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| Map Sri Lanka |
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| Sri Lanka (off the coast of India) |
Sri Lanka (off the coast
of India)
|
|
Geography
|
|
Location
|
Indian
Ocean
|
Coordinates
|
7°N 81°E
|
Area
|
65,610 km2
(25,330 sq mi)
|
Area
rank
|
25th
|
Coastline
|
1,340 km
(833 mi)
|
Highest elevation
|
2,524.13 m
(8,281.27 ft)
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Highest point
|
Pidurutalagala
|
Country
|
|
Sri Lanka
|
|
Largest
city
|
Colombo (pop. 752,993)
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Demographics
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|
Population
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20,277,597
(as
of 2012)
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Density
|
323 /km2
(837 /sq mi)
|
Ethnic
groups
|
Sinhalese - 70%, Sri Lanka
Tamils - 10%, Sri Lankan Muslims 8%
|
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| Map of Asia showing the location of Sri Lanka |
Adam's Bridge, a land connection to
the Indian mainland, is now mostly submerged with only a chain of limestone
shoals remaining above sea level. According to temple records, this natural causeway
was formerly complete, but was breached by a violent storm (probably a cyclone)
in 1480. In South Asia, the formation is known as Rama's Bridge, as, according to Hindu mythology, it was
constructed during the rule of Rama.
GEOLOGY
More than 90% of Sri Lanka's surface
lies on Precambrian strata, some of it dating back 2 billion years. The
granulite facies rocks of the Highland Series (gneisses, sillimanite-graphite
gneisses, quartzite, marbles, and some charnokites) make up most of the island
and the amphibolite facies gneisses, granites, and granitic gneisses of the
Vinjayan Series occur in the eastern and southeastern lowlands. Jurassic
sediments are present in very small areas near the western coast and Miocene
limestones underlie the northwestern part of the country and extend south in a
relatively narrow belt along the west coast.[1] The metamorphic
rock surface was created by the transformation of ancient sediments under
intense heat and pressure during mountain-building processes. The theory of plate
tectonics suggests that these rocks and related rocks forming most of south
India were part of a single southern landmass called Gondwanaland. Beginning
about 200 million years ago, forces within the Earth's mantle began to separate
the lands of the Southern Hemisphere, and a crustal plate supporting both India
and Sri Lanka moved toward the northeast. About 45 million years ago, the
Indian plate collided with the Asian landmass, raising the Himalayas in
northern India, and continuing to advance slowly to the present time. Sri Lanka
does not experience earthquakes or major volcanic events because it rides on
the center of the plate.
The island contains relatively limited
strata of sedimentation surrounding its ancient uplands. Aside from recent
deposits along river valleys, only two small fragments of Jurassic (140 to 190
million years ago) sediment occur in Puttalam District, while a more extensive
belt of Miocene (5 to 20 million years ago) limestone is found along the
northwest coast, overlain in many areas by Pleistocene (1 million years ago)
deposits. The northwest coast is part of the deep Cauvery (Kaveri) River Basin
of southeast India, which has been collecting sediments from the highlands of
India and Sri Lanka since the breakup of Gondwanaland.
TOPOGRAPHY
Extensive faulting and erosion over
time have produced a wide range of topographic features. Three zones are
distinguishable by elevation: the Central Highlands, the plains, and the
coastal belt.
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| Topography of Sri Lanka |
Most of the island's surface consists
of plains between 30 and 200 meters above sea level. In the southwest, ridges
and valleys rise gradually to merge with the Central Highlands, giving a dissected
appearance to the plain. Extensive erosion in this area has worn down the
ridges and deposited rich soil for agriculture downstream. In the southeast, a
red, lateritic soil covers relatively level ground that is studded with bare,
monolithic hills. The transition from the plain to the Central Highlands is
abrupt in the southeast, and the mountains appear to rise up like a wall. In
the east and the north, the plain is flat, dissected by long, narrow ridges of
granite running from the Central Highlands.
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| Rama's Bridge, a shoal "connecting" (northwestern) Sri Lanka (Talaimannar on Mannar island in that district) and (southern) India (Dhanushkodi (extinct)/Rameswaram in Ramanathapuram District) between the Gulf of Mannar (southwest) from the Palk Strait (northeast). |
Rama's Bridge, a shoal "connecting" (northwestern) Sri Lanka (Talaimannar on Mannar island in that district) and (southern) India (Dhanushkodi (extinct)/Rameswaram in Ramanathapuram District) between the Gulf of Mannar (southwest) from the Palk Strait (northeast).
A coastal belt about thirty meters
above sea level surrounds the island. Much of the coast consists of scenic
sandy beaches indented by coastal lagoons. In the Jaffna Peninsula, limestone
beds are exposed to the waves as low-lying cliffs in a few places. In the
northeast and the southwest, where the coast cuts across the stratification of
the crystalline rocks, rocky cliffs, bays, and offshore islands can be found;
these conditions have created one of the world's best natural harbors at Trincomalee
on the northeast coast, and a smaller rock harbor at Galle on the southwestern
coast.
