Niger River

Category: Inland Aquatic Biomes.

Geographic Location: West Africa.

Summary: Largest river in western Africa, the Niger waters 10 nations and supports up to 100 million people—but its flow, habitats, and native species are at risk from a host of natural and human-made threats.

West Africa’s Niger River is the third-largest river on the continent, at 2,600 miles (4,180 kilometers) long, and it has the ninth-largest drainage basin in the world, at approximately 808,000 square miles (nearly 2.1 million square kilometers). The Niger has a rambling water course that runs through seven countries, most of which is in Nigeria. The river originates just 150 miles (240 kilometers) from the Atlantic Ocean, and flows for 800 miles (1,287 kilometers) into the Sahara Desert before forming the largest delta of Africa in the Gulf of Guinea. More than 200 fish species are found in the river, 20 of which are found exclusively in this region. The Niger River has another delta at the midrange of its course, referred to as the Inner Niger Delta.

The Niger originates from the landward side of the Fouta D’jallon highlands in southern Guinea and emerges from a deep ravine about 2,800 feet (about 800 meters) below sea level to the Tembi River. Within a short distance of flow, the Tembi is joined by two rivulets, the Tamincono and Falico, which are joined by some tributaries to form the Niger. Instead of flowing to the Atlantic Ocean, the river flows in the opposite direction into the Sahara Desert, cutting through Guinea, Mali, Niger, and the Benin Republic until it finally empties into the Gulf of Guinea in Nigeria. All told, the river has about 14 tributaries

The Niger basin encompasses parts of 10 countries: Algeria, Benin Republic, Burkina Faso, Cameroon, Chad, Côte D’Ivoire, Guinea, Mali, Niger, and Nigeria. Geographically, the river is divided into four sub-basins: the upper Niger Basin, the Central Delta, the middle Niger Basin, and the Lower Niger Basin.

Temperatures in the region range from an average of 63 degrees F (17 degrees C) in January to 94 degrees F (34 degrees C) in April and May, with lows dipping to 62 degrees F (16 degrees C) in winter, and highs rising to 106 degrees F (41 degrees C) in April. Mean annual precipitation decreases northward, from more than 160 inches (4,100 millimeters) in the delta area to less than 10 inches (250 millimeters) in Timbuktu. Rainfall declines from about 90 inches (2,300 millimeters) near the Niger’s source to 10 inches (less than 250 millimeters) in the bend between Timbuktu and Bourem, then increases as the river flows southward to about 160 inches (4,000 millimeters) at its mouth.

Biodiversity

The river harbors 36 families and nearly 250 freshwater fish species, including catfish, African carp, Nile perch, tiger fish, barbel, lungfish, and tilapia. Twenty of these fishes are found nowhere else on Earth (they are endemic to this biome), and 11 of the 18 families of freshwater species are endemic to Africa and represented in the river. One of these is Gobiocichla wonderi, a small cichlid with an elongated body.

The inland wetlands and floodplains support a wide variety of animals such as manatees, crocodiles, hippopotamuses, mongoose, African otter, snakes, lizards, elephants, lions, and leopards. Various other species, such as antelopes and monkeys, live in many parts of the river basin, and buffaloes and jackals have more limited ranges.

The Inner Niger Delta serves as a major gathering spot for migratory birds from Europe. Some of these include black-crowned cranes, Egyptian plover, rock pratincole, goliath heron, and spur-winged goose.

The coastal delta of the river in Nigeria is the largest in Africa, and is rich in plant species, including mangroves that form the largest remaining tract in Africa. These mangroves, primarily the red and white types but with other mangrove species represented as well, cover an area of about 4,054 square miles (1 million hectares). The moist woodland savanna vegetation of the upper basin gives way to progressively drier savanna and semidesert conditions in Mali, where the river bends at the edge of the Sahel-Sahara Desert. After the river turns southward, it flows through increasingly moist and lush savanna, and through tropical forest near Onitsha. In the delta, the swamp forest contains many oil palms where the water is fresh, and mangroves where the water is brackish.

Human Influence

The River Niger is the source of water and livelihood to more than 100 million people. Fishing is an important activity, supplying food to regions along and beyond the river’s course. The floodplains of the delta support agriculture and animal rearing. Dams built upstream provide water for agriculture and hydroelectric power for two countries. The discovery of crude oil and natural gas in the river’s coastal delta in 1962 has led to the mixed economic fortunes of Nigeria. The river is threatened by climate change, increasing temperatures, siltation, repercussions from dam construction, pollution, and desertification.

