Published on and written by Cyril Jarnias
Sandwiched in the heart of West Africa, The Gambia is a unique case on the continent. The smallest country in mainland Africa, it is a long, narrow ribbon-like country that stretches inland, following almost to the millimeter the course of the river from which it takes its name. Understanding the geography of The Gambia means first understanding this intimate link between a waterway, a territory, and the people who have organized themselves around this liquid backbone.
A Tiny Mainland State Facing the Atlantic
The Gambia occupies a strip of land between latitudes 13°N and 14°N and longitudes 13°W and 17°W. Its area is approximately 11,300 km², of which a little over 10,000 km² is land and about 1,180 km² is water. At its widest point, the country is no more than 50 kilometers wide. On three sides, it is completely surrounded by Senegal; only the western side opens onto the Atlantic Ocean, with a coastline of about 80 kilometers, between the mouth of the Allahein River in the south and Buniadu Point in the north.
The country’s average elevation, a thin ribbon of river plain, is about 34 meters above sea level.
The capital, Banjul, illustrates this atypical geography. Built on St. Mary’s Island, at the mouth of the river into the Atlantic, it lies largely below sea level, caught between the estuary, mangroves, and the ocean. It is simultaneously the main metropolitan center, the administrative heart, and the country’s maritime hub.
The Gambia River: The Country’s Backbone
It is impossible to approach the geography of The Gambia without detailing the role of the Gambia River. About 1,120 km long from its sources on the Fouta Djallon plateau in Guinea, this river flows successively through Guinea, Senegal, and The Gambia before emptying into the Atlantic at Banjul. Its drainage basin covers 78,000 km², but The Gambia represents only about 13% of this area, compared to over three-quarters for Senegal.
Within Gambian borders, the river follows an east–west trajectory for nearly 400 km. It first crosses the Barrakunda Falls before entering the country near Koina. Then, its course becomes sinuous, multiplying meanders, secondary channels, and islands. The river valley, carved into a Miocene-Pliocene sandstone plateau, has a variable width, generally ranging between 20 and 40 km. Approaching the Atlantic, the river widens to over 10 km at its mouth, forming a drowned estuary (a ria).
The lower half of the river is navigable. In The Gambia, it is navigable for its entire length, even allowing seagoing vessels to travel up to 190 km inland. This rare feature in West Africa makes it a major logistical and commercial artery for the country.
A River System Structured by Tide and Salt
The very flat topography allows the tide to penetrate deep inland. The tidal range at the mouth reaches about 1.6 meters. Depending on the season, the “tongue” of saltwater extends more or less far. During the rainy season, the inflow of freshwater pushes salinity back to about 70 kilometers from the Atlantic; in the dry season, the saline tide advances up to 250 kilometers upstream, turning long sections into brackish water.
Hydrologists thus distinguish three main sections in the valley:
A tropical river can be divided into three distinct sections based on salinity and water regime: an Upper Valley where water remains fresh, with some seasonal flooding; a Central Valley subject to tidal influence, fresh during the rains but brackish in the dry season; and a Lower Valley that is persistently salty, close to the estuary and mangroves.
This organization has profound consequences for water use, agriculture, and ecosystems. The surface area of inland waters – river and flooded areas – can reach nearly 1,965 km² during flood season, almost one-fifth of the national territory. Irrigation potential is theoretically rich, but salinity limits the direct use of surface water in many downstream areas, leading to heavy reliance on groundwater.
Tributaries, Bolongs, and the Hydrographic Network
Beyond the main course, The Gambia is dotted with small tributaries and secondary channels locally called bolongs. In the lower reaches, they form a labyrinth of channels, creeks, and mangroves. Among the best-known bolongs are Bintang Bolon – the largest, which joins the river from the south – as well as Sami Bolong, Jurunku, Kutang, Nianji, and Sandugu.
Upstream, the Sandougou and Sofianiama rivers are major tributaries. In the southwest, the Allahein River (or San Pedro) forms part of the border with Senegal, although its flow is modest.
