Niger River

The Niger River, the largest river in West Africa, stretches approximately 2,600 miles (4,180 kilometers) and flows through ten countries, impacting the lives of over 100 million people. Known for its extensive drainage basin, it is significant for its diverse aquatic ecosystems, housing more than 200 fish species, including many endemic to the region. The river originates from the Fouta D'jallon highlands in Guinea and flows in an unusual direction toward the Sahara Desert before forming the largest delta in Africa at the Gulf of Guinea. The river's basin supports a variety of wildlife, including migratory birds and unique plant species, particularly in its coastal delta, which features significant mangrove forests.

Despite its importance for local livelihoods, agriculture, and hydroelectric power generation, the Niger River faces severe threats from climate change, pollution, and habitat degradation. Rising temperatures and reduced water flow have led to environmental concerns and conflicts over water management. Human activities such as overgrazing, unsustainable agricultural practices, and industrial pollution further exacerbate these issues. Efforts by authorities like the Niger Basin Authority aim to address these challenges, highlighting the need for sustainable management of this vital waterway.

Full Article

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-longest river on the continent, at 2,600 miles (4,180 kilometers) long, and it has a drainage basin of approximately 817,600 square miles (nearly 2.1 million square kilometers). The Niger has a rambling water course that runs through Guinea, Mali, Niger, Benin (border), and Nigeria, with a large portion of its basin extending into other West African countries. The river originates just 150 miles (240 kilometers) from the Atlantic Ocean, and flows inland toward the Sahara Desert before forming the extensive delta of Africa in the Gulf of Guinea. More than 250 fish species are found in the river, about 20 of which are found exclusively in this region. The Niger River has another delta-like floodplain at the midrange of its course, referred to as the Inner Niger Delta.

The Niger originates from the landward side of the Fouta Djallon highlands in southern Guinea and emerges from a deep ravine about 2,800 feet (about 800 meters) above sea level at the Tembi River. Within a short distance of flow, the Tembi is joined by several small tributaries before larger contributing streams, including the Mafou, Niandan, Milo, Sankarani, and Tinkisso rivers, help form the Niger. Instead of flowing to the Atlantic Ocean, the river first flows toward the Sahara Desert, cutting through Guinea, Mali, Republic of Niger, and the Benin until it finally empties into the Gulf of Guinea in Nigeria. All told, the river has numerous tributaries

The Niger basin encompasses parts of nine countries: Benin, Burkina Faso, Cameroon, Chad, Côte D’Ivoire, Guinea, Mali, Republic of Niger, and Nigeria. Geographically, the river is divided into four major sections: the upper Niger Basin, the Inner Niger Delta, the middle Niger Basin, and the Lower Niger Basin.

Temperature ranges vary across the Niger basin, with cooler averages in the upper basin and much hotter conditions in the interior Sahel, often exceeding 100 degrees F (38 degrees C) in the dry season.  Mean annual precipitation decreases northward, from about 75-95 inches (approximately 1,900–2,400 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, then increases as the river flows southward to the southern coastal basin, where rainfall is significantly higher.

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 the vulnerable black-crowned cranes, rock pratincole, goliath heron, and spur-winged goose. The Egyptian plover is present in parts of the basin.

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 3,260 square miles (844,243 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 for 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 several countries. The discovery of crude oil and natural gas in the river’s coastal delta in the mid-1950s 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, 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 the Republic of Niger. 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, which provides a significant share of Nigeria’s hydroelectric power. Large dam projects on the Niger River, such as the Kandadji Dam, are intended to support hydroelectric power generation, irrigation, and flow regulation.

The Niger is also used for navigation, with long stretches 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 90 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  Niamey, the Republic of Niger. Water volume and river flow has been very low; it has been reported that the river loses 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, the shrinkage of natural wetlands, and the 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 decrease in water has caused regional destabilization and conflict. A 2011 report by International Alert, analyzed the effects of climate change on the Niger River, but it did not conclusively find any increase in conflict between the citizens and the state over water flow management. Other reports found the effects of climate change on the river might have caused wider conflicts within the region; however, the 2011 report did not support those conclusions.

Other environmental threats include unsustainable agricultural practices, overgrazing, bushfires, and deforestation, all of which remove vegetation cover. Oil spills have damaged large areas of mangrove trees, a development that has allowed invasive species such as the nipa palm. The cover of this species increased from 2007 to 2017 by nearly 700 percent. Mangrove cover decreased by 12 percent during this period. Between 1988 and 2023 there was a reported decrease in the mangrove cover within the Niger Delta, with about 2,536 square kilometer area lost in thirty-eight years.

The Niger Basin Authority (NBA) has observed that mining activities and deforestation in headwater areas contribute to pollution and sedimentation of the riverbed. Other threats include pollution from industrial wastes and the proliferation of water hyacinth and water lettuce on the waterways, which steal oxygen from fish and other aquatic animals. Climate aridification and desertification will likely catalyze the rate of vegetation loss along the riverbanks, thereby increasing siltation still more.

Hydrological observations indicate increasing variability in the Niger River’s flow, with periods of extreme low flow alternating with episodes of high-water levels and flooding. The 2024–25 flood events along the river and its tributaries have resulted in substantial human displacement, infrastructure damage, and loss of life.

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


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