Tunisia North-West is located in the extension of the Atlas mountain range which starts in southern Morocco and is divided into two rows facing east-west: the Tell Atlas following the Mediterranean coast and the Saharan Atlas fading arriving in Cap Bon and the Gulf of Hammamet to the sea.
Between the north coast and the valley of the Medjerda the Northern Tell is in the form of three lesser high rows, reaching the eastern coastline between Cape Blanc and Ghar El Melh, which are: the mountains of Khroumirie (rising to 1000 m), Nefza Mountains (rising to 600 m) and Mogods (rising to 500 m).
South of these mountains, the valley of the Medjerda is served by several wadis (Mellègue, Tessa, Beja, Zarga), then follows the hilly area of the Monts de Téboursouk between the city of El Kef and the Gulf of Tunis: the Higher Tell.Further south, the Tunisian Ridge stretches from west to east, from the Mountains of Tebessa to the Algerian border, to Cap Bon on the eastern coastline. It consists of mountain ranges alternating with steep plateaus and depressions: Djebel Chaambi (1544 m), Jebel Semmam (1314 m), Djebel Serj (1347 m), Jebel Zaghouan (1295 m), Djebel Sidi Abderrahmane in the Cap Bon (637 m).
Further south the Ridge, the Saharan Atlas is reduced to a few units scattered throughout the mountainous high steppes: Djebel Mghilla (1378 m), Jebel Selloum (1373 m).The region of high plains to the west and low plains to the east is crossed from west to east by a few isolated mountains: Djebel. Majoura (874 m), Djebel. Bouhedma (790 m), Djebel. Orbata (1165 m), Djebel. Asker (608 m).
South of Gafsa major depression Chotts mark the beginning of the horizontal part of the Sahara. South of the Chott to the ends of Dahar, the Grand Erg Oriental is extended.
The Dahar Mountains, the plains of Jeffara and El Ouara complete the landscape of southern Tunisia near the eastern Mediterranean with the island of Djerba.
Bioclimatic diversity, geological and morphological diversity combined with diversified soils (natural vegetation, rainfed crops and irrigated crops) is at the origin for the existence of a mosaic of genetically different soils.
These soils are faced with convergent natural factors (soft rock, steep slopes, sharp showers, sparse vegetation cover) that are responsible for the state of degradation. This is essentially the water and wind erosion, and salinization.
Three main regions are distinguished by the nature of their soils and modes of exploitation of their land.
It is divided into two parts, the North West and North East:
It is an agro-pastoral region, dominated equally by:
It is a pastoral region distinguished by the presence of numerous oases around the water points. It is characterized by: