Chad has four bioclimatic zones. The northernmost Saharan zone averages less than 200 mm (8 inches) of rainfall annually. The sparse human population is largely nomadic, with some livestock, mostly small ruminants and camels. The central Sahelian zone receives between 200 and 600 mm (24 inches) rainfall and has vegetation ranging from grass/shrub steppe to thorny, open savanna. The southern zone, often referred to as the Sudanian zone, receives between 600 and 1000 mm (39 inches), with woodland savanna and deciduous forests for vegetation. Rainfall in the Guinea zone, located in Chad's southwestern tip, ranges between 1000 and 1200 mm (47 inches).
The country's topography is generally flat, with the elevation gradually rising as one moves north and east away from Lake Chad. The highest point in Chad is Emi Koussi, a mountain that rises 3100 meters (10,200 ft.) in the northern Tibesti Mountains. The Ennedi Plateau and the Ouaddaï highlands in the east complete the image of a gradually sloping basin, which descends towards Lake Chad. There are also central highlands in the Guera region rising to 1500 meters (4900 feet).
Lake Chad is the second largest lake in west Africa and is one of the most important wetlands on the continent. Home to 120 species of fish and at least that many species of birds, the lake has shrunk dramatically in the last four decades due to the increased water from an expanding population usage and low rainfall. Bordered by Chad, Niger, Nigeria, and Cameroon, Lake Chad currently covers only 1350 square kilometers, down from 25,000 square kilometers in 1963. The Chari and Logone Rivers, both of which originate in the Central African Republic and flow northward, provide most of the surface water entering Lake Chad.
Located in north-central Africa, Chad stretches for about 1,800 kilometers from its northernmost point to its southern boundary. Except in the far northwest and south, where its borders converge, Chad's average width is about 800 kilometers. Its area of 1,284,000 square kilometers is roughly equal to the combined areas of Idaho, Wyoming, Utah, Nevada, and Arizona. Chad's neighbors include Libya to the north, Niger and Nigeria to the west, Sudan to the east, Central African Republic to the south, and Cameroon to the southwest.
Chad exhibits two striking geographical characteristics. First, the country is landlocked. N'Djamena, the capital, is located more than 1,100 kilometers northeast of the Atlantic Ocean; Abéché, a major city in the east, lies 2,650 kilometers from the Red Sea; and Faya Largeau, a much smaller but strategically important center in the north, is in the middle of the Sahara Desert, 1,550 kilometers from the Mediterranean Sea. These vast distances from the sea have had a profound impact on Chad's historical and contemporary development. The second noteworthy characteristic is that the country borders on very different parts of the African continent: North Africa, with its Islamic culture and economic orientation toward the Mediterranean Basin; West Africa, with its diverse religions and cultures and its history of highly developed states and regional economies; Northeast Africa, oriented toward the Nile Valley and Red Sea region; and Central or Equatorial Africa, some of whose people have retained classical African religions while others have adopted Christianity, and whose economies were part of the great Zaire River system. Although much of Chad's distinctiveness comes from this diversity of influences, since independence the diversity has also been an obstacle to the creation of a national identity.
Lake Chad, located in the southwestern part of the basin at an altitude of 282 meters, surprisingly does not mark the basin's lowest point; instead, this is found in the Bodele and Djourab regions in the north-central and northeastern parts of the country, respectively. This oddity arises because the great stationary dunes (ergs) of the Kanem region create a dam, preventing lake waters from flowing to the basin's lowest point. At various times in the past, and as late as the 1870s, the Bahr el Ghazal Depression, which extends from the northeastern part of the lake to the Djourab, acted as an overflow canal; since independence, climatic conditions have made overflows impossible.
North and northeast of Lake Chad, the basin extends for more than 800 kilometers, passing through regions characterized by great rolling dunes separated by very deep depressions. Although vegetation holds the dunes in place in the Kanem region, farther north they are bare and have a fluid, rippling character. From its low point in the Djourab, the basin then rises to the plateaus and peaks of the Tibesti Mountains in the north. The summit of this formation--as well as the highest point in the Sahara Desert--is Emi Koussi, a dormant volcano that reaches 3,414 meters above sea level. The basin's northeastern limit is the Ennedi Plateau, whose limestone bed rises in steps etched by erosion.
