Chandigarh Administration to employ sound wave tech to assess silt, depth of Sukhna

The water storage capacity of the city’s iconic Sukhna Lake has dropped by nearly 50% over the past seven decades, prompting the UT Administration to employ modern technology to assess the extent of siltation and plan for restoration.

For the first time, sound wave-based bathymetric profiling will be carried out to determine the lake’s current depth, silt levels and areas where dredging is feasible.

According to the Administration’s newly prepared Integrated Sukhna Management Plan, the lake’s water-holding capacity has fallen from 1,074 hectare metres in 1958 to just 545 hectare metres in 2015. Officials said although the lake’s storage capacity saw a temporary 27% rise in 2002—after its height was increased by two feet—it has since continued to lose depth due to unchecked siltation and evaporation losses.

The Forest and Wildlife Department, in collaboration with the World Wide Fund for Nature, a Swiss-based international NGO, has drawn up a five-year action plan aimed at rejuvenating the lake, which serves as the city’s lifeline — supporting its ecology, groundwater recharge and tourism.

To identify and tackle the problem zones, the Administration will carry out a bathymetric profile assessment, a modern technique used globally to study underwater topography. Using echo sounders (sonar technology), sound waves will be transmitted into the lake, and the time they take to reflect back after hitting the lakebed will help measure the depth and sediment levels with high precision. The data will then be integrated with GPS coordinates to create a detailed 3D model of the lakebed.

Officials said areas with excessive silt accumulation will be marked for wet dredging, which involves removing silt without completely draining the lake. If dredging is not possible in some portions, the Administration may explore increasing the lake’s height again to improve its storage capacity.

In addition to sonar, Lidar (Light Detection and Ranging) technology may also be used. Lidar employs laser pulses to calculate underwater depth and will complement sonar readings in creating an accurate bathymetric map.

Experts said the exercise will also help determine whether parts of the lake that remain submerged throughout the year can be desilted safely. At present, silt removal is limited to the shallow, dried-out sections during summers. However, as the lake has not fully dried up in recent years, desilting operations have been minimal, leading to steady sediment build-up.

Sukhna Lake and its surrounding catchment have already been declared a wetland, and a proposal has been sent to the Central Government to include it in the Ramsar list of internationally significant wetlands.

Officials said the upcoming bathymetric survey will provide a scientific foundation for all future interventions at Sukhna — marking a shift from periodic, ad-hoc desilting to a long-term, data-driven conservation approach.