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Browsing Applied Physics by Author "Hlatywayo, Dumisani J."
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- ItemApplication of Remote Sensing and Geographical Information Systems in Determining the Groundwater Potential in the Crystalline Basement of Bulawayo Metropolitan Area, Zimbabwe(Scientific Research, 2013) Chuma, Constant; Hlatywayo, Dumisani J.; Orimoogunje, Oluwagbenga O.I.; Akinyede, Joseph O.This study is concerned with the identification and delineation of aquiferous zones for potential groundwater development across Bulawayo Metropolitan from remotely sensed data and geological inference. Attempts have been made to review literatures on groundwater exploitation in the study area and the constraints to effective and sustainable management of underground water in the study area. Remote Sensing and Geographical Information Systems (GIS) is 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. Six thematic maps were produced from remote sensing data and other ancillary data - Land use/landcover, drainage density, slope map, contact density, lithology and lineament density. GIS modeling technique of 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 Great Dyke. Proximity to lineaments is 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 work is a reconnaissance which needs to be validated by the use of high-resolution terrain data and satellite imagery and the quantitative analysis should be done using geophysical and hydrogeological surveys.
- ItemA comparison of crystalline basement aquifers and Kalahari aquifers in exploration of groundwater occurrence in Zimbabwe(2016-07) Chuma, Constant; Hlatywayo, Dumisani J.; Midzi, Vunganai; Gumbo, Mervyn; Muchingami, Innocent; Mashingaidze, Robin TExploration of groundwater occurrence becomes complex if there is inadequate information to explain the its dynamics. The paper compares the major aquifers found in Zimbabwe in order to maximise the exploration of groundwater in the semi-arid regions. Geophysical and geospatial tools have proved to be useful tools in divining for groundwater in different geological settings. Crystalline basement aquifers are characterised by impervious rock which confines water in the upper layers whilst Kalahari sands provide high yielding unconsolidated aquifers. Transmissivity and conductivity decreases with depth in crystalline whilst the reverse is true for Kalahari sands.
- ItemDielectric barrier discharge CO2 TEA laser operated at frequencies up to 400 Hz(SA Institute of Physics, 2011) Baricholo, Peter; Stehmann, Timo; Rohwer, Erich G.; Collier, M.; Hlatywayo, Dumisani J.; Von Bergmann, Hubertus M.A dielectric barrier discharge CO2 TEA laser excited by a thyratron driven power supply has been developed and characterized. Laser output was observed at frequencies up to 25 Hz for an electrode separation of 10 mm with 1.8 mm suprasil glass covering the electrodes. At this gap separation, pulsed power output of about 9 W was detected for gas pressures between 100 and 400 mbar. The laser has a pulse duration was about 0.3 flS with a risetime of ~100 ns. Changing the electrode separation to 5 mm and using 1.4 mm suprasil glass dielectric increased the output power to 23 Wand enabled laser output to be observed at gas pressures up to 700 mbar and maximum pulse excitation frequencies of up to 400 Hz. The developed laser does not require water cooling since the system operates in burst pulse mode.
- ItemGeospatial Analysis of the Aquiferous Potential Zones in the Crystalline Basement of Bulawayo Metropolitan Area, Zimbabwe(The International Astronautical Federation., 2013) Hlatywayo, Dumisani J.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.
- ItemInfluence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp.(AOSIS Open Journals., 2011-11) Baricholo, Peter; Hlatywayo, Dumisani J.; Von Bergmann, Hubertus M.; Stehmann, Timo; Rohwer, Erich G.; Collier, M.A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV) emission at 126 nm and near infrared (NIR) lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from deexcitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar2* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar.
