oa The Use Of Geophysical Techniques To Site High Yielding Water Supply Boreholes

Geological and climatic conditions in South<br>Africa are not generally conducive to the<br>formation of large scale aquifers capable of<br>sustaining high yielding boreholes. Over 80% of<br>the country is underlain by old consolidated rocks<br>with negligible primary porosity and 75% of the<br>country receives <250 mm/a of rainfall. With this<br>information as background it is not surprising<br>that, although groundwater is found almost<br>everywhere in the country, most boreholes have<br>sustainable yields of «51/s. It is also not<br>surprising that groundwater supplies only about<br>13% of the total water consumption in South<br>Africa, the remainder coming from surface water<br>sources. This ratio is reversed in many European<br>countries.