Chad is a large country in Central Africa, and like many places, its rivers are super important! They provide water for people, animals, and plants, and they help shape the land. Rivers are like the veins of the Earth, carrying water from higher places down to lakes or oceans.
Chad exhibits two striking geographical characteristics. First, the country is landlocked. 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.
Although Chadian society is economically, socially, and culturally fragmented, the country's geography is unified by the Lake Chad Basin. Once a huge inland sea (the Pale-Chadian Sea) whose only remnant is shallow Lake Chad, this vast depression extends west into Nigeria and Niger.
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. Of the Kanem region create a dam, preventing lake waters from flowing to the basin's lowest point.
Although vegetation holds the dunes in place in the Kanem region, farther north they are bare and have a fluid, rippling character. 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.
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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. 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.
Permanent streams do not exist in northern or central Chad. Following infrequent rains in the Ennedi Plateau and Ouaddaï Highlands, water may flow through depressions called enneris and wadis.
The rivers in Chad are organized into different groups based on where their water eventually ends up. Some rivers flow into huge lakes within Chad, while others connect to much larger river systems that eventually reach the ocean. Even though Chad is far from the ocean, some of its rivers are part of a massive system that reaches the Atlantic Ocean!
The Mayo Kébbi river is a key river in southwestern Chad. It flows out of Chad and eventually joins the Benue River in Nigeria. The Benue River then flows into the mighty Niger River, which finally empties into the Gulf of Guinea on the Atlantic coast.
Lake Chad and its Tributaries
Lake Chad is a very important lake in Central Africa, and many rivers in Chad flow into it. This lake is like a giant oasis in the semi-desert region, providing water for millions of people and animals across several countries.
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The Chad Basin covers an area of about 1×106 km2 (390,000 sq mi), and is injected by the Chari, Logone, and Yobe Rivers.
The water supply of the lake is seasonal. Most of the precipitation comes from the Adamawa Plateau in the south of the basin, which is transported to the lake basin through the Chari River and the Logone River. The two contribute 95% of the total inflow of Lake Chad, while the Yobe River only contributes less than 2.5%.
The lake seeps through the underground to the lowest point of the Chad Basin, the Bodélé Depression, approximately 480 km (300 mi) northeast of Lake Chad, with the deepest point reaching an elevation of only 155 m (509 ft) above sea level. This takes away most of the salinity and maintains the low salinity of Lake Chad.
The water volume of most large lakes in Africa depends on rainfall and evaporation, which means that temperature and precipitation are crucial for regulating the water balance of these bodies of water, and any fluctuations can cause significant changes in their water level and area.
Lake Chad is a shallow inland lake, and the rainfall in the Chad basin is very sensitive to small changes in atmospheric circulation, so the surface area of Lake Chad is greatly affected by climate change.
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Dry climate due to vegetation loss from overgrazing and deforestation and large-scale irrigation projects that diverted water from the rivers that feed the lake are the main reasons for the shrinkage of Lake Chad.
The Atlantic multidecadal oscillation and the El Niño-Southern Oscillation have affected precipitation in the Sahel region.
In 1870, the area of Lake Chad was about 28,000 km2 (11,000 sq mi). The lake was able to flow out of the Bahr el-Ghazal during the rainy season. At the turn of the 20th century the area of Lake Chad shrank briefly, and reached a new high in the middle of the 20th century and overflowed from the Bahr el-Ghazal again.
A major drought started in the Sahel region in the late 1960s and caused severe damage in 1972 and 1984. From June 1966 to January 1973, the area of Lake Chad shrank from 22,772 to 15,400 km2 (8,792 to 5,946 sq mi), further shrunk to 4,398 km2 (1,698 sq mi) in 1975, and only 1,756 km2 (678 sq mi) in February 1994. Since then, the area of Lake Chad has entered a relatively stable stage with a slight increase.
From 1995 to 1998, it fluctuated within the range of 1,200 to 4,500 km2 (460 to 1,740 sq mi).
The wetland plants in the south mainly include cyperus papyrus, etc. Reeds mainly grow in the north where the salinity is high, and the floating plant pistia sometimes covers large areas of open water.
The lake has been designated an Important Bird Area (IBA) by BirdLife International.
It is permanently or seasonally inhabited by hundreds of species of birds such as northern shoveler, Egyptian goose and marabou stork. It is an important wintering ground for European anatidae and wading birds.
The once common large mammals include red-fronted gazelle, dama gazelle, patas monkey, striped hyena, cheetah and caracal, while African elephant, otter, hippopotamus, sitatunga and kob are distributed in the wetlands.
The entire Chad Basin has 179 species of fish, of which 127 are the same as the Niger River Basin, 85 are the same as the Nile River Basin, 47 are the same as the Congo River Basin, and 84 fish species are distributed in the lake. This makes it a rich fishing ground for communities across Nigeria, Niger, Chad, and Cameroon.
