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Location: Western Africa, bordering the Gulf of Guinea,
between Benin and Cameroon
Geographic coordinates: 10 00 N, 8 00 E
Map references: Africa
Area:
total: 923,768 sq km
land: 910,768 sq km
water: 13,000 sq km
Area - comparative: slightly more than twice the size of
California
Land boundaries:
total: 4,047 km
border countries: Benin 773 km, Cameroon 1,690 km, Chad 87
km, Niger 1,497 km
Coastline: 853 km
Maritime claims:
continental shelf: 200-m depth or to the depth of exploitation
exclusive economic zone: 200 nm
territorial sea: 12 nm
Climate: varies; equatorial in south, tropical in center,
arid in north
Terrain: southern lowlands merge into central hills and
plateaus; mountains in southeast, plains in north
Elevation extremes:
lowest point: Atlantic Ocean 0 m
highest point: Chappal Waddi 2,419 m
Natural resources: petroleum, tin, columbite, iron ore,
coal, limestone, lead, zinc, natural gas, hydropower, arable land
Land use:
arable land: 33%
permanent crops: 3%
permanent pastures: 44%
forests and woodland: 12%
other: 8% (1993 est.)
Irrigated land: 9,570 sq km (1993 est.)
Natural hazards: periodic droughts
Environment - current issues: soil degradation; rapid deforestation;
desertification; recent droughts in north severely affecting marginal
agricultural activities
Environment - international agreements:
party to: Biodiversity, Climate Change, Desertification,
Endangered Species, Hazardous Wastes, Law of the Sea, Marine Dumping,
Marine Life Conservation, Nuclear Test Ban, Ozone Layer Protection
signed, but not ratified: none of the selected agreements
Nigeria
GEOGRAPHY
Size: 923,768 square kilometers.
Boundaries: Southern limits set by Gulf of Guinea
(bights of Benin and Biafra); inland frontiers shared with Cameroon
(east), Chad (northeast), Niger (north), and Benin (west). No demarcation
reached regarding Nigeria-Chad-Niger- Cameroon boundary in Lake
Chad, leading to disputes.
Topography: Five major geographic divisions: low
coastal zone along Gulf of Guinea; succeeded northward by hills
and low plateaus; Niger-Benue river valley; broad stepped plateau
stretching to northern border with highest elevations over 1,200
meters; mountainous zone along eastern border, which includes country's
highest point (2,042 meters).
Climate: Tropical with variations governed by
interaction of moist southwest monsoon and dry northeast winds.
Mean maximum temperatures of 30-32ēC (south), 33-35ēC (north). High
humidity in south February-November, June-September in north; low
humidity during dry season. Annual rainfall decreases northward;
about 2,000 millimeters in coastal zone (Niger Delta averages over
3,550 millimeters); 500 to 750 millimeters in north.
Data as of June 1991
Nigeria
PHYSICAL SETTING
Relief and Main Physical Features
Much of Nigeria's surface consists of ancient crystalline rocks
of the African Shield. Having been subject to weathering and erosion
for long periods, the characteristic landscape of this area is extensive
level plains interrupted by occasional granite mountains. These
features form a major landscape type of Nigeria and of West Africa
as a whole. There are also smaller areas of younger granites found,
for example, on the Jos Plateau .
Sedimentary strata dating from various periods overlay the older
rocks in many areas. The sedimentary areas typically consist of
flat-topped ridges and dissected plateaus and a characteristic landscape
of extensive plains and no major rocky outcrops. This landscape
is generally true of the basins of the Niger and Benue rivers as
well as the depressions of the Chad and Sokoto basins in the far
northeast and northwest of the country, respectively. The most dramatic
of the sedimentary landscapes are in southeastern Nigeria, where
thick sedimentary beds from the Abakaliki Uplift to the Anambra
Basin have been tilted and eroded. This process has resulted in
a rugged scarp land topography with east-facing cliffs at in the
Udi Hills, north of Enugu, and in the area around Nanka and Agulu.
Although relatively little of the Nigerian landscape has been shaped
by volcanic episodes, there are two main areas of volcanic rock.
They are found on the Biu Plateau in the northeast, extending into
some localized volcanic areas along the eastern border with Cameroon,
and on the Jos Plateau in the northern center of the country.
The elevational pattern of most of Nigeria consists of a gradual
rise from the coastal plains to the northern savanna regions, generally
reaching an elevation of 600 to 700 meters. Higher altitudes, reaching
more than 1,200 meters in elevation, are found only in isolated
areas of the Jos Plateau and in parts of the eastern highlands along
the Cameroon border. The coastal plain extends inland for about
ten kilometers and rises to an elevation of forty to fifty meters
above sea level at its northern boundary. The eastern and western
sections of the coastal plain are separated by the Niger Delta,
which extends over an area of about 10,000 square kilometers. Much
of this is swampland, separated by numerous islands. The coastal
plain region penetrates inland about seventy-five kilometers in
the west but extends farther in the east. This region is gently
undulating with elevation increasing northward and a mean elevation
of about 150 meters above sea level. Much of the population of southern
Nigeria is located in these eastern and western coastal plains and
in some of the contiguous areas of the coast and the lower Niger
Basin.
