Geography of Madagascar

Topography

Madagascar can be divided into five geographical regions: the east coast, the Tsaratanana Massif, the central highlands, the west coast, and the southwest. The highest elevations parallel the east coast, while the land slopes more gradually toward the west coast.

The east coast consists of a narrow lowland band about fifty kilometers wide, formed from alluvial soil sedimentation. An intermediate zone, composed of steep bluffs and ravines, borders an escarpment approximately 500 meters in elevation, providing access to the central highlands. This coastal region extends from north of Baie d'Antongil—formed by the Masoala Peninsula—to the far south of the island. The coastline is mostly straight, except for the bay, offering fewer natural harbors than the west coast. The Canal des Pangalanes (Lakandranon' Ampalangalana), an 800-kilometer-long lagoon formed naturally by sand deposition and river silting, serves as a transport route and fishing area. The beach slopes steeply into deep waters, and the east coast is considered dangerous for swimmers and sailors due to the presence of sharks.

The Tsaratanana Massif, at the northern end of the island, contains Madagascar’s highest peak at 2,880 meters. South of this is the volcanic Montagne d'Ambre (Ambohitra). The deeply indented coastline features Antsiranana (Diégo Suarez), an excellent natural harbor, and Nosy Be, a large island to the west. However, the mountainous terrain to the south limits the potential of Antsiranana’s port by restricting traffic flow from other parts of the island.

The central highlands, ranging from 800 to 1,800 meters in altitude, exhibit diverse topography, including rounded hills, granite outcrops, extinct volcanoes, eroded peneplains, and alluvial plains converted into irrigated rice fields. This region extends from the Tsaratanana Massif in the north to the Ivakoany Massif in the south. The escarpments along the east coast clearly define the highlands, which gently slope toward the west coast. Notable features include the Anjafy High Plateaux, the volcanic formations of Itasy (Lake Itasy sits in a volcanic crater), the Ankaratra Massif (2,666 meters), and the Ivakoany Massif. The Isalo Roiniforme Massif separates the central highlands from the west coast. Antananarivo, the national capital, is located at 1,468 meters above sea level.

A notable feature of the central highlands is a north-south rift valley east of Antananarivo, which includes Lac Alaotra, Madagascar’s largest lake (40 km long). The lake, at 761 meters above sea level, is bordered by cliffs rising 701 meters to the west and 488 meters to the east, resembling East Africa’s rift valleys. This region experiences frequent earth tremors due to geological subsidence.

The west coast, composed of sedimentary formations deposited over time, is more indented than the east coast, especially in the northwest, providing well-sheltered harbors like Mahajanga. Deep bays and secure harbors have historically attracted explorers, traders, and pirates from Europe, Africa, and the Middle East. The broad alluvial plains along the coast between Mahajanga and Toliara have significant agricultural potential but remain sparsely populated and underutilized.

The southwest is bordered by the Ivakoany Massif to the east and the Isalo Roiniforme Massif to the north. It includes the Mahafaly Plateau and the arid desert region inhabited by the Antandroy people.

Rivers flowing east from the central highlands to the Indian Ocean include the Mananara, Mangoro, and Maningory (which originates from Lake Alaotra), as well as the Bemarivo, Ivondro, and Mananjary. These rivers are short and fast due to the steep terrain, often forming waterfalls. The west coast’s rivers, such as the Sambirano, Mahajamba, Betsiboka, Mania, Mahavavy (North and South), Mangoky, and Onilahy, are longer and slower due to the gentler slope. The Ikopa River, a tributary of the Betsiboka, flows past Antananarivo. The Mangoky River has a basin area of 50,000 km², while the Ikopa and Betsiboka Rivers have basin areas of 18,550 km² and 11,800 km², respectively. The Mandrare River in the south has a basin area of 12,435 km² but runs dry for part of the year. Important lakes include Lake Kinkony in the northwest and Lake Ihotry in the southwest.

Madagascar is often called the "Great Red Island" due to its dominant red lateritic soils. These soils are prevalent in the central highlands, though richer soils exist in former volcanic regions like Itasy, Ankaratra, and Tsaratanana. A narrow band of alluvial soil runs along the east coast and at river mouths on the west coast. Clay, sand, and limestone mixtures characterize the western regions, while the south features shallow lateritic and limestone soils.

Madagascar - Climate

Madagascar’s climate is driven by southeastern trade winds from the Indian Ocean anticyclone, a high-pressure system that shifts seasonally. The island has two seasons: a hot, rainy season from November to April and a cooler, dry season from May to October. However, climate variations arise due to differences in elevation and exposure to prevailing winds.

The east coast, with a subequatorial climate, receives the most rainfall, up to 3.5 meters annually. It is known for its hot, humid conditions, endemic tropical fevers, and destructive cyclones during the rainy season. The central highlands, shielded by mountains, are drier and cooler, with frequent thunderstorms in the rainy season and lightning hazards.

Antananarivo receives most of its 1.4 meters of annual rainfall between November and April. The dry season is sunny and cool, with chilly mornings. Frost is rare in the city but common at higher elevations. The west coast is drier, and the southwest is semi-desert, receiving as little as 0.3 meters of rainfall annually at Toliara. Surface water is abundant along the east coast and in the far north but scarce in the extreme south.

Madagascar is prone to cyclones. In February 1994, Cyclone Geralda, the worst since 1927, caused significant destruction, leaving 500,000 people homeless and inflicting $45 million in damages. Infrastructure repair efforts have involved the World Bank and European organizations.

Madagascar - Flora and Fauna

Madagascar is often described as a "world apart" due to its unique biodiversity. Its flora and fauna reflect the island’s ancient origins as part of Gondwanaland and its long isolation. Many species found here do not exist elsewhere, such as the iconic "traveler’s tree" (*Ravenala madagascariensis*), which stores potable water in its trunk.

The island lacks large African mammals like elephants, giraffes, and lions but has 66 unique land mammal species, including lemurs. Madagascar also lacks venomous snakes. Over time, many extinct species have survived here, and new species have evolved, making its biodiversity globally significant.

Once covered by forests, Madagascar has suffered extensive deforestation, especially in the central highlands. Rainforests now primarily exist along the steep eastern slopes. Secondary growth, including traveler’s trees, raffia, and baobabs, has replaced original forests in many areas. The central highlands and west coast feature savannas, while the southwest supports desert-adapted vegetation.

Madagascar is home to 900 orchid species, along with bananas, mangoes, coconuts, and vanilla. Eucalyptus, introduced from Australia, is widespread. Wood and charcoal provide 80% of domestic fuel, leading to deforestation. The World Bank has promoted reforestation with pine and eucalyptus plantations to alleviate fuel shortages.