Physical Geography

Four major physical regions make up Tunisia: the Atlas Mountains in the north; the central plateau; the Sahel, or eastern coastal plain; and the Sahara in the south.

The Atlas Mountains of Tunisia, part of the great North African chain, consist of the wooded Tell Atlas and the Saharan Atlas ranges. Generally low in elevation, they descend gradually to the northeast and end at Cape Blanc and Cape Bon. Tunisia's highest point, nearly 5,100 feet (1,550 m), is in the Saharan Atlas near the Algerian border. Between the two ranges lies the fertile valley of the Medjerda, Tunisia's only river with a year-round flow.

The central plateau lies south of the Atlas ranges at an elevation of 1,000 to 2,500 feet (300 to 760 m). There are a few hills and low mountains, but much of the region is a flat steppe sloping gently toward the east coast. The few rivers that cross the plateau flow only after occasional heavy rains.

The Sahel begins near Bizerte in the far north and extends southward to the vicinity of Sfax. It is a flat, low plain with a few salt flats, and is interrupted only by the northeastern tip of the Saharan Atlas.

The Sahara, beginning at about the latitude of the Gulf of Gabès, is a large, arid region occupying roughly half of Tunisia. West of Gabès is a broad depression lying as much as 70 feet (20 m) below sea level and containing several intermittent salt lakes, or chotts. Farther south is the Great Eastern Erg, a vast region of dunes and drifting sand. Separating this region from the coast are the barren Ksour Mountains, which stretch southward from Gabès into Libya.

Northern Tunisia has a typically Mediterranean climate with hot, dry summers and mild, moderately rainy winters. Temperatures in the coastal areas average near 80° F. (27° C.) during summer and 55° F. (13° C.) in winter. Precipitation totals roughly 15 to 30 inches (380 to 760 mm) annually, depending on location. Lower temperatures and larger amounts of precipitation, including snow, occur in the Atlas Mountains. South of the mountains the climate becomes progressively hotter and drier, reaching an extreme in the Sahara. Little or no rain occurs in the Sahara, and temperatures there often exceed 110° F. (43° C.) during summer.

A very hot, dry wind from the Sahara, locally called a chili, occasionally blows northward across the country, especially during spring.