Geospatial Analysis of the Aquiferous Potential Zones in the Crystalline Basement of Bulawayo Metropolitan Area, Zimbabwe

摘要

Efforts have been made to review the literatures on groundwater exploitation and the constraints to effective and sustainable management of groundwater in Bulawayo Metropolitan, Zimbabwe. However, the attempts are hindered by the underlain crystalline basement aquifers which are complex in nature and highly heterogeneous in yield. Therefore this study seeks to demarcate the potential aquiferous zones in Bulawayo Metropolitan for groundwater development using satellite data and geological inference. Remote Sensing and Geographical Information Systems (GIS) are useful in the recognition and delineation of aquiferous zones for potential groundwater in crystalline basement aquifers. LANDSAT ETM+ image, SRTM data, aeromagnetic data and other ancillary data sets were utilized to extract information on the groundwater storing controlling features of this study area. GIS modeling using the index overlay method was used to produce the groundwater potential map. The study revealed that the regional lineaments correlate with faults, fracture zones, and lithological contrasts along fold belts in the crystalline basement rocks, while the main direction of faulting and jointing is north-north-west to north, with several faults oriented to the north-north-east parallel to the Zimbabwe Great Dyke. The areas close to lineaments are the highest zone of increased porosity and permeability, which in turn have a greater chance of accumulating groundwater. The results have shown massive spatial variability of ground water potential ranging from very good to poor. The variability closely followed variations in the structures, geology, topography/slope, drainage density and land use/land cover in the project area. This exploratory work needs to be validated by the use of high-resolution terrain data and satellite imagery, along with quantitative analysis, which should be done using geophysical and hydrogeological surveys.