Aquifer flow unit analysis using stratigraphic modified Lorenz plot: a case study of Edem, eastern Nigeria

Abstract

Abstract The present study aimed at evaluating aquifer flow unit of Edem by means of stratigraphic modified Lorenz plot (SMLP) employing vertical electrical sounding. The results from the vertical electrical sounding field data analysis shows that resistivity and thickness of the aquifer layer ranges from 34.8 to 67561.2 Ωm and 29.7 to 147.6 m respectively having an average aquifer thickness value of 70.248 m. Aquifer layer permeability and fractional porosity range from 1.5942 to 1657444 mD and 0.2558 to 0.3265 respectively. Results from stratigraphic modified Lorenz plot delineated a total of eight flow-units, FU1, FU2, FU3, FU4, FU5, FU6, FU7, and FU8 for the aquifer units and three different process speeds. Aquifer flow units FU1, FU3, and FU8 fall within the speed zone, flow units FU5 and FU7 are associated with the baffle zone, while flow units FU2, FU4, and FU6 make up the barrier zone of the process speeds. The aquifer flow unit speed ranges from 265406.4 to 5076424 mD with an average value of 826310.2 mD. The contour maps generated revealed the western part of the study area as characterized with high values of aquifer storage capacity and aquifer flow capacity with the highest storage and flow capacities delineated along the northwestern part of the study area. The Dykstra-Parsons coefficient of 0.99 revealed an extremely heterogeneous aquifer in the study area. This flow unit analysis will serve as a guide in accurate design and management of the aquifers.

Keywords

• Aquifer storage capacity
• Flow unit
• Fractional porosity
• Permeability
• Heterogeneity