territory and flows north to form most of the border between the Far North and Chad. It eventually meets the Chari, which also rises in Chad. The Chari forms the remainder of the Chad-Cameroon border beginning at Kousséri before emptying into Lake Chad. These rivers all follow a tropical regime, fluctuating between high water in the wet season (May to September) and low water in the dry season (October to April). At the height of the dry season, many of the waterways disappear completely or else diminish to a mere trickle. The Logone all but disappears during the wet season. The low elevation of the Chad basin (200–500 metres) causes flooding during the wet season; the Logone is especially prone to this, and much of its basin is marshlike conditions along its length during the wet season. Even during the dry season, some of these remain, called Yaéré in Fulfulde. The El Beïd and Serbewel Rivers drain these marshy areas into Lake Chad. The Diamaré Plain, part of the Chad plain, occupies the southeastern third of the province. It is not as prone to flooding due to a number of inselbergs through the area. The province is also home to a number of lakes. The most prominent of these is Lake Chad. The lake was formed by a tectonic depression that has since been filled in by the area's rivers. However, over time, these rivers have deposited sediment as well, making Lake Chad nearly disappear in the past. This is a cause of concern, since when the Logone and Mayo Kébi flood, they meet. This diverts water from the Logone to the Kébi, and ultimately the Bénoué. This has caused some scientists to predict that in the future, river capture will occur, depriving Lake Chad of one of its major sources. Much of Lake Chad evaporates each year and must be replaced by rains from the wet season. Other lakes include Lake Fianga, which exists only during the seasonal flooding of the Logone; during the dry season, it is at best a swamp. Maga Lake, south of the town of the same name at the eastern border, is an artificial body of 6,000 square metres. It is known for its fishing. Relief Most of the Far North lies at a relatively low elevation. This lower-lying portion makes up part of the Chad Plain and slopes gently from about 500 metres