Sonar technology survey of silt in Sutlej at Sunni from Dec 15: DC

Deputy Commissioner Anupam Kashyap yesterday said that the Kol Dam management would soon conduct a survey with the help of sonar technology on silt in the Sutlej in the Sunni region of Shimla district. He added that the survey would commence on December 15 and was expected to be completed within the next 15 to 20 days. Later, the Kol Dam management would submit a report.

Kashyap along with SSP Sanjeev Gandhi and other officials was on a visit to Sunni and inspected the rising water level and silt accumulation in the Sutlej. He highlighted the risk factors due to the rising water level of the river as well as silt accumulation in it. He said, “Houses as well as land in Sunni are under threat due to the rising water level of the river. This year, during the monsoon season, several residential areas, ITI, Sunni campus, a rest house and cowsheds submerged after the accumulation of water and silt in the area.”

He said, “Our priority is to ensure the safety of people and their property. An amount of Rs 10 crore has already been approved for the repair of the Thali bridge, the work on which will be initiated this month. The repair as well as restoration works will be completed before the monsoon season next year”.

About the sonar technology, the Deputy Commissioner said that it was a technique that used sound waves (Sound Navigation and Ranging) to detect, map and survey underwater objects. “It is crucial for a detailed inspection of underwater structures such as bridges or riverbeds especially in low-visibility conditions where cameras or GPS cannot function effectively,” he added.

Kashyap said, “This technology works by sending sound waves from the sonar equipment and measuring time it takes for the reflected waves to return after hitting underwater objects.” He added that from 2014 to 2024, a team of the Indian Institute of Technology (IIT), Roorkee, conducted a study on silt accumulation in the Sutlej and its report revealed that there were no major change in the silt levels between 2014 and 2021. However, the silt deposit saw a massive spike after 2021. In the Zone 1 (Tatapani), silt in the Sutlej increased from seven hectares in 2022 to 27 hectares in 2023. In the Zone 2 (Sunni), the silt rose from 0.5 hectares in 2022 to 10 hectares in 2023 while in the Zone 3 (Chaba), the silt

accumulation increased from 1.7 hectares to eight hectares in 2023.

He said, “While the report stated that the accumulated silt in the Sutlej at Sunni is suitable for construction purposes, it also suggested proper silt mining to reduce the water level of the river. The NTPC is prepared to issue an NOC to the state government for carrying out mining.”