Physical Geography of Sri Lanka
Physical Geography of Sri Lanka
Location separate Island from the Indian subcontinent,
encircled by the Indian Ocean strategic location near major Indian Ocean sea
routes located 5 0.5— 90.5 North Latitude and 790.52 - 81 0.52 Eastern Longitudes 29 Kilometers off from the southeastern coast of India, but
connected to India till about 5000 BC.
Bay of Bengal to the
east and Gulf of Mannar and Palk Straits on west in Paleolithic period Sri
Lanka and India was connected by means of a land bridge even today one can see
1 8 Islands (limestone shoals) from Talai Mannar to Rameswaran in India 8 of these belong to Sri Lanka and the rest to India after
submerging the bridge this chain of mounds, remain above the sea level
according to Ramayana, the Hindu Epic, this is the remnant of the brick that was built by Hanuman ji total extent of Sri Lanka is
65,610 square km and inland water covers about 2905 square km Tear-drop shaped
island extending from south tip of India but some say it is like a pendent
hanging from India the breadth of the broadest part (Colombo to mount Sangamam) is 227 km.
length from north to
south (Point Pedro, the northern point to Point Dondra) is 434 km mostly low lands around the central hills
and these hills are located in south central interior three zones could be
identified by elevation; i.e. coastal plains, intermediate zone & central
hills
Coastal Plains
Right round the island
with altitude lower than 30m is identified as coastal plains ringed with palm
trees; i.e. north and east Palmyra trees and the rest mostly coconut trees most
of the area is covered with sandy beaches and coastal lagoons for fishing and
salt industry limestone beds exposed to waves as low-lying cliffs in extreme
north, Jaffna Peninsula there had been so many ancient ports round the island
and some of them are still functioning natural harbor at Trincomalee on north east
coast is a deep-water port earlier this was known as Gokanna, a major port on east coast facing Bay of Bengal
smaller rock harbor at Galle on southwestern coast was important for ancient
trade routes Mantai is another
ancient port located near Mannar Island, 64 km south of Jaffna this was a large
trade emporium at a critical location for east-west trade because of this port,
Sri Lanka was well known to Greeks and called Taprobane the prehistoric Thiruketisvaram Hindu Temple is
situated in Mannar District
Intermediate Zone
These are the higher
level plains between 30m and 200 m above sea level soils of this area change from sandy and saline to fertile loams
(a rich soil containing clay, sand and decayed vegetable matter)
Southwest, ridges and valleys rise gradually, merge with Central
Highlands.
transition from plain to Central Highlands ends
abruptly in southeast part of the Island plain dissected by long, narrow ridges
of granite from Central Highlands this intermediate Zone is sub-divided into
three parts
I. Southwestern
Section of intermediate Zone is known as Dakkhinadesa in ancient times series of ridges and valleys could be seen from Deduru Oya to
Hambantota in this region ancient landscape much eroded by heavy rains
commercial Capital of Sri Lanka Colombo also located in this region
Province where
the location of Gem-bearing gravel beds too, included in this Zone Ratnapura, Kelaniya, Kotte-Jayawardenapura, Panadura, Beruwala are some
prominent cities
Southeastern section of intermediate Zone is known as Rohana or Ruhunu Rata, also known as Atadahas Rata and Dolosdahas Rata mountains
of interior rise sharply from this Zone separated by River Mahaweli and River Kaluganga in ancient times
this zone extends as far as Mahaweli Ganga and Trincomalee Bay now sparse population but archaeological evidence indicates as once
populous
3.
Northern section of intermediate Zone is known as Rajarata or king's
country located between Mahaweli Ganga on east and Deduru Oya on west very
flat plain portion of land tapering towards Jaffna Peninsula peninsula area oflimestone and very
different from remainder
Anuradhapura, Polonnaruwa and Yapahuva are prominent
ancient cities.
Central Highlands, the Hill country
Remarkably different from the other parts of country occupies about one-fifth
of territory of island in south-central portion durutalagala in Nuwara Eliya is the
highest point of the island and the height is 2524m from Mean Sea Level.
The other highest mountains are:
Kirigalpottha in
Nuwara Eliya 2395m
Mt. Totapola in Nuwara
Eliya 2357m
Adam's peak in Nuwara
Eliya 2238m
Hatton Plateau is one of the series of upland plains
hill country is remarkable as it remained independent of foreign rule for the
longest period Kandy, Gampola, Kurunegala, Dambadeniya are some of the
important capitals
Climate
Equatorial situation
and tropical condition of the island is influenced by elevation above sea level
rainfall too, uneven throughout the year annual rainfall varies from
1200-1900mm in the Dry zone mountain and southwestern part of the country is
known as the wet zone wet zone receives 2500mm annual rainfall southeast, east,
and northern parts of country comprise the dry zone northwest and southeast
coasts are arid zones which receive least rain i.e. 600-1200mm humidity
typically higher in southwest and mountainous areas.
Monsoons
normally three monsoons are experienced every year
southwest monsoon from May to September with heavy rains northeast monsoon from
November to March both monsoons precipitate the central hills convectional
rains to the whole island during April and October as inter-monsoon.
