Tunga Bhadra Reservoir: Crest gate collapse raises concerns

The Tunga Bhadra Reservoir, one of Karnataka’s largest and most significant water bodies, is facing a major crisis following the collapse of one of its crest gates. This has led to an uncontrolled release of water, resulting in fears of floods in the lower regions and raising serious concerns about water management and irrigation in the state.

Constructed in 1953, the reservoir holds a pivotal place in Karnataka's history. With a storage capacity of 105.78 TMC (thousand million cubic feet), it serves as a crucial water source for irrigation, drinking water and power generation for both Karnataka and Andhra Pradesh.

Managed by states

The dam is jointly managed by the governments of Karnataķa, Telangana and Andhra Pradesh with the supervision of the Central Water Commission. The responsibility of maintenance is divided between the states.

The reservoir, with a water level maintained at 1,633 feet, was almost at full capacity when the incident occurred.

On August 10, the inflow to the reservoir was recorded at 40,925 cusecs, and 28,133 cusecs were being released. The collapse of the 19th crest gate on August 11 night led to an unexpected surge of water at over 1 lakh cusecs, causing panic in the surrounding areas.

Technical glitch

The crest gates, including the now-collapsed one, were installed nearly 70 years ago when the dam was first built. These gates, made from iron plates welded together in a chain-link structure, have withstood the test of time — until now. Experts believe the welding joints, which may have become loose, most likely contributed to the gate's failure.

The construction of this reservoir was initiated in 1948, just a year after independence, and was completed in 1953. Since 1954, water has been released from the reservoir into the canals.

The problems were with the canals through which water was released from the reservoir, not with the reservoir gates themselves, some say. This is the first time in 70 years that a gate chain has broken.

What experts think

According to experts, gates and chains should be replaced every 50 years. Going forward, the Tungabhadra Board and the state governments will take appropriate measures as per expert recommendations, said an official with the Water Resources Department to The Federal.

Tunga Bhadra Board Secretary ORK Reddy has acknowledged that the aging infrastructure might have been a factor in the collapse. The damage to the crest gate means that approximately 50 to 60 TMC of water will need to be released to allow for repairs, which involves replacing the broken gate with a new one.

This has raised significant concerns about water availability for irrigation during the coming summer. Farmers worry about how they will manage their crops with the reduced water supply.

Need for repairs

The reservoir's management involves several stakeholders including the Central Water Commission as well as Andhra Pradesh, Telangana and Karnataka. The collapse of the crest gate has brought to light the urgent need for better maintenance and timely repairs of these critical infrastructures.

Karnataka water resources minister DK Shivakumar stated that around 50 TMC of water would need to be released to facilitate the repair of the collapsed gate. This, involving emptying nearly half of the reservoir, is expected to take at least four to five days, given the current outflow rate of one lakh cusecs per hour.

Implications of accident

The reservoir is not only vital for Karnataka but also for the neighbouring states of Andhra Pradesh and Telangana. Annually, these states receive 115 TMC of water from the reservoir, with 25 TMC already released this year.

The sudden need to empty half the reservoir has created a severe water-sharing crisis, which the states will need to address through dialogue and negotiation.

Shivakumar reassured Karnataka's farmers, urging them not to panic and emphasizing that the priority is to preserve the integrity of the reservoir. He said the gate needs to be repaired now; water-sharing issues will be then addressed.

Broader concerns

The reservoir incident is not an isolated case. In the past month alone, similar gate malfunctions have been reported at the Bhadra Reservoir and the Tunga Reservoir, both of which are critical to Karnataka's water supply.

The recurrence of such technical failures has raised questions about the overall maintenance and repair protocols for the state’s aging reservoir infrastructure.

The Bhadra Reservoir, which experienced a sluice gate malfunction in July, saw a similar scenario where a technical glitch led to the unintended release of water. Likewise, the Tunga Reservoir, near Shivamogga, faced challenges with a damaged crest gate that made it dangerous to operate.

Vulnerabilities in water management

These repeated incidents underscore the need for a comprehensive review of the maintenance and repair schedules for Karnataka's reservoirs, ensuring that such critical infrastructure can withstand the pressures of time and use. The crest gate collapse is a stark reminder of the vulnerabilities that exist in the water management systems and the urgent need for proactive measures to prevent future crises.

“I discussed the situation with Kannaiah Naidu, an expert engineer in gate construction and safety. The repair work is currently underway under his supervision,” Karnataka Chief Minister Siddaramaiah said after visiting the place where the incident occurred.

Repair work is on

This year, the reservoir holds 115 TMC of water, of which 25 TMC has already been released for irrigation. Farmers need 90 TMC of water for their first crop. This amount is currently available in the reservoir.

However, due to the breakage of the gate, 35,000 cusecs of water are being released uncontrollably. It is impossible to carry out the repair work without reducing the water level in the reservoir.

The water level is being lowered. Even after that, 64 TMC of water will remain. The repair work on the gate will take four-to-five days.

Temporary gate to come up

Hindustan Engineering and Narayana Engineering have been entrusted with the preparation of a new gate.

The Tungabhadra Dam Board has decided to install a temporary gate. The installation work on the 19th crest gate has already begun, with efforts focused on completing the installation before the reservoir's water is depleted.

The work on the permanent gate is yet to commence, and it will be installed at the site under the guidance of technical experts, according to official sources.