THE RELIEF OF THE ISLAND
In respect of relief the Island may be divided into five major regions:-
(1)The central Highlands, including the Knuckles and the Rakwana massif.
(2)The well-watered southwest country, having a characteristic topography of
scarp lands, cuestas, hogs backs, strike ridges, with
gentle dip slopes and steeper scarp edges, alternating with longitudinal
valleys and showing a well developed trellis drainage
pattern.
(3)The drier, east and south-east country of residual hills, monadnocks,
buttes, and monolithic outcrop domes, with a morphology of the inselberg
type.
(4)The northern lowland and slope with residual ridges and hills,
diminishing gradually in height and width with distance from the central
highlands, eventually to be buried under the mantle of recent alluvium and
gravels.
(5)The coastal belt of lowland, including the fringe of lagoons, spits, and
dunes.
The central highlands are situated in the south central region of Sri Lanka.
These highlands have a highly dissected terrain consisting of plateaus,
ridges, escarpments, and inter-montane basins and valleys. The highest
mountains of Sri Lanka, Pidurutalagala(8281 ft.or 2524 metres),Kirigalpotta(7858
ft or 2395 metres), and Adam's Peak (7,559 ft.or 2303 metres) are all
situated in this area. The highlands are defined by a series of escarpments,
the most spectacular being the so-called World's End, a near vertical
precipice of about 4,000 ft.
Another important feature in the central highlands is the existence of a
series of flats or plains at varying elevations.eg:-
1).Horton Plains
-mean altitude 7,000 ft.
2).Moon plains,Elk plains,kandapola,Ambewala -6,200 ft.
3).The Ragala ledge- 4,900 ft.
4).The Hatton and Madulsima platform- 4,500 ft-4,200 ft.
5).The Welimada basin-4,200 ft.
6).the Southern platform, Kandy plateau, and the Badulla
basin-2,000-1,600ft.
7).The Mahavalatanna-Tanjantanna step-1,500-1,200 ft.
The presence of
these plains had a bearing on siting of settlements and agricultural land
use.
The south-central highlands is an extensive and lofty mountain zone,
commonly known as the upcountry. It is a cool, healthy and invigorating
region, well watered by perennial streams and rivers which frequently
descend in picturesque waterfalls and rapids. It is endowed with a luxuriant
natural vegetation and posses great scenic attractions. The panoramas
presented from it's passes and commanding heights being exceptionally
expansive and beautiful.
THE CLIMATE
1.TEMPERATURE
Sri Lanka being a tropical country situated closer to the equator, has
mainly a tropical climate. The temperatures are perennially high, but there
are variations in temperature between the lowlands and the central
highlands, determined more by the elevation rather than the season. Higher
the elevation cooler is the temperature .In the lowlands the average monthly
temperature varies from 26 deg. celsius to about 31 deg. celsius around thr
year. However in the central highlands the monthly average varies between 7
deg. celsius and 22 deg. celsius. In Nuwara Eliya situated at an elevation
of 1,525 metres the monthly average vary from about 13 deg, celsius in
December to 20 deg.celsius in May.
2.RAINFALL
The predominant factor that influences the climate of the country is the
occurrence of two regional wind systems known as the Monsoon winds that blow
in opposite directions across the Island at different times of the year.
During the first Monsoon period that occurs between May to October, the
winds blow in a south-westerly direction, and bring rain-laden clouds from
the Indian Ocean. There is heavy rainfall during this period affecting
mainly the southern and western parts of the country and the central
highlands.
In the second monsoon period that takes place between December and March,
the winds reverse direction and blow from the north-east, bringing
moisture-laden clouds from the Bay of Bengal. The north-east Monsoon brings
rain to the north-east as well as the central highlands, and the southern
and western parts of the country. In between the two Monsoon periods there
are short inter-Monsoon periods which bring normal convectional rains,
Thus based on the precipitation received the Country can be divided into two
main climatic zones:-
(1)The wet zone
(2)The dry zone
(1)THE WET ZONE
The wet zone receives rain from both the south-west and north-east Monsoons,
as well as the inter-Monsoon period. The annual precipitation in this region
varies from 80 ins.(2,032 mm) to 200 ins.(5,080 mm) and is evenly
distributed throughout the year. The wet zone can be divided into the
low-country wet zone and the montane or up-country wet zone.