Bridges, Ferries, and Links Between the Two Banks
The geography of The Gambia is that of a territory cut in two by its own vital artery. Connecting the two banks is a matter of national integration, but also regional, as the Trans-Gambia Highway serves as a strategic corridor for Senegambian trade.
For a long time, ferries handled most crossings: Banjul–Barra at the mouth, Banni–Kerewan further upstream, Farafenni–Yelitenda, and Kau-ur–Jessadi. The opening of the Senegambia Bridge, 1.9 km long between Farafenni and Soma, profoundly changed the situation. It now connects the northern and southern sections of the Trans-Gambia Highway and facilitates transit for Senegalese trucks, especially towards Casamance. Further east, the bridges at Basse Santa Su and Fatoto, inaugurated in 2021, complete this network. Together, they help reduce the isolation of certain regions and structure the national space, always within the logic of a country organized around a river.
Relief, Soils, and Major Landscapes
With its low elevations, The Gambia is characterized by subtle relief, consisting mainly of river plains, gentle slopes, and small sandy hills. Geographers distinguish five main types of natural landscapes that succeed one another from the coast inland, or from the floodplain to the plateaus.
The coastal fringe consists of flat coastal strips formed by nutrient-poor aeolian sands. This zone includes dunes stabilized by scrub vegetation, coastal woodlands in places, and beaches highly exposed to marine erosion. Further inland, around the river estuary, lies a mangrove swamp area, developing on highly saline clay soils.
Further up, one finds the Banta Faros, these grassy floodplains bordering the river, composed of light alluvial silt particularly suitable for rice cultivation. Above them, sandy hills with shallow valleys support wooded savanna of baobabs, néré trees, kapok trees, and tall grasses. Finally, the sandstone plateaus, with their well-drained sandy soils suitable for groundnut cultivation, dominate the landscape of many interior regions.
These relief forms, modest but varied, closely condition human settlement and agricultural practices. Villages are often located at the edge between river plains and plateaus, combining access to water, fertile land, and well-drained soils.
Tropical Climate: Between Monsoon, Harmattan, and Drought
The Gambia belongs to the tropical belt, with a savanna climate (Aw in the Köppen-Geiger classification). The year is organized into two main periods: a rainy season, short but intense, and a long dry season.
The wet season generally runs from June to October, with a maximum of precipitation between July and September. It is driven by the West African monsoon, itself linked to the movement of the Intertropical Convergence Zone (ITCZ). The country experiences a unimodal rainfall regime: one rainy season per year. The dry season, from November to May, is marked by the influence of the harmattan, a hot, dry, dusty continental wind from the Sahara, especially prevalent from March to May.
Temperatures: Constant Heat, Coastal Nuances
Temperatures remain high throughout the year. Daytime highs most often range between 31 and 35 °C, while nighttime lows are generally between 17 and 25 °C. The heat is more intense inland than on the coast, where the sea breeze moderates extremes.
This is the maximum temperature peak, exceeding 42 °C, recorded at some stations in the interior part of the country during the dry season.
This coast–interior difference is clearly reflected in regional averages. The Upper River region, in the east, records an annual mean temperature close to 31.9 °C, making it the hottest part of the country. Conversely, Banjul and the Western Region have annual averages around 27.1 °C, the coolest in the country.
Rainfall: A Gradient from West to East and South to Center
Rainfall amounts vary considerably by area and year. Overall, the country receives between 800 and 1,000 mm of rain per year, with an average around 1,020 mm. But this average masks strong interannual fluctuations, some years falling below 750 mm, others exceeding 1,500 mm.
The southwest, closer to oceanic influence, is the wettest. The Sibanor area, in the southern part of the western sector, is among the rainiest, likely due to denser vegetation that promotes moisture retention. Conversely, some central areas receive the lowest totals.
Analysis of data from 10 weather stations over the period 1981–2020 reveals strong regional contrasts. In the east of the country, Sapu station holds the record for the highest monthly rainfall total over the entire study period. Paradoxically, in the same eastern region, Fatoto stands out as one of the driest stations between May and October. On the western side, Jenoi station records the lowest rainfall totals from June to October.
