Published on and written by Cyril Jarnias
Senegal occupies a unique geographical position on the African continent. Serving as both the gateway of West Africa to the Atlantic, an interface between the Sahara and the Gulf of Guinea, a crossroads of trade routes, and a migratory corridor for birds, the country concentrates a remarkable diversity of climates, landscapes, soils, and ecosystems within a relatively modest territory. Understanding the country’s geography in Senegal also means understanding part of the challenges of the Sahel: demographic pressure, desertification, coastal fragility, and the challenges of rain-fed agriculture in the face of climate change.
A Country at the Extreme West of Africa
Officially named the Republic of Senegal, the nation is located at the extreme west of West Africa, around 14° North latitude and 14° West longitude. It is not only the westernmost country of mainland Africa: the Pointe des Almadies, on the Cape Verde peninsula where Dakar is located, also constitutes the westernmost point of the entire Old World (Afro-Eurasia).
This is the length in kilometers of Senegal’s coastline on the Atlantic Ocean.
The situation is made even more singular by the almost complete landlocking of The Gambia: a narrow strip of territory that follows the estuary and then the Gambia River valley for over 300 km into the country, de facto isolating the southern region of Casamance from the rest of the national territory.
The following table summarizes some orders of magnitude regarding territory and borders.
| Indicator | Approximate Value |
|---|---|
| Total area | 196,000 – 197,000 km² |
| Land area | ~192,000 km² |
| Inland water | ~4,180 – 4,190 km² |
| Length of land borders | 2,640 km |
| Length of coastline | 531 km |
| Border with Mauritania | 813 km |
| Border with Mali | 419 km |
| Border with Guinea | 330–338 km |
| Border with Guinea-Bissau | 338 km |
| Border with The Gambia | 740 km |
On a global scale, the country ranks in the middle of the pack in terms of area, comparable to about four-fifths of the United Kingdom or one and a half times Greece.
Relief: Vast Plains, Some Hills, and Sand Deserts
Seen from an airplane, the country’s geography in Senegal reveals a very gentle relief. Almost the entire territory lies within a vast sedimentary basin, the Senegalo-Mauritanian Basin, with altitudes often below 200 meters. This configuration explains the dominance of slightly undulating sandy plains, characteristic of the western Sahel.
Senegal’s relief features two notable zones. In the west, on the Cape Verde peninsula, are the Mamelles, two volcanic hills about 105 meters high overlooking Dakar and the ocean. In the far southeast, near the border with Guinea, the terrain rises to form the Baunez ridge. This point, located near Népen Diakha, is the country’s highest summit with an altitude of about 648 meters, on the edge of the Fouta Djallon massif.
In contrast, the lowest point is of course sea level along the Atlantic coast. Between these extremes, the relief consists of sandy plains, weakly incised plateaus, valleys of major rivers, and some desert formations like the Ferlo in the center and the small Lompoul desert in the north, composed of orange dunes near Saint-Louis.
The major relief units can be summarized as follows:
| Region/Relief Unit | Main Characteristics |
|---|---|
| Senegalo-Mauritanian Basin | Large sedimentary depression, low altitudes and gentle relief |
| Cape Verde Peninsula | Small volcanic plateaus, coastal cliffs, hills |
| South-East (Baunez, Bassari, Kédougou) | Fringes of ancient massifs linked to the Fouta Djallon, steep valleys, Dindefelo Falls |
| Ferlo (center) | Semi-desert plateau, sandy, sparsely populated |
| Lompoul (northwest) | Small desert of dunes near the coast |
This overall flat topography favors the expansion of crops and pastoral lands, but also makes the territory very sensitive to wind and water erosion, salinization in low-lying areas, and flooding in river valleys and coastal zones.
Coastline, Rivers, and Lakes: A Structuring Hydrological Network
Even if the country is associated in people’s minds with the image of the dry Sahel, water deeply structures the country’s geography in Senegal. Two rivers, in particular, organize vast regions: the Senegal River in the north and the Gambia River in the center, while the Casamance and the Sine-Saloum system shape the south and west-central part.
The Senegal River originates in Mali at the confluence of the Bafing and Bakoyé rivers, coming from Guinea. It then receives tributaries from the Falémé, Karakoro, and Gorgol, forming part of the country’s northern border before flowing into the Atlantic Ocean near Saint-Louis. Its length is estimated between 1,000 and 1,800 km, and its watershed (270,000 to 450,000 km²) is shared between Guinea, Mali, Mauritania, and Senegal.
