Proposal for installation of ‘Gated Spillway’ at V V Sagar Dam

Chitradurga: As the monsoon season intensifies, a proposal has been submitted to the Union Ministry of Jal Shakti for the installation of a ‘Gated Spillway’ at the Vani vilas . Sagar Dam, located under the Bhadra Upper Dam Project. This move aims to control the floodwaters flowing into the dam and enhance its safety. The proposal is awaiting approval.

The V.V. Sagar Dam, which is currently serving as the water reservoir for the Bhadra Project, is set to store water from both the Bhadra river and the dam. With two TMC (thousand million cubic feet) of water allocated to the dam, there is a possibility of continuous water flow in the future, especially as the Bhadra project continues its work. As this water combines with rainfall, floodwaters could exceed the dam’s storage capacity, potentially leading to the risk of flooding. To prevent this, the installation of a ‘Gated Spillway’ is being considered, which will regulate the water release during heavy rainfall.

In the wake of the alarming incident where the crest gate of the Tungabhadra Reservoir broke, causing widespread concern, the state government instructed a thorough inspection of the safety conditions of all major reservoirs in the state. According to a report from expert engineers, no immediate danger was found regarding the safety of the V.V. Sagar Dam. However, to address the potential risks associated with the dam’s water overflow during floods, the proposal to install a ‘Gated Spillway’ has been put forward by the Visvesvaraya Irrigation Development Corporation (VIDC).

The Vani Vilas Sagar Dam, which stands at a height of 130 feet and has a water storage capacity of 30 TMC, is a historic structure that has been operational since 1933. However, in 2022, the dam faced a critical incident when the ‘Kodi’ (breach) occurred after 89 years, leading to significant concerns. During this breach, the water level rose just one meter above the breach point, resulting in the flooding of large areas downstream and raising questions about the safety of the dam.

Though experts have assured that the safety of the reservoir is not under immediate threat, additional flood control measures are necessary to ensure that the water level remains at a safe limit and does not overflow. Hence, the ‘Gated Spillway’ proposal has been included in the Dam Rehabilitation and Improvement Project (DRIP).

A ‘Gated Spillway’ is a system designed to control the flow of excess water from a reservoir, particularly during floods. It is built based on the estimated inflow of water into the reservoir, considering both past flood data and the potential intensity of future flood events. During such conditions, the spillway ensures that the water level of the dam remains within safe limits, allowing excess water to flow out in a controlled manner, thus preventing the risk of flooding.

Some have raised concerns, wrongly assuming that the installation of the ‘Gated Spillway’ would lower the height of the dam or reduce its water storage capacity. This misinformation has caused confusion among farmers and locals. However, irrigation experts have clarified that the installation of the spillway does not imply any reduction in the dam’s height or storage capacity. On the contrary, it is a safety measure that will allow the dam to safely release excess water during floods while maintaining its full storage capacity.

According to F.H. Lamani, Chief Engineer of the Bhadra Upper Dam Project, the proposed ‘Gated Spillway’ will ensure that the water volume and storage capacity of the V.V. Sagar Dam, which is currently 130 feet, will remain unchanged. This addition is vital for flood control and will mitigate the risk of potential inundation downstream.