To the north, at the southern scarp of the Qattara Depression, the Egyp-
tian Nubian Aquifer System is interfaced with saline groundwater, while in
the east it borders the crystalline Basement Complex east of the Nile, which
is poor in groundwater. In the south, the Jebel-Uweinat-Safsaf-Aswan Uplift
Axis of the basement divides the Nubian Aquifer System between Egypt
and the Sudan. The Misaha Graben, however, links the two sections of the
Nubian Aquifer System. It is directed to the south and interrupts the uplift.
This graben is of minor importance as regards the recharge of the Egyptian
groundwater system from the wetter areas of the Sudan over a distance of
1,500 km, since the speed of the northward groundwater movement is only
3 cm/year. The groundwater of the Nubian System in Egypt, which is fossile
and whose potential recharge must necessarily be of local origin, dates from
the more humid climatic phases of the Late Pleistocene and the Holocene.
The groundwater of Wadi el-Gedid (New Valley) has an estimated age of
more than 20,000 years. It is difficult to measure its exact age with the 14C
and 36CL methods which have been applied so far, since the water lifted from
the boreholes does not usually originate from one single layer.