14C ages of confined groundwater from the Gwandu aquifer, Sokoto Basin, northern Nigeria

Abstract

Groundwater samples from the confined aquifer of the Gwandu Formation, Sokoto Basin, northern Nigeria were dated by the 14C method. Conventional ages from 3000 to 30,000 yr. B.P. were determined. Hydroisochrons (i.e. lines of equal age) were constructed. From these the velocity of the groundwater was calculated and the direction of flow determined. A low rate of recharge from 10,000 to 20,000 yr. ago, comparable to observations in the Central Sahara, was established. Because values for recently recharged groundwater are not available it is not possible to calculate the present recharge. © 1980, All rights reserved.