Sabkhas of
Qattara depression, Western Desert, Egypt :A Survey.
Abdou El Bassyony
Qattara Project Authority, Cairo, Egypt |
The sabkhas of the Qattara Depression are
considered a terra incognita. They have been formed by evaporation of ground water
seepages. The modern estimate of seepage water into the depression is equivalent to the
total evaporation of the water from the sabkhas.
To estimate the total evaporation and its relationship to sabkha formation, intense field
work was conducted. Crossing the main body of the sabkhas to classifying them into
different categories, was the main task of this first handled survey. Aerial photos,
photomozaics and Landsat images were also used for these aims. The sabkhas are here
divided into seven types related to the evaporation rates. These are:
1. Salt floes,
2. Hard rough salt crust,
3. Hard salt crust,
4. Salt marsh,
5. Sabkha with bushes,
6. Sabkha covered with sand and
7. Salt plateau.
Chemical and sand, grain-size analyses have been conducted on these sabkha types. The
relationship between the common nature of the sabkhas and the salinity of the water brines
indicates their mutual intimacy. The origin of these waters is considered to be partly
rain-water and mainly ground-water from the Moghra aquifer in eastern Qattara and ground
-water from the Nubian Sandstone in western Qattara. The Middle Miocene ground-water
shares the Nubian aquifer in the Siwa and Qara Oases.
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