DEVELOPMENT OF THE TUSHKA LAKES IN THE SOUTHWESTERN DESERT OF EGYPT

Egypt has a rapidly growing population now exceeding 60 million, concentrated in less than 5% of its land area. Like other arid and semi-arid nations, Egypt faces demand for development of new agricultural lands to support its increasing population. Overflow of Lake Nasser through a natural flood diversion in Egypt's southwestern desert has formed several new lakes that represent a newly available resource. We are delineating and simulating the natural development of Tushka Lakes resulting from rerouting of excess water from Lake Nasser, as well as projecting the future trend of lake growth.

The past gradual formation of the Tushka Lakes, changes in lake extent, and lake stages were analyzed by using a series of Landsat TM, MODIS, ASTER, and shuttle images as well as DTED, and ASTER derived elevation data. The first lake, which emerged in 1998 on the Tushka depression west of Lake Nasser, covered an area of 400 km², with a lake stage 172 m above mean sea level (AMSL). In 2000, excess water from Lake Nasser spread farther west, forming three additional lakes across a lowland area of 750 km², with lake stages decreasing from east to west (162 m AMSL at the second lake to 147 m at the fourth lake). A recently developed fifth lake to the northwest has a lake stage of 144 m AMSL. All five newly developed Tushka lakes cover a total area of 1,300 km², which is more than 20% of the area of Lake Nasser at maximum capacity. The surface water model was constructed and calibrated by adjusting routing parameters against lake stages identified for 1998-2002. The simulation based on the calibrated model suggests that lakes will continue to develop northwestward, toward a large depression including the Darb El-Arbeain area and the southern Kharga Oasis area, bounded by escarpment on the west. Further development of new lakes will generate significant recharge of fresh water to fossil groundwater in the underlying Nubian aquifer and will provide excellent water resources to the Darb El-Arbeain and the southern Kharga Oasis areas in the southwestern desert of Egypt.