Chad, Lake at English => English (The Britannica Concise) Of Explained:
Lake, W Africa. Located at the juncture of the boundaries of Nigeria, Niger, and Chad, its S part forms the N extent of Cameroon. Fed by the Chari River, its area varies from year to year, usually ranging between 3,800 and 9,900 sq mi (9,850-25,600 sq km). In the 1970s and '80s it dropped to about 1,500 sq mi (3,900 sq km), a change apparently related to the desertification of the surrounding Sahel region. The lake was first explored by Europeans in 1823.