Ageing dams are ‘ticking time bombs’

[NEW DELHI] Perched high up in the Western Ghats, adjacent to Kerala’s famed Periyar wildlife sanctuary, is a 126-year-old dam that has dangerously outlived the 50 years of life intended for it by colonial British engineers.

N.K. Premachandran, a member of parliament from Kerala, describes the 53.6 metre-high Mullaperiyar dam on the Periyar river as “a ticking timebomb waiting to explode, not only because of its antiquity but also because it is located on an acknowledged seismic zone”.

“As Kerala’s water resources minister (from 2006 to 2011), I commissioned studies on the safety of the dam by the Indian Institute of Technology (IIT) at Roorkee, which specialises in dams and irrigation, and IIT-Delhi. Both institutes had deemed Mullaperiyar fit to be decommissioned but the issue got bogged down in political wrangling and litigation in the Supreme Court,” Premachandran tells SciDev.Net.

Cross-section of the Mullaperiyar Dam. Image credit: Captain (CC BY-SA 3.0).

Premachandran is happy to see Mullaperiyar listed among the world’s big dams that need to be decommissioned in a report released 22 January by the UN University – Institute for Water, Environment and Health (UNU-INWEH). “Let’s hope the UN study will encourage authorities, including the Supreme Court, to decide early to decommission this dam that threatens the lives of millions,” he adds.

“Dams as a means of water security are passé, as pointed out by the UN-sponsored study,”

C.P. Rajendran, National Institute of Advanced Studies

Duminda Perera, an author of the study and an expert on water resources and water-related disasters, says: “We selected Mullaperiyar dam as a good example of an aged but still functioning dam in a seismically active area amidst structural flaws, political stresses, and environmental issues —as recorded in published literature.”

Opposition to decommissioning

Decommissioning Mullaperiyar is strongly opposed by Tamil Nadu state, which inherited a lease agreement between the former princely state of Travancore (now Kerala) and the British government. The lease allows Tamil Nadu to operate the dam and divert 640 million cubic metres of water annually for irrigation and power generation through a tunnel bored into the Western Ghat mountains that form a wall between the two states.

But Mullaperiyar ticks all the boxes that the UNU-INWEH study identifies for decommissioning — public safety, growing maintenance costs, reservoir sedimentation and environmental restoration. Large dams, even if structurally sound, are regarded as ‘high hazard’ infrastructure because of the potential for massive loss of human lives, livelihoods and destruction in the event of failure, the study said.

“Our study discusses the dam ageing issue globally, bringing the topic to the surface and hoping to get the national level policymakers’ attention,” Perera tells SciDev.Net. “The decommissioning decision should be taken after a careful and in-depth analysis of a dam and its links with the economy and society.”

“There are many strong advocates for increasing safety-related investment in dams. For example, the World Bank, in just the last few years, has invested over US$1 billion in a dam rehabilitation improvement programme in India,” says Perera.

Ageing dams globally

China, the US and India top the list of countries with a significant number of large dams. China alone hosts 40 per cent of the of the world’s large dams (numbering 23,841), their average age being 45 years. According to official records, India has 209 dams that are over 100 years old, built when design practices and safety were far below current norms.

Africa has far fewer large dams than other continents, though there are notable structures like the Akosombo Dam in Ghana, Kariba Dam in Zambia and Zimbabwe, and Egypt’s Aswan Dam. While Africa increasingly relies on hydropower, the average age of Africa’s dams is less than 50 years, the…