On its lower course, the river splits into two branches forming the Île à Morfil. It is connected to Lake Guiers by the Ferlo, and empties into an estuary separated from the ocean by a long sandy spit, the Langue de Barbarie. In this area, an artificial breach was made in the spit in the early 2000s to limit flood risks, a breach that has since widened considerably under the action of currents and swell.
Farther south, the Gambia River crosses the country from east to west, forming The Gambia state. The Casamance River meanders through a region of plains and forests, with a wide estuary at Ziguinchor. In the west-central part, the Sine and Saloum form a complex delta of tidal creeks (bolongs), islands, and mangroves, classified as a national park and Biosphere Reserve.
The main hydrological units also include several notable lakes and wetlands. Lake Guiers, in the north, is a crucial reservoir for the drinking water supply of part of the country, including Dakar. Near the capital, Lake Retba – better known as Lake Rose (Pink Lake) – features waters naturally tinted pink by the presence of a halophilic algae, Dunaliella salina. This lacustrine ecosystem, separated from the ocean by a dune cordon, illustrates the close link between continental waters, coastal dunes, and human exploitation (salt production, tourism, etc.).
In quantitative terms, renewable water resources are estimated at nearly 38.8 km³. But this relative abundance hides strong seasonal and regional disparities, with extreme dependence on monsoon rains and increased vulnerability in case of rainfall deficit.
A Tropical, Sahelian, and Coastal Country: Understanding the Climates
The country’s geography in Senegal can also be read through its skies and seasons. The climate is generally tropical, but strongly marked by the Sahelian transition. Two main seasons structure the year: a long dry season, dominated by continental trade winds and the dust-laden Harmattan wind, and a rainy season – the “hivernage” – linked to the northward movement of the monsoon and the Intertropical Convergence Zone (ITCZ).
This is the total annual precipitation, in millimeters, in northern Senegal, where the rainy season lasts only a few weeks.
In the far south, in Casamance, the “hivernage” starts earlier, sometimes as early as late May, and lasts until the end of October. Rainfall totals commonly exceed 1,400–1,600 mm per year, with episodes of more sustained rain. In some areas near the Guinean border, annual rainfall can reach up to 1,800 mm locally.
The country’s climatic map is divided into three main types in the Köppen-Geiger classification. In the north, the regions of Louga, Matam, and Saint-Louis fall under a hot desert climate (BWh). In the center, a broad band including Dakar, Thiès, Kaolack, Diourbel, Fatick, and Kaffrine experiences a hot semi-arid climate (BSh). In the south, the regions of Ziguinchor, Kolda, Sédhiou, Tambacounda, and Kédougou have a tropical savanna climate with distinct seasons (Aw).
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| Main Climatic Zone | Regions Concerned (examples) | Köppen Type | Indicative Annual Precipitation |
|---|---|---|---|
| Hot desert climate (north) | Saint-Louis, Matam, Louga | BWh | 240–350 mm |
| Hot semi-arid climate (center) | Dakar, Thiès, Kaolack, Fatick, Diourbel, Kaffrine | BSh | 400–700 mm |
| Tropical savanna climate (south) | Ziguinchor, Kolda, Sédhiou, Tambacounda, Kédougou | Aw | 1,400–1,800 mm |
Temperatures remain high year-round, with a relative coolness from December to April, especially on the coast where a cool ocean current limits extremes. Dakar thus benefits from a significantly more temperate climate than the interior: average highs hover around 26 °C in the middle of “winter,” while nights can sometimes drop to around 18 °C. In contrast, the continental interior can be scorching hot before the rains: in cities like Tambacounda, peaks of 50 °C, and even over 54 °C near the Malian border, have been recorded.
This climatic mosaic is also structured by finer agro-ecological zones, distinguishing, for example, an arid Sahel, a semi-arid Sudanian savanna, more humid Guinean savannas in the south, or a narrow coastal strip that is cooler and more humid near the Atlantic coast.
Contrasted Soils and a Predominantly Agricultural Territory
The soil structure reflects both the sedimentary context and the climatic history of the country. In the middle valleys of the Senegal and Saloum rivers, one finds silty-sandy or clay alluvium which, when not salinized, are well-suited to irrigation and rice cultivation. Near the mouths, soils become salty under the influence of tides, forming “tannes” where only some halophilic grasses and extensive grazing are possible.
