Source and course through Cameroon
The Benue rises in the Adamawa Plateau of northern Cameroon, a few miles north of the city of Ngaoundéré, and initially flows northwest through the Cameroonian town of Garoua and its reservoir, Lake Lagdo, before turning west into Nigeria S1. Two independent geographic references — WorldAtlas and the Freshwater Ecoregions of the World database — put its total length at approximately 1,400 km (870 mi), making it the longest tributary of the river niger and, by discharge, one of West Africa's major rivers; the Freshwater Ecoregions dataset describes the Benue as flowing "westward for 1,400 km" before its confluence with the Niger near Lokoja S1S2. Along its middle and lower course, rainfall in the basin rises sharply, from under 400 mm a year in the drier Sahelian reaches of the wider Niger-Benue system to around 1,400 mm near the delta, a gradient that also drives the river's strongly seasonal flow S2
Entry into Nigeria
After crossing the border, the Benue takes a broadly southwestward path through Nigeria, passing below the Mandara Mountains and through the twin cities of Jimeta and Yola in Adamawa State, then on through Ibi in Taraba State and Makurdi, the capital of Benue State, from which the river takes its Nigerian name S1. Its major tributaries include the Mayo-Kébi, Gongola, Pai, Wase, Ankwe, and Mada rivers on its left bank and the Faro, Taraba, Donga, and Katsina-Ala rivers on its right, several of which drain the Mambilla and Jos plateau highlands further north and east S1. The Benue is markedly seasonal but broad enough near its mouth — over a mile wide at Lokoja — to remain navigable year-round for much of its lower course, with discharge cited at around 122,800 cubic feet per second (roughly 3,475 m³/s), placing it among the world's larger rivers by volume S1
Floodplain and ecology
The Benue's Nigerian course is bordered by extensive seasonal floodplains that the Freshwater Ecoregions of the World database, part of the wider Lower Niger-Benue ecoregion, measures at about 5,673 km² in flood compared with only 2,062 km² in the dry season, a contrast that shapes both the river's ecology and the farming and fishing calendar of communities along its banks S2. These floodplains and gallery forests support two fish genera found nowhere else, including the freshwater stingray, and migratory fish species that travel as far as 640 km upstream during the wet season, some possessing lung-breathing capability and drought-resistant eggs adapted to the river's long dry spells S2. This seasonality — an annual swing between flood and near-drought within the same channel — is characteristic of the wider Niger-Benue system and is one reason the two rivers are usually described and managed together rather than separately S2S5
The confluence at Lokoja
The Benue joins the Niger at Lokoja, in Kogi State, in a Y-shaped meeting of waters that has made the town a strategically important river crossing since the nineteenth century and remains the reference point the Nigeria Hydrological Services Agency uses to track combined flood risk from both rivers each rainy season S1S5. Downstream communities are watched closely: a 2026 agency advisory noted that although Cameroon's Lagdo Dam was not spilling at the time, heavy rainfall and runoff on the Nigerian side were already causing flooding around Yola North, Yola South, Girei, and Numan in Adamawa State, the Benue's first major Nigerian catchment S5
Lagdo Dam and the unfinished Dasin Hausa Dam
The Benue's upper Nigerian reaches are shaped heavily by decisions made upstream in Cameroon. The Lagdo Dam, built on the river's Garoua tributary system, is managed to release water gradually — starting around 100 m³/s and increasing based on inflow — in an effort to avoid overwhelming the Benue's capacity downstream, according to the Nigeria Hydrological Services Agency S4. In practice, Nigerian officials have traced most of the country's worst Benue-basin flood events to these Lagdo releases, including the 2022 floods that killed more than 600 people and destroyed roads, farmland, and housing across the basin, one of the worst such disasters in a decade S4. Nigeria and Cameroon agreed decades ago to build a complementary Nigerian dam, Dasin Hausa in Adamawa State, intended as a "shock absorber" to hold back exactly this kind of surge, but although construction began in the 1980s the dam remains unfinished, leaving downstream states — Adamawa, Taraba, Benue, Nasarawa, and Kogi — recurrently exposed whenever Lagdo's operators release water S4
Exploration and later significance
European geographers only settled the Benue's basic course in the mid-nineteenth century. The German explorer Heinrich Barth, travelling as part of a British-sponsored scientific and commercial expedition from Tripoli that began in 1850, reached the Benue's upper reaches in 1851 and established that it flowed into the Niger — resolving it from the neighbouring Shari River, which instead empties into Lake Chad, a distinction earlier European mapmakers had not reliably drawn S3. That clarification, folded into Barth's wider account of a six-year, roughly 10,000-mile journey across North and Central Africa, gave later British colonial administrators and traders one of their first reliable pictures of the river system linking the interior to the Niger and, through it, to the Atlantic coast S3. Today the Benue remains a key artery of Nigeria's inland waterway network alongside the river niger, administered by the national inland waterways authority and discussed within the country's wider physical geography in geography of nigeria and nigeria climate zones S1