Commencement of the Mahaweli Scheme - Engr. S. Arumugam. Mahaweli Authority, UNDP/FAO, CBSL
Extract from Water Resources of Ceylon by Engr. S. Armugam 1969
Investigations for Development
Three Teams of engineers and
other specialists investigated various aspects of the development that could be
undertaken utilising the water resources of the Mahaweli Ganga.
USOM Team
A team from the U.S.O.M. was
assigned the task of investigating the most suitable means of augmenting water
supplies to the (Dry Zone) areas of the North Central Province with the
Mahaweli water. This was done in collaboration with the Irrigation Department,
during 1958-1961. Their report, which was published in 1961, out- lined a
scheme to divert 2500 cusecs of the Mahaweli flow at Prim- rose in Kandy and
convey the discharge in a lined canal to assure double cropping of 97,000 acres
of existing paddy land and open- ing up 155,000 acres of undeveloped land. The
plans included four hydro-power stations with installed capacities of 120 MW.,
45 MW., 45 MW., and 33 MW. The construction cost of this diversion scheme
without land development and infra-structures cost was estimated at Rs. 1203
million.
Hunting Survey Corporation Ltd.
In keeping with an agreement
between the Governments of Ceylon and Canada, the Hunting Survey Corporation
Ltd., of Canada were awarded in 1955 the task of evaluating the land and water
resources of the Island. They worked in collaboration with the Survey
Department. As far as the Mahaweli Ganga basin was concerned, their task was
more explicit, for in addition to evaluating the land and water resources, they
had to evaluate the land potential for development and to prepare tentative
plans for future use and to specify additional investigations required before
development could be undertaken. They did their field work in 1958 and
published their report (2 volumes) in 1961.
The UNDP-FAO Team
The third team which consisted
of experts in irrigation, hydro- power, agriculture, sociology, economy etc.
from the F. A. O. worked in collaboration with the Irrigation and other
government counterparts to prepare a Master Plan for the complete utilization
of the water resources of the Mahaweli Ganga for irrigation and hydro-power
development and for flood protection. They com- menced their investigations in
March 1965 and published an ad-hoc report in March 1967 outlining the
development potential of the Mahaweli Ganga. In the next stage of their
investigations they studied the first priority structures and areas in more
detail and finalised the main parameters of the Master Plan. Their
investigations showed, that it would be possible to supply 5,800,000 acre feet
of water, from the proposed and existing reservoirs on the Mahaweli Ganga and
in the N.C. P. for the irrigation of 9.000,000 acres. The extents to be
benefited in the Mahaweli and Maduru Oya basins is estimated as 473,000 acres
while the balance 427,000 acres will be in the North Central Province.
Proposals envisage an assured water supply to 246,000 acres of already irrigat-
ed lands for rotational cropping and opening up 654,000 acres of uncultivated
lands for irrigated agriculture. Based on the soil type diversified
agricultural cultivation has been proposed making the project economic and also
catering to the food and other demands of the country. In addition to the
agricultural benefits, the combined use of the reservoir and canal drops permit
development of 2611 K. W. H. of electrical energy annually, with an installed
capacity of 507 M.W. The estimated cost of the project for providing
irrigation, drainage and flood protection facilities, land development and
settlement and power production is Rs. 5,583 million. This includes the cost of
land clearing and levelling for water delivery to the farmers fields. The
foreign exchange component of the expenditure is estimated at 38%. . The total
capital cost of the project including power transmission lines, overhead
expenditure etc. is estimated at Rs. 6.700 million. It is estimated that the
annual benefits from agricul- tural and power production when the scheme has
been fully developed will be Rs. 1,320 million and Rs. 114 million
respectively. In view of the vast financial implication, the project has been planned
to be implemented in 3 phases over a period of 20 years. The first phase has
again been sub-divided into three steps. The estimated cost of the first phase
is Rs. 1549.9 million while the first step is estimated to cost Rs. 575.7
million.
The target period set for the
completion of the first step is 1972.
