Rensburg, G

    African journal of range & forage science. 2021 Mar. 12, v. 38, no. 1

    2021  

    Abstract: The Lets’eng-la-Letsie wetland is an official Ramsar site, but the wetland and upland catchment areas suffer from overgrazing, erosion and over exploitation. Chrysocoma ciliata has a reputation as an unpalatable invader and is particularly common on the ... ...

    Abstract The Lets’eng-la-Letsie wetland is an official Ramsar site, but the wetland and upland catchment areas suffer from overgrazing, erosion and over exploitation. Chrysocoma ciliata has a reputation as an unpalatable invader and is particularly common on the drier northern slopes. The objectives of the study were to quantify the phytomass of this shrub with the aid of a developed allometric phytomass quantification technique and to evaluate the ecological significance of this shrub within the area. Highly significant (p < 0.001) positive regressions with coefficients of determinations as high as r ² = 0.94 between phytomass and plant canopy diameter were achieved. The upland slopes support a high density of more than 35 000 C. ciliata plants ha⁻¹ with a phytomass of more than 3 600 kg DM ha⁻¹ and a correspondingly low herbaceous phytomass of 446.57 kg DM ha⁻¹. The edible parts of the plants (flowers, leaves and shoots <2.0 mm in diameter) were estimated to be 1 198 kg DM ha⁻¹, with a crude protein content of 8.84%. There was evidence that C. ciliata is intolerant of wet conditions and the degradation of the catchment areas will result in drier soil profiles, which will favour the further spread of this species.
    Keywords allometry ; canopy ; crude protein ; forage and feed science ; highlands ; phytomass ; shrubs ; watersheds ; wetlands ; Lesotho
    Language English
    Dates of publication 2021-0312
    Size p. 102-109.
    Publishing place Taylor & Francis
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 1160792-0
    ISSN 1727-9380 ; 1022-0119 ; 0256-6702
    ISSN (online) 1727-9380
    ISSN 1022-0119 ; 0256-6702
    DOI 10.2989/10220119.2020.1853605
    Database NAL-Catalogue (AGRICOLA)

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