ABSTRACT

ABSTRACT: The mechanisms and the rate of recharge have been assessed in the surrounding of Timbuktu, Mali, by the use of chloride budgets. The area has a Sahelian climate and receives a mean rainfall of 225 mm. Two clusters of wells and three soil profiles were sampled for the purpose. The well cluster in the vicinity of the river Niger showed effects of induced infiltration. For the well cluster further away from the river and near the town of Timbuktu a mean recharge of 3.7 mmwas found. The recharge occurs preferably in depressions between dunes due to channeling by soil crusts on the slopes of the dunes. Occasional contents of high nitrate contents in soil and groundwater may be due to N-fixation by cyano-bacteria found on the soil surface.