Engineering marvels :

Multi-purpose irrigation and power projects

By P. Krishnaswamy

Food security in the country being one of the major concerns of the UPFA Government and one of the main outputs for increasing food productivity being advanced irrigation facilities, the Department of Irrigation, under the purview of the Ministry of Irrigation and Water Resource Management, started several reservoir projects, exclusively utilising the services and expertise of Sri Lankan engineers.

Some of these projects have proved to be engineering marvels even by the standards of many other countries in the region. Under its short-term and long-term programs of providing better irrigation facilities, the Department also took steps to enhance facilities in most of the existing irrigation tanks and reservoirs in the major agro-ecological zones of the country.

Besides the Irrigation Department, the Mahaveli Authority of Sri Lanka too launched several large-scale multi-purpose irrigation and power projects.

The main reservoir projects launched in the recent years by the Irrigation Department are summed up below as apprised to the Sunday Observer by senior irrigation engineers, including Deputy Directors of the department:

The Rambukkan Oya Reservoir Project in Maha Oya Divisional Secretary Division in the Eastern Province is targeted to irrigate 1400 ha of new lands which include 400 ha of high lands. The Rambukkan Oya river discharges more than 50 MCM water annually to the Indian Ocean through the Mundani Aru river, mainly during the North-East monsoonal season, and this source has been tapped to improve agricultural productivity and other facilities in the divisional secretary area. More than 2200 agricultural families are directly benefited under this project while more than 25,000 families will get other benefits including drinking water and replenishment of ground water aquifers. The gross storage of reservoir is 56 MCM, the water spread area is 800 ha and the designed flow is 5.7 m3/sec. Under the canal system, the length of the main canal is 7 km, length of distributory canals is 39 km and the length of field canals is 84 km .Eight minor tanks will also receive water from the canals. The catchment area of the reservoir is 128 Sq.km The other benefits include pipe borne water supply to the Maha Oya area and improved road network within the project area.

The project will be completed at the end of 2012 and impounding the tank will be in April 2012.

Tract cultivation in two tracts can be started before the next Maha season, according to Deputy Director (Major Construction) Nihal Siriwardena.

The Rs.6.7 billion Deduru Oya Reservoir Project , providing irrigation facilities to some of the cultivable lands, about 30,000 acres in extent situated in Yapahuwa, Wariyapola, Nikeweratiya, Panduwasnuwara, Bingiriya and Anamaduwa electoral districts is nearing completion. About 15,000 agricultural families will be directly benefited under this project while about 50,000 families will be indirectly benefited.

The storage capacity of reservoir is 75 MCM. Of the estimated payment of compensation of Rs. 1.8 billion to the 900 families getting displaced under the project, an amount of Rs. 942 million has already been paid. Infrastructure facilities to the people of the Maha Oya Divisional Secretary division include road networks, electricity, schools and clean drinking water, and will contribute to the improvement of the quality their life. Everything, beginning from conducting the feasibility study to designing the various components of the reservoir construction, was done by engineers of the Irrigation Department and considered to be a unique achievement of the Sri Lankan engineers. Project Director W.L.H.M.T. Bandara expressed optimism that paddy cultivation in the zone will be increased many fold during the 2012/13 Maha season with irrigation water to be released in the LB canal soon.

The Weheragala Reservoir constructed across the Menik Ganga has been completed. Its gross storage capacity is 60,000 acre feet. The river water is diverted to the Lunugamwehara Tank and there are multiple benefits under this project, including irrigation facilities to 25,000 acres of paddy land belonging to over 20, 000 agricultural families , drinking water and bathing facilities to people of the area and also to the large number of pilgrims to the Kataragama shrine. Part of the reservoir being located within the wildlife park It also helps to protect the flora and fauna and provides water to the wildlife in the sanctuary which attracts a large number of tourists. Various infrastructure facilities have been provided to the areas covered by the project, including road networks, electricity and facilities to grow subsidiary food crops. It ensures regular release of water to the Manik Ganga during the dry season, greatly benefiting the pilgrims, Deputy Director (1) - Regional Works D.M.A. Deheriyagoda said.

The Kekirioboda Reservoir project in Hambantota district, with a dam constructed across the Kirama Oya river, has been completed.

It will provide irrigation facilities to about 5600 acres of paddy land benefiting the owners of these lands. The project covers parts of areas in Tangalla and Walasmulla. The project provides infrastructure facilities, including drinking water and road networks. A pilot project of drip irrigation system has been introduced in 08 acres in the Ranminitenne Left Bank canal area in Lunugamwehera for horticulture.

In Ellepothana in the Anuradhapura district an anicut has been constructed across the Yan Oya with two canals feeding water to several minor irrigation tanks, benefiting about 1100 agricultural families engaged in paddy cultivation.

This being a dry zone the levels of the water tables in the surrounding areas have been elevated providing easy access to drinking water from the ground.

In the Kandy district a concrete dam is being constructed across the Gurugal Oya tributary river.

The work is in progress. On completion it will provide irrigation facilities to about 220 acres of paddy land and benefit over 2400 families. The 300 meter concrete dam over the deep river valley will also provide easy access for the people of Hanguranketa to Kandy and vice versa. The Wemedilla Reservoir project in Matale district was completed three years ago.

Irrigation facilities are being provided to 1142 acres of existing paddy lands and 720 acres of new paddy lands benefiting 1350 families. Other infrastructure facilities have also been provided under the project.

Work is in progress on the construction of the Athikkawa anicut across the Kirindi Oya river to provide irrigation water to the existing 2500 acres of paddy lands which are not being cultivated now due to scarcity of water. Over 2500 farmer families will be benefited under this project and there will be other benefits that go with such reservoir project, including safe drinking water, water for bathing, road networks and elevation of the levels of water table in the surrounding areas.

The Regional Directors of Irrigation in Ampara and Batticaloa are engaged in executing functions with regard to the Gal Oya Navodaya Program, which covers the Gal Oya Valley Development Program under the Senanayake Samudra.

The process involves irrigation and water resources, productivity enhancement program in agriculture, social infrastructure and , agro-based industries.

The total cost of the program is Rs. 1,260 million and the total acreage benefited is 50,000 ha, Deputy Director (2) P. Balasubramaniam said.

The Mahaweli Authority of Sri Lanka plays a key role in Moragahakanda-Kalu Ganga development project, the biggest multi purpose development venture undertaken by the Government.

The Mahaweli Authority has a track record of building and maintaining Sri Lanka's biggest dams, power and irrigation projects such as Kotmale and Victoria.

The project comprises the building of two main dams and they are being supported by saddled dams. he projects aims to irrigate 81,422 hectares in the Central and North Central provinces, benefiting over 100, 000 families in addition to providing drinking water and generating hydro-power.

One of the major plus points of this multi purpose development venture is the ability to generate 20 MW power to the national grid.

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. Once the Moragahakanda project is completed a large number of farmers in the Northern part of the country will benefit. Under the second phase of the Moragahakanda project a channel named 'NCP channel' will be constructed up to Iranamadhu.

This would be a 100 km channel and would be Sri Lanka's longest channel.

The completion of the Moragahakanda reservoir project will increase the island's agricultural crop intensity from 165 percent to 185 percent, with a total value of US $ 17 million. People have been talking about King Parakramabahu for centuries for constructing the Parakrama Samudraya.

The Moragahakanda - Kalu Ganga development project would be four times bigger than the Parakrama Samudraya and people will talk about this project in a manner more than about the Parakrama Samudraya.