There are also east–west nuances in the rainfall calendar: the onset of the wet season tends to occur earlier in the eastern sector than in the western half. In the latter, most precipitation is concentrated between June and October, whereas the east may receive rains as early as May.
In Banjul, the annual average ranges from about 840 to 980 mm depending on the dataset. The July–September period concentrates the bulk of showers, with each of these three months often exceeding 200 mm. August is generally the wettest month, with peaks above 300 mm. April, on the contrary, remains nearly dry across the country.
To summarize, the opposition between dry season / rainy season and the intensity of rainfall in Banjul can be schematically represented as follows:
| Period | Climatic Characteristics in Banjul (approx.) |
|---|---|
| November – May | Dry season, harmattan influence, very little rain |
| June – October | Rainy season, West African monsoon |
| July – September | Peak precipitation, > 200 mm/month |
| April | Driest month, almost no rain |
| August | Wettest month, > 300 mm possible |
Humidity, Sunshine, Winds
With the rains comes a sharp rise in humidity. The relative humidity level fluctuates throughout the year between about 49% and 81%. The most humid months are August and September; those from December to March are the driest. Sunshine is generous during the dry season, especially from February to June, when the average daily sunshine duration reaches about 9 hours. From January to May, cloud cover is minimal, averaging around 26%. During the wet season, the sky becomes more overcast, especially in July and August.
Winds are generally weak to moderate. They strengthen between February and June, when the harmattan blows strongest, which can raise fine dust and reduce visibility. Winds then calm down from August to December.
Sea Temperature and Coastline
On the Atlantic coast, water temperature varies between about 21 and 29 °C. From January to April, the sea is relatively cool (21–22 °C); it warms up during the rainy season and remains warm until November, with maxima around 27–29 °C between August and November. This thermal gradient plays a significant role in the local climate by moderating temperatures on the coast.
But the Atlantic front is also the scene of another phenomenon: coastal erosion. Some studies estimate its current rate between 1 and 2 meters per year, with land loss possibly reaching 20 meters per year on a kilometer of highly exposed beach, such as along the Senegambia/Kololi hotel strip before protective works. Nationally, this represents an annual loss of several hectares of land and several hundred thousand cubic meters of sediment.
Water Resources: A Country Poor in Relief but Rich in Aquifers
Beyond the river and its branches, The Gambia rests on a vast sedimentary aquifer system, shared with Mauritania, Senegal, and Guinea-Bissau. Total renewable water resources are estimated at about 8 km³ per year. About 3 km³ comes from precipitation and internal runoff, while the river brings about 5 km³ from Senegal. Groundwater contributes about 0.5 km³ per year as base flow to streams.
Volume in cubic kilometers of water reserves in the deep sandstone aquifer.
For agriculture, estimates of irrigation potential vary depending on source and period. As early as the 1980s, potential was mentioned at about 80,000 hectares irrigable, but the area actually equipped remains modest: by the late 1990s, barely more than 2,000 hectares had controlled irrigation, while a little over 13,000 hectares of lowlands and inner valleys benefited from a more rudimentary form of “water management,” notably via tides in areas where water remains fresh.
Withdrawing one cubic meter per second from the river could push the salt front back upstream by about 4 kilometers.
Land, Agricultural Uses, and Demographic Pressure
Out of approximately 1,046,000 hectares of total land area, Gambian land is mainly dedicated to agriculture, pastures, and forests. Nearly 56% of the territory is considered suitable for cultivation, i.e., a little over 550,000 hectares. This potential is divided into 339,000 hectares of upland and 216,000 hectares of lowland. Among the latter, a little over 81,000 hectares would theoretically be irrigable.
Only 5,000 hectares have been put under irrigation in 30 years, representing about 6% of the potential.
