Assessment of the Protective Capacity of Vadoze Zone over Aquifer Systems Using Secondary Geoelectrical Parameters: A Case Study of Kaltungo Area North East, Nigeria

An assessment of the protective capacity of the vadose zone overlyingthe aquifer systems in the Kaltungo area was carried out to determine itsinfluence on groundwater quality. Applying the schlumberger array with amaximum electrode spread AB/2 = 100m through VES, thirty water wellpoints were surveyed using Omega terrameter (PIOSO1) resistivity meter.The field data was first subjected to manual interpretation through curvemarching and then digitized modeled curves using computer software. Theinterpreted data revealed that the area is characterized by eleven differentcurve types representing three to five geo electrical layers. In order toassess the protective capacity of the vadoze zone over the aquifer systems,the longitudinal conductance (S) and transverse resistance (T) (secondarygeoelectric parameters) were computed from the primary data using theDar Zarouk formula. The values of S obtained range from 0.0018 to 0.4056ohms with a mean value of 0.0135 ohms while the values of T range from0.55 ohms to 1195.68 ohms with a mean value of 39.84 ohms. The valuesof S and T obtained reveal that 90% of probed points has poor protectivecapacity, 10 % has moderate protective capacity and 83 % has hightransmissivity, 17 % has intermediate transmissivity. The T and S values areskewed towards poorly protective capacity thus making groundwater in thearea highly vulnerable to contamination from the surface. To achieve goodgroundwater quality in the area, proper completion of newly constructedwells should install protective casing through the entire vadose zone.

Integrated Geophysical and Hydrogeochemical Characterization and Assessment of Groundwater Studies in Adum West Area of Benue State,Nigeria

Integration of geophysical and hydrogeochemical methods has been scientifically proven to be useful in vulnerability study and groundwater characterization.Subsurface geoelectric parameters such as resistivity and thickness obtained from geophysical method(Vertical Electrical Sounding VES)was used to determine aquifers vulnerability,longitudinal resistance(ρL)and transverse unit resistance(Rt).Thirty four water samples were collected from groundwater sources for physicochemical analysis.Estimated results from longitudinal conductance(S),(Rt)and(ρL)showed that the values ranges from 0.03 to 2.5mhos,103.64 to 1964417.8Ω/m^(2) and 215.41 to 65731.68Ω-m respectively.Result from S suggested that 50%of groundwater is considered to be vulnerable to contamination from the earth surface,while the remaining 50%is considered to be slightly vulnerable to surface contamination.Further findings obtained from hydrogeochemical analysis such as Gibb’s and Chadba plots revealed that groundwater is highly influenced by rock water interaction,groundwater is classified to be Na^(+)+HCO_(3)^(-),Ca^(2+)+Mg^(2+)+HCO_(3)^(-),Na^(+)+Cl^(-)and Ca^(2+)+Mg^(2+)+Cl^(-)water type.Deduction from Soltan classification suggested that groundwater is classified to be of Na^(+)+HCO_(3)^(-) and Na^(+)-SO_(4)^(2-) water type.Results obtained from Ec and pH suggested that the values were below WHO permissible limit,while result obtained from TDS showed that at some sampling points TDS values were above WHO limit.Based on pH value obtained groundwater within the study area fell within slightly basic to acidic.

Evaluation of aquifer hydraulic properties from resistivity and pumping test data in parts of Gwagwalada,Northcentral Nigeria

Population upsurge in Gwagwalada increased water demand in the area,thereby stressing water resources in the area.Aquifer properties in parts of Gwagwalada in North-Central Nigeria were therefore investigated using resistivity and hydrogeological approaches.Static water level measurements of hand dug wells were used to determine the groundwater flow direction for the area which coincides with the North East-South West joint direction.Constant rate pumping test was adopted for the research and 10 boreholes were pumped.The weathered/fractured basement range from 7.5 m to 56.7 m.The transmissivity values in the area ranged from 0.35 m^(2)/d to 3.63 m^(2)/d while the hydraulic conductivity range from 0.045 m/d to 0.18 m/d.The Vertical Electrical Soundings(VES)were carried out on the area.The geoelectric sections revealed four to five layers and the longitudinal conductance varied from 0.11Ω^(-1)to 0.37Ω^(-1).The results of the investigation characterized the groundwater potential in the study area into low and moderate while the aquifer protective capacity into weak and moderate zones.The efficacy of resistivity and pumping test data in quantifying aquifer properties has been established in this study.The findings of this study shed light on the properties of ground water and aquifer protective capacity in the area,hence assist in the effective future groundwater resources exploitation.