Himachal, Punjab dams see reduced water inflows as rainfall forecast eases

The outflow of water from Pong Dam has reduced to around 70,000 cusecs on Monday morning from around 99,900 cusecs on Sunday, with the inflows into the dam also coming down.

The water level recorded at Pong at 11 am was 1,391.03 feet, just about a foot above the maximum permissible level. The dam lies on the Beas river in Himachal Pradesh and had experienced unprecedented inflows during the monsoons, requiring to excessive discharge downstream.

At Bhakra, that lies on the Sutlej in Himachal, the outflow is being maintained at 65,000 cusecs as compared to 70,000 yesterday morning. The water level at Bhakra today morning was 1,677.25, about three feet below the top mark.

The water level recorded at Thein Dam on the Ravi in Punjab today morning was 524.516 metres, just a few centimetres lesser than yesterday. Inflow and outflows from this day was 20,490 cusecs and 29,226 cusecs, respectively, compared to 37,375 cusecs and 39,154 cusecs at the same time yesterday.

Since the meteorological department has not forecast heavy rains during the next seven days in Himachal and only scattered rainfall is expected over some parts of the state, the inflows and consequently the release of water can be further reduced, sources said.

While the stipulated upper limit for filling the reservoirs at Bhakra and Pong is 1,680 feet and 1,390 feet, respectively, BBMB sources said that adequate space leeway to cater to unexpected heavy inflows resulting from freak weather events like cloudbursts in the dams’ catchment area. This year, Pong had experienced the highest ever inflow into its reservoir.

Bhakra dam has been designed with a capacity of 1,890 feet, while Pong dam level can go up to 1,421 feet. The Bhakra Beas Management Board (BBMB), which manages these two dams, has developed ‘rule corves’ based on historical data, present water level current level of inflows and meteorological forecasts to determine the water level to be maintained and amount of water to be released.

The catchment areas of the Beas and Sutlej lie in Himachal Pradesh and western Tibet. While the reservoir at Pong is primarily rain fed, inflows into the Bhakra are primarily dependent on snow melt. In addition, there are numerous rain-fed tributaries and ‘nullahs’ that also feed both the reservoirs.

Seasonal rainfall in Himachal as well as Punjab has been above normal this year and is the reason cited for floods that affected parts of these states. From June 1 till September 8, rain has been surplus by 45 per cent in Himachal and by 55 per cent in Punjab, IMD data shows. There are also numerous streams and ‘nullahs’ downstream of the dams that contribute to ingress of water into the Beas and Sutlej rivers.