65 tmcft water lost to silt in dams
BENGALURU: Close to 65 tmcft of storage capacity in major reservoirs has been lost to siltation. This means that every year, 65 tmcft of water that could have been stored, is wasted across reservoirs in the Cauvery and Krishna basins. This quantity of water is nearly three times Bengalurus annual water requirement of over 22tmcft. Karnataka has 14 major reservoirs, including KR Sagar, Malaprabha, Bhadra, Harangi, Kabini, Almatti, Tungabhadra, Hemavathy and others. In an unstarred question by Congress MLA Dr Ajay Dharam Singh, Deputy CM and Water Resources Minister DK Shivakumar replied that they dont have any programme to remove silt. He said there are no specific guidelines to remove silt from reservoirs, and neither is there a coordination programme between the Central and State governments. Tungabhadra has 31.6 tmcft of silt, Narayanapura has 10.55 tmcft, Almatti 7.5 tmcft and Ghataprabha has 4.9 tmcft. Reservoirs that come under Krishna Bhagya Jal Nigam, Visvesvaraya Jal Nigam and others are surveyed by Karnataka Engineering Research Centre. The Central Water Commission had recommended a survey of silt in reservoirs once in five years. In many state reservoirs, survey was done from 2008 to 2019. Over time, as silt starts accumulating, the live storage capacity comes down and water overflows, leading to water loss. Silt accumulation is not uniform, and removing it is not economically viable. Former irrigation secretary and water expert Captain Raja Rao told TNIE that silt accumulation is a natural process which cannot be avoided. Silt accumulation in reservoirs of the Cauvery basin is less compared to Krishna basin reservoirs, because Cauvery reservoirs have forests or many trees nearby. This prevents silt entering dams, whereas near Krishna basin reservoirs, there are few trees. Also, mining is a major issue here, he explained. There is a need to grow more trees, which can prevent silt to a large extent, he added. A senior water resource department official said removing silt is a tedious process, as water has to be pumped out before silt can be removed. To dump the silt, they need acres of land, which is not available in and around dams. For this, they have to place pipes for longer distances, water has to be pumped out through these pipes. It is expensive. The Odisha government tried it in Hirakud reservoir, but failed, he said.
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