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Sri Lanka Topography
Extensive faulting and erosion over time have produced a wide
range of topographic features, making Sri Lanka one of the most
scenic places in the world. Three zones are distinguishable by
elevation: the Central Highlands, the plains, and the coastal
belt
(see
fig. 3).
The south-central part of Sri Lanka--the rugged Central
Highlands--is the heart of the country. The core of this area is
a high plateau, running north-south for approximately sixty-five
kilometers. This area includes some of Sri Lanka's highest
mountains. (Pidurutalagala is the highest at 2,524 meters.) At
the plateau's southern end, mountain ranges stretch 50 kilometers
to the west toward Adams Peak (2,243 meters) and 50 kilometers to
the east toward Namunakuli (2,036 meters). Flanking the high
central ridges are two lower plateaus. On the west is the Hatton
Plateau, a deeply dissected series of ridges sloping downward
toward the north. On the east, the Uva Basin consists of rolling
hills covered with grasses, traversed by some deep valleys and
gorges. To the north, separated from the main body of mountains
and plateaus by broad valleys, lies the Knuckles Massif: steep
escarpments, deep gorges, and peaks rising to more than 1,800
meters. South of Adams Peak lie the parallel ridges of the
Rakwana Hills, with several peaks over 1,400 meters. The land
descends from the Central Highlands to a series of escarpments
and ledges at 400 to 500 meters above sea level before sloping
down toward the coastal plains.
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.
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 sixteen principal rivers longer than 100 kilometers in
length, with twelve of them carrying about 75 percent of the mean
river discharge in the entire country. The longest rivers are the
Mahaweli Ganga (335 kilometers) and the Aruvi Aru (170
kilometers). 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
(see Sri Lanka - Agriculture
, ch. 3). Several hundred
kilometers of canals, most of which were built by the Dutch in
the eighteenth century, link inland waterways in the southwestern
part of Sri Lanka.
Data as of October 1988
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