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From the Website of the Mahaweli Authority of Sri Lanka
Development Plan
Ceylon can be divided into a Dry Zone and a wet Zone by a line following approximately the 795 inch isohyet. The wet zone corresponds roughly to the southwest quadrant , which covers about 30 percent of the island's area. However this area contains more than three quarters of the total population of Ceylon. It will be noted from figure I that the population of Ceylon has risen very sharply from around 1945, and the density in the Wet Zone has in fact reached a figure of around 1,200 people per square mile. This situation has brought clearly into focus the necessity to develop agricultural production in the Dry Zone.
As Agriculture in the Dry Zone is almost entirely development upon irrigation, its development is virtually impossible without securing an assured water simply. To this end the Government initiated several investigations of the area.
Among them were those of the United States Operations Mission (1958-
Missions of the International Bank for Reconstruction and Development visited the area in 1961 and reported that the development proposed for a multi-
Initiation Of Present Project
In 1961 the government of Ceylon requested assistance from the special fund of the United Nations to survey the Mahaweli Ganga Basin and the Dry Zone areas in the North and Central Provinces. The request was approved by the governing Council of the special fund in june, 1964.
The plan of operation was drawn up and signed on 12 october, 1964 on behalf of the government of Ceylon, the United Nations Special fund and the Food and Agriculture Organization of the United Nations acting as executing agency. The co-
The UNDP allocated US $ 1,146,000 to cover the cost specialist personnel, contractual services, fellowships and equipment. The government contribution in kind was estimated at US $ 837,000.
Purpose Of The Project
The project was designed to achieve the following objectives :-
• To provide basic information on the land and water resources of the Mahaweli Ganga Basin and the Dry Zone areas of the North Central Provinces;
• To provide an overall water management plan with a view to the effective use of water for irrigation and power generation;
• To provide technical plans , preliminary design of works , cost estimates, priorities, phasing and financing needed for implementation of the plan.
Execution Of The Project
The project became operational on 27 October,1964 and field work was concluded in May, 1968. This was followed by UNDP/FAO Mission to investigate and report upon Organizational and Management requirements, from 15 June to 25 July.
The survey was carried out over a period of three years in two stages the field investigations of the first stage, carried out between March, 1965 and February, 1967 comprised mainly a reconnaissance of the entire project area. The principal aim was to work out an outline for a Master Plan for full development of the water resources for irrigation and hydropower.
The second stage of the survey was carried out between February , 1967 and May , 1968. During this period , all the three phases of development for the entire scheme were identified. Additional investigations were made of the areas selected, for the three projects to be included in the first phase of development and detailed designs were prepared.
The effect of the project on the social and economic structure of the country was also considered and analyzed in some detail. For example problems of settlement, of maintenance and operation of the project works, and of the development of a sound agricultural programme based on the optimum use of irrigation facilities ware considered. In addition , cropping patterns and farming practices and methods for the improvement of existing cultivation were studied and workable cropping patterns were devised for the new areas.
The Project Area
The project area covers 39 present of the whole island and 55 percent of the Dry Zone. It includes the mahaweli Ganga basin, the basin of the Maduru Oya and rivers in the north central part of the island.
Land Resources
The area classified as suitable for irrigation extends to approximately 1.5 million acres , of which 900,000 acres would be commended by the proposed irrigation systems (of this 246,000 acres are at present partially irrigated). There remains therefore 600,000 acres of land of which 54,000 acres presently cultivated, but not commanded by the irrigation systems. Its envisaged that the balance of 546,000 acres will remain under forests of the new land to be developed for irrigation, which is 654,000 acres (900,000 – 246,000),360,000 acres area in the basins of the Mahaweli Ganga and Maduru Oya, and 294,000 acres are in the north central part.
