GEOELECTRICAL EVALUATION OF GROUNDWATER QUALITY OF GASSOL, TARABA NORTHEAST NIGERIA USING DARZARROUK PARAMETERS

Abstract

Twenty-five (25) resistivity VES points were sounded in five wards of Gassol, Taraba, Northeastern Nigeria; Gunduma, Shira, Mutum-biyu ward A, Mutum-biyu ward B, and Namne ward to evaluate the groundwater quality of the area using secondary geoelectric resistivity parameters (Dar-Zarrouk parameters; total longitudinal unit conductance S, transverse resistance T and reflection coefficient ) acquired from the primary resistivity field data (apparent resistivity and thickness) interpreted by IXD Interpex software. Result from the S proportional to aquifer protective capacity APC of the study area ranging from 0.009069 mho – 10.498660 mho and this shown that 52 % of the VES points APC were poor, 20 % were weak, 4 % were moderate and only 24 % were good and excellent. Transverse resistance T of the area varied from 778.6767 − 352920.9895 Ω-m² and area of very low T yield quality groundwater as seen in Mutum-biyu ward A where VES 13, 14 and 15 were conducted. However, locations with high T values possessed high groundwater potential. The reflection coefficient R_C range from - 0.9996 to + 0.9984, with an average value of -0.3461, indicating that the study area possessed good prospect for groundwater potential. Groundwater flow direction map revealed areas of recharge and discharge and it is deduced that water recharge areas were located along Southern and North Eastern part while discharge area was visibly situated at the North Western part of the study area. The study area was characterized having poor/weak APC and only 24 % of its VES points APC possessed good and excellent APC rating and the earth material (clay) drives this hydrogeology protection observed in different VES points; VES 9, 11, 12, 13, 14 and 15. Consequently, 76 % of the water bearing formation units due to APC of the study area is prone to contaminant and this hydro-geologically affects the quality of the groundwater exploited from boreholes with high groundwater potential. Measures to protect the anthropogenic pollution of the groundwater resources of the area include; refuse dumping site or any groundwater polluting activity locations should be provided and managed by the government and the development site for this project was recommended at the NW or NE part of the area in order to protect groundwater pollution in areas with low APC as observed in most VES locations.