Mullaperiyar Dam - Dam Safety

Dam Safety

After the 1979 Morvi Dam failure which killed up to 15,000 people, safety concerns of the aging Mullaperiyar dam's and alleged leaks and cracks in the structure were raised by the Kerala Government. A Kerala government institution, Centre for Earth Science Studies (CESS), Thiruvananthapuram, had reported that the structure would not withstand an earthquake above magnitude 6 on the Richter scale. The dam was also inspected by the Chairman, CWC (Central Water Commission). On the orders of the CWC, the Tamil Nadu government lowered the storage level from 142.2 feet to 136 feet, conducted safety repairs and strengthened the dam.

Strengthening measures adopted by Tamil Nadu PWD from 1979 onwards include cable anchoring of the dam's structure and RCC backing for the front slope. During a recent scanning of the Mullaperiyar dam using a remotely operated vehicle by the Central Soil and Materials Research Station on directions from the Empowered Committee of the Supreme Court, the Kerala Government observer opined that "mistakes in the strengthening works carried out by Tamil Nadu" in 1979 damaged the masonry of the dam.

Current safety concerns hinge around several issues. Since the dam was constructed using stone rubble masonry with lime mortar grouting following prevailing 19th century construction techniques that have now become archaic, seepage and leaks from the dam have caused concern. Moreover, the dam is situated in a seismically active zone. An earthquake measuring 4.5 on the Richter scale occurred on 7 June 1988 with maximum damage in Nedumkandam and Kallar (within 20 km of the dam). Consequently several earthquake tremors have occurred in the area in recent times. These could be reservoir-induced seismicity, requiring further studies according to experts. A 2009 report by IIT Roorkee stated that the dam "was likely to face damage if an earthquake of the magnitude of 6.5 on the Richter scale struck its vicinity when the water level is at 136 feet".