In the northwest, prioritize peanut cultivation on “dior” soils (ochre sand dunes rich in iron oxides). In the finer depressions between these dunes, cultivate sorghum or millet instead. In the center and south, where a laterite crust outcrops under a thin sandy layer, and in Casamance, where leached clay soils, red or brownish and rich in iron oxides dominate, opt for more intensive agroforestry systems.
Approximately half of the national territory is considered agricultural land in the broad sense. Recent estimates mention about 49% of the area as agricultural land, of which nearly 19–20% is arable land for annual crops and less than 1% is permanent crops. Irrigated areas remain modest on a national scale, around 1,200 km², mainly concentrated along the Senegal River, the Gambia River, and in some lowlands of Casamance or the Sine-Saloum delta.
Peanuts occupy about 40% of cultivated land in Senegal, nearly two million hectares.
The paradox is that, despite this strong agricultural vocation – with 46% of the territory involved and up to 70–80% of the rural population engaged in this sector – the country remains largely dependent on imported foodstuffs. It is estimated that about 70% of food needs, including rice, wheat, corn, palm oil, sugar, and potatoes, are met by imports, which increases food vulnerability.
Vegetation, Ecosystems, and Wildlife: From the Sahel to Mangroves
The country’s geography in Senegal is also reflected in the vegetation gradient from north to south. In the north, the Sahelian zone appears as a shrub and tree steppe, where baobabs, acacias, and thorny shrubs punctuate a seasonal grassy carpet. These steppes cover about a third of the northern part of the territory. During the “hivernage,” abundant grass grows, offering vast pastures; but in the dry season, the grassy cover largely disappears, leaving the soil bare and exposed to erosion.
Farther south, the savanna becomes denser in the Sudanian zone, with shrub or tree savannas, groves, and open forests. This zone presents a great diversity of woody species (over 80 in some areas), including various acacias, baobabs, as well as large trees like mahogany, teak, or kapok. The southernmost regions, like Casamance and some valleys, host dense dry forests and forest-savanna mosaics characteristic of the Guinean ecoregion.
The coastlines, particularly in the Sine-Saloum delta and Casamance, host significant mangroves. These mangrove ecosystems colonize estuaries, tidal creeks (bolongs), and bay bottoms, playing a major role in protection against coastal erosion, water filtration, fisheries production, and carbon sequestration. The Guinean mangroves even constitute one of the four major terrestrial ecoregions identified in the national territory, alongside the West Sudanian savanna, the Sahel acacia savanna, and the Guinean forest-savanna mosaic.
The wildlife reflects this habitat diversity. In the east, Niokolo-Koba National Park – a UNESCO World Heritage site and biosphere reserve – still protects populations of large African mammals: elephants, buffalo, hippopotamuses, various antelopes, lions, leopards, cheetahs, warthogs, and monkeys. In the southwest, Basse-Casamance National Park is home to forest buffalo, bay colobus, cercopithecus monkeys, galagos, and a rich forest avifauna.
The northern wetlands, on the other hand, are a paradise for migratory waterbirds. Djoudj National Bird Sanctuary, in the Senegal River delta, hosts over a million birds each year, including African spoonbills, white pelicans, cormorants, purple herons, Gambian geese, and vast colonies of weaver birds. The Langue de Barbarie National Park and the Guembeul Reserve, farther south, complete this string of protected coastal areas where one can observe flamingos, terns, sea turtles, and threatened gazelles.
Aquatic environments – rivers, lakes, tidal creeks, and marine waters – produce considerable fishery biodiversity. They host fish (like the capitaine, or Nile perch, in the lower Senegal), crustaceans, manatees, turtles, and dolphins. But overfishing and habitat degradation (cut mangroves, polluted estuaries, dams altering flood regimes) are among the major threats.
Protected Areas: A Quarter of the Territory Under Conservation Status
Faced with this ecological richness, authorities have gradually established a network of protected areas covering a significant part of the territory. Figures vary depending on definitions, but recent data indicate that about 26% of land area falls into a protection category (parks, reserves, etc.), while about 8% of the territory is explicitly classified as strictly protected areas.
Niokolo-Koba National Park is the largest in Senegal, covering an area of over 9,000 km².
Basse-Casamance, with its 5,000 hectares, completes this southern network, while Djoudj, in the north, stands as a world-class ornithological sanctuary. Alongside these national parks, numerous wildlife reserves, classified forests, biosphere reserves, and Ramsar zones crisscross the territory, from Lake Guiers to coastal forests like Mbao and Sébikotane.