THE LOW-COUNYRY WET ZONE
The low-country wet zone extends over three provinces-the Western Province,
the Southern Province' and the Sabaragamuwa Province-consisting of the
following districts:-Gampaha, Colombo, Kalutara, Galle, Matara, Ratnapura
and Kegalle. The average annual rainfall varies between 80ins. to 125
ins.(2,032mm-3,175mm),and rises to 130 ins.to 200 ins(3302 mm to 5080 mm) in
the Ratnapura and Kalutara districts, parts of Kegalle and Galle districts
and the lower valley of the Kelani Ganga. In this region floods are a
recurrent problem. The vegetation is luxuriant and dense, and farmers in
this area have to struggle
continuously to control the growth of weeds that can invade cleared and
cultivated land. The rivers are perennial, broad and deep. the need to store
water for irrigation does not arise, as there is no lack of water at any
time. Sometimes droughts do occur but they are not prolonged and do not
cause any serious problems. The land is flat only near the Sea coast, but
rises gradually inwards, often interrupted by high outcrops, to the
foothills of the central mountains.
In modern Sri lanka the main population centres are all situated in the
low-country wet zone,but in ancient times before 10th century A.D., there is
no evidence of any settled population in the south-western region from Kalu
Ganga in Kalutara to Nilwala Ganga in Matara, and in the Ratnapura district,
which lies immediately inland of it. The earliest inscriptions from this
region belongs to the 10th century A.D. It is recorded that in the 12th
century A.D.Parakramabahu I drained the swamps and marshes of Pasdun Korale
in Kalutara district,into the rivers and made the land habitable. However
inscriptions recovered from Colombo, Gampaha, and Kegalle districts and
Chilaw, show that these areas were populated in pre-Christian times.
THE UP-COUNTRY WET ZONE OR MONTANE ZONE
The up-country wet zone extends over the entire south-central highlands,
that include the Central and Uva Provinces, consisting of the following
districts:-Kandy district, Matale district, Nuwara-Eliya district and
Badulla district. The average rainfall is 80 ins.to 125 ins (2,032 mm -3,175
mm), rising to 140 ins. to 200ins.(3,556 mm-5080 mm) in the upper valley of
the Mahaweli Ganga around Ramboda and the Knuckles, and falling away to 65
ins.to 100 ins (1,651 mm to 2,540 mm) in the mountains of Uva and the
easterly hills, which form a drier sub-zone. The wettest town in Sri Lanka,
Watawala, having the highest annual rainfall of over 200 ins.(5080 mm) is
situated in this region.
The Montane zone above 2,500 ft.(762 metres) was largely unpopulated till
the 10th century, but large scale movement of people into the hills did not
take place untill the fall of the Polonnaru kingdom and the virtual
abandonment of the northern plains in the 13th Century. However by the end
of the Ist Century B.C.the lower montane zone between 1,000 ft to 2,000
ft.(305 metres to 610 metres) in elevation, was populated as indicated by
rock inscriptions left in the Buddhist monasteries, mainly in the regions
such as the Mahaweli Ganga valley, around Teldeniya, Kandy, and Gampola, and
the lesser hills to the north-west of Badulla and the northern and western
slopes of the Matale hills. The Kandyan Kingdom, the last stronghold of the
Sinhalese Monarchy, was essentially a mountain kingdom, a refuge of
independence from the European enemies below.
(2)THE DRY ZONE
The low-country dry zone is historically the most important region in Sri
Lanka, because it was the cradle of the Sinhalese Civilization. The main
population centers in ancient times were situated in this region, including
the kingdoms of the Sinhalese Monarchies from the 6th century B.C. up to the
13th Century A.D. The highly sophisticated irrigation systems consisting of
vast irrigation tanks and an intricate system of irrigation channels, that
has marveled and earned the respect and admiration of modern day Scientists
and Engineers, was developed in this region, and was responsible for
converting the dry zone into the main food producing area of the country.
The dry zone embraces the north-western, northern, north-eastern,
north-central, eastern, and south-eastern parts of Sri Lanka, which
constitutes about 70% Of the total land area. The provinces that fall under
this area are the North-Western, North-Central, Eastern, Northern and parts
of Uva and Southern Provinces. The districts that come under this area are
Puttalam, Anuradhapura, Polonnaruwa, Batticaloa, Trincomalee, Digamadulla,
Jaffna,Vanni, Moneragala and Hambantota.