Temperature
Temperature in Colombo and suburbs varies from 25 0C-28 0C temperature in Central hills and other higher elevations are 140C-160C as 100 meters rise-up the altitude, one Centigrade of temperature
goes down average yearly temperature for the country from 260C-28 0C December and January are the coolest months and March to May, the
hottest months normally day and night temperature vary from 40-70 C
Vegetation
Typical ground cover,
scrub forests could be seen in general, mixed with tough bushes and cactus's in
the driest area plants grow fast from November-February as the rain fall is
heavy, but stop growing during hot season, March-August forests cover almost Whole
Island but recently depleted to 20%
Mangroves
Goes under water when water level is high one could
see them in Batticoloa, Negombo, Puttalam, Bentota, Gintota, Nagarkoil, Kumana etc. structure for adaptation: - Prop roots and breathing roots high
bio-diversity
Forest communities
wet Zone rainfall over
2500mm and no dry period, temperature about 27oc
Tropical ever green forest
(Rain forests)
altitude up to 1000 m high forest has three layers i.e. Emergent up to 45m, Canopy between 25-30m Sub-canopy between I O- 15m
e.g.
Sinharaja (World
Heritage), Gilimale, Kan Eliya, and Kottawa etc.
Sinharaja: 143 tree
species and 60% of them are endemic many mosses, creepers, lianas, and
epiphytes are freely available as strictly reserved forest this has escaped the activities of man
Sub-Tropical Mountain Forests
located between
1000-1500m of altitudes normally, low temperature and the coldest months go
below 160 C rainfall high, but shorter trees mostly, and canopy level lower
10-15m twisted and gnarled trees due to cold wind tree trunks covered with
mosses, lichens, fungus, algae, and epiphytes etc.
mid country forests is
called Sub-Mountain Tropical Wet Evergreen Forests (intermediate forests)
Dry zone
Two third of the country gets around 1800mm, annual average
rainfall pronounced Dry season during south-west monsoon, some trees deciduous,
others evergreen most widespread canopy level 20m, sometimes emergent 3m over
canopy drier areas are Puttalam, Mannar, Hambantota etc. thorny species and shrub species are also common to these
areas forests are untidy, messy and tangled
Intermediate Zone
Intermediate Evergreen
forests and Tropical Semi-evergreen forests could be seen in Kurunegala and
Moneragala respectively Wet zone species towards the wet zone and dry zone species towards
the dry zone
Wet Zone
Grasslands between 460-1500m altitudes tall bushy
grass 'Cymbopogon confertiorous' (Maana) common in dry patana Wet patana in
Central mountain ridges such as Horton, Moon, and elk Plains also called wet
black patana scattered trees, mainly 'Rhododendron arboreum' (Maha rath mal)
which is endemic to Sri Lanka Dry Zone grasslands could be found in Flood
Plains, Mahaweli, Somawathie National park etc. 'Villu', moist grasslands
common to these parts
Planted Forests
Pinus (wet),
Eucalyptus (wet & dry) Tecona or Teak, Mahogany, Ipil Ipil, Casurina and Jak
are common trees in planted forests
Native or indigenous plants
these plants have come to Sri Lanka without the
intervention of man
90% of them are land
or terrestrial 10%/maritime and fresh water
Endemic
830 species are endemic out of 3368 plants in the Island (25%) this is a very high percentage
Sri Lanka three times
smaller than England but has three times more endemic species most endemic
plants are in the wet zone which has come to 60%
Infrodenceal Plants or
introduced plants brought by man intentionally or unintentionally with grains,
fertilizer, packing materials etc.
most of the weeds have
come to Sri Lanka in this manner
Naturalized Plants,
when introduced they adapt themselves and Sri Lanka has about 200 of! them .
Lantana camara (Gandapana), Anacardium occidentale (Cashew nut),
Mimosa pudica (Nidikumba)
Eg
Natural water sources
most rivers are short
as the country is a small Island only 16 rivers are longer than 100km
12 rivers carrying
about 75% of Mean River discharge in the entire country longest rivers are
Mahaweli Ganga, 335km and the next longest is Malwathu Oya 170km
Mahaweli Ganga flows from Horton Plains to northeast coast at Trincomalee Malwathu Oya from Ritigala to Manthai Kala Oya flows from interior to northwest coast at Dutch Bay,
north of Puttalam lagoon Deduru Oya flows from
interior to west coast at Chlaw Maha Oya flows from interior to west coast at Kocchikade, north of Negombo Kelani Ganga flows from
interior to west coast at immediately north of Colombo Kalu Ganga flows from interior to west coast at Kalutara south Bentota Ganga flows from
interior to west coast at Bentota Gin Ganga flows from interior to southwest coast at Gintota, north of Galle Polwatte Ganga flows from
interior to south coast atWeligama and Weligama Bay Nilwala Ganga flows from
interior to south coast at Matara Walawe Ganga flows from interior to south coast at Ambalantota rivers radiate
from Central Highlands, flow in radial patter toward sea Highlands, river
courses frequently broken by terrain once at the plain, slow down and waters meander across flood plains
and deltas upper reaches or rivers are wild, impossible to navigate lower
reaches are prone to seasonal flooding
Man-made reservoirs for irrigation
Human intervention has
altered flows of some rivers and created a hydraulic management system Sri
Lanka home is to one of early hydraulic cultures in the world rivers in north,
north central, east and southeast feed artificial reservoirs for irrigation
from ancient times, function to provide storage for water during dry season
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