Water flows down a spillway at India’s Bhakra Dam into a steep forested valley with electric towers.
Bhakra Dam supplies water and electricity to states throughout northern India. Credit: Gurpreet Singh

When it opened in 1963, Bhakra Dam was called a “new temple of resurgent India” by Jawaharlal Nehru, India’s first prime minister. Today the dam is threatened as its reservoir rapidly fills with silt.

Much to the worry of hydrologists monitoring the situation, the reservoir—Gobind Sagar Lake—has a rapidly growing sediment delta that, once it reaches the dam, will adversely affect power generation and water deliveries.

Bhakra Dam stands 226 meters tall and stretches 518 meters long, making it one of the largest dams in India. Electricity generated by the dam supports the states of Himachal Pradesh (where the dam is located), Punjab, Haryana, and Rajasthan, and the union territories of Chandigarh and Delhi. The reservoir supplies these areas with water for drinking, hygiene, industry, and irrigation. Loss of reservoir capacity as a result of sedimentation could thus have severe consequences for the region’s water management system and power grid.

A Leopard’s Leap to a Green Revolution

In 1908, British civil services officer Sir Louis Dane claimed to have witnessed a leopard leaping from one end of a gorge on the Sutlej River to the other. “Here’s a site made by God for storage,” he wrote. Little happened, however, until 40 years later, when Nehru took up the proposal as one of the first large infrastructure projects in India after independence.

“Before the canal brought water to our area, we were poor [and] used to live [lives] of nomads, in the sand dunes. Now we grow a variety of crops…and we are referred [to] as affluent farmers.”

Bhakra Dam’s waters quickly catalyzed the nation’s green revolution of increased agricultural production. In the early 1960s, for instance, 220,000 hectares of rice were under paddy cultivation in Punjab. Within 10 years, that number increased to 1.18 million, which doubled by 1990. Today Punjab contributes up to 50% of India’s rice supply.

Parminder Singh Dhanju, a rural resident of Rajasthan whose village is about 565 kilometers from Bhakra Dam, has a farm fed by canals originating from the reservoir. “The water availability has changed the lives of us villagers,” he said. “Before the canal brought water to our area, we were poor [and] used to live [lives] of nomads, in the sand dunes. Now we grow a variety of crops such as wheat, rice, cotton, and citrus fruits (oranges and kinnows), and we are referred [to] as affluent farmers.”

The Saga of Silt

According to investigations led by D. K. Sharma, former chairman of the Bhakra Beas Management Board (BBMB, the power company responsible for the dam), nearly a quarter of Gobind Sagar Lake has filled with silt. The sedimentation flows from the lake’s catchment areas, which are spread over 36,000 square kilometers in the Himalayas.

“The storage of the reservoir is 9.27 billion cubic meters, out of which 2.13 billion cubic meters are filled with silt, which is an alarming situation,” explained Sharma. He said the studies related to silt pileup are carried out every 2 years.

Sharma and other BBMB engineers submitted a report last year on siltation at Bhakra Dam. In it, Sharma said the dam was projected to be an effective reservoir for at least 100 years. However, he explained, the silt buildup will likely shorten that time frame. “It depends on the amount of silt in the reservoir,” he said. “The increase in siltation will hasten the process of turning the dam into a dead project, making the canal system downstream vulnerable to deposition of silt and floods.”

The Way Out

To combat siltation, Sharma suggested extensive reforestation in the reservoir’s catchment area. “The partner states of BBMB—Punjab, Haryana, Rajasthan, and Himachal Pradesh—need to plan forestation to bind the loose soil,” he said.

“If we can reduce silt inflows by 10%, the dam’s life can be extended by 15–20 years,” he added.

“We need to act fast and engage local population and NGOs to carry out plantation, before it’s too late.”

BBMB joint secretary Anurag Goyal heads the reforestation project around the dam. He said that in 2019, 600,000 saplings were planted over the reservoir’s catchment area. “We have resumed plantation that was temporarily halted in 2020 due to COVID-19 pandemic.”

Other suggestions to prevent or mitigate siltation include dredging the reservoir, although Goyal dismisses that idea as cost prohibitive. Goyal agreed with Sharma that reforestation or other mitigation projects must include local governments. “Reforestation over [such a] vast area needs a road map and the involvement of the north Indian states…. We need to act fast and engage local population and NGOs to carry out plantation, before it’s too late.”

—Gurpreet Singh (@JournoGurpreet), Science Writer


Singh, G. (2021), Siltation threatens historic north Indian dam, Eos, 102, https://doi.org/10.1029/2021EO159370. Published on 09 June 2021.

Text © 2021. The authors. CC BY-NC-ND 3.0
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