Silt inflow into Bhakra reservoir to be checked

Vijay Mohan

Tribune News Service

Chandigarh, December 18

As climatic change and deforestation impact the pattern of water inflow and silt accumulation in the Bhakra Dam’s reservoir, the Bhakra Beas Management Board (BBMB) is undertaking a survey to identify “hot spots” along the reservoir’s periphery that have become a major source of silt influx.

“The board is approaching the Indian Institute of Technology, Ropar, to conduct the survey,” a senior BBMB functionary said.

“Once the hot spots such are barren tracts of land, rivulets and nullahs, landslide-prone areas and human habitations are identified and indexed, we will work out an appropriate solution to check silt and soil inflow at these points. Large-scale afforestation in the peripheral area is also being seriously considered,” he added.

While the dam’s 90-km-long reservoir has a surface area of 168.35 sq km, its catchment area along the Sutlej is 56,980 sq km. “Apart from the main river that mostly flows through barren terrain, there are numerous rivulets and choes along the reservoir’s periphery that bring in silt. Severe deforestation in the area around the reservoir, human interference, large-scale construction, cultivation and uncharacteristic climatic events have compounded the problem,” an official said.

The dam’s capacity has dwindled by almost one-fourth due to the inflow of silt since 1958, when the flow of the river was impounded.

The BBMB is undertaking a fresh silt survey to assess the rate of silt inflow and the level of sedimentation in the reservoir. An estimated 38 million cubic metres (MCM) silt flows into the reservoir every year. The reservoir’s storage capacity, which was 9,868 MCM in 1958, was assessed as 7,769 MCM in the last documented silt survey of 2012.

The Central Water Commission data reveals that while the designed rate of siltation at Bhakra was 0.43 thousand cubic meters per sq km per year, the actual rate is noticeably higher at 0.68 thousand cubic meters per sq km per year.