An Integrated Geophysical Survey of Groundwater Resources, Mamre Area, Western Cape Province

Abstract

The town of Mamre is located on the water-scarce western coast of South Africa, and has been completely dependent on treated (softened and chlorinated) groundwater from the Atlantis wellfield, located about 10 km to the south. Atlantis wellfield water has also been used for livestock watering and irrigation. In an effort to conserve potable water reserves within the Atlantis wellfield and reduce the cost of irrigation water, locally occurring groundwater was investigated as an alternative source of irrigation water. The fractured zone within the Malmesbury shale in a study area proximal to Mamre was identified as the target for groundwater exploration, based on previously acquired borehole and geophysical data. To assess the potential for development of an aquifer in the Malmesbury shale within the study site and with a view to identifying prospective borehole locations, an integrated geophysical data set was acquired. The non-invasive techniques used, were shallow reflection seismics, electromagnetics, and resistivity. The interpretation of the geophysical data was constrained by previously acquired resistivity data and borehole control. The integrated geophysical survey was successful. The seismic data were used to quantitatively determine depth to bedrock and the electromagnetic and resistivity data were used to qualitatively delineate zones of deeper weathering. Areas prospective for the presence of fractured Malmesbury shale (with associated enhanced porosity and permeability) were identified. Priority locations for exploratory boreholes were also delineated.

Department(s)

Geosciences and Geological and Petroleum Engineering

Sponsor(s)

Council of Scienctific and Industrial Research

Keywords and Phrases

Borehole Geophysics; Data Set; Electrical Resistivity; Electromagnetic Method; Fracture Zone; Geophysical Survey; Groundwater Exploration; Groundwater Resource; Permeability; Porosity; Seismic Reflection; Well Water; Africa; Cape Province; South Africa; Southern Africa; Sub-Saharan Africa

Geographic Coverage

South Africa

International Standard Serial Number (ISSN)

1012-0750

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2006 Geological Society of South Africa, All rights reserved.

Publication Date

01 Dec 2006

Link to Full Text

Share

 
COinS