Climate, Relief and Distribution of Population


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
(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

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.You are welcome to discuss this post/related topics with Dr Shihaan and other experts from around the world in our FORUMS (
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