East of the lake, the basin rises gradually to the Ouaddaï Highlands, which mark Chad's eastern border and also divide the Chad and Nile watersheds. Southeast of Lake Chad, the regular contours of the terrain are broken by the Guéra Massif, which divides the basin into its northern and southern parts.
South of the lake lie the floodplains of the Chari and Logone rivers, much of which are inundated during the rainy season. Farther south, the basin floor slopes upward, forming a series of low sand and clay plateaus, called koros, which eventually climb to 615 meters above sea level. South of the Chadian border, the koros divide the Lake Chad Basin from the Ubangi-Zaire river system.
Chad's major rivers are the Chari and the Logone and their tributaries, which flow from the southeast into Lake Chad. Both river systems rise in the highlands of Central African Republic and Cameroon, regions that receive more than 1,250 millimeters of rainfall annually. Fed by rivers of Central African Republic, as well as by the Bahr Salamat, Bahr Aouk, and Bahr Sara rivers of southeastern Chad, the Chari River is about 1,200 kilometers long. From its origins near the city of Sarh, the middle course of the Chari makes its way through swampy terrain; the lower Chari is joined by the Logone River near N'Djamena. The Chari's volume varies greatly, from 17 cubic meters per second during the dry season to 340 cubic meters per second during the wettest part of the year.
The Logone River is formed by tributaries flowing from Cameroon and Central African Republic. Both shorter and smaller in volume than the Chari, it flows northeast for 960 kilometers; its volume ranges from five to eighty-five cubic meters per second. At N'Djamena the Logone empties into the Chari, and the combined rivers flow together for thirty kilometers through a large delta and into Lake Chad. At the end of the rainy season in the fall, the river overflows its banks and creates a huge floodplain in the delta.
The seventh largest lake in the world (and the fourth largest in Africa), Lake Chad is located in the sahelian zone, a region just south of the Sahara Desert. The Chari River contributes 95 percent of Lake Chad's water, an average annual volume of 40 billion cubic meters, 95% of which is lost to evaporation. The size of the lake is determined by rains in the southern highlands bordering the basin and by temperatures in the Sahel. Fluctuations in both cause the lake to change dramatically in size, from 9,800 square kilometers in the dry season to 25,500 at the end of the rainy season. Lake Chad also changes greatly in size from one year to another. In 1870 its maximum area was 28,000 square kilometers. The measurement dropped to 12,700 in 1908. In the 1940s and 1950s, the lake remained small, but it grew again to 26,000 square kilometers in 1963. The droughts of the late 1960s, early 1970s, and mid-1980s caused Lake Chad to shrink once again, however. The only other lakes of importance in Chad are Lake Fitri, in Batha Prefecture, and Lake Iro, in the marshy southeast.
The soudanian region is predominantly savanna, or plains covered with a mixture of tropical or subtropical grasses and woodlands. The growth is lush during the rainy season but turns brown and dormant during the five-month dry season between November and March. Over a large part of the region, however, natural vegetation has yielded to agriculture.
Area - comparative: slightly more than three times the size of California
Coastline: 0 km (landlocked)
Maritime claims: none (landlocked)
arable land: 3%
permanent crops: 0%
permanent pastures: 36%
forests and woodland: 26%
other: 35% (1993 est.)
Irrigated land: 140 km² (1993 est.)
Environment - current issues: inadequate supplies of potable water; improper waste disposal in rural areas contributes to soil and water pollution; desertification
Environment - international agreements:
party to: Biodiversity, Climate Change, Desertification, Endangered Species, Nuclear Test Ban, Ozone Layer Protection, Wetlands
signed, but not ratified: Law of the Sea, Marine Dumping
Chad has seen significant reduction in certain wildlife species in recent decades. For example, elephant herds were substantial in number as recently as 1970 with an estimated population of 300,000; however, by 2006 the number has dwindled to about 10,000. The African elephant nominally has governmental protection, but the implementation practices of the government (backed with certain EU help) has been insufficient to stem the slaughter by poachers
Another problem facing Chad today is the growing Sahara Desert. Desertification is a huge issue in all Saharan countries