Water Resources
The long term mean annual yield of the Mahaweli Ganga river at the lowers diversion weir (Kandakadu) is 6,400,000 acre-
Extract from a FAO Report on the Mahaweli Basin
https://www.fao.org/4/x6861e/x6861e10.htm
Initial planning
Hunting Survey Corporation of Canada
Report 1962
The earliest detailed survey of the Mahaweli Basin was carried out by Hunting Survey Corporation, as a result of an agreement made by the Canadian and Sri Lankan (then Ceylon) governments through the Colombo Plan Administration. The Mahaweli Basin study was one of the three river basin studies undertaken under this agreement. The report on the Mahaweli Basin was presented in 1962 to the Government. The survey provided an inventory of land and water resources of the basin and provided a basis for evaluation of the potential for development, and preparation of tentative plans for the future use of land and water resources.
UNDP/FAO Master Plan
Report 1969
The availability of this detailed study may have prompted many political leaders who had interests in irrigational works, to give serious consideration to harnessing the resources of this river basin which covered one-sixth of the island. By the early 1960s it was generally accepted that the vast water resource of the Mahaweli Ganga had to be harnessed effectively. It is in this context that the then Ceylon Government requested assistance from the Special Fund of the United Nations to survey the Mahaweli Ganga Basin and the dry zone areas in the North and Central Provinces of the island in order to provide basic information for a plan to develop the land and water resources for irrigation and hydropower. The final agreements were signed on 12 October 1964 between the Government of Ceylon, the United Nations Development Programme and the Food and Agriculture Organization of the United Nations.
The initial survey was carried out in two stages between March 1965 and February 1967 and included the Mahaweli Basin, Maduru Oya Basin and the rivers of the West side of the North and Central Provinces.
The Master Plan envisaged to utilize 5,800 × 106m3 of water of the Mahaweli and its tributaries, supplemented by further 1,111 × 106 m3 of water from Maduru Oya and the rivers of the North-Central Province. The potentially usable resource of 6,911 × 106 m3 per year was considered sufficient to irrigate 285,000 ha of paddy throughout the year, or 530,000 ha of alternate crops such as cotton and groundnuts.
Of the total grassland area of 2.53 × 106 ha in the project, the total suitable land area for irrigation was estimated as 610,000 ha, of which 122,000 is already under cultivation. Nearly 90% of the latter land is irrigated, the remainder being used for rain-fed crops.
The proposed scheme was expected to bring under command 366,000 ha of which 266,000 ha would be underdeveloped land, of which about 150,000 ha or 56% would be in the Mahaweli Ganga and Maduru Oya Basins and the remainder would be in the north-central part of the country.
The proposal to meet the above demands contained the impoundment of 15 reservoirs, 11 of them with hydropower stations with a total installed capacity of 508 megawatts and with a total output of firm power of 2,037 million kwh per annum.
The overall project was to be completed in three phases, each phase with its own set of projects, spanning a thirty-year period.
Each phase was to take into consideration the changes in demand for power, irrigation needs, etc., with time and was to be independent of each other in execution and subsequent evaluation.
The three phases suggested were:
| (a) Phase 1: 3 Projects - | Polgolla Diversion (1969–1973) |
| Victoria-Minipe Diversion (1973–1977) | |
| Moragahakanda Multipurpose Unit (1977–1980) | |
| In this phase an estimated 133,000 ha was to be irrigated, of which 56% would be under new irrigation. The hydroelectric capacity envisaged was 200 megawatts, capable of producing 820 million kwh of energy per annum. | |
| (b) Phase II: | Completion of the development in the Mahaweli and Maduru Oya basins, having met the water requirements of systems A and B (see also Fig.24) |
| (c) Phase III: | Irrigation of land in the north-central part of the country and completion of hydropower development of the Mahaweli Ganga and its tributaries. Total irrigated area would be 14,000 ha of which 76% would be under new irrigation. |
It was envisaged that on completion of the scheme the agricultural production will: match the expected population increases; satisfy the expected rise in the demand for agricultural produce per caput; minimize the food imports and be a net exporter for certain agricultural produce; and increase the farm income.
Main Features of the Master Plan as outlined by Engr. M. C. M. Navaratne of MASL.
