periodic cyclones, drought, and locust infestation
Environment - current issues:
soil erosion results from deforestation and overgrazing; desertification; surface water contaminated with raw sewage and other organic wastes; several species of flora and fauna unique to the island are endangered
Environment - international agreements:
party to: Biodiversity, Climate Change, Climate Change-Kyoto Protocol, Desertification, Endangered Species, Hazardous Wastes, Law of the Sea, Marine Life Conservation, Ozone Layer Protection, Wetlands signed, but not ratified: none of the selected agreements
Geography - note:
world's fourth-largest island; strategic location along Mozambique Channel
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,
whereas the land slopes more gradually to the west coast.
The east coast consists of a narrow band of lowlands, about fifty
kilometers wide, formed from the sedimentation of alluvial soils, and an
intermediate zone, composed of steep bluffs alternating with ravines
bordering an escarpment of about 500 meters in elevation, which gives
access to the central highlands. The coastal region extends roughly from
north of Baie d'Antongil, the most prominent feature on the east coast
of the island formed by the Masoala Peninsula, to the far south of the
island. The coastline is straight, with the exception of the bay,
offering less in the way of natural harbors than the west coast. The
Canal des Pangalanes (Lakandranon' Ampalangalana), an 800-kilometerlong
lagoon formed naturally by the washing of sand up on the island by the
Indian Ocean currents and by the silting of rivers, is a feature of the
coast; it has been used both as a means of transportation up and down
the coast and as a fishing area. The beach slopes steeply into deep
water. The east coast is considered dangerous for swimmers and sailors
because of the large number of sharks that frequent the shoreline.
The Tsaratanana Massif region at the north end of the island
contains, at 2,880 meters, the highest point on the island and, north of
this, the Montagne d'Ambre (Ambohitra), which is of volcanic origin. The
coastline is deeply indented; two prominent features are the excellent
natural harbor at Antsiranana (Diégo Suarez), just south of the Cap
d'Ambre (Tanjon' i Bobaomby), and the large island of Nosy-Be to the
west. The mountainous topography to the south, however, limits the
potential of the port at Antsiranana by impeding the flow of traffic
from other parts of the island.
The central highlands, which range from 800 to 1,800 meters in
altitude, contain a wide variety of topographies: rounded and eroded
hills, massive granite outcrops, extinct volcanoes, eroded peneplains,
and alluvial plains and marshes, which have been converted into
irrigated rice fields. The central highlands extend from the Tsaratanana
Massif in the north to the Ivakoany Massif in the south. They are
defined rather clearly by the escarpments along the east coast, and they
slope gently to the west coast. The central highlands include the Anjafy
High Plateaux; the volcanic formations of Itasy (Lake Itasy itself is
found in a volcanic crater) and the Ankaratra Massif, reaching a height
of 2,666 meters; and the Ivakoany Massif in the south. The Isalo
Roiniforme Massif lies between the central highlands and the west coast.
Antananarivo, the national capital, is located in the northern portion
of the central highlands at 1,468 meters above sea level. A prominent
feature of the central highlands is a rift valley running north to
south, located east of Antananarivo and including Lac Alaotra, the
largest body of water on the island, having a length of forty
kilometers. The lake is located 761 meters above sea level and is
bordered by two cliffs, rising 701 meters to the west and 488 meters to
the east, which form the walls of a valley resembling the rift valleys
of East Africa. This region has experienced geological subsidence, and
earth tremors are frequent here.
The west coast, composed of sedimentary formations deposited in
several layers over time, is more indented than the east coast,
especially in the northwest, thus offering a number of fine harbors
sheltered from cyclones, such as the harbor at Mahajanga. Deep bays and
well-protected harbors have attracted explorers, traders, and pirates
from Europe, Africa, and the Middle East since ancient times; thus, the
area has served as an important bridge between Madagascar and the
outside world. Yet the broad alluvial plains found on the coast between
Mahajanga and Toliara, which are believed to have great agricultural
potential, are thinly inhabited and remain largely unexploited.
The southwest is bordered on the east by the Ivakoany Massif and on
the north by the Isala Roiniforme Massif. It includes two regions along
the south coast, the Mahafaly Plateau and the desert region occupied by
the Antandroy people.
The Mananara and Mangoro rivers flow from the central highlands to
the east coast, as does the Maningory, which flows from Lake Alaotra.
Other rivers flowing east into the Indian Ocean include the Bemarivo,
the Ivondro, and the Mananjary. These rivers tend to be short because
the watershed is located close to the east coast. Owing to the steep
elevations, they flow rapidly, often over spectacular waterfalls. The
rivers flowing to the west coast and emptying into the Mozambique
Channel tend to be longer and slower, because of the more gradual slope
of the land. The major rivers on the west coast are the Sambirano, the
Mahajamba, the Betsiboka (the port of Mahajanga is located at the
mouth), the Mania, the North and South Mahavavy, the Mangoky, and the
Onilahy. The Ikopa, which flows past Antananarivo, is a tributary of the
Betsiboka. The Mangoky River has a basin area of some 50,000 square
kilometers; the Ikopa River and the Betsiboka River have basin areas of
18,550 and 11,800 square kilometers, respectively. The principal river
in the south, the Mandrare, has a basin area of some 12,435 square
kilometers, but it runs dry during certain months in this desert region.
Important lakes, aside from Alaotra, include Lake Kinkony in the
northwest and Lake Ihotry in the southwest.
