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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REPORT
MAHAWELI GANGA DEVELOPMENT
PROJECT I, STAGE II
Development of Kala Oya Basin
Stage II of Project I of the
Mahaveli Ganga Development Plan envisages the development of 71,000 acres of
new lands with irrigated agriculture for 2 to 3 crops per year in the Kala Oya
Basin. This area is presently covered by the
jungle. A comprehensive feasibility study covering the aspects of Land
Classification and Usage, Irrigation and Drainage, Agro-Socio Economic Data,
Marketing, Credit and Service Facilities, General Infrastructure, Industrial Development
Potential, Agricultural Extension and Community and Rural Development Services
etc. has been conducted by MDB along with some specialists from Sogreah
(France), Consultant to MDB. A Feasibility
Report has been prepared in-8 volumes in 1972. This was accepted by the
government in 1973 and allocated Rs. 15 millions to carry out the preliminary
work required in connection with the construction works in Stage II area.
Description of the Project and Main Items of Work
Stage II proposals include the
development of about 71,000 acres of new farm lands under Kandalama and
Kalawewa Tanks (presently in jungle) with irrigated agriculture using a part of
the irrigation potential created under Stage I. Settlement of some 28,000 farm
families, provision of roads, medical, postal, educational, communication and
other infrastructure facilities,, training of farmers in improved methods of
irrigated farming (including efficient usage of water, fertilizer, agro
chemicals etc.), community development, supply of agricultural inputs,
extension services and other service facilities required for farmers,
establishment of agro-based indus tries in.the area and ensure optimum economic
develop ment in the project area.
The 1976 programme covers the completion of con struction works in about 20,000 acres of land on the left bank of Kalawewa (11,000 acres under Kalawewa) and under Kandalama Tank. New construction units are being set up in these areas. State Construction Organizations such as the Army, Department of Machinery and Equipment, TCEO, SD & CC, RVDB along with other main constructing firms have undertaken the work in the main and branch canals, roads, jungle clearing and land levelling works, earth embankments, and concrete structures in new reservoirs and reservoirs to be reconstructed. About 15 village tanks in this area will be reconstructed and integrated into the water distribution system. Field Drainage and Distributary canals under the irrigation systems along with the connected structures will,be done manually along with light and medium jungle clearing. A large number of groups of people will be organised to take up this work. This will enable the settlement of about 8000 farm families.
The balance work under Stage II
development will take place during the next 3 years with an average of 20,000
acres per year.
Apart from these construction works, settlement and selection of farm families, sociological and community development activities, training of farmers and provi sion of inputs and other agricultural extension services, co-ordination with other government organisations for the provision of infrastructure facilities and connected, services (such as marketing, transport, storage, process ing and supply of agricultural inputs) are also coming under the responsibility of the MDB. Creation of employment facilities by opening up of other industries (mainly agro-based) in the area also will be done by the MDB. Agricultural implements, straw board, wood work, brick and earthenware, paper, -handlooms; food processing, manioc starch, sugar cane crushing, silk production and twine making are some of the industries under consideration for setting up in the area. Action will also be taken to develop inland fisheries and animal husbandry.
Each family will be given 2$ acres of irrigable land and I an acre for homestead. About 100 families will be grouped together to form a hamlet or a village. About 5 hamlets form a cluster where a township will be formed. A group of clusters form a sub-area or a district. Action will also be taken to supply 2-wheel and 4-wheel agri cultural tractors for farmers.
Benefits and Costs
Estimated, cost of development of Stage
II was about Rs. 550 million, of which about 30% was in foreign exchange. About
28,000 farm families will be settled in this area of 71,000 acres. Nearly
84,000 persons will find employment in the agriculture and MDB organizations. About
16000 persons will find employment opportunities in the developed area and 5000
persons will get temporary employment in the construction sector during the
period of construction. Increase in crop production under irrigated farming in
the developed area can be listed as follows:—
Crop Annual Production
Paddy 8,543,000
Bu
Maize. 250,000
Cwt
Groundnuts 200,000 Cwt
Soyabeans 150,000 Cwt
Onions 170,000
Cwt
Chillies (dried) 113,000 Cwt
Cotton (seed) 256,000 Cwt
Pulses 257,000
Cwt
Apart from the above, a large number of economic activities will take-place in the homesteads and other highland areas. This will bring about a considerable saving in foreign exchange and a large contribution to the food production effort in Sri Lanka.
Main items of work can be listed
as follows:
(a) Raising of the Kalawewa bund
by 4 feet and remodelling of the spill in order to increase the capacity of
Kalawewa by 20,000 ac. ft.
(b) Construction, of a new main
road Class B Type from Balaluwewa to Andarawewa, 18 miles long.
(c) Building a new reservoir
across Dambulu Oya on the left bank of the Kandalama Tank along with a main
canal 4 miles long and 11 miles of branch canals to irrigate 6000 acres on the
left bank on Kandalama (H9 area). (
d) A new main canal 18 miles long
and a new sluice from Kalawewa along with 2 branch canals 11 miles long to
irrigate some 17,000 acres on the left bank of Kalawewa (Hi and H2 areas).
(e) A new main canal about 28
miles long and a new sluice from Kalawewa to irrigate 40,000 acres of land on
the right bank of Kalawewa (H4 and Hj areas).
(f) A new sluice, widening of the
Kandalama existing RB main canal and extending it by 13 miles to irrigate 8000
acres on the RB of Kandalama (H7 area).
(g) Irrigation and drainage
network including distributary, field and drainage canals in the above areas.
(h) 12 ft. wide unpaved roads
along the field canals, 16 ft. wide gravelled roads along distributaries and
branch canals and 20 ft. wide gravelled roads along main canals.
(i) Clearing the vegetative cover
and stumps from the forests and levelling the land into 2.} ac. farm units and
(j) On-farm work including furrows, laterals, soil conservation bunds and
turnout works including structures.
Reported by
W. N. M. Boteju
Chief Engineer (Planning)
Mahaweli Development Board
.
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