In July, with copious rains filling up reservoirs in southern Karnataka, chief minister Siddaramaiah and his deputy D.K. Shivakumar had offered the traditional ‘bagina’, or thanksgiving, at the Krishna Raja Sagar dam near Mysuru. The reservoir, whose stock of water had been dwindling last year due to a particularly harsh drought, is now just shy of full-storage capacity.
This month, a similar thanksgiving event had been planned at the Tungabhadra reservoir in Hospet, which too was nearly full after a long and dry summer. But that event had to be postponed owing to an emergency at the dam when one of the crest gates gave way on August 10. A large volume of stored water had to be let out to be able to repair the damaged gate.
The dam, at 97.75 thousand million cubic feet (TMC) of water, was 92 per cent full on August 12. But the outflow reduced it to 86 per cent on August 13 (91.31 TMC). On August 14, it was further down to 79 per cent, at 83.74 TMC.
Siddaramaiah, who visited the Tungabhadra dam on August 13, said the 64 TMC of water that would remain in the reservoir after the total outflow would be sufficient to meet the irrigation needs of farmers downstream for their first crop. Water from the reservoir serves 900,000 hectares of farmland in Karnataka and 300,000 hectares in neighbouring Andhra Pradesh and Telangana.
Spanning the Tungabhadra river at Hospet, the dam, commissioned in 1953, has been a lifeline for districts such as Ballari, Vijayanagara and Koppal in Karnataka, besides Kurnool and Anantapur in Andhra. Located a few kilometres downstream is Hampi, a UNESCO World Heritage Site, where the ruins of the 14-16th century Vijayanagara empire are a major tourist destination.
The multi-purpose dam has 33 spillway gates. At 10.50 pm on August 10, while 10 gates were being operated, a chain link at Gate 19 broke, causing the gate to get washed away from its groove.
“In view of the broken chain link of crest gate 19, we have opened all the crest gates to reduce stress on the dam. Currently, 98,000 cusecs of water are being released, including 35,000 cusecs from crest gate 19,” Shivakumar, also the minister for water resources, said after an inspection of the dam on August 11. A cusec is a unit of flow equal to 1 cubic foot per second. Shivakumar pointed out that the irrigation channels had been opened and efforts were on to fill up tanks and water-bodies.
An inter-state project, the dam is managed by the Tungabhadra Board, whose chairman is appointed by the Union government and four members represent the three riparian states and the Centre.
Experts have been called in and work on installing a gate is underway. The repairs would take about 4-5 days, said Siddaramaiah, who pointed out that this was the first such mishap in the dam’s 71-year-long history.
A chain link, which is connected to a hoist, is used to open the gates to release water, explained Hubballi-based dam expert Dr S.G. Joshi, who serves on dam safety review panels in Maharashtra, Gujarat and Bihar. The standard procedures for maintenance typically involve detailed inspections before and after the monsoon season. The reports are sent to the Central Water Commission and the state dam safety organisation.
“There is a set procedure and it has become more stringent after the passing of the Dam Safety Act of 2021,” explained Joshi. The Act provides a comprehensive framework for proper surveillance, inspection, operations and maintenance of all dams in the country specified as ‘large’ in order to ensure safe functioning and avoid dam failure-related disasters.
Holding the Congress government responsible for maintenance of the dam, Karnataka’s main opposition party, the BJP, demanded that the dispensation immediately provide a compensation of Rs 50,000 per hectare to farmers besides conducting an investigation into the crest-gate failure. “We need 115 TMC of water, but 20 TMC has already been wasted. We expect about 40 TMC of water from the upcoming rains, but that depends on nature. Given the situation, it will be difficult to cultivate a second crop,” said former chief minister Basavaraj Bommai, who inspected the dam on August 12 with other BJP leaders.
Bommai said silt accumulation over the years has been a major challenge at the Tungabhadra reservoir as it has reduced water-storage capacity by 30 TMC. He said the time was opportune to take up the proposal of a parallel reservoir in the region, for which a project report is ready. The proposal is for a balancing reservoir at Navali to compensate for the water-storage deficit caused by silt in the Tungabhadra reservoir.
Siddaramaiah said the Navali project would cost Rs 15,000 crore and require approval from Andhra Pradesh and Telangana. The respite for now, he said, was weather forecasts indicating rains later this month. “I’m confident that the Tungabhadra dam will fill up again and we will be able to offer bagina,” he said.
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