Himachal dams filled to the brim with onset of monsoon
This pre-monsoon surge is driven by the intense heat that has accelerated glacier melt, pushing water levels in many dams to precarious thresholds.
As Himachal braces for the imminent monsoon, the state’s dam reservoirs are already teeming with water, nearing critical danger levels. The pre-monsoon surge is driven by intense heat that has accelerated melting of glaciers, pushing water levels in many dams to precarious thresholds.
The reservoirs at Bhakra and Pong dams stand out as the few which are yet to their maximum levels — currently 31 and 28 metres below their respective maximum levels.
However, the situation has set the alarm bells ringing as even these dams are expected to hit the cap soon. The state has 23 operational large dams and their safety is the principal concern of the directorate of energy.
Preemptive warnings about potential water releases have been sent out, with the Satluj Jal Vidyut Nigam (SJVN) issuing alerts to release water from the Nathpa Dam on the Sutlej River and advising residents to avoid riverbanks.
Stakes high for neighbours
The increased water levels is a double-edged sword. While they bode well for the electricity and water needs of neighbouring states Punjab and Haryana, which heavily depend on Himachal’s rivers, there is a looming risk of devastation from potential floods during heavy monsoon rains.
The abundance of water is also crucial for agriculture in Punjab, Haryana, Delhi, and Rajasthan.
Nathpa, Karcham close in to danger level
The Nathpa Dam’s reservoir has reached 1,493 m, a mere 2.5 m below its danger level. Similarly, the Karcham Dam’s reservoir stands at 1,809 m, just 3 m shy of its danger level of 1,812 m.
The Chamera-2 project’s reservoir is currently filled up to 1,156 m, only 6 m below danger level. Other dams on glacier-fed rivers are also nearing capacity due to the unprecedented heat wave in Himachal this year, which has caused rapid glacier melt. Larji barrage in Kullu district was also almost full to its 969.5 m capacity.
The water was gradually released from the 1,500-megawatt Nathpa Jhakri Hydel Project after the reservoir brimmed with water amid glacial melting at the Satluj basin. Similarly, water has been released from Pandoh, Chamera III, Sainj Barrage, Karcham, Kuppa Barrage, Malana I, Buddhil, and Bhabha.
The Himachal Environment Science and Technology Department is closely studying the phenomenon, with a detailed report expected soon.
The dams possess a large amount of water. Sometimes, unexpected release of even a small quantum of water during day-to-day operations catches people unawares, triggering mishaps. A decade ago, 24 students were swept away in the gushing waters of the Beas river when the Larji dam opened its radial gates which led to a sudden increase in the water level downstream.
Despite the widespread filling of other reservoirs, the Bhakra Dam reservoir remains 31.47 m below its danger level, at 483.64 m. The Pong Dam also stands 25 m below its danger level at 398.1 m.
SJVN plant executive director head Narender Kumar said, “Two days ago, there was a flash flood in Baspa river, the water level rose by 150 cumecs, and the dams absorbed the water. Glacial melt has accelerated water flow helping us to generate more power. Right now the situation is under control.”
Monsoon prep underway
With the monsoon now reaching Himachal, significant rainfall has so far been recorded only in Shimla, which received 154.4 mm rainfall, Pandoh 106 mm, Sujanpur Tira with 80 mm and Dharamshala with 48.4 mm. While 34.2 mm of rainfall was recorded in Mandi, Sundernagar witnessed 30.6 mm of rainfall in the last 24 hours.
The weather department has already predicted more rainfall in the state till July 8, with the monsoon set to intensify by the start of the next week.
Dam authorities have already been directed to set up a monitoring network and set up an early warning system (EWS) as mandated under law.
“Besides, river basin monitoring and EWS integrating the network of all power projects need to be put in place immediately. State disaster management authority is keeping a close tab on the water levels in the dams,” state disaster management authority director DC Rana said.
Changing climate patterns
Given the changing climate over the mountainous region, the cryosphere regions of the higher Himalayas comprising snow and glaciers are being affected due to the higher warming rates.
Himalaya in different basins shows deglaciation at different rates with Chenab basin reflecting a total deglaciation of 5.48 %, Beas 7.03%, Ravi 4.67%, Baspa 6.52% and Spiti 4.62% in the glacier area between 2001-2017.
Besides, the changing snowfall pattern over the years has also adversely affected the river flow pattern.
“We are not getting snowfall during the peak winter months from October to February, which now have shifted to the latter half. As a result, snowfall does not sustain for a long time and melts very fast affecting the discharge. The changing patterns have also resulted in enhancing the threat from climate-induced hazards like that of Sikkim Himalayas by way of the formation of several moraine-dammed glacial lakes in front of glacier snouts or supra glacier lakes within the glacier bodies themselves,” Dr SS Randhawa, principal scientific officer at the state centre on climate change said.
