Groundwater occurrence and quality in Bulawayo province, Zimbabwe

• Main Authors: Nygren, Anton, Nordenskjöld, Edvard, Östblom, Erik
• Format: Others
• Language: English
• Published: Uppsala universitet, Institutionen för geovetenskaper 2016
• Subjects: total dissolved solids; salinity; electrical conductivity; electrical resistivity tomography; vertical electrical sounding; magnetic field; auger holes; saturated hydraulic conductivity
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-300718

This study focused on determining the groundwater flow paths in the crystalline subsurface rocks of the Bulawayo metropolitan, Zimbabwe, through analysing the discontinuities of the electrical properties of the ground, as well as in the magnetic field of the underlying rocks. Further, borehole water quality was analysed by measuring and mapping several chemical parameters, specifically TDS, salinity and the electrical conductivity. The electrical and magnetic anomalies were measured at two field sites within the Bulawayo province, the Harry Allen Golf Course and the Barbour Fields dumpsite, while 120 boreholes were sampled for water quality in a large part the province. Two magnetometers were used to measure the magnetic field and the time and location of the measurements, which resulted, after processing in SURFER, into the magnetic field map of these areas. This was used, in conjunction with the geologic map of the Bulawayo province, in order to determine useful locations for the electrical resistivity surveys. These included electrical resistivity tomography and vertical electrical sounding and were performed with an earth resistivity/induced polarization (IP) meter in order to measure the electrical resistivity of the ground. Inverse modelling was used in the RES2DINV software program to produce the topographic image of resistivity. The results for the borehole sampling showed that the maps for the three chemical parameters were very similar, with the western and northern parts of the mapped area displaying higher concentration values. The results of the electrical resistivity surveying showed probable areas of groundwater flow with its relationship to electric conductivity.