PAPER TITLE :DELINEATION OF FRESH WATER AQUIFER IN SOME PARTS OF LAGOS COASTAL ENVIRONMENT, SOUTHWESTERN NIGERIA

JOURNAL OF EARTH AND ATMOSPHERIC RESEARCH | VOLUME 3 NUMBER 1 2020

Paper Details

  • Author(s) : Ifarajimi, W. T., Alli, S. A. and Olayanju, G. M.
  • Abstract:

Saline water intrusion has been reported within Badore–Ajah area of Lagos coastal environment
which necessitated electrical resistivity survey involving the use of Vertical Electrical Sounding
(VES) and 2-D imaging with the aim of delineating fresh water aquifer in the area. Twenty-eight
(28) VES and 2-D data along four (4) traverses were acquired within the study area. The
interpretation of the 2-D data was carried out using the DIPPRO software, while the results of the
inverted VES data using partial curve matching technique was improved with the aid of
WINRESIST software. Results obtained were further refined with output data constrain using
wireline log and lithology log. The results of the sounding curves revealed four geoelectric layers
comprising of topsoil (mixture of sand and clayey sand) with resistivity values ranging from 61 to
920 Ωm, clayey sand (61-98 Ωm), sandy clay (35-56 Ωm), clay (5-19 Ωm) and sand (123-495
Ωm) respectively. The topsoil has layer thickness values that vary between 0.9 m and 1.4 m. The
second stratum consists of sand with some lenses of clayey sand, having layer thickness values
that ranges from 2.3 and 20.6 m. The third layer is predominantly sandy clay with some
intercalation of sand and clay with layer thickness values ranging from 17.0 to 56.2 m and depth
extending from 26.0 to 65.6 m. The fourth horizon is predominantly sand on traverses 4 and 5, and
mostly clay on traverse 2, which falls within the swamping area. It was established that sand
horizons on traverses 1, 4 and 5 were potential fresh water aquifers from depth of 50 meters and
above. The correlation of the geo-sections with the wireline and borehole lithology logs have
established the distribution of freshwater aquifer within the study area to vary from 50 to about
130 meters. From this study, VES 1, 3, 23, 27 and 28 locations were recognized to be favourable
for groundwater development with fresh water aquifers at depth equal or greater than 50 m.