Sedimentation
in Nile High Dam reservoir, 1987-1992, and sedimentary futurologic aspect
Mohamed ElDardir
National Inst. Oceanography and Fisheries, Aswan, Egypt |
The amount of sediments accumulated during the
period 1987 - 1992 in the Aswan High Dam reservoir is estimated to he 594 million m3. Field and laboratorial studies have been conducted on these
sediments and on the reservoir water. The grain size of sediments generally decreases from
south to north. This is generally a reflection of decrease in the flowing current
competency. The wanning of the water velocity is related to its approach to the High Dam
and to the development of back currents. It also changes in time from 0.06 to 0.89 cm/sec.
and during Nov. 1991 from 0.01 to 0.55 cm/sec. in Dec. 1992.
The organic matter content of the sediments varies from 0.8 and 4.0%. The lower values are
recorded in the main sedimentation zone. Generally, the lower content is parallel to the
higher sedimentation in the new southern Nile delta. This is due to the great clastic
influx diluting and probably inhibiting partially the organic matter development and
accumulation. With the increase of clastic accumulation, the sediments of the developed
delta get to be more brown.
Futurologically from the sedimentation data of the 5 years study interval 1987 - 1992,
together with published data prior this period, several sedimentary aspects are
anticipated in the reservoir. Considering several hydraulic and sedimentation factors, it
can he stated that a central silted part will appear on the surface with nearly complete
closure of the reservoir course near the mid. 21st century. This naturally will have its
consequencial sedimentary and geomorphic scenario which may give a background for future
development and prospects in the area and in Egypt as a whole.
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