Earth Sciences

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Browsing Earth Sciences by Author "Ally, Ally Mgelwa"

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    A fuzzy logic-based approach for modelling uncertainty in open geospatial data on landfill suitability analysis
    (MDPI, 2020) Lyimo, Neema Nicodemus; Shao, Zhenfeng; Ally, Ally Mgelwa; Twumasi, Nana Yaw Danquah; Altan, Orhan; Sanga, Camilius A.
    Besides OpenStreetMap (OSM), there are other local sources, such as open government data (OGD), that have the potential to enrich the modeling process with decision criteria that uniquely reflect some local patterns. However, both data are affected by uncertainty issues, which limits their usability. This work addresses the imprecisions on suitability layers generated from such data. The proposed method is founded on fuzzy logic theories. The model integrates OGD, OSM data and remote sensing products and generate reliable landfill suitability results. A comparison analysis demonstrates that the proposed method generates more accurate, representative and reliable suitability results than traditional methods. Furthermore, the method has facilitated the introduction of open government data for suitability studies, whose fusion improved estimations of population distribution and land-use mapping than solely relying on free remotely sensed images. The proposed method is applicable for preparing decision maps from open datasets that have undergone similar generalization procedures as the source of their uncertainty. The study provides evidence for the applicability of OGD and other related open data initiatives (ODIs) for land-use suitability studies, especially in developing countries.
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    Identification of potential groundwater zones in semi-arid areas: a case study of Bahi district central Tanzania
    (Elsevier, 2019) Mayunga, Selassie; Ally, Ally Mgelwa
    This study used an integrated approach of Remote Sensing, Geographic Information System and Analytical Hierarchy Process to identify the potential groundwater locations in semi-arid area in Central Tanzania. Landsat8 data was used to produce ten thematic layers of geomorphology, lithology, drainage density, lineament, rainfall, land use and land cover, magnetic intensity, slope, soil and watershed. The weights and ranking of the reclassified thematic layers were integrated into GIS and Analytical Hierarchy Process (AHP) to generate the groundwater potential map. The result shows that 5.1 % of Bahi district has very high potential locations of groundwater which is about 284.048km2, 40.4% has good potential which is about 2,229.142, 43.60% has moderate which is , 0.23% which is has poor and 0.67% which is very poor potential. The final potential groundwater map was validated using existing 35 bore holes and showed that 57 percent of the existing bore holes were on poor potential locations while 8.6 percent were on high potential locations. The identified high potential areas are mainly located towards Sulunga dam and towards the downstream in Bahi district. It was finally observed that the integration of remote sensing, GIS, and Analytical Hierarchy Process is a powerful approach for identification of potential groundwater locations particularly in semi-arid areas.