Land-use impacts on the quality of groundwater in Bulawayo

Abstract

The impacts of land use from commercial, industrial and domestic activities in the second largest city (Bulawayo) in Zimbabwe on groundwater quality are investigated in this paper. Thirty-two boreholes that are located in the Matsheumhlope Wellfield, a basement aquifer that underlies the city of Bulawayo, were monitored during the period between August 2000 and August 2001. The results showed that the majority of the parameters (iron, manganese, copper, nitrate, fluoride, sulphate and cyanide) at most sampling stations are within the recommended and permissible limits specified in Zimbabwe drinking water standards guidelines (SAZS 560:1997). The water can therefore be used for drinking purposes. However, levels of hardness higher than the maximum allowable according to Standard Association of Zimbabwe (SAZ) guidelines were encountered. Microbiological analysis indicates that 27% of the samples showed positive total coliform and 8% positive faecal coliform with their occurrences being randomly distributed spatially and temporally. Comparison of the water quality in the industrial and residential areas revealed statistically significant differences in water quality of the two areas. The study reveals that leaks from industrial and domestic sewers, commonly being experienced due to the age of the sewer lines, are increasingly compromising the quality of the groundwater, while unusually high levels of EC encountered at two sampling stations seem to be related to the geological formation. The results from sampling groundwater within the vicinity of the landfill site in Richmond do not present a picture that is different from the other residential areas monitored, suggesting that leachate is being contained within the landfill liner and does not, as yet, pose an environmental threat to the aquifer.


Key Words: Groundwater, Water quality, Land use, Environmental impact


WaterSA Vol.30(4) 2004: 453-464