Madagascar has been called the "Great Red Island" because
of the supposed preponderance of red lateritic soils. The red soils
predominate in the central highlands, although there are much richer
soils in the regions of former volcanic activity--Itasy and Ankaratra,
and Tsaratamana to the north. A narrow band of alluvial soils is found
all along the east coast and at the mouths of the major rivers on the
west coast; clay, sand, and limestone mixtures are found in the west;
and shallow or skeletal laterite and limestone are located in the south.
The climate is dominated by the southeastern trade winds that
originate in the Indian Ocean anticyclone, a center of high atmospheric
pressure that seasonally changes its position over the ocean. Madagascar
has two seasons: a hot, rainy season from November to April; and a
cooler, dry season from May to October. There is, however, great
variation in climate owing to elevation and position relative to
dominant winds. The east coast has a subequatorial climate and, being
most directly exposed to the trade winds, has the heaviest rainfall,
averaging as much as 3.5 meters annually. This region is notorious not
only for a hot, humid climate in which tropical fevers are endemic but
also for the destructive cyclones that occur during the rainy season,
coming in principally from the direction of the Mascarene Islands.
Because rain clouds discharge much of their moisture east of the highest
elevations on the island, the central highlands are appreciably drier
and, owing to the altitude, also cooler. Thunderstorms are common during
the rainy season in the central highlands, and lightning is a serious
hazard.
Antananarivo receives practically all of its average annual 1.4
meters of rainfall between November and April. The dry season is
pleasant and sunny, although somewhat chilly, especially in the
mornings. Although frosts are rare in Antananarivo, they are common at
higher elevations. During this time, the blue skies of the central
highlands around Antananarivo are considered by many to be among the
clearest and most beautiful in the world.
The west coast is drier than either the east coast or the central
highlands because the trade winds lose their humidity by the time they
reach this region. The southwest and the extreme south are semidesert;
as little as one-third of a meter of rain falls annually at Toliara.
Overall, surface water is most abundant along the east coast and in the
far north (with the exception of the area around Cap d'Ambre, which has
relatively little surface water). Amounts diminish to the west and
south, and the driest regions are in the extreme south.
Madagascar suffers the impact of cyclones from time to time. From
February 2-4, 1994, Madagascar was struck by Cyclone Geralda, the worst
cyclone to come ashore on the island since 1927. The cyclone killed
seventy people and destroyed enough property to leave approximately
500,000 homeless, including 30,000 in Antananarivo and 80,000 in
Toamasina. The cyclone also significantly damaged the country's
infrastructure, most notably coastal roads, railroads, and
telecommunications, as well as agriculture. Damage has been estimated at
US$45 million, and the World Bank's International Development
Association and various European organizations are engaged in financing
the reconstruction. The Madagascar government will contribute US$6
million toward the infrastructure rehabilitation.
The island of Madagascar has been described as an "alternate
world" or a "world apart" because of the uniqueness and
rarity of many of its plant and animal species. Their characteristics
are believed to reflect the island's origins as a part of Gondwanaland
and its many millions of years of virtually total isolation following
the breakup of the landmass. Thus, certain plants, including the
"traveler's" tree (so called because its trunk holds potable
water), are found both in Madagascar and on the South American
continent, but not in Africa. Many of the most characteristic African
species, particularly such large mammals as the elephant, rhinoceros,
giraffe, zebra, and antelope and such beasts of prey as the lion and
leopard, do not exist in Madagascar. In addition, the island has been
spared the great variety of venomous snakes indigenous to the African
continent. Although it is assumed that most life forms on the island had
an African (or South American) origin, many millions of years of
near-complete isolation have allowed old species--elsewhere extinct--to
survive and new species unique to the island to evolve. Thus, a great
number of plant, insect, reptile, and fish species are found only in
Madagascar, and all indigenous land mammal species--sixty-six in
all--are unique to the island.
Madagascar was once covered almost completely by forests, but the
practice of burning the woods to clear the land for dry rice cultivation
has denuded most of the landscape, especially in the central highlands.
Rain forests are concentrated on the steep hillsides along a slender
north-south axis bordering the east coast, from the Tsaratamana Massif
in the north to Tolagnaro in the south. Secondary growth, which has
replaced the original forest and consists to a large extent of
traveler's trees, raffia, and baobabs, is found in many places along the
east coast and in the north. The vegetation of the central highlands and
the west coast is for the most part savanna or steppe, and coarse
prairie grass predominates where erosion has not exposed the orange-red
lateritic soil. In the southwest, the vegetation is adapted to desert
conditions.
The remaining rain forest contains a great number of unique plant
species. The country has some 900 species of orchids. Bananas, mangoes,
coconut, vanilla, and other tropical plants grow on the coasts, and the
eucalyptus tree, brought from Australia, is widespread.
Wood and charcoal from the forests are used to meet 80 percent of
domestic fuel needs. As a result, fuelwood has become scarce. The World
Bank in 1990 launched an environmental program that has increased the
planting of pine and eucalyptus to satisfy fuel needs.
The following is excerped from the Country Studies--Area Handbook program of the U.S. Department of the Army. The original version of this text is available at the Library of Congress.
Full index of Country Studies-Madagascar
Almost all pictures on this site were taken with a Konica Minolta
Recent articles
Madagascar fires mapped with Google Earth in real-time Every year as much as one-third of Madagascar, one of the planet's most biodiverse islands, goes up in flames. Now a new tool gives scientists the ability to monitor and track Madagascar's fires in real-time through the Internet.
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