High water losses If the calculations of some Egyptian experts are correct,
the High Dam led to Egypt losing water instead of gaining it. The following
are the most important causes of the heavy water losses that are occurring:
1. Evaporation and seepage in the storage lake According to reliable Egyptian
sources (e.g. Shalash 1977) the annual loss in the lake itself is not 10 billion
m3
, as formerly believed, but should rather be calculated at 16 billion m3
. The
calculations are based on the assumption that the annual evaporation is 2,754
mm/m3
, which means that if the average size of the lake surface is 5,500
km2
, the loss of water through evaporation alone must be 15.147 billion m3
per year. According to official Egyptian publications the water surface in the
1980s was 6,000 km2 (CAPMAS 1987: 64) and the water loss through seepage
alone into the coarse-grained Nubian Sandstone at the oscillation line along
the banks of the lake was 1 billion m3 (CAPMAS 1987: 72).