Herders, mainly the Fulani, depend on the river for water and on its floodplains for dry season pastures for their cattle, sheep, and goats. Water from the river supports agriculture in all the countries the river runs through, enlivening such crops as rice, wheat, cotton, and sugarcane in Mali; millet and sorghum in northern Nigeria; and yams, cocoyams, and maize in the lower regions of Nigeria.

Several dams were built to foster irrigation on the Niger and along its tributaries. Other dams are proposed, built, or underway in Guinea, Mali, and Niger Republic. The river has been used as a source of hydroelectric power in Nigeria. Among the power-generating dams are Kainji, the largest on the river, providing Nigeria with about one-sixth of the nation’s hydroelectric power.

The Niger also is used for navigation, with about 3,106 miles (5,000 kilometers) of the river and its tributaries navigable. The Niger is a center of energy resources, including petroleum and natural gas reserves. Including the delta, the Niger River system is the setting for most of the hydrocarbon extraction industry that forms some three-quarters of Nigeria’s total income and 95 percent of its foreign exchange earnings.

Environmental Concerns

In spite of the river’s significance, it faces serious environmental threats, the most significant of which is related to rising temperatures from climate change. In June 1985, the Niger completely dried up for the first time in history in Malanville, Benin Republic, and in Niamey, Niger Republic. Water volume and river flow has been very low since 1984, and was reported to lose about two-thirds of its flow at the Inner Delta between Segou and Timbuktu, Mali, due to seepage and evaporation.

Rising temperatures due to climate change will result in higher evaporation rates, shrinkage of natural wetlands, and reduction of fish diversity. Warming temperatures will increase both torrential rainfall and runoff, which will transport heavier loads of silts and sediments, leading to increased turbidity in the river and its tributaries, and degradation of water quality.

The derease in water has caused regional destabilization and conflict. A 2011 report by the United States Agency for International Development (USAID) analyzed the effects of climate change on the Niger River, and found an increase in conflict between the citizens and the state over water flow management. Other reports found the effects of climate change on the river have caused wider conflicts within the region, however, the USAID report did not support those conclusions.

Other environmental threats include unsustainable agricultural practices, overgrazing, bush fires, and deforestation, all of which remove vegetation cover. Oil spills have resulted in the death of large areas of mangrove trees, a development that has allowed invasive species such as the nipa palm. Cover of this species increased from 2007 to 2017 by nearly 700 percent. Mangrove cover decreased by 12 percent during this period.

The Niger Basin Authority (NBA) has observed mining activities and deforestation around the Fouta D’jallon area, leading to pollution and sedimentation of the riverbed. Other threats include pollution from industrial wastes, and the recent proliferation of water hyacinth and water lettuce on the waterways, which steal oxygen from fish and other animals. Climate aridification and desertification will likely catalyze the rate of vegetation loss along the riverbanks, thereby increasing siltation still more.

In addition, the building of dams on the river for hydroelectric power and irrigation will also greatly reduce the flow of the river. The NBA and other authorities have their work cut out for them.

Bibliography

Gleick, Peter H. The World’s Water, 2000–2001: The Biennial Report on Freshwater. Island Press, 2000.

Goulden, Marisa and Few, Roger. “Climate Change, Water and Conflict in the Niger River Basin.” USAID, Dec. 2011, www.international-alert.org/app/uploads/2021/09/Climate-Change-Water-Conflict-Niger-River-EN-2011.pdf. Accessed 2 Oct. 2024.

Stock, Robert. Africa South of the Sahara: A Geographical Interpretation. Guilford Press, 2000.

Sunday, Orji. "Niger Delta Mangroves in 'Grave Danger' from Oil Spills, Poverty, Invasive Species." Mongabay, 22 Aug. 2022, news.mongabay.com/2022/08/niger-delta-mangroves-in-grave-danger-from-oil-spills-extraction-invasive-species/. Accessed 2 Oct. 2024.

Zwarts, Leo, et al. The Niger, A Lifeline: Effective Water Management in the Upper Niger Basin. Altenburg & Wymenga, 2005.