- ItemModelling the Subsurface Geology and Groundwater Occurrence of the Matsheumhlope Low Yielding Aquifer in Bulawayo Urban, Zimbabwe(Canadian Center of Science and Education, 2013-08) Chuma, Constant; Hlatywayo, Dumisani J.; Zulu, Joseph; Muchingami, Innocent; Mashingaidze, Robin T.; Midzi, VunganaiThis study is focused on determining the nature, extend and spatial variation of the subsurface and groundwater in the Matsheumhlope low yielding aquifer so as to improve the understanding of groundwater occurrence within Bulawayo Metropolitan area. The abstraction and utilisation of groundwater from crystalline basement complexes have often been hampered by the high rate of borehole failure. For instance, borehole failure in the Matsheumhlope wellfield that characterises the greater part of Bulawayo City, Zimbabwe, is often ascribed to many factors which are yet to be investigated locally and regionally. The electrical resistivity method was used to establish the depth, thickness and sequence of geological units in the low yielding aquifer. Satellite data were used to delineate the lineaments and assess the topographic features of the area. Geological samples obtained from boreholes were correlated with the geophysical pseudo sections to give a better view of the subsurface and groundwater occurrence in the area. Geographic Information Systems (GIS) was used to model the geophysical characteristics of the subsurface giving the potential groundwater occurrence in the area. The study confirmed that the Matsheumhlope aquifer is a heterogeneous unconfined aquifer with a shallow depth to the basement rock in highlands of the study area. The results also showed high spatial variation of subsurface formations and groundwater potential over short distances, thereby indicating the complex nature of mapping basement aquifers. Borehole failure in the area was attributed to the occurrence of shallow depth of the bedrock underlying some parts of the aquifer. Therefore the results of the study recommended that the structural and geodynamic analysis of the fractures of the whole Matsheumhlope aquifer should be done using both structural mapping and geophysical methods.
- ItemModelling the subsurface geology and groundwater occurrence of the Matsheumhlope low yielding aquifer in Bulawayo urban, Zimbabwe(Canadian Center of Science and Education., 2013-08-19) Chuma, Constant; Hlatywayo, Dumisani J.; Zulu, Joseph; Muchingami, Innocent; Mashingaidze, Robin T.; Midzi, VunganaiThis study is focused on determining the nature, extend and spatial variation of the subsurface and groundwater in the Matsheumhlope low yielding aquifer so as to improve the understanding of groundwater occurrence within Bulawayo Metropolitan area. The abstraction and utilisation of groundwater from crystalline basement complexes have often been hampered by the high rate of borehole failure. For instance, borehole failure in the Matsheumhlope wellfield that characterises the greater part of Bulawayo City, Zimbabwe, is often ascribed to many factors which are yet to be investigated locally and regionally. The electrical resistivity method was used to establish the depth, thickness and sequence of geological units in the low yielding aquifer. Satellite data were used to delineate the lineaments and assess the topographic features of the area. Geological samples obtained from boreholes were correlated with the geophysical pseudo sections to give a better view of the subsurface and groundwater occurrence in the area. Geographic Information Systems (GIS) was used to model the geophysical characteristics of the subsurface giving the potential groundwater occurrence in the area. The study confirmed that the Matsheumhlope aquifer is a heterogeneous unconfined aquifer with a shallow depth to the basement rock in highlands of the study area. The results also showed high spatial variation of subsurface formations and groundwater potential over short distances, thereby indicating the complex nature of mapping basement aquifers. Borehole failure in the area was attributed to the occurrence of shallow depth of the bedrock underlying some parts of the aquifer. Therefore the results of the study recommended that the structural and geodynamic analysis of the fractures of the whole Matsheumhlope aquifer should be done using both structural mapping and geophysical methods.
- ItemSeismic hazard assessment in Eastern and Southern Africa.(ANNALI DI GEOFISICA,, 1999-12) Midzi, Vunganai; Hlatywayo, Dumisani J.; Chapola, Lostina S.; Kebede, Fekadu; Atakan, Kuvvet; Lombe, Daniel K.; Turyomurugyendo, Gadi; Tugume, Fred AlexSeismic hazard assessment for the Eastern and Southern Africa region was done using the probabilistic approach. Seismic hazard maps for 10% exceedance in 50 years, 10% exceedance in 100 years, as well as for 50 and 100 years return periods were prepared using the FRISK88M software. The area involved covers a wide region bounded by latitudes 400 S-25°N and longitudes 100E and 55°E. Input parameters for the computations were obtained using the recent earthquake catalogue compiled by Turyomurugyendo. The catalogue which covers the time period 627-1994, contains earthquakes within the area bounded by 400 S-25°N and 100 E-55°E, with homogeneous magnitudes (M). Since a Poisson model of earthquake occurrence is assumed, dependent events were cleaned from the catalogue. Attenuation relations for the Eastern and Southern Africa region based on the strong motion data are virtually non-existent. However, attempts have been made recently by Jonathan 'and Twesigomwe to establish an average attenuation relation for the region. These relations were used in the computations. Possible uncertainties in the attenuation relations were accounted for using the logic-tree formalism. The results are presented in seismic hazard maps in terms of Peak Ground Acceleration (PGA) for the mean and the 85th percentile. The distribution ofPGA values indicate relatively high hazard along the EastAfrican rift system. In the northern segments of the rift system, they exceed 250 gals for 10% probability of exceedence in 50 years.