Benin's geography: a narrow strip from the lagoons to the Niger

How a short coast leads inland to the Niger

The shape is the first fact about Benin's land. The coastline measures 121 kilometres, and from the sea the territory runs north to the Niger, which forms part of the border with Niger. The sources disagree on how far: Wikipedia's country article gives about 650 kilometres from the Niger to the Atlantic, Britannica about 675, and Wikipedia's geography article 700. At its widest the country measures about 325 kilometres, and the geography article describes the outline as key-shaped.

The area is measured differently as well. Wikipedia and the World Factbook material it reproduces give 112,622 square kilometres, of which 2,000 are water; the record beside this article carries a larger figure. The territory lies between about 6°30′ and 12°30′ north. Its land borders total 2,123 kilometres, and the longest of them is with Nigeria.

Most of the land is low. Wikipedia's geography article gives an average elevation of 200 metres and describes a relief map with little variation. The Factbook material lists the natural resources as small offshore oil deposits, limestone, marble and timber, and puts arable land at 23.94% of the area and permanent crops at 3.99% in 2012.

Why lagoons line the southern coast

The shore is a long sandbar. Britannica describes the coastal region as low, flat and sandy, backed by tidal marshes and lagoons, with clumps of coconut palms on the bar itself. Wikipedia gives the coastal plain a highest elevation of 10 metres and a width of at most 10 kilometres, and notes that sandbanks make the coast hard to approach, with no natural harbours, river mouths or islands.

The lagoons differ from west to east. In the west they are narrower and many have silted into marsh; in the east they are wider and some are joined. The Grand-Popo Lagoon runs west into Togo. The Porto-Novo Lagoon gives a natural waterway to the port of Lagos in Nigeria, although Britannica notes that the border discourages its use. The lagoons reach the sea at only two places, Grand-Popo and Cotonou, and Cotonou's opening is where the country's port stands. Lake Nokoué, behind Cotonou, receives one branch of the Ouémé.

Low ground near the sea is exposed. Wikipedia's country article notes that with most people living in low-lying coastal areas, a rise in sea level could affect both the economy and the population.

What the barre country and the plateaus hold

Behind the lagoons lies what Britannica calls the barre country, from the Portuguese barro, clay. It is a fertile plateau crossed by the Lama Marsh, a wide swamp stretching from Abomey towards Allada, and it rises in occasional hills to about 400 metres. Four further plateaus sit around Abomey, Kétou, Aplahoué and Zagnanado. They are clays on a crystalline base: Britannica gives the Abomey, Aplahoué and Zagnanado plateaus heights of 300 to 750 feet and the Kétou plateau up to 500 feet.

Wikipedia divides the same land into four bands from south to north instead of Britannica's five natural regions. After the coastal plain come the plateaus of the south at 20 to 200 metres, cut by valleys running north and south along the Couffo, the Zou and the Ouémé. Then comes flat country dotted with rocky hills around Nikki and Savé, which seldom reach 400 metres, and last the Atakora range along the northwest border.

Abomey, the capital of the old kingdom of Dahomey, stands on the first of these plateaus. The original rain forest that covered most of the south has largely been cleared except along the rivers, and Britannica describes oil palms and rônier palms planted in its place with food crops between them. North of Abomey forest and savanna mix, and farther north the savanna takes over.

Why the Atakora's height depends on the source

The Atakora Mountains run southwest to northeast along the border with Togo, as a continuation of the Togo Mountains, with a core of highly metamorphosed quartzite. They are also a watershed: Britannica describes them as the divide between the Volta and Niger basins.

Their highest point is recorded two ways. Wikipedia and the country's record name Mont Sokbaro at 658 metres. Britannica gives the range's highest altitude as 641 metres and names no summit. The difference is 17 metres on the country's highest ground, and neither source says which survey it follows.

The northwest has a settlement pattern of its own. Britannica notes the thatched, turreted houses of the Somba region, and UNESCO lists Koutammakou, the land of the Batammariba, as a World Heritage property with dates of 2004 and 2023.

Where the rivers of Benin run

Two drainage systems share the country. The Niger and its tributaries the Mékrou, the Alibori and the Sota drain the northeast. The rest runs south to the Atlantic through three main rivers named by Britannica. The Mono rises in Togo and forms the border near the coast. The Couffo flows south from the plateaus near Abomey into the coastal lagoons at Ahémé. The Ouémé rises in the Atakora and flows south for 280 miles; near its mouth it splits, one branch draining east into the Porto-Novo Lagoon and the other west into Lake Nokoué.

The extreme points follow the rivers. The northernmost point is the confluence of the Mékrou and the Niger on the border with Niger, in Alibori, and the southernmost is where the Togo border meets the Atlantic, in Mono. The Factbook material puts total renewable water resources at 26.39 cubic kilometres in 2011.

