ABSTRACT
The extremely arid conditions in the Sahara suggest that there is currently no recharge to the Saharan aquifers. This assumption is based on work carried out on the North Western Sahara Aquifer System flow model (NWSAS). The model reproduces the natural non-influenced reference state of the aquifer for the year 1900. An attempt is made to reproduce this state after a 10,000 year simulation, starting from the beginning of the Holocene period (10,000 BP), during which zero recharge is assumed to occur. The initial conditions are based on a pre-Holocene humid climate, which has filled the reservoirs up to their overflow level. From 10,000 BP to the present, the system behaves purely as a depletion regime. The results of the model indicates that, the present zero recharge hypothesis is plausible in the southern part, which, according to the model, contributes a relatively small quantity to the recharge of the NWSAS, but it is not the case for the northern part, notably on the Saharan Atlas outcrops, which provide the main share of the present recharge. This suggests that there has been a high recharge rate for the whole Holocene period as well as for the present, otherwise, it is impossible to replicate the observed behaviour of the aquifer system as it is seen today.
