Overview of the Mahaweli Project

The Mahaweli Project is the largest Multi Purpose Development Project ever undertaken in Sri Lanka. Mahaweli Master Plan drawn up during 1964 – 1968 for harnessing the waters of the Mahaweli envisaged the development of 365,000 ha for agriculture and installation of 600 MW of Hydro-Power capacity.
The total Mahaweli Project Area covers 39 percent of the whole island, 55 percent of the Dry Zone, and encompasses 60 percent of the irrigable land area of Sri Lanka

The Project is to provide Irrigation for agriculture and water for domestic use, generate hydro-power for the whole range of agro-based industry in the Mahaweli areas and elsewhere, provide effective flood control and most importantly open up new land for agriculture development.

The project comprises five Major Dams; Kotmale, Victoria, Randenigala–Rantambe, Maduru Oya and Moragahakanda which has yet to be constructed.

Moragahakanda & Kaluganga Development Projects

Moragahakanda & Kaluganga Development Project is the largest reservoir project to be taken up for development under the Mahaweli River Development Programme.

A full feasibility study of the Moragahakanda Project combined with the Kaluganga Development Project was completed in 2004 by the Lahmeyer International, in association with the Central Engineering Consultancy Bureau (CECB) of Sri Lanka, United Consulting Group (KUWAIT) and Chuo Kaihatsu Corporation, Japan.

Objectives of the Projects

- To provide irrigation water facilities to 81,422 ha in the Dry Zone of Sri Lanka

- Potable and Industrial Water Supply to Anuradhapura and Trincomalee towns

- Generation of electricity by hydro power

Location

The project area is located in the Central and North Central Provinces in Sri Lanka.

Project Configuration

The project consists of

(a) Construction of two major reservoirs namely; Moragahakanda and Kaluganga reservoirs,

(b) A conveyance system consisting of two tunnels and transfer canals and

(c ) A power house of 20 MW installed capacity.

Principal Project Features

Moragahakanda Reservoir

Type of Dam: A roller compacted concrete main dam and two rock fill saddle dams.

Maximum dam height: 65 metres

Active Storage : 521 million cubic metres

Kaluganga Reservoir

Type of Dam A rock fill main dam and two saddle dams, one rock fill and the other earth

Maximum Dam Height 67 metres

Active Storage 144 million cubic metres
Conveyance System
Tunnels 1. Kalunga – Moragahakanda transfer tunnel 15 m3/sec. capacity, length
3.2 km

2. Second Bowatenna Tunnel 25 m3/sec. capacity, length 7.2 km

Conveyance Canals : Total length approximately 50 Km.

Project Cost

Cost benefit

The investment cost of the project is US $ 382 million. The Economic Internal Rate of Return (EIRR) is 22%.

Direct Benefits

Agriculture :

Cropping intensity which varies less than 100% to 154% in the different areas will be raised to around 181% on the average. The direct benefits include increased rice yield per hectare with an additional agricultural production of 109,000 tons annually. The net annual agricultural benefit will be US $ 27.7 million in financial terms.

Inland Fishery:

The average annual fish production potential of the reservoir is estimated to be around 4,700 tons per year, representing a net benefit of US $ 1.67 million annually.

Potable and Industrial Water Supply :

An increased supply of 64 MCM (by the year 2032) could be ensured towards meeting the potable and industrial water needs in the district of Matale, Anuradhapura, Trincomalee and Polonnaruwa from the surface water sources in the Ambanganga basin and its associated tanks and canals with the implementation of the project.

Power generation:

Annual fuel cost savings with the hydropower produced will be around US $ 2.49 annual average.

Environmental Management Plan

The following constitute the environmental management action plan that has been proposed as part of the project :

a) Reforestation of about 2000 ha in the Amban Ganga Basin
b) Clearing of elephant corridor between Giritale – Minneriya nature reserve
c) Habitat enrichment in proposed corridor between Wasgamuwa National Park and Victoria – Randenigala – Rantambe Sanctuary.
d) Research and development in the proposed corridor
e) Establishment of a 100 m wide reservation around the reservoirs.
f) Rehabilitation of tanks in adjacent nature reserves
g) Establishment of electric elephant fence around the resettlement area

Project Implementation

Project implementation period will be 5 years which includes design and construction. Expected year of commencement of work will be 2007.

Implementation Responsibility

The project will be implemented by the Mahaweli Authority of Sri Lanka under the supervision of the Ministry of Agriculture, Irrigation & Mahaweli Development.