Sri Lanka's rivers rise in the Central
Highlands and flow in a radial pattern toward the sea. Most of these rivers are
short. There are 16 principal rivers longer than 100 kilometers in length, with
twelve of them carrying about 75% of the mean river discharge in the entire
country. The longest rivers are the Mahaweli Ganga (335 km) and the Aruvi
Aru (170 km). In the highlands, river courses are frequently broken by
discontinuities in the terrain, and where they encounter escarpments, numerous
waterfalls and rapids have eroded a passage. Once they reach the plain, the
rivers slow down and the waters meander across flood plains and deltas. The
upper reaches of the rivers are wild and usually unnavigable, and the lower
reaches are prone to seasonal flooding. Human intervention has altered the
flows of some rivers in order to create hydroelectric, irrigation, and
transportation projects. In the north, east, and southeast, the rivers feed
numerous artificial lakes or reservoirs (tanks) that store water during the dry
season. During the 1970s and 1980s, large-scale projects dammed the Mahaweli
Ganga and neighboring streams to create large lakes along their courses.
Several hundred kilometers of canals, most of which were built by the Dutch in
the 18th century, link inland waterways in the southwestern part of Sri Lanka.
CLIMATE
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| Rama's Bridge, a shoal "connecting" (northwestern) Sri Lanka (Talaimannar on Mannar island in that district) and (southern) India (Dhanushkodi (extinct)/Rameswaram in Ramanathapuram District) between the Gulf of Mannar (southwest) from the Palk Strait (northeast) |
The rainfall pattern is influenced by
the monsoon winds of the Indian Ocean and Bay of Bengal and is marked by four
seasons. The first is from mid-May to October, when winds originate in the
southwest, bringing moisture from the Indian Ocean. When these winds encounter
the slopes of the Central Highlands, they unload heavy rains on the mountain
slopes and the southwestern sector of the island. Some of the windward slopes
receive up to 2,500 mm (98.4 in) of rain per month, but the leeward
slopes in the east and northeast receive little rain. The second season occurs
in October and November, the intermonsoonal months. During this season,
periodic squalls occur and sometimes tropical cyclones bring overcast skies and
rains to the southwest, northeast, and eastern parts of the island. During the
third season, December to March, monsoon winds come from the northeast,
bringing moisture from the Bay of Bengal. The northeastern slopes of the
mountains may be inundated with up to 1,250 mm (49.2 in) of rain
during these months. Another intermonsoonal period occurs from March until
mid-May, with light, variable winds and evening thundershowers.
Humidity is typically higher in the
southwest and mountainous areas and depends on the seasonal patterns of
rainfall. At Colombo, for example, daytime humidity stays above 70% all year,
rising to almost 90 percent during the monsoon season in June. Anuradhapura
experiences a daytime low of 60% during the intermonsoonal month of March, but
a high of 79% during the November and December rains. In the highlands, Kandy's
daytime humidity usually ranges between 70 and 79%.
ECOLOGICAL ZONES
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| Precipitation and irrigation map of Sri Lanka |
The natural vegetation of the dry zone
is adapted to the annual change from flood to drought. The typical ground cover
is scrub forest, interspersed with tough bushes and cactuses in the driest
areas. Plants grow very fast from November to February when rainfall is heavy,
but stop growing during the hot season from March to August. Various
adaptations to the dry conditions have developed. To conserve water, trees have
thick bark; most have tiny leaves, and some drop their leaves during this
season. Also, the topmost branches of the tallest trees often interlace,
forming a canopy against the hot sun and a barrier to the dry wind. When water
is absent, the plains of the dry zone are dominated by browns and grays. When
water becomes available, either during the wet season or through proximity to
rivers and lakes, the vegetation explodes into shades of green with a wide
variety of beautiful flowers. Varieties of flowering acacias are well adapted
to the arid conditions and flourish on the Jaffna Peninsula. Among the trees of
the dry-land forests are some valuable species, such as satinwood, ebony, ironwood,
and mahogany.
In the wet zone, the dominant
vegetation of the lowlands is a tropical evergreen forest, with tall trees,
broad foliage, and a dense undergrowth of vines and creepers. Subtropical
evergreen forests resembling those of temperate climates flourish in the higher
altitudes. Montane vegetation at the highest altitudes tends to be stunted and
windswept.
Forests at one time covered nearly the
entire island, but by the late 20th century lands classified as forests and
forest reserves covered only one-fifth of the land. The southwestern interior
contains the only large remnants of the original forests of the wet zone. The
government has attempted to preserve sanctuaries for natural vegetation and
animal life, however. Ruhunu National Park in the southeast protects herds of
elephant, deer, and peacocks, and Wilpattu National Park in the northwest
preserves the habitats of many water birds, such as storks, pelicans, ibis, and
spoonbills. During the Mahaweli Ganga Program of the 1970s and 1980s in
northern Sri Lanka, the government set aside four areas of land totalling
1,900 km² as national parks.
