In the northern reaches of the country, the Tibesti Mountains dominate the landscape of the surrounding Sahara Desert.
The Sahel, on the southern edges of the ever-expanding Sahara Desert, is a transition zone between the dry areas of the north and the tropical areas of the south. It receives very little rain, and most of the vegetation is a savanna growth of sparse grasses and shrubs.
The land rises into the Ennedi and Wadai plateaus along the eastern border with Sudan, where elevations reach near 2000 ft (609 m).
In the south, the forested land is nourished by the Chari and Logone Rivers. During the monsoon rains, Lake Chad often overflows, causing floods in the lowland depression of the south.
The highest point of Chad is Emi Koussi, which rises 11,204 ft (3,415 m); the lowest point of the country is the Djourab Depression at 524 ft (160 m).