The Lake Chad basin covers a surface area of 2, 300, 000 km2. It is divided in secondary endoreic basins whose the largest is the one of the Lake Chad (between 6° and 20° N, 7° and 25° E), which is a relic of a vast lakeside surface area, which is equivalent to the Caspian Sea, which existed 600 years AC. The Lake Chad is fed by the Chari and Logone rivers. The Logone slope occupies close to 700,000 km2 and presents vast plains with monotonous relief, which are invaded by water during rise in the water level. In the western part, another tributary, the Komadogou Yobé also crosses a marshy plain. The Lake Fitri which is an endoreic basin fed by the Batha is a miniature reply of the Lake Chad. It is located in the far south west of the Batha division. The size of the Lake Fitri varies from 45km2 at low water level to 600km2 at the highest water level. The flooded surface area can reach 1,000 km2. The water level varies from 280 to 290 mm above the level of the sea. It reaches its maximum depth in late September: 1.5-2.00 m. Since 1900, the lake Fitri dried up thrice or once each period of thirty years, the last drying up coincided with the 1984- 1985 drought. It is the terminal unit of the Batha river flow and a few local watercourses. According to the Fitri’s Sultan, El hadj Akélélé, the Lake’s name comes from this position, which is a resting point for water from Batha. Finally, the spillage of the left bank of the Logone river originates the Toubouris lakes, which are drained downstream by the Mayo Kebi, affluent of the Benoué river. This connection between Chad and Niger basin is considered as belonging to the Niger basin. We are unable to explain in detail various wetlands of the Chadian basin for which, apart from the lake, we do not have enough data.
The Lake Chad is shared by Chad, Niger, Nigeria and Cameroon. It is located between 12° and 14° 20 N, 13° and 15° 20 E. The sailing area is situated at the altitude of 283 m.
According to climate fluctuations, the Lake Chad occupies part or whole of the endoreic basin estimated at 25,000 km2. The Chadian basin covers 2,300,000 km2 between 5° and 25° N, 7° and 25°E. Presently, feeding basins are Chari and Logone, which are located in the southern part of the basin and only stand for 25% of the whole size of the basin.
The Lake Chad occupies a part of an erg oriented SE-NW. Its eastern shore is surrounded by dunes. The relief is extremely flat except Hadjer el Hamis rocks from volcanic origin. It displays three major types of landscape.
- Many islands located in the eastern bank, which match the emerged summit of immerged erg dunes.
- Rooted or floating vegetation islands called bench islands (mostly Cyperus papyrus and water reeds).
- Areas of open water.