The Hindu : New Delhi News : New structure replacing Mullaperiyar dam only solution, avers Kerala

Online edition of India's National Newspaper
Sunday, Jul 12, 2009
ePaper | Mobile/PDA Version

New Delhi

New Delhi

New structure replacing Mullaperiyar dam only solution, avers Kerala

J. Balaji

NEW DELHI: Construction of a new dam, 1,300 feet downstream of the present Mullaperiyar reservoir, is the only solution to save the people of Kerala from the existing “high-risk structure, which can fail any time causing havoc downstream,” the Kerala government has claimed.

In a detailed report ‘Mullaperiyar dam — a permanent threat to Kerala,’ presented to Prime Minister Manmohan Singh a few days ago, it has sought sanction for decommissioning of the existing dam and building a new one.

The report stated: “People of Kerala are always known for their magnanimity and good neighbourly attitude. They are keen to ensure continued supply of the Mullaperiyar water to the needy farmers of Tamil Nadu. But, Keralites cannot sacrifice their lives and properties for this.” The report says the old dam, which does not satisfy modern technical standards, has to be decommissioned well before it collapses. Its front and rear faces dam were built using uncoursed rubble masonry in lime surkhi mortar. The hearting, which accounts for 62 per cent of the dam volume, is of lime surkhi concrete. In the 1980s, a concrete backing of 10-metre width was added to the dam on the downstream face as a measure to strengthen the structure. Thus, the present dam is a composite heterogeneous structure, which cannot be analysed using criteria adopting parameters applicable to regular masonry dams. “Analyses so far done by Tamil Nadu and the Central Water Commission (CWC) assuming homogeneity, on the basis of which the dam has been declared safe, are not at all acceptable.”

The report claims that experts, including those from IIT-Delhi, have confirmed that the dam is hydraulically unsafe. In the event of its collapse, the Idukki reservoir, which is 50 km downstream the Mullaperiyar, will not be able to accommodate the water even up to 136 ft (total dam height is 155 ft).

“A collapse of Mullaperiyar dam will result in a cascading failure of three dams of the Idukki project.” A huge 2,500 million cubic metre of water will rush down the Periyar, causing unimaginable havoc to people and their properties. The reports says concurrent filling of Mullaperiyar and Idukki reservoirs resulting in the latter exceeding the maximum capacity has happened six times in the last 30 years. More than 50 lakh people of Kerala and their properties may have been affected on any one of these six occasions if the dam had collapsed. “In short, the 114-year-old Mullaperiyar dam is a high-risk structure, which needs urgent replacement.”

Recalling the dam strengthening measures undertaken on the recommendations of CWC in eighties, the report says measures such as adding weight on the top portion of the dam by providing RCC capping and provision of 10-metre thick concrete have rendered the dam more vulnerable to seismic forces instead of making it quake resistant.

Printer friendly page
Send this article to Friends by E-Mail

New Delhi