Historical Background The original idea of diverting the Mahaweli Ganga was very much in the minds of our ancients. They diverted it at minipe, Kalinga, and Kandekadu along the main river. they also diverted the main branch of the mahaweli, namely, the Ambanganga , at Elahera and Angamadill. They were in a position to do so at that time using the river were in a position to do so at that time using therun of the river water to cultivate vast acerages of paddy since the flow was copious, with the upper catchment being well forested. The lesson we learn is that we should emulate the wisdom of the ancients by encouraging the reforestation of the upper catchment rather than building new damslike upper kothmale. They had even diverted the waters across basins from the amban ganga to Kala Oya Basin. This transbasin diversion was achieved by diverting the spill waters from a dam at Demata Oya in the catchment of amban Ganaga to the catchment of the Kala Oya in a unique and classical way.
Our ancients further built reservoirs in the B.C. period using a sluice. A unique device developed by them, which could control water issues up to a water head of 30 feet, or 10 metres. When they had to control water heads over 30 feet they solved this complex problem by simply replicating the sluices at different levels, so that they always operated them at heads of less than 30 feet starting from the topmost sluice. These instructions were clearly inscribed in stone for all to strictly follow; any deviation from these instructions would have spelt disaster, with the sluice failing.
Our hydraulic civilization had a temporary setback in the 11th century with the incursion of chola invaders when they laid waste the irrigation works in the rajarata, and the capital Anuradhapura had to be shifted to polonnaruwa. The ancient hydraulic civilization reached its climax under Parakrama Bahu the Great in the 12th century. His motto was:
"It is not meet that men like us
Should live and enjoy what has come to our hands
And not care for the people.
In a country like this not even the least quantity
Of rain water should be allowed to flow to
The ocean without profiting man.
Let there not be left anywhere in my kingdom
A piece of land though it be of the smallest dimension,
That does not yield some benefit to man"
The renowned hydraulic civilization that was known the world over as supporting the granary of the east for several millennia, fell in the 13th century. Though historians conjecture that the fall of our hydraulic civilization was due to the incursions of kalinga maha, followed by the javenese Chandra bhanu, scientific evidence from aero space surveys have confirmed that the real reason for the fall of our havdraulic civilization was a cataclysm in the 13th century. This I was fortunate to discover in 1965 in the course of my investigations for the Mahaweli project in the planning stage.
The unique sluices that were developed by our ancients were found in all major reservoirs. I was fortunate to discover and record the ancient sluice of the maduru oya dam in 1982. But before that several ancient sluices were discovered and recorded at first hand for posterity by renowned pioneers and scholars in the course of field investigations. By Dr John Davy Sir Emmerson Tennent(1845), Henry Parker(1890) and R.L.Brohier(1933),During the British period after the pioneering work of Henry Parker, who investigated our ancient irrigation works based on isolated contour surveys and not connected to a level network in respect of levels, the then government commenced the production of a one mile to the inch Topographical Survey of the entire country. This survey conducted by the pioneer surveyors in the Survey Department who did so under trying conditions revealed the numerous ruins of Ancient irrigation works both large and small and their interconnections, as well as the numerous connected monuments of our ancient hydraulic civilization. The British commissioned in 1900 a renowned Irrigation Engineer, Mr. W.T. Strange, to report on the ancient irrigation works discovered by Mr. Henry Parker and recorded by the Survey Department. It was he who first recommended that the Mahaweli Ganga by diverted to the Dry Zone as our ancients had done before. In the Meantime the Survey Department started in establishing a level network. That was essential to undertake any necessary restoration and diversion structures. With the availability of the one-inch to the mile topographical sheet and the level network, it was most fortunate that Hon D.S.Senanayake commissioned R.L. Brohier to report on the Ancient Irrigation Works of Ceylon. This Brohier did in 1932 in a very short time of two years making use of all the information available to him. His "Ancient Irrigation Works of Ceylon" is a classic and will continue to be a reference work on the subject for all time. It need updating only when new only facts emerge, as when new investigation s are undertaken like in the Mahaweli Basin, which is very rare.
Our early leaders D.S. Senanayake, Bulankulame Dissawa, Dudley Senanayake, C.P. de Silva and many others were inspired by our ancient heritage, having read the works of scholars, especially that of Henry Parker and R.L. Brohier, and made various suggestion, To direct the waters of the perennial Mahaweli to the parched dry zone for the benefit of our people. Speacial mention would have to be made of the Hon C.P. de Silva, the then Minister of Lands, Irrigation and Power who pushed the project at every level, and at the every stage, till the completion of the Feasibility studies and the inauguration of the project in 1970.
Preliminary studies in this connection were first made by the irrigation Department. The Resources of the Mahaweli Basin were studied by the Canada Ceylon Colombo Plan Project using modern aerospace techniques and was also concurrently done by the USOM. Both these Studies were done in the late fifties in close cooperation with the Survey Department, the Irrigation Department, Agriculture Department and other government departments, and Published. These studies indicated that there would be a surplus of water according to the envisaged plan and therefore the government wanted to modify the plan to fully utilize the Mahaweli Waters by diverting these excess waters to adjacent basins. As a consequence the FAO/UNDP were requested to prepare a Master Plan to include trans basin development. This was also done in collaboration with all the departments which collaborated in the earlier studies. This Master Plan was completed in 1968.