There are more than 30 million residents in the Chad Lake Basin. There are more than 70 ethnic groups around the lake, most of whom are distributed on the south bank, where the population density exceeds 100/km2 (260/sq mi). They rely on the water source of Chad Lake for irrigation, breeding, animal husbandry and drinking.
Local self-sufficient crops include sorghum, maize, finger millet, beans, and vegetables. Gourd is widely planted for making utensils. The collection of forest products such as gum arabic, honey, beeswax, and firewood is of great significance in the region.
However, the reduction in forest area has had a negative impact on the production of these products, and the explosive growth of cattle herds has exacerbated this impact. Cattle are the most important livestock raised, as well as poultry, goats, sheep, camels, horses, and donkeys.
Fishing has traditionally been the most important economic activity for the people of the lake area, which almost ceased during drought periods and only resumed in the mid-1990s. Most fishing products are dried, pickled, or smoked. The natron produced in the depression on the northeast bank of the lake has long been of significant economic significance. Traditionally, it has been excavated in blocks and transported across the lake to enter the Nigerian market.
Since the drought in the 1970s, the soil that can be planted without irrigation and fertilization has been exposed at the bottom of the lake, and it has been reclaimed as a polder for planting maize, cowpea, rice, sorghum and other crops.
Farmers have shifted from planting mainly dry crops, such as wheat, to rice with high water demand, resulting in more serious soil salinization and water eutrophication.
The adverse effects of reduced water sources on fishing, farming, and herding outweigh the benefits of new land from the receding waters.
Since 1970, five countries in the southern part of the basin have constructed numerous water conservancy projects in the upper reaches of the Chari River, Logone River, and Yobe River to intercept river water, resulting in a sharp decrease in the amount of water entering the lake.
The average annual inflow of the Chari River and the Logone River from 1970 to 1990 was only 55% of that from 1950 to 1970. Since the 1980s, one-third of the water in the Chari River and the Logone River has been diverted and intercepted by the Central African Republic located upstream for agricultural irrigation and hydroelectric power generation.
The dams built on the upper reaches of the rivers entering the lake changed the time and scope of seasonal floods and disrupted the migration of fish, resulting in a sharp reduction in the populations of Alestes baremoze and Nile perch, the main catches of Lake Chad, and a significant reduction in the catch.
At the same time, the conflicts between countries and ethnic groups competing for water and land are also escalating.
Cameroon, Niger, Nigeria, and Chad established the Lake Chad Basin Commission on 22 May 1964. The Central African Republic joined in 1996, and Libya joined in 2008. The headquarters of the committee is located in N'Djamena, Chad.
The Chari River is the most important river that flows into Lake Chad. It provides about 90% of the lake's water! The Chari River starts in the Central African Republic and flows northwest through Chad.
The Chari River, or Shari River, is a 1,400 kilometres (870 mi) long river, flowing in Central Africa. It provides 90 percent of the water flowing into Lake Chad. The watershed of the river covers 548,747 square kilometres (211,872 sq mi). As of 2016, Chad remains one of four countries where Guinea worm disease remains endemic. The river supports an important local fishing industry.
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.
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.
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 Lake Chad Basin embraces a great range of tropical climates from north to south, although most of these climates tend to be dry.
Apart from the far north, most regions are characterized by a cycle of alternating rainy and dry seasons. Great air masses--a maritime mass over the Atlantic Ocean to the southwest and a much drier continental mass.
The Saharan region covers roughly the northern third of the country, including Borkou-Ennedi-Tibesti Prefecture along with the northern parts of Kanem, Batha, and Biltine prefectures.
In northern Biltine Prefecture, a region called the Mortcha plays a major role in animal husbandry. Dry for nine months of the year, it receives 350 millimeters or more of rain, mostly during July and August.
The semiarid sahelian zone, or Sahel, forms a belt about 500 kilometers wide that runs from Lac and Chari-Baguirmi prefectures eastward through Guéra, Ouaddaï, and northern Salamat prefectures to the Sudanese frontier.
The humid soudanian zone includes the southern prefectures of Mayo-Kebbi, Tandjilé, Logone Occidental, Logone Oriental, Moyen-Chari, and southern Salamat. Between April and October, the rainy season brings between 750 and 1,250 millimeters of precipitation.
Temperatures are high throughout the year. The soudanian region is predominantly savanna, or plains covered with a mixture of tropical or subtropical grasses and woodlands.
Lake Chad was once one of Africa’s largest freshwater lakes, spanning an area roughly the size of North America’s present-day Lake Erie. With a warming climate, decreasing rainfall, and increasing demands from an increasing population, Lake Chad has been shrinking over the last several decades.
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