Delhi Jal Board to begin dredging, desilting in Yamuna riverbed

The purpose of the exercise is to increase the water holding capacity of the adjacent barrage and improve the quality of water in the river channel

The Delhi Jal Board (DJB) will soon start dredging and desilting on the Yamuna riverbed and the Wazirabad pondage area to increase the water holding capacity of the adjacent barrage and improve the quality of water in the river channel, according to officials aware of the matter.

Dredging means clearing the riverbed of sediments and debris. (HT Photo)

The exercise will entail the removal of around 387,000 cubic metres of silt over a period of about eight months, a senior DJB official said on Wednesday.

The work is expected to start only after mid-September, once the monsoon ends, and bids have been invited. The modalities are likely to be finalised on August 16, the official said.

Dredging involves the removal of sediments and debris from the bottom of rivers and other water bodies, typically to deepen the water. Desilting refers to the removal of silt or fine particles from a waterbody to improve water flow and prevent flooding.

DBJ last initiated dredging in 201 3, but the activity was stayed at the time by the National Green Tribunal (NGT) citing environmental concerns. The stay was later vacated in 2015.

The Wazirabad pondage region acts as the primary holding area for drinking water from the Yamuna, and pumps raw water to the primary major Wazirabad, Okhla and Chandrawal water treatment plants, which supply a quarter of the city’s daily water requirement.

Officials said that the dredging and desilting will help improve water holding capacity of the pond area which acts as reservoir for raw water and subsequently prevent shortage of water supply, especially during the summer season.

The exercise will involve the removal of weeds with roots above the slushy soil and removal of silt and sand by dredging from riverbed by deploying cutter-suction dredgers with pipelines for disposing of water slurry, the official cited above said. “This slurry material will be transported to the shore of the lake area downstream for its disposal away from the river,” the official said.

According to an assessment carried out by DJB in March 2023, the optimum level the riverbed level at Wazirabad should be 671ft and the depth of pond area should be 14ft, but due to the accumulation of silt, the average depth is nearly 7ft. After the dredging, the level of the riverbed is expected to reach around 661 feet, officials said.

The Delhi government’s water agency plans to deploy dredgers attached with a kilometre-long 30cm wide pipelines, which will remove the slurry at a rate of 1,200 cubic metres per hour. For its disposal, a private contractor will be hired, who will also sell the sand against a portion and royalty to DJB and the revenue department, officials said.

According to a DJB report, the work for desilting of Yamuna at Wazirabad was last initiated at a smaller scale in 2013. It was, however, stopped by NGT over concerns about sand mining. But in 2015, the tribunal permitted the work. However, DJB cancelled the contract since the project made little progress.Diwan Singh, an environmental activist, said,“It is fine if they (DJB) wishes to remove the silt... but DJB should ensure they do not go below the natural river bed level.”