A Population Concentrated on the Coast and in the Peanut Basin
On a human level, the country’s geography in Senegal is marked by strong density disparities. The population – around 18 million inhabitants according to recent estimates – is largely concentrated in the western half of the country, particularly along the Atlantic coast. It is estimated that about 70% of inhabitants live in the coastal zone, a figure that rises to over 80% if only the western half of the territory is considered.
The Dakar region concentrates about a third of Senegal’s population on only 0.3% of the national surface area.
The table below gives a contrasted overview of some regions.
| Region | Geographical Characteristics | Approximate Density |
|---|---|---|
| Dakar | Urban coastline, Cape Verde peninsula | > 1,000 inh./km² (urban area) |
| Thiès, Mbour, Rufisque | Coastline, peanut basin, Niayes | 100–300 inh./km² |
| Kaolack, Diourbel | West-central, peanut basin | 50–150 inh./km² |
| Saint-Louis (interior), Louga | Northern Sahel, Ferlo, desertic in places | 10–30 inh./km² |
| Tambacounda, Kédougou | East, savannas, more marked relief | ~10–15 inh./km² |
This distribution is due to several factors. The coast offers economic assets (ports, fishing, tourism, services, industries), climatic advantages (more moderate temperatures, relative humidity), and historical ones (colonial settlement, infrastructure). The west-central part, often called the “peanut basin,” benefited from early agricultural development and road and rail infrastructure linking the interior to the port of Dakar.
The south (Casamance) is rich in agricultural land, water, and forests, but its relative isolation (separated by The Gambia), the history of an internal conflict, and a lower density of infrastructure have limited spectacular urbanization comparable to that of the northern coast.
Desertification, Land Degradation, and the “Great Green Wall”
Located in the heart of the Sahelian band, the country is on the front lines of the desertification process. In this transition zone between the hyper-arid Sahara and the more humid Sudanian savannas, soils are naturally fragile, poor in phosphorus and nitrogen, and easily erodible. Prolonged drought episodes – like those that marked the region from the late 1960s to the mid-1980s, and again in the early 2010s – have accelerated the decline in biological productivity.
This dynamic is fueled by both climatic factors (rainfall irregularity, rising temperatures, increasing aridity) and human practices: overgrazing, uncontrolled clearing, forest exploitation for firewood or charcoal, expansion of rain-fed crops onto marginal lands, inappropriate deep plowing, and sometimes deficient land management.
Percentage of arable land already affected by degradation, mainly due to erosion and salinization.
At the level of the Sahel as a whole, over 80% of land is said to be degraded and the advance of the Sahara southward is estimated, according to some studies, at several tens of kilometers per year, even if these figures should be taken with caution. Regardless, the effect on food security, rural livelihoods, and migratory dynamics is considerable.
The country has adopted a National Action Plan to Combat Desertification, a national framework for investments in sustainable land management, and has become a pilot country for Land Degradation Neutrality under the United Nations Convention to Combat Desertification.
The most emblematic initiative remains the Great Green Wall. Launched at the African Union level, it aims to restore, by 2030, a band of degraded land several thousand kilometers long across the entire Sahel, from Dakar to Djibouti, combining reforestation, assisted natural regeneration, water and soil conservation techniques, and agroforestry systems. The first symbolic “tree” of this project was actually planted on Senegalese soil, and the country claims to have planted about 12 million drought-resistant trees within this framework. Other programs, like “Regreening Africa” supported by the European Union or the FAO’s “Action Against Desertification” initiative, have enabled the restoration of several thousand hectares through the rehabilitation of fallows, pastures, and forests.
Coasts Under Pressure: Niayes, Deltas, and Sea Level Rise
While the north and center battle the advance of the desert, the coasts are on the front line facing marine erosion and sea level rise. The country’s Atlantic shoreline, straight north of Dakar and more indented to the south, is largely formed of sandy beaches and dune cords, shaped by the swell and the Canary Current. The estuaries and deltas (Senegal, Sine-Saloum, Casamance) end in zones of mangroves, marshes, mudflats, and “tannes”.
The Senegalese coastal zone concentrates major cities, strategic infrastructure, and vital agricultural areas like the Niayes region, an essential market gardening area for Dakar’s supply. This zone, however, suffers strong pressure due to rapid urbanization and sand quarry expansion, destabilizing dunes and worsening wind erosion as well as groundwater salinization.
