Don’t Let Old Dams Be Damned
Before writing this column, a little bit of Google search about dams in India and around the world, produced interesting snippets. India’s oldest (and the world’s fourth oldest) dam ‘Kalanai’ aka ‘Grand Anicut’, on the Kaveri in Tamil Nadu, with a storage capacity of just over 15 metres cube (3,650 cubic metres) built by the Cholas in 150 CE is still in use! Our largest dam now – Indira Sagar on the Narmada in Madhya Pradesh (MP) has a capacity of 12.22 billion cubic metres. And world’s largest, the Kariba in Zambia, finished in 1960, claims 185 billion cubic metres. Three Gorges Dam in China, measured for power generation capacity, boasts of an awe inspiring 22,500 MW – way ahead of any other single location utility in the world.
The parliamentary report (source National Register of Large dams – 2019) had listed 234 functional dams, all over 100 years old and ‘possibly unsafe’. Oldest of these – Thonnur Tank in Karnataka – was commissioned in the year 1000. The next 14 (five in Maharashtra, four in Rajasthan, three in Uttar Pradesh and one each in Andhra and Odisha) were all commissioned between the years 1500 to 1860. Looking at all 234 – covering MP, Maharashtra, Gujarat, Rajasthan, Telangana, Uttar Pradesh (more than 50 in each state) Karnataka, Chhattisgarh, Andhra, Odisha, Bihar, Kerala and Tamil Nadu.
Even though the dams are normally designed for 100 years ‘useful life’ and their functional life decreases with progressive reservoir sedimentation, none of the dams in India have so far been ‘decommissioned’. In all fairness, I must add that ‘decommissioning of a dam’ is a complicated and lengthy process. First, the hydel power generation facilities must be dismantled and removed from the site. Next – and far more difficult – is recontouring of the river channels through ecologically viable interventions in the vast catchment areas. So, few countries ever decommission a dam, and over time, sedimentation fills up most of the reservoir and the dam becomes virtually dysfunctional and power generation turbines and pipe works just remain there for posterity.
Be that as it may, the question of potential risk from old dams is a real one. India itself has had 36 reported dam disasters. The most recent was perhaps the one on the night of 27-28 October 2023 when a massive landslide hit the 2,000 MW Lower Subansiri hydel project on the Assam-Arunachal border. Washing away of the 1,200 MW Teesta dams in Sikkim, that happened just a few weeks earlier, is also a recent memory. There have been many more such incidents. When there were some problems with Tehri Dam in Uttarakhand, there were widespread newspaper and television coverage about the possibilities of colossal damage if this
dam collapses. It was feared that in case of such an eventuality, Rishikesh and even Hardwar could get wiped off!
So, what is the way out?
Dams are a critical part of national infrastructure for irrigation, power generation, flood control and supply of drinking water and industrial use too. India has made huge investments in the sector and in view of the inherent dangers in case of a dam failure – human and animal life, industrial, commercial and residential property as well as dislocation of people – it is important that regular inspection and maintenance is carried out to minimise chances of any such eventuality. Regular inspection and maintenance of all dams is crucial and must not be ignored or compromised. Central Dam Safety Organization – a wing of the Ministry of Water resources– has issued detailed ‘Guidelines for safety Inspection of Dams’. The latest document on record is the one issued in January 2018.
Author is trustee of the Climate Project Foundation India. He is past president of AIMA and former BOG member of IIMC.
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