The 3 Chotts of southern Tunisia
On more than 350 km, between the Algerian border and Gabes, three Chotts of different sizes cut Tunisia in two:
– To the west, Chott el Gharsa, the smallest (600 km2), separates Tozeur from mountain oases.
– The largest, most spectacular, Chott el Djerid, with an area of 4,600 km2
– In the East, Chott el Fejaj, eastern extension of Chott el Djerid (800 km2)
On a map of Tunisia, you can not miss them. They are often represented as lakes, all in blue.
Other Chotts exist, much smaller.
A show constantly renewed
No vegetation grows on these huge surfaces made of clays, salts and gypsum.
In the hot season, the salts crystallize and form a translucent white layer, hardened by the sun. A dazzling spectacle that only the mountains stop. A land of mirages under the burning rays. Throughout the day, an extraordinary play of light, especially at sunset.
In the rainy winters, the Chotts are transformed into an amazing sea. When the water gradually recedes, revealing a sparkling white salty surface, one might think to be on the ice floe.
The sand winds of spring give them a local color, more or less ocher depending on the humidity.
Along the road crossing the Chott el Djerid, the dug channels reveal waters with multiple colors: blue, green, but also red, pink, purple … Colors changing over the day, but also depending on the side of the road .
The Chotts are filled with winter rains, runoff from nearby mountains, but also and especially groundwater. A superficial sheet near the surface. but also deep aquifers – from 300 m in the Chott El Fejaj to 2500 m in the Chott el Djerid – which constitute large deposits of water more or less salty.
These waters, mixed with sand, clay and salt, arise locally from artesian springs. They then form small reliefs with solid elements. Small reliefs that become by far a large hillock under the effect of the mirage.
The different amounts of water do not resist the heat of the sun’s rays on such a flat surface. Evaporation, 7 times greater than the volume of the inputs, quickly gives the Chotts their cracking face to crystallized salts.