DETERMINATION OF POTENTIOMETRIC SURFACE EQUATION AND HYDRAULIC GRADIENT OF ANAMBRA BASIN USING THREE-POINT SOLUTION TECHNIQUES

Abstract

The study aimed at determination of potentiometric surface equation and hydraulic gradient of Anambra Basin using three-point solution techniques derived from calculated from vertical electrical sounding (VES) data. The study adopted scalar triple vector techniques in order to model the groundwater piezometric surface within the basin. A three-point estimation method was also used to determine the hydraulic gradient, and other groundwater flow characteristics. Two types of VES curve has been interpreted: A-type and AK-type curves. The result of the hydraulic gradient shows that the formation plane inclined towards the recharge areas on Udi hill outcrop go beyond the basin, which is at a much higher elevation than the discharge area. The result also depicts that the hydraulic head dips 6⁰ from the Udi Cuesta towards the southwest region. Hydraulic gradient and hydraulic gradient vector were determined. The magnitude of the hydraulic gradient wasfound to be .004706 m/m, which depict the hydraulic potential for flow of the study area. The gradient of the direction of flow was 41.53^o in the direction of the northeast-southwest (NE-SW). The result also depicts that the kinematic porosity of the study area is 30% and the kinematic seepage velocity value determined across the area is 0.0175m/day. With the result obtained from the kinematic seepage velocity and the gradient of the direction of flow, the study concludes that the groundwater flow at any point in the region can be ascertained.