No desilting ever at Bhakra, capacity down 19%

As Punjab battles one of its worst floods in decades, it has come to light that the holding capacity of the Bhakra Dam, built upstream on the Sutlej, has reduced by about 19 per cent since its inception in 1963. The primary reason, officials say, is that the dam’s reservoir has never been desilted all these years.

The revelation comes amid criticism of the Bhakra Beas Management Board (BBMB) for “failing to hold back water” in the Bhakra and Pong dams when heavy rain wreaked havoc across Punjab recently. The release of additional water from the two dams, which have the largest reservoirs in the North, is being blamed for compounding the situation in the state.

The Bhakra reservoir, known as Gobind Sagar Lake, is one of the largest man-made lakes in the country. Spread over 88 sq km across Bilaspur and Una districts of Himachal Pradesh, the lake’s original storage capacity was 7.4 lakh billion cubic metres, which has reduced to around 6 lakh billion cubic metres.

The reservoir was originally expected to receive 33.61 million cubic metres of silt annually, but the actual inflow has been 39.01 million cubic metres. The reservoir’s storage ranges between the minimum of 1,462 feet and the maximum 1,680 feet. Sources said in recent decades, the water level has never fallen below 1,540 feet.

According to BBMB officials, the rise in construction activity and natural erosion in the Sutlej catchment areas in Himachal have contributed to the silt problem. Sources in the BBMB said the silt inflow particularly rose between 2003 and 2015 when the Kol Dam was being constructed upstream on the Sutlej in Bilaspur.

The sources said the inflow decreased between 2015 and 2017, but rose again from 2018 onwards when construction began on four-lane highways in Himachal. BBMB authorities said the inflow was likely to increase in the coming years. About two years ago, the BBMB had proposed desilting of the reservoir near Bilaspur town and had even sent a proposal to the Himachal government, offering to pay it a royalty for the extracted material.

Bhakra Dam Chief Engineer CP Singh said the BBMB had completed the formalities for the desilting and was ready to float tenders. “However, as the reservoir falls within Himachal’s jurisdiction, the state’s approval is a must. We have had meetings with the Himachal Industries Department, which looks after mining, but their approval is awaited for more than a year,” he said.

The Chief Engineer also said the BBMB had submitted a proposal to the Union Ministry of Water Resources recommending that dam silt should be mandatorily used in the construction of roads by the National Highways Authority of India. “Studies by IIT-Roorkee have confirmed that dam silt is an excellent construction material,” he said.