BBMB proposes twin tunnels for discharge of floodwater at Pandoh Dam | Chandigarh News
Kullu: The Bhakra Beas Management Board (BBMB) has proposed construction of twin tunnels at Pandoh Dam in Himachal Pradesh’s Mandi district to provide an additional route for safe discharge of floodwater.The proposal follows the Central Water Commission’s (CWC) review of the dam’s design flood levels. The review found that the volume of Probable Maximum Flood (PMF) — the maximum flood considered possible at the site — had increased, considering changing rainfall patterns and the growing incidence of cloudbursts and flash floods.The existing spillway arrangement does not have adequate capacity to safely discharge the revised flood volume, prompting the BBMB to explore an additional discharge mechanism.A memorandum seeking administrative approval for preparing a detailed project report (DPR) has been submitted to the BBMB headquarters. The project is currently at a preliminary stage, with detailed investigations yet to begin.According to the preliminary proposal, the twin tunnels will provide a bypass route from upstream of Pandoh Dam to downstream, avoiding Pandoh town and exiting beyond the market area. The proposed tunnel system is estimated to be around 1,200 metres long and is planned to discharge approximately 2,000 cumecs (cubic metres per second) of water.Chandramani Sharma, additional superintending engineer (ASE), BBMB, said the proposal was necessitated by the upward revision in the PMF and the need to create an alternative flood-discharge route without altering the old dam structure.“Since the PMF has increased, there is a need to ensure that the additional floodwater can be discharged safely from the dam. Pandoh is an old structure, so we cannot make modifications to the dam directly. Instead, an alternative route is being considered so that, if such a flood scenario arises, the water can be safely manoeuvred through another route.”According to noted environmentalist and Himalaya Niti Abhiyan coordinator Guman Singh, increasingly unpredictable weather patterns have heightened risks to the safety of dams in the region.“We are in an era of global warming when heavy rain can strike at any time and glacier collapses can trigger massive floods. Our rivers flow through deep gorges, so any sudden surge in water poses a serious risk to dams. You simply cannot claim that our dams are safe, particularly when we are also located in a highly seismic zone,” Singh said.
