Large scale renovation of dams by Mahaweli Authority | Sunday Observer

Large scale renovation of dams by Mahaweli Authority

Victoria Dam
Victoria Dam

Ensuring the safety of dams, especially, those that have been categorized as ‘high risk dams’ must gain urgent attention to avert colossal losses to irrigation, agriculture and power generation in the country, irrigation experts said.

According to experts, unattended irrigation systems have the potential to snowball into a major environmental and social catastrophe leading to enormous economic losses.

The need for speedy remedial measures and comprehensive rehabilitation of dams surfaced after the collapse of the Kanthale dam in 1986.

Therefore, with the aim of preserving the country’s ancient irrigation system and dams, subsequent governments undertook measures time and again to ensure the safety of the dams across the country.

With the completion of the first phase which comprised renovation of around 31 dams the rehabilitation of another 31 dams has been undertaken by the Dam Safety and Water Resource Planning Project (DSWRPP) of the Mahaweli Authority of Sri Lanka.

These dams have been selected as high risk dams from among 80 major dams to be rehabilitated, with additional funding from World Bank.

Director, Headwork of the Sri Lanka Mahaweli Authority (SLMA), S.R.K.Aruppola said, the renovation of the 31 dams are now underway, supervised by the Irrigation Department, the Mahaweli Authority, Ceylon Electricity Board and Water Supply and Drainage Board.

The Installation of Hydro-meteorological Management Information System (HMIS) have been completed in 144 stations. HMIS will provide real time data on rainfall, wind speed, humidity levels and temperature. The system has been installed in many of the vital river basins in the Mahaweli, Kelani, Iranamadu and Kanakayaaru.

“We have also undertaken to set up a flood control centre in Polgolla which would be completed by March 2018. Electrifying and automating 31 spill gates at Rajangana and Kaudulla to control floods in the Medirigiriya area and the renovation of the Thondamanaru Barrage which had not been maintained for over three decades, to stop salt water seeping into the lagoon are some of the other projects undertaken under the DSWRPP, Aruppola said.

Engineer in charge, Victoria Dam, Wasantha Ehelapitiya said, all renovation and protective measures including the major renovation of the Victoria Dam were undertaken to consolidate the structures of the dams to last a considerable period.

The government also has focused attention on large scale infrastructure development projects to build livelihoods of those once battered by the brutal war in the North.

Muthiyankaddu tank

Accordingly, three sub projects, Muthiyankaddu and Periyapandivirichchan dam rehabilitation, and renovation of Thondamanaru Barrage in the Northern Province have been selected under the DSWRPP Additional Financing Project (DSWRPP AF) of the Ministry of Mahaweli Development and Environment.

Muthiyankaddu dam is located in the Oddusudan Divisional Secretariat division in the Mullaitivu district and it is 24 km from Mullaitivu on the Mankulam road. The Muthiyankaddu tank is an ancient tank restored in 1960 for the cultivation of subsidiary food crops considering the suitability of the soil condition.

Muthiyankaddu has been a thriving farming area producing paddy and other cash crops such as chili, vegetables and cereals. The estimated value of the annual agricultural production under the Muthiyankaddu tank is over Rs.500 million. Paddy is cultivated mainly in the Maha season with the use of rain water as the main source and Muthiyankaddu tank only supplements water when needed.

Periyapandivirichchan Dam

The renovation of the Periyapandivirichchan Dam has been fully completed by the Department of Irrigation. The renovation was done under the Dam Safety and Water Resource Planning (DSWRPP) Additional Financing Project (DSWRPP AF) of the Ministry of Mahaweli Development and Environment. Rehabilitation work of the project was begun in November 2014 and the government invested Rs.65.3 million from the DSRPP AF funds.

Periyapandivirichchan tank is located in the Madhu DS Division in the Mannar District in the Northern Province. It is in the Nay Aru river basin below the Periyathambanai tank and the tank is close to the Madhu Church.

Thondamanaru Barrage

Thondamanaru Barrage Renovation is part of the “River for Jaffna” project identified by the National Water Use Master Plan. The “River for Jaffna” project envisages the conversion of three large salt water lagoons, Elephant Pass, Vadamarachchi and Upparu, into fresh water storage areas. The Jaffna Peninsula does not have any river or waterways to provide fresh water and the people depend on ground water sources for their requirements for domestic use as well as agriculture, which is the main livelihood of the majority of the population.

The salt water lagoons would be converted into fresh water by flooding the lagoons with rainfall generated round off. Under the DSWRPP Additional Financing project the government has invested Rs.405 million to renovate the Thondamanaru Barrage in the north end of the Vadamarachchi lagoon. The objective is to prevent salt water flow into the lagoon. This project will address water scarcity in the Jaffna Peninsula. The fresh water lagoons will act as sources to recharge ground water.

According to Project Director- DSWRPP AF Ananda Sellahewa, over the years ancient hydraulic structures and reservoir dams built in therecent past have been facing various structural deficiencies and shortcomings of operation. The maintenance of such structures threaten the safety of those downstream and also affect the operational efficiency of the dams and appurtenances. Failure of a dam structure or emergency spillway operation, could lead to disaster which could result in hazards such as, physical damages, loss of life, and long term economic losses associated with loss of water storage capacity for many users. Therefore, dam structures and reservoirs demand both regulatory and operational safety measures and timely remedial repairs.

Pix : Susantha Wijeyagunasekara