The structure of agricultural land use can be summarized as follows:
| Land Type or Use | Estimated Area (hectares) | Main Comment |
|---|---|---|
| Total arable land | ≈ 555,240 | 56% of territory |
| Cultivable upland | 339,119 | Uplands |
| Cultivable lowland | 216,121 | Of which ≈ 81,120 irrigable |
| Actually cultivated land / year | ≈ 320,000 | 57% of potential agricultural area |
| Area under crops in a given year | > 180,000 | Of which ≈ 90,000 ha of coarse grains |
| Share farmed for subsistence | ≈ 188,000 | 39% of cultivated land |
| Lowland rice (rainfed or tidal) | ≈ 20,000 | Mainly rainfed, irrigation still limited |
Rainfed agriculture dominates overwhelmingly, with over 99% of cultivated land directly dependent on seasonal rainfall. This makes the country extremely vulnerable to climate variability and drought episodes. The main crops are millet, sorghum, rice, maize, and groundnuts, while a booming horticultural sector is developing especially in the western part and along the north bank. Women play a key role: they represent about 40% of overall agri-food production and up to 60% for rice.
Three Main Agroecological Zones
The Gambia, though compact, presents three main agroecological zones, largely defined by rainfall gradients and soil types:
The Gambia is divided into three main climatic zones that determine the types of crops possible, depending on annual rainfall.
Receives less than 600 mm of rain per year. Soils have low water retention, suitable for short-cycle, drought-resistant crops like cassava, cowpea, or sesame.
Records between 600 and 900 mm of rain per year. Uplands are suitable for groundnuts, sorghum, or cotton. Alluvial plains are suitable for rice cultivation in tidal paddies.
Benefits from 900 to 1,200 mm of annual rainfall. Crops include early millet, groundnuts, rice, maize, vegetables, cowpea, and sesame.
In the background, soils have suffered progressive degradation for several decades. Erosion, loss of organic matter, salinization in lowlands, and demographic pressure weigh on fertility. About 30% of the territory is already degraded, with pockets of desertification and high salinization, notably in lowland rice paddies where the rise of the “salt tongue” threatens production.
Biodiversity, Forests, and Wetlands
Despite human pressure and deforestation, The Gambia still harbors remarkable biodiversity. Three major terrestrial ecoregions coexist: the Guinean forest–savanna mosaic, the West Sudanian savanna, and the Guinean mangroves.
Mangroves, in particular, form a band nearly 97 km long along the lower river valley. They cover about 45,000 hectares in total, with dense cores such as the Tanbi complex, on the outskirts of Banjul, which alone contains nearly 6,000 hectares of coastal marsh, including 4,800 of mangroves. Dominant species include Avicennia africana, Rhizophora spp., and halophytic herbs like Sesuvium portulacastrum. These environments play a triple role: barrier against erosion, nursery for many fish species, and refuge for countless birds, including migrants from Europe.
The Gambia River basin is estimated to harbor around 1,500 plant species.
Among the emblematic animals are the hippopotamus (and locally the pygmy hippopotamus), the crocodile, otters, warthogs, monkeys, baboons, various antelopes, and the spotted hyena, the national animal. The river waters host species such as tigerfish, various characins, African pike, snapper, ladyfish, and sea salmon. Coastal and estuarine areas also host marine mammals, including the West African manatee, dolphins, and occasionally cetaceans.
Jinack Island, located in Niumi National Park, illustrates the importance of Gambian wetlands for migratory birds. A banding program there has shown that the site constitutes a crucial stopover on the West African migratory route for many warbler species. This concrete case fits into a national context rich in over 500 bird species, with more than 400 species recorded specifically along the Gambia River.
Despite this richness, the Forest Landscape Integrity Index reached only about 4.56/10 in 2018, reflecting the cumulative effects of deforestation, charcoal production, burning, poaching, and land conversion. Forest policies now aim to classify 30% of the territory as managed forests and to place 75% of forest land under scientific or community management.
Protected Areas: An Expanding Network
To preserve its ecosystems, The Gambia has established a network of protected areas currently covering between 3 and 8.6% of the territory depending on the source and reference date. There are officially 23 protected areas, covering about 94,700 hectares, although some documents still mention 38,000 hectares. To this are added 66 forest parks and numerous community reserves.
Among the best-known sites are:
The Gambia has a network of varied natural protected areas, ranging from gallery forests to coastal mangroves, essential for biodiversity conservation.
