A study of the sand and gravel deposits around the permanent site of the Federal Unviersity of Tehcnology, Owerri using the vertical electrical sounding (VES) technique

Abstract

A geophysical investigation of the sand and gravel deposits at the Federal University of Technology Owerri was carried out using the vertical electrical sounding (VES) approach. The aim of the study was to determine the occurrences and depths of sand and gravel deposits at the study area. This was done using the Schlumberger electrode configuration technique with the ABEM Terrameter Signal Averaging System (SAS 4000) Model. Twenty one (21) soundings were carried out at selected locations within the study area. An average overburden thickness of about six meters (6 m) was inferred from the study, this is lateritic in composition and was  underlain by sand and gravel deposits of average thicknesses of eighteen meters (18 m) and seventy- eight meters (78m) respectively were  deduced. The high resistivity values encountered at depth of 30 m to 100 m and even beyond which is typical of fresh-water-saturated sand and gravel showed that the ground water potential of the study area could be utilized for regional water supply. However considering the nature and thickness of the overburden and the non-existence of impermeable units overlaying this aquifer, it is strongly proposed that the construction of sewage systems at this area should be avoided for this will pose very serious health hazards to the aquifer catchments. Generally results showed that the study area is actually underlain by the sand and gravel deposits in commercial quantities. However, extraction of these deposits is highly discouraged considering its adverse ecological consequences on the University community, unless proper mining methods are adopted.

Keywords: Resistivity, Sand and Gravel deposit, aquifer, fresh water.