LAND USE AND SETTLEMENT
PATTERNS
The dominant pattern of human
settlement during the last 2,500 years has consisted of village farming
communities. Even in the 1980s, the majority of people lived in small villages
and worked at agricultural pursuits. Traditional farming techniques and
life-styles revolve around two types of farming--"wet" and
"dry"—depending upon the availability of water.
The typical settlement pattern in the
rice-growing areas is a compact group of houses or neighborhood surrounding one
or several religious centers that serve as the focus for communal activities.
Sometimes the houses may be situated along a major road and include a few
shops, or the village may include several outlying hamlets. The life-sustaining
rice fields begin where the houses end and stretch into the distance. Some
irrigated fields may include other cash crops, such as sugarcane, or groves of
coconut trees. Palmyra trees grow on the borders of fields or along roads and
paths. Individual houses also may have vegetable gardens in their compounds.
During the rainy seasons and thereafter, when the fields are covered by growing
crops, the village environment is intensely verdant.
The nature of agricultural pursuits in
Sri Lanka has changed over the centuries and has usually depended upon the
availability of arable land and water resources. In earlier times, when
villagers had access to plentiful forests that separated settlements from each
other, slash-and-burn agriculture was a standard technique. As expanding
population and commercial pressures reduced the amount of available forestland,
however, slash-and-burn cultivation steadily declined in favor of permanent
cultivation by private owners. Until the 13th century, the village farming
communities were mainly on the northern plains around Anuradhapura and then Polonnaruwa,
but they later shifted to the southwest. In the 1970s, wide expanses of the
northern and eastern plains were sparsely populated, with scattered villages
each huddled around an artificial lake. The Jaffna Peninsula, although a dry
area, is densely populated and intensively cultivated. The southwest contains
most of the people, and villages are densely clustered with little unused land.
In the Central Highlands around Kandy, villagers faced with limited flat land
have developed intricately terraced hillsides where they grow rice. In the
1960s and 1970s, the wet cultivation area was expanding rapidly, as the
government implemented large-scale irrigation projects to restore the dry zone
to agricultural productivity. In the 1970s, the area drained by the Mahaweli
Ganga changed from a sparsely inhabited region to a wet rice area similar to
the southwest. Through such projects, the government of Sri Lanka has planned
to recreate in the dry zone the lush, landscape associated with the irrigation
works in ancient Sri Lanka.
Beginning in the 16th century and
culminating during the British rule of the 19th and 20th centuries, the
plantation economy came to dominate large sections of the highlands. Plantation
farming resulted in a drastic reduction in the natural forest cover and the
substitution of domesticated crops, such as rubber, tea, or cinnamon. It also
brought about a changed life-style, as the last hunting-and-gathering societies
retreated into smaller areas and laborers moved into the highlands to work on
plantations. Through the late 20th century, workers on large plantations lived
in villages of small houses or in "line rooms" containing ten to
twelve units. The numerous plantations of small landholders frequently included
attached hamlets of workers in addition to the independent houses of the
plantation owners.
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| Aerial view of the Southern Province showing the land use patterns of the coastal belt. |
The coastal belt surrounding the island contains a different settlement pattern that has evolved from older fishing villages. Separate fishing settlements expanded laterally along the coast, linked by a coastal highway and a railway. The mobility of the coastal population during colonial times and after independence led to an increase in the size and number of villages, as well as to the development of growing urban centers with outside contacts. In the 1980s, it was possible to drive for many kilometers along the southwest coast without finding a break in the string of villages and bazaar centers merging into each other and into towns.
STATISTICS
Land use:
arable land: 13.96%
permanent crops: 15.24%
other: 70.8% (2005)
arable land: 13.96%
permanent crops: 15.24%
other: 70.8% (2005)
Irrigated land: 5,700 km²
(2003)
Total renewable water resources: 5,700 m³
(1999)
Natural hazards: occasional
hurricanes and tornadoes
Environmental issues: deforestation; soil erosion; wildlife populations
threatened by poaching and urbanization; coastal
degradation from mining activities and increased pollution; freshwater
resources being polluted by industrial wastes and sewage runoff; waste
disposal; air pollution in Colombo
MARITIME CLAIMS
contiguous zone: 24 nmi (44.4 km; 27.6 mi)
continental shelf: 200 nmi (370.4 km; 230.2 mi) or to the edge of the continental margin
exclusive economic zone: 200 nmi (370.4 km; 230.2 mi)
territorial sea: 12 nmi (22.2 km; 13.8 mi)
ECOLOGICAL ZONES
The
mountains and the southwestern part of the country, known as the "wet
zone," receive ample rainfall (an annual average of 2500 millimeters).
Most of the southeast, east, and northern parts of the country comprise the
"dry zone, which receives between 1200 and 1900 mm of rain annually
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