Storage
* Six million acre feet of water in 15 reservoirs located on the Mahaweli Ganga river, its tributaries and the Maduru Oya.
Power Generation
* 508 MW from 11 power stations . Total output of firm power 2,037 million KWH per year
Irrigation
* Reservoirs : Randenigala and Victoria for irrigation of Mahaweli Basin areas and Moragahakanda, Polgolla and Kotmale for the North Central Area.
The irrigation areas are grouped into 14 irrigation systems.
Eight of these (A, B, C, D-1, D-2, E, F, G) are located in the Basin of the Mahaweli Ganga and Maduru Oya. (Irrigated area of 470,000 acres ).
Remaining six systems (H, I, M, K, J) are in the North-Central Area..
Implementation of Stage 1 - the Polgolla Diversion
In February 1970, Prime Minister Dudley Senanayake with the then Minister of Lands, Irrigation and Power, Mr. C.P. de Silva, laid the foundation stone to commence Stage 1 of the the project : the Polgolla Diversion.
However, the Dudley Senanayake government was defeated at the General Election of 1970, and Sirima Bandaranaike assumed duties as Prime Minister and Maithripala Senanayake was appointed as the Minister of Lands, Irrigation and Power.
The Polgolla Barrage and Bowatenne Dam , tunnels, power stations and connected works were carried out under the new government and the work commenced after a delay of about two years due to a multitude of reasons.
 |
| Polgolla Barrage |
 |
| Ukuwela Hydro Power Station |
Polgolla Barrage, Tunnels and Ukuwela HydroPower Station
It comprised of a barrage across the Mahaweli Ganga at Polgolla to divert a maximum of 2,000 cusecs through a 5 mile long pressure tunnel to the Ukuwela Power Plant of 40 MW installed capacity situated in the adjacent Amban Ganga basin.
The tail race water flows down a tributary of the Amban Ganga into a reservoir at Bowatenna formed by a concrete dam across the river, which diverts part of the flows into the adjacent Kala Oya basin, through a 4 Mile long tunnel and a Tran basin canal into Kalawewa and Kandalama reservoirs.
The rest of the diverted water along with the natural flow of the Amban Ganga is sent down the river to be diverted at the existing Elahera and Angamedilla diversion weirs into existing conveyance canals.
The total extent of land benefited by Project I is 132,000 acres of existing fields and 91,000 acres of new lands.
The discharge of 1,300 cusecs is sent farther down the Amban Ganga and diverted at the Elahera anicut through Elahera – Minneriya- Kantalai-Yoda Ela canal to Minneriya, and from there to Kaudulla and Kantalai tanks, which supply water to system D-1. The Mahaweli System ‘G’ is irrigated directly from this canal.
The remaining 700 cusecs is transferred through the Polgolla-Kala Oya canal (P K) to Kalawewa and Kandalama tanks, from which 70 percent of System ‘H’ is irrigated.
 |
| Bowatenne Power Station |
Bowatenne Dam, Reservoir and Hydro Power Station
The Bowatenna complex consists of a high diversion dam on the Amban Ganga at Bowatenna,. a 4-mile-long diversion tunnel on the left bank followed by about a mile long lined canal up to Dambulla Oya, a bifurcation structure at Dambulla Oya to release part of the flows to the Dambulla Oya which discharges into the Kalàwewa tank and the remaining part into a short earthen canal which will feed the Kandalama tank.
The government adopted the policy of mobilizing the experienced local construction agencies like the existing River Valley Development Board (RVDB), the newly established Mahaweli Development Board (MDB) and the private sector Ceylon Development Engineers (CDE) and other local contractors to undertake certain development activities pertaining to the project.
Stage 1 of the Project was completed and commissioned in February 1976. 52,800 hectares of existing paddy land in the Anuradhapura, Polonnaruwa and Trincomalee districts were benefitted by the Polgolla and Bowatenna complexes.
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Extract from CBSL on the Progress of Stage 1
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