Separating the two segments of the coastal plain and extending
to the northeast and northwest are the broad river basins of the
Niger and Benue rivers. The upper reaches of these rivers form narrow
valleys and contain falls and rapids. Most of the lower portions,
however, are free from rapids and have extensive floodplains and
braided stream channels. To the north of the Niger and Benue basins
are the broad, stepped plateau and granite mountains that characterize
much of northern Nigeria. Such mountains are also found in the southwest,
in the region between the western coastal plains and the upper Niger
Basin. The western wedge between Abeokuta and Ibadan and the Niger
Basin reaches elevations of 600 meters or more, while the extensive
northern savanna region, stretching from Kontagora to Gombe and
east to the border, includes extensive areas with elevations of
more than 1,200 meters or more at its center. The mountainous zone
along the middle part of the eastern border, the Cameroon Highlands,
includes the country's highest point (2,042 meters). In the far
northeast and northwest, elevation falls again to below 300 meters
in the Chad Basin in the far northeast and the Sokoto Basin in the
northwest.
Data as of June 1991
Nigeria
Climate
As in most of West Africa, Nigeria's climate is characterized by
strong latitudinal zones, becoming progressively drier as one moves
north from the coast. Rainfall is the key climatic variable, and
there is a marked alternation of wet and dry seasons in most areas.
Two air masses control rainfall--moist northward-moving maritime
air coming from the Atlantic Ocean and dry continental air coming
south from the African landmass. Topographic relief plays a significant
role in local climate only around the Jos Plateau and along the
eastern border highlands.
In the coastal and southeastern portions of Nigeria, the rainy
season usually begins in February or March as moist Atlantic air,
known as the southwest monsoon, invades the country. The beginning
of the rains is usually marked by the incidence of high winds and
heavy but scattered squalls. The scattered quality of this storm
rainfall is especially noticeable in the north in dry years, when
rain may be abundant in some small areas while other contiguous
places are completely dry. By April or early May in most years,
the rainy season is under way throughout most of the area south
of the Niger and Benue river valleys. Farther north, it is usually
June or July before the rains really commence. The peak of the rainy
season occurs through most of northern Nigeria in August, when air
from the Atlantic covers the entire country. In southern regions,
this period marks the August dip in precipitation. Although rarely
completely dry, this dip in rainfall, which is especially marked
in the southwest, can be useful agriculturally, because it allows
a brief dry period for grain harvesting.
From September through November, the northeast trade winds generally
bring a season of clear skies, moderate temperatures, and lower
humidity for most of the country. From December through February,
however, the northeast trade winds blow strongly and often bring
with them a load of fine dust from the Sahara. These dust-laden
winds, known locally as the harmattan, often appear as a dense fog
and cover everything with a layer of fine particles. The harmattan
is more common in the north but affects the entire country except
for a narrow strip along the southwest coast. An occasional strong
harmattan, however, can sweep as far south as Lagos, providing relief
from high humidities in the capital and pushing clouds of dust out
to sea.
Given this climatological cycle and the size of the country, there
is a considerable range in total annual rainfall across Nigeria,
both from south to north and, in some regions, from east to west.
The greatest total precipitation is generally in the southeast,
along the coast around Bonny (south of Port Harcourt) and east of
Calabar, where mean annual rainfall is more than 4,000 millimeters.
Most of the rest of the southeast receives between 2,000 and 3,000
millimeters of rain per year, and the southwest (lying farther north)
receives lower total rainfall, generally between 1,250 and 2,500
millimeters per year. Mean annual precipitation at Lagos is about
1,900 millimeters; at Ibadan, only about 140 kilometers north of
Lagos, mean annual rainfall drops to around 1,250 millimeters. Moving
north from Ibadan, mean annual rainfall in the west is in the range
of 1,200 to 1,300 millimeters.
North of Kaduna, through the northern Guinea savanna and then the
Sudan savanna zones,
the total rainfall and the length of the rainy season decline steadily.
The Guinea savanna starts in the middle belt, or southern part of
northern Nigeria. It is distinguished from the Sudan savanna because
it has more trees whereas the Sudan few trees. Rainy seasons decline
correspondingly in length as one moves north, with Kano having an
average rainy period of 120 to 130 days, and Katsina and Sokoto
having rainy seasons 10 to 20 days shorter. Average annual rainfall
in the north is in the range of 500 to 750 millimeters.
The regularity of drought periods has been among the most notable
aspects of Nigerian climate in recent years, particularly in the
drier regions in the north. Experts regard the twentieth century
as having been among the driest periods of the last several centuries;
the well publicized droughts of the 1970s and 1980s were only the
latest of several significant such episodes to affect West Africa
in this century. At least two of these droughts have severely affected
large areas of northern Nigeria and the Sahel region farther north.
These drought periods are indications of the great variability of
climate across tropical Africa, the most serious effects of which
are usually felt at the drier margins of agricultural zones or in
the regions occupied primarily by pastoral groups.
Temperatures throughout Nigeria are generally high; diurnal variations
are more pronounced than seasonal ones. Highest temperatures occur
during the dry season; rains moderate afternoon highs during the
wet season. Average highs and lows for Lagos are 31° C and 23°
C in January and 28° C and 23° C in June. Although average
temperatures vary little from coastal to inland areas, inland areas,
especially in the northeast, have greater extremes. There, temperatures
reach as high as 44° C before the onset of the rains or drop
as low as 6° C during an intrusion of cool air from the north
from December to February.
Data as of June 1991
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