By A. C. Ekwe1 And A. I. Opara
The combination of layer resistivity and thickness in the so called Da-zarrouk parameters S (longitudinal
conductance) and R (transverse resistance) have proved useful in the evaluation of the transmissivities of the aquifers
around Owerri and environs. The area is underlain by the unconsolidated to semi-consolidated coastal Benin Formation.
The surface direct current electrical resistivity method was used in the study. Seven Vertical Electrical Soundings (VES)
data by the Schlumberger array was acquired in the area. A maximum current electrode spacing (AB) of 1000 m was
used for data acquisition. Four of the soundings were carried out near existing boreholes. Computer modelled interpretative
methods was utilized in processing the data. Results show that the depth to the water level is shallow around Ife and
Egbu areas with a mean depth of 30 m. Semi- deep aquifers were encountered around Okpalla and AVU areas with a
mean depth of 90 m while very deep aquifers were sensed around Owerri and Obinze areas with a mean depth
of 125 m. Aquifer thicknesses in the study area range from 8 m at Ife and 117 m at Owerri. The diagnostic Kσ = constant
value have proved so useful in calculating transmisivities and hydraulic conductivities of all the sounding locations
including areas where no boreholes exist. Hydraulic conductivity varies between 6.19m/day at Ife and 24.7 m/day at
Obinze. Transmissivity values also very between 51.39 m2/day at Ife and 1379.56 m2/day at Owerri. It is hoped that the
results would help in long term planning of groundwater exploitation schemes within the study area.The combination of layer resistivity and thickness in the so called Da-zarrouk parameters S (longitudinal
conductance) and R (transverse resistance) have proved useful in the evaluation of the transmissivities of the aquifers
around Owerri and environs. The area is underlain by the unconsolidated to semi-consolidated coastal Benin Formation.
The surface direct current electrical resistivity method was used in the study. Seven Vertical Electrical Soundings (VES)
data by the Schlumberger array was acquired in the area. A maximum current electrode spacing (AB) of 1000 m was
used for data acquisition. Four of the soundings were carried out near existing boreholes. Computer modelled interpretative
methods was utilized in processing the data. Results show that the depth to the water level is shallow around Ife and
Egbu areas with a mean depth of 30 m. Semi- deep aquifers were encountered around Okpalla and AVU areas with a
mean depth of 90 m while very deep aquifers were sensed around Owerri and Obinze areas with a mean depth
of 125 m. Aquifer thicknesses in the study area range from 8 m at Ife and 117 m at Owerri. The diagnostic Kσ = constant
value have proved so useful in calculating transmisivities and hydraulic conductivities of all the sounding locations
including areas where no boreholes exist. Hydraulic conductivity varies between 6.19m/day at Ife and 24.7 m/day at
Obinze. Transmissivity values also very between 51.39 m2/day at Ife and 1379.56 m2/day at Owerri. It is hoped that the
results would help in long term planning of groundwater exploitation schemes within the study area.