Of the total 5,334 existing large dams in the country, at least 227 dams are more than 100 years old, thus posing greater safety risks, cost higher in terms of maintenance and have declining functionality due to sedimentation. Apart from these 5,334 dams, at least other 411 large dams are under various stages of construction across the States.
Overall, Maharashtra leads with 2,394 dams, while Madhya Pradesh and Gujarat are at the second and third spots in terms of the number of dams. India’s dams annually store about 300 billion cubic metres of water. As many as 80 per cent of dams are exceeding 25 years of age and over , said an official from the Central Water Commission (CWC) under the aegis of the Department of Water Resources.
He said the ageing of dams and deferred maintenance of the dam have made dam safety a matter of concern. “To deliberate on their safety and consequent challenges, a one-day national workshop is being held on Dam Safety Act, 2021 for Dam Safety governance in India on June 16 in the national Capital here,” he said.
The Dam Safety Act 2021 was enacted by the Parliament and came into force on December 30, 2021. The Act is aimed at ensuring surveillance, inspection, operation and maintenance of the specified dam for prevention of dam failure-related disasters and to provide for an institutional mechanism to ensure their safe functioning.
The brainstorming session follows a recent study that pointed out that India must analyse the costs versus benefits of its ageing dams, and conduct timely safety reviews in order to ensure safety of the structures, and the safety of those who inhabit the areas downstream.
A study by the Canada-based United Nations University Institute for Water, Environment and Health, released in January had pointed out that climate change is also likely to accelerate the ageing of dams.
All over the world, many large dams built in the 20th century may start to show signs of ageing, and many may already be operating at or beyond their design life, the study said. For India, 2025 is set to be a big year as more than 1,000 dams would turn roughly 50 years or older, it noted
Fifty years is not a defining age for all dams because the design life also depends on factors such as construction and maintenance, the study said, adding that a well constructed and well maintained dam can go up to a 100 years. However, 50 is roughly the age when a dam may begin to show signs of ageing. In some cases, dam components such as gates and motors may need to be replaced after 30 to 50 years, it added.
Therefore, an assessment of the structure should be carried out, and, if needed, the dam should be decommissioned, said the study.