Near Lamin, one of the country’s oldest protected areas, centered on a gallery forest along a groundwater-fed stream.
An archipelago of river islands covered in forests, home to hippos and reintroduced chimpanzees as part of a rehabilitation project.
Protects a portion of the northern coastline with mangroves, sandy islands, and wooded dunes, in ecological continuity with the Saloum Delta in Senegal.
A vast mosaic of savanna, mangroves, and marshes on the south bank, one of the country’s main wildlife reserves.
East of Niumi, encompasses estuary, salt marshes, wooded savanna, and mangrove forests in a network of branching bolongs.
Peri-urban mangrove on the outskirts of Banjul, designated a Ramsar site.
Includes the Bijol Islands, important nesting sites for terns and other seabirds.
In addition to these “national” units, there are community conservation areas, such as Bolong Fenyo near Gunjur, or ecotourism projects like Makasutu Cultural Forest and Bijilo Forest Park, known for their monkeys and coastal dune forest.
Number of additional hectares of protected area thanks to a project supported by the Global Environment Facility.
Administrative Organization and Human Geography
The geography of The Gambia is not just about physical landscapes; it is also reflected in its administrative divisions, its towns, and the distribution of its population.
The country, officially the Republic of The Gambia, is a unitary state. It is subdivided into five regions – Central River, Lower River, North Bank, Upper River, and West Coast – and one city, Banjul. These larger entities also correspond, along with the Kanifing municipality, to eight Local Government Areas (LGAs): Banjul, Kanifing, Brikama, Mansakonko, Kerewan, Kuntaur, Janjanbureh, and Basse. The Western Region has officially been renamed West Coast, and the former MacCarthy Island Division is now called Central River.
Each LGA (Local Government Area) in The Gambia is named after its capital: Brikama (West Coast), Kerewan (North Bank), Basse (Upper River), Janjanbureh (Central River east), Kuntaur (Central River west), and Mansa Konko (Lower River). The Greater Banjul urban area, which includes Banjul and Kanifing, now extends to the outskirts of Brikama, illustrating rapid urbanization along the coast and lower river valley.
The LGAs are themselves divided into districts, numbering 40 to 40+ depending on the source (some count 37, others 43 or 48, due to historical divisions or groupings). These districts are headed by traditional chiefs, the Seyfolu, and each groups several villages and towns led by an Alkalo.
Demographic Weight and Coastal Urbanization
The Gambian population, estimated at about 2.4 million inhabitants, is one of the densest on the continent, given the small national area. Density already exceeded 250 inhabitants per km² in 2024, with projections pushing it beyond 400 inhabitants per km² by 2050. Most of the population is concentrated along the river, especially at the mouth, around Banjul, Serekunda, Bakau, and Brikama.
The urban density in the Greater Banjul area in The Gambia is estimated to be about 3,800 inhabitants per square kilometer.
In 2013, the West Coast region was already the most populous, with nearly 700,000 inhabitants, while Lower River remained the least populated, with just over 80,000 inhabitants. Statistics also show a pronounced youth: more than half the population is under 20 years old, with a median age around 18–22 depending on the source and year.
This demographic explosion, combined with growth rates above 2% per year, increases pressure on land, forests, wetlands, and coastlines. It also fuels rural exodus towards the coast and the capital, and pushes some Banjul residents to migrate to outlying communes (the Kombos), partly due to flood risks and the vulnerability of the city center to climate hazards.
A Geography Under Pressure: Climate, Coastline, and Risks
The Gambia is regularly ranked among the most vulnerable countries to climate change. This assessment stems as much from its physical geography – low river plain, sandy coastline, a capital partly below sea level – as from its socio-economic structure, with an economy still heavily dependent on rainfed agriculture, fishing, and coastal tourism.
Climate projections, based on CMIP6 models, suggest a possible increase in average temperatures of 3 to 4.5 °C by mid-21st century, accompanied by high uncertainty regarding precipitation trends (from sharp decreases to moderate increases depending on scenarios). Regardless of the scenario, increased evapotranspiration and greater rainfall variability point to more frequent and intense drought episodes, interspersed with extreme rains causing flash floods.