The dry zone receives rain only during the north-east Monsoon between the
months of December and March, while during the south-west Monsoon it
undergoes a period of drought. The average annual rainfall is between 50
ins. to 75 ins.(1,270 mm to 1,905 mm) and decreases to 30ins. to 45ins. (762
mm to 1,143 mm) in the two arid sub-zones, Hambantota in the south-east and
Mannnar-Puttlam in the north-west.
During the annual drought the temperature rises and a strong dry south-west
wind blows throughout the day .The grass dries up and turns to stubble and
can be easily set on fire. The vegetation droops and the under-growth dies
out. The smaller irrigation tanks dry up or shrink to muddy pools. The
streams and water courses run dry. The larger rivers except the Mahaweli
Ganga and Walawe Ganga, are reduced to mere trickle of flowing water or
break up into disconnected pools. Thus the main problem in the dry zone is
the lack of an adequate supply of water during the annual drought, for
agricultural and domestic purposes.
The ancient
Sinhalese fully realizing this drawback in the dry zone areas, built a
sophisticated irrigation system, consisting of large and small reservoirs,
some rain fed and others receiving water along artificial canals from rivers
that were dammed at higher levels. The creation of this vast irrigation
network was a great boon to the population of the dry zone, in overcoming
water shortages during he annual drought period, as well as at times when
the north-east Monsoon rains failed.
After the fall of the Polonnaru Kingdom early in the 13th Century,the
North-Central Province was abandoned ,and the vast irrigation systems were
neglected and fell into total ruin. Malaria became a serious scourge and
large scale population movements took place from the dry zone, towards the
low-country and up-country wet zone regions, which subsequently became the
main population centers of country. The re-occupation and re-development of
the dry zone was possible only in the recent past after the second world
war, following the extensive use of the insectide DDT to eradicate the
Malarial vector, the Anopheles mosquito.
After the eradication of Malaria in the early 1940s,the Government embarked
upon a massive re-construction and re-habilitation project, the primary aim
of which was to reconstruct and restore the major ancient irrigation tanks
and channels in the dry zone, and encourage farmers in re-occupying the land
which they abandoned during the Malarial scourge. Independent Sri Lanka's
first Prime Minister Honorable Don Stephen Senanayake was deeply involved in
these projects, and was also instrumental in the construction of a massive
irrigation project in the Eastern Province, under the Gal oya development
scheme ,which resulted in the creation of a vast irrigation tank, known as
the Senanayake Samudra, that supplied much needed water to thousands of
acres of old and new paddy lands, and led to the establishment of new
settlements and townships.
However, the perennial problem of water shortages in other parts of the dry
zone persisted until the Government of Sri Lanka in the decade 1980 to 1990
embarked upon the most ambitious development project ever undertaken in
post-independent Sri Lanka
known as the Mahaweli Ganga diversion project,in which the longest,
perennial river in Sri Lanka was dammed at several places,creating
artificial lakes,the waters of which were subsequently channeled through
underground and overland irrigation channels,to join the existing ancient
network of irrigation channels and vast irrigation tanks situated in the
North-Central and Eastern Provinces, thus providing adequate water supplies
to these tanks ,for irrigated agriculture during the annual drought period.
Hydro-Electric power was also generated at several points, under this
massive irrigation cum hydropower project, thus giving a major boost to
hydro-electric power generation in the country. The project has now been
successfully completed and thousands of acres of new land have been brought
under cultivation of rice and other food and cash crops. Simultaneously new
farmer settlements have sprung up all over the North-central and Eastern
Provinces .This has helped to reduce the rural-urban drift of the
population. Thus Sri Lanka is one of the few developing countries, where the
majority of the population still live in rural areas. The country has also
achieved self-sufficiency in rice, the staple diet of the majority of Sri
Lankans. Before the implementation of the Mahaweli Ganga diversion project,a
failure in the north-east Monsoon, would have meant disaster for the farmers
living in the area. But now, such occurences have become a thing of the
past.
Much of the credit for the successful implementation of the Mahaweli Ganga
diversion Project should go to the first executive President of Sri Lanka,
who is also the father of the free market economy in the country, Honourable
Junius Richard Jayewardene,who entrusted the vital development project, to
his able and efficient Minister of Lands, Power and Irrigation, Honourable
Gamini Dissanayake, setting an ambitious time frame of six years for the
completion of the project. The project was re-named as the Accelerated
Mahaweli Development Project and was completed with assistance from the
World Bank and other friendly countries such as the U.S.A., the U.K.,
Canada, Germany, Sweden, etc.