How rainfall changes from the coast to the north

Britannica distinguishes two climatic zones. The south has four seasons: the main rains from mid-March to mid-July, a short dry season to mid-September, short rains to mid-November, and the main dry season until March. Rain increases towards the east. Grand-Popo receives about 800 millimetres a year, while Cotonou and Porto-Novo both receive about 1,270. Temperatures in the south stay between about 22 and 34 °C, with high humidity. The two Wikipedia articles give the coastal average as 1,300 and 1,360 millimetres, and a Cotonou average maximum of 31 °C and minimum of 24 °C.

The north has one rainy season, May to September, with most of the rain in August. Britannica gives about 1,346 millimetres a year in the Atakora and central Benin and about 965 millimetres farther north. The harmattan, a hot dry wind from the northeast, blows from December to March; dust veils the sky, the grass dries and farmers burn brush in the fields. Day and night temperatures differ widely, and in March, the hottest month, the daytime temperature can reach 43 °C.

The World Bank's Climate Change Knowledge Portal gives the national averages. For 1995 to 2014 the mean annual temperature was 27.56 °C and annual precipitation 1,055.16 millimetres. Since 1970, by the ERA5 reanalysis, temperature has risen by 0.26 °C a decade and precipitation has changed by minus 20.32 millimetres a decade. For 2040 to 2059 under the high-emission scenario SSP3-7.0 the portal projects a median warming of 1.41 °C against 1995 to 2014.

What survives in the northern savanna parks

The far north is protected land. Britannica gives the W National Park an area of 5,019 square kilometres, extending into Burkina Faso and Niger, and the Pendjari National Park 2,751 square kilometres; Wikipedia gives Pendjari 2,755. Both belong to the W-Arly-Pendjari Complex, which UNESCO first inscribed in 1996 for the Niger section and extended in 2017. The property covers 1,714,831 hectares in nine protected areas, with a buffer zone of 1,332,147 hectares, and UNESCO credits it with 85% of the region's savanna elephants. Its assessment adds that fire linked to human occupation, perhaps for some 50,000 years, has shaped the vegetation.

The animal counts differ by source and by year. Wikipedia's Pendjari article records more than 800 elephants counted in the park between 2005 and 2010 and more than 3,800 in the whole complex. It puts the complex's lions at about 100 in 2009, where the country article gives an estimate of 246 to 466 for the same parks. Cheetahs in Pendjari and the W park numbered about 5 to 13 in 2007, and waterbuck fell from about 3,000 in the 1970s to 120 in 2004. On the African wild dog the two Wikipedia articles disagree: the geography article considers it extirpated from Benin, while the Pendjari article records it in a survey of April 2000. About 300 bird species are recorded in the park. Britannica's list for the W park adds leopards, antelope, monkeys, wild pigs, crocodiles and buffalo, pythons and puff adders among the snakes, and guinea fowl, wild duck and partridge among the birds. Wikipedia's Pendjari article notes that heavy rain from June to November can cut off parts of the park, which receives about 1,100 millimetres a year.

How the departments divide the land

The administrative map follows the same south-to-north stretch. Benin has twelve departments, subdivided into 77 communes. There were six until 1999, when each was split in two, according to Wikipedia. The World Bank's climate portal lists them as Alibori, Atakora, Atlantique, Borgou, Collines, Couffo, Donga, Littoral, Mono, Ouémé, Plateau and Zou.

The names map the land. Littoral is the department of Cotonou on the coast, Atlantique and Mono take the shore to the west, and Ouémé and Plateau hold the east, along the river and the Kétou plateau. Zou, Couffo and Collines cover the plateau country around Abomey and to its north. Borgou, Alibori, Atakora and Donga share the north: Alibori reaches the Niger at the Mékrou confluence, and Atakora and Donga run along the hills of the northwest.

Two cities carry most of the urban weight. The country's record gives Cotonou about 780,000 people and Porto-Novo 234,168, both dated 1 January 2025. Porto-Novo, the official capital, sits on its lagoon in the southeast corner, and Cotonou lies on the sandbar between Lake Nokoué and the sea.

Why most people live in the southern quarter

Britannica states that the southern provinces make up one-fourth of the area and hold more than two-thirds of the population, clustered around Cotonou and Porto-Novo, where maize, cassava and yams are farmed intensively on the edge of town. Northward the villages scatter, some areas are empty except for Fulani herders, and Parakou is the market town of the north.

The forest has shrunk under that population. Wikipedia, citing the FAO series, gives forest cover of about 28% of the land in 2020, or 3,135,150 hectares, down from 4,835,150 hectares in 1990; planted forest made up 23,000 hectares of the 2020 figure. Global Forest Watch, counting canopy of more than 30% density, records 47,919 hectares of tree cover lost between 2001 and 2024, about 28.5% of the 2000 extent. The Factbook material lists deforestation, desertification, poaching and short supplies of drinking water as the main environmental issues.