2. Objectives of the Master Plan
According to the FAO/UNDP Master Plan the project was to develop 900,000 acres of land by providing irrigation facilities as the first priority. This comprised 650,000 acres of new land and extra irrigation facilities for 250,000 acres of already irrigated lands which. However, did not have sufficient irrigation water for the cultivation of two crops per year. This was on the assumption that 10 acre ft of water per acre of land would be sufficient to cultivate two crops of paddy per year.
The irrigation water issues from the reservoirs would be used to generate hydropower as a by-Product to develop 2,600 million GWh of hydropower energy, with an Installed capacity of 507 MW. The whole development programmed was to be constructed in three phases over a 30 year period at an estimated cost of Rs 6,700 million, at 1968 prices. (See Map 1)
In 1970 the Prime Minister Dudley Senanayake with the then Minister of Lands, Irrigation and power, Mr. C.P. de Silva, laid the foundation stone to commence the project. The UNP lost the 1970 general election, and it was left to the Hon Sirimavo Bandaranayake, as Prime Minister, and Hon Maithripala Senanayake, the Minister, to implement Stage I of the project namely, pogolla, Bowatenne diversions and tunnels and connected works. This was undertaken by Ingra of Yogoslavia. The Policy of the then government was to us local expertise as far as possible, mobilizing the experienced local construction agencies like the River Valley Development Board (RVDB), the Mahaweli Development Board (MDB) and the Ceylon Development Engineers (CDE) and others local contractors.
The benefits derived from the first diversion was the additional cultivation of aroud 30,000 acres of existing lands by supplementing extra irrigation issues in System H, and to the Huruluwewa scheme, called System M(H), which did not have sufficient irrigation water (from the time it was commissiond).In addition, the excess water was sent down the Amban Ganga from Bowatenne and was diverted to the Elahera channel to supply the major reservoirs of Minneriya ,Giritale,Kaudulla and Kantalai. In addition hydro power was generated from water following from these diversions. The enlightened policy of using local expertise and construction agencies resulted in the low cost of construction of this stage of the project that cost Rs 350 million. The construction costs were paid back in 5 years from agricultural production and power generation. The Internal Rate of Return for this stage of the project was in the region of per cent,which was economically very viable.
3. Accelerating the Mahaweli project with Modified Objectives
With the elections of 1977 the UNP government came to power. The decision was taken by the then president Mr.J.R Jayawardane to accelerate the Mahaweli project to its realistic limites, in order to make the country self-sufficient in rice, generate sufficient hydro power for industrial use, and find employment for nearly 1.2 million unemployed youth in our country. From the experience gained in other colonization schemes under major irrigation schemes and also under both Galoya and Walawe the government of the time was aware that although the theoretical water requirement per acre was around 10n acre ft per annum, the reality was that the farmers use double this quantity of water for two seasons for various practical reasons. It was therefore very clear that it would be possible to cultivate only half the area that the Master plan envisaged, namely 450,000 acres of the original 900,000 acres planned for development.
The government realized the important and priority that should be given to water management if we are to develop the entire area envisaged. Therefore the government took a definite policy decision not to construct the central province (ncp) canal which was set aside altogether from the project. This was to secure the water issues to satisfy the prescriptive or riparian rights of those lands already receiving tham,which were outside the Mahaweli Basin like in the Kalawewa and Yan Oya basins. This was in fact the rationale for modifying the original Master plan and drawing up the (AMP) Accelerated Mahaweli programme (see Map 2).
It was in this context that the government decided that in addition to the development of 71,000 acres of new land in System H, it should accelerate the Mahaweli programme and and cultivate around 320,000 acres of new lands and 80,000 acres of existing irrigated lands for double cropping in the Mahaweli basin in Systems known as A,B,C and D and its immediate basins. For this purpose it was necessary to construct the Kotmale Dam, Victoriya Dam,Randenigala Dam, and the Maduru Oya Dam in order to regulate the waters irrigating these lands. Electricity was to be generated from the irrigation issues in order to cater for the immediate needs of the country. This plan,drawn up by the government to carry out the major part of the country. This plan, drawn up by the government to carry out the major part of Mahaweli Master plan, was called the Accelerated Mahaweli programme.
It was envisaged to compete the Accelerated Mahaweli project in five years, in less than a third of the time it would have otherwise taken the AMP, wish was in effect half the original Master plan, estimated to cost Rs.20,000 million. It was to divert Mahaweli waters to about 500,000 acres of land in the Dry Zone,settle around 140,000 new settlers and theirs families in addition to the farmers and settlers already living in the areas to be developed. It was to provide the necessary network of roads, schools, hospitals, townships and other amenities. In short, it was to benefit nearly a million people directly, to ease the population congestion in the densely populated areas by giving new opportunities in the Mahaweli area for the poorest of the poor, and to make our country self-sufficient in basic food.