Syllabus section: Geography

Why in News?
United Nations have released its report titled ‘Ageing water infrastructure: An emerging global risk’ on the ageing of the dams in India.

Highlights:
• most of the 58,700 large dams worldwide were constructed between 1930 and 1970 with a design life of 50 to 100 years
• some thousand large dams in India will be around 50 years old in 2025.
• The report also notes that by 2050 most people on Earth will live downstream of the thousands of dams that were built in the 20th century.
• According to the report, the world is unlikely to witness another large dam-building revolution as in the mid-20th century, but dams constructed then will inevitably be showing their age.
India
• 1,115+ large dams in India that will be roughly 50 years old in 2025
• 4,250+ large dams in India that will be 50+ years old in 2050
• 64 large dams in India that will be 150+ years old in 2050
• 3.5 million: the approximate number of people at risk if India’s Mullaperiyar Dam, built 100+ years ago, were to fail. The dam, in a seismically active area, shows significant structural flaws and its management is a contentious issue between Kerala and the Tamil Nadu States

Ageing signs
Some of the signs of ageing include:
• Increase in the cases of dam failures,
• Increasing costs of dam repair and maintenance,
• Increase in the reservoir sedimentation, and
• Loss of functionality and effectiveness of the dams “strongly interconnected” manifestations.

Mullaperiyaru Dam
It is a masonry gravity dam on the Periyar River in Kerala. It is located 881 m above mean sea level. It stands on the Cardamom Hills of the Western Ghats in Idukki District of Kerala. The dam was constructed between 1887 and 1895 by John Pennycuick. The Periyar National Park is also located around the dam’s reservoir. It is built at the confluence of Mullayar and Periyar rivers. The dam is located on the river Periyar in Kerala but is operated and maintained by Tamil Nadu.