The fact that this negative balance has not yet been fully
felt in Egypt is due to two different factors:
• The Sudan is not yet fully able to utilize its share of the Nile water of 18.5
billion m3
 annually, so that Egypt can make use of a proportion of it.
• In the 1980s a climatic dry phase was prevailing in Africa, which caused
the Nile run-off to fall under its mean for several years and reduced the
surface of Lake Sadd el-Ali, so that evaporation and seepage rates were
relatively low.
The uncontrollable rise of the storage-lake water table (see Figure 6.3) When
in 1975 the water table of the Sadd el-Ali storage lake reached 175 m above
sea level, while the maximum permissible level is 182 m above sea level,
the situation was considered alarming and the construction of the Toshka
Canal (see Figure 6.1) as a spillway was started in great haste and without
the necessary preliminary studies. It was completed in 1980 and connected
to a natural reservoir with a storage capacity of 120 billion m3
. Through this
canal water should be conducted in an emergency from a bay in the west of
Lake Sadd el-Ali, about 250 km south of the dam, over a distance of about
25 km to the Toshka Depression in the Western Desert, some 100 km south
of the New Valley oases