Urban areas, especially Banjul and its periphery, experience seasonal flooding, runoff, violent thunderstorms, and windstorms. The 2022 episode, one of the worst in decades, affected more than 50,000 people and displaced over 7,000, with Banjul as the epicenter.
Sea Level Rise and Threats to the Capital
The vulnerability of the coastline is particularly concerning. The expected rise in sea level, potentially reaching around one meter in the long term under some scenarios, would directly threaten more than 8% of the national territory. Impact analyses show that such a scenario could submerge over 61% of current mangroves, a third of marsh areas, more than 20% of lowland rice paddies, and render over half of the capital Banjul virtually uninhabitable.
Beyond Banjul, several localities (Barra, Jangjabureh, Kuntaur), as well as port facilities, wharves, and riverside infrastructure, are threatened. Chronic erosion of tourist beaches, worsened by sand mining and mangrove clearing, exacerbates the situation.
Land and Forest Degradation
Inland, soil degradation, deforestation, and advancing drought are gradually transforming savanna landscapes. Nearly 347,700 hectares of wooded savanna and 83,500 hectares of forests are under increasing pressure, largely due to demand for firewood and charcoal, which still provides 80 to 85% of domestic energy for the vast majority of households.
Salinization of lowlands, salt intrusion in rice paddies, saline intrusion into aquifers, and pasture degradation complete this picture of weakening. In response, projects like the Great Green Wall, mangrove restoration, community reforestation, and integrated watershed management are attempting to restore key ecological functions.
A Territory Shaped by Transportation and Infrastructure
Finally, the geography of The Gambia is increasingly marked by the development of road and energy networks, which are reshaping relationships between regions. The main axes logically follow the river and the coast: the Trans-Gambia Highway, the South Bank Highway on the south bank, roads linking Banjul to Brikama, Serekunda, and further east.
Authorities are investing in infrastructure to open up rural areas, reduce poverty, and strengthen climate resilience. Programs include building hundreds of kilometers of roads, extending the electricity network to dozens of villages, developing soft mobility corridors, and modernizing the Port of Banjul and Yundum International Airport.
These projects also address a numerical reality: over 400,000 Gambians still lack reliable access to a passable road, and the rural access rate to all-weather roads barely exceeds 55%. Dirt roads and tracks, often impassable during the rainy season, reinforce the marginalization of areas farthest from the river and major urban centers.
In parallel, the extension of the electricity grid (the national initiative targeting universal access by 2030) and investment in renewable energy – requiring new lines and substations – are also part of a geographical recomposition of the country, where the lines of force will no longer be defined solely by the river and the coast, but also by modern infrastructure.
A Ribbon-Like Country Facing the 21st Century
In the end, The Gambia offers a striking example of how geography can shape a country’s destiny. The narrowness of its territory, its dependence on a river shared with several neighbors, the fragility of its coastline, and the concentration of its population on a low-lying river plain constitute both strengths and vulnerabilities.
The richness of ecosystems – from the mangroves of Tanbi to the marshes of Bao Bolong, from the savannas of Kiang West to the gallery forests of Abuko – coexists with strong human pressure, rapid urbanization, and acute environmental challenges. In this context, the country’s future will largely depend on its ability to reconcile land-use planning, protection of natural environments, securing agricultural land, and adaptation to climate change, while leveraging its strategic position in the heart of West Africa and on the banks of one of the continent’s great rivers.
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Cyril Jarnias is an independent expert in international wealth management with over 20 years of experience. As an expatriate himself, he is dedicated to helping individuals and business leaders build, protect, and pass on their wealth with complete peace of mind.
On his website, cyriljarnias.com, he shares his expertise on international real estate, offshore company formation, and expatriation.
Thanks to his expertise, he offers sound advice to optimize his clients' wealth management. Cyril Jarnias is also recognized for his appearances in many prestigious media outlets such as BFM Business, les Français de l’étranger, Le Figaro, Les Echos, and Mieux vivre votre argent, where he shares his knowledge and know-how in wealth management.