Climate change adds a worrying dimension: projections indicate that sea level off West Africa could rise faster than the global average. Within a few decades, a rise on the order of several tens of centimeters is anticipated, which, combined with extreme events (swells, storms, storm surges), threatens coastal neighborhoods, industrial, port, and tourist zones, as well as low-lying agricultural land. In Saint-Louis, for example, entire neighborhoods built on the Langue de Barbarie or in flood-prone areas are already highly vulnerable.
Climate Change: A Multiplier of Geographical Risks
The latest generation of climate models (CMIP6) converge in predicting a rise in average temperatures in West Africa on the order of 1.5 to 4 °C by the middle or end of the century, compared to late 20th-century levels. For the country’s geography in Senegal, this translates into an increase in the number of extreme heat days (over 35 °C), especially in the northeast and east, an intensification of heatwaves, increased evapotranspiration, and a decrease in soil moisture.
Climate projections indicate a slight decrease in total annual rainfall, but above all a strong increase in variability. This will translate into alternating prolonged droughts and more intense rainfall episodes, like ‘mega-downpours’ causing floods. The “hivernage”, becoming shorter and more irregular, will directly impact rain-fed crops (millet, sorghum), whose yields are expected to decline significantly.
Cropland exposed to drought is expected to increase, land degradation will continue, while water resources per capita will decrease, under the combined effect of climate and population growth. Models also suggest that agro-ecological zones could shift southward, leading to a displacement of the boundaries between the Sahel, Sudanian savanna, and Guinean forests, with potential impacts on biodiversity and production systems.
Urban and coastal infrastructure is vulnerable to the effects of climate change. Roads, weakened by heatwaves and intense rains, will require higher maintenance and reconstruction costs. Ports and coastal neighborhoods will have to face rising sea levels and erosion. At the same time, the proportion of the population exposed to heatwaves and mortality linked to heatstroke, especially in cities, will increase significantly.
Land Governance, Agriculture, and Land Tenure Issues
The country’s geography in Senegal is not limited to its reliefs, rivers, and climates: it is also shaped by land tenure rules and social dynamics. Since the law on the National Domain, adopted in 1964, the land tenure system rests on a hybrid system combining modern law and local customs. Lands are largely considered to belong to the nation, managed by local authorities, but usage rights and traditional rules continue to play a major role in access to land and management of common resources.
Demographic pressure, the development of agribusiness and extractive industries, and often ineffective reforms, have exacerbated conflicts related to land access. This translates into informal privatizations, a reduction of land for smallholders, and compensation deemed unfair for displaced populations.
These issues are particularly sensitive in areas where land is both scarce and coveted: the Niayes strip, urban peripheries like around Dakar or Thiès, irrigated valleys of the Senegal River, fertile lands of Casamance. Here, physical geography – deep soils, access to water, proximity to cities – combines with issues of power and governance.
The Emerging Senegal Plan aims to modernize the land sector and promote sustainable resource management. However, reconciling large-scale investments with local food security, the rights of rural communities, and ecosystem protection remains a complex exercise.
A Geography at the Heart of Future Trajectories
Observing the country’s geography in Senegal is thus reading a territory that is both coherent and contrasted, stretched between multiple gradients: dry north versus humid south, densely populated coastline versus sparsely populated interiors, vulnerable sandy plains versus relict forests rich in biodiversity, deltas threatened by salinization versus plateaus succumbing to aridity.
The country’s geography poses several major challenges: ensuring food security with a primarily rain-fed agriculture and degraded lands, combating desertification in the central and northern regions, protecting coasts and cities from rising sea levels and storms, and preserving ecosystems weakened by overexploitation and rapid urbanization.
It also offers levers. The great rivers – Senegal, Gambia, Casamance, Sine-Saloum – provide considerable hydro-agricultural, fisheries, and energy potential, provided that dams, irrigation, and associated ecosystems are managed carefully. The mangroves and forests, if restored and protected, can become natural shields against erosion, carbon sinks, and reservoirs of biodiversity. The savannas, with the right agroforestry practices, can reconcile production, livestock, and soil regeneration.
The country occupies a strategic regional position, at the junction of Sahelian, Guinean, and Atlantic spaces. This location has historically influenced caravan routes, the slave trade, colonization, and migratory movements. Today, it conditions its future in a changing Sahel, where geography constitutes the framework for the balance between climate, environment, development, and society, making this region one of the most vulnerable in the world.
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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.
