Delhi govt to build ‘silt traps’ along drains to prevent waterlogging

Delhi: The Delhi government has unveiled a Drainage Master Plan that proposes the construction of ‘silt traps’ along major drains to prevent waterlogging.

The initiative, aimed at modernising the city’s outdated drainage infrastructure, is inspired from a successful pilot project in Chennai.

“We constructed ‘silt traps’ in drains in Chennai a few years ago as an experiment which brought a drastic decrease in waterlogging episodes in the city,” said Gyanasis Jena, one of the private consultants hired by the government to prepare the plan.

According to the plan, traps will be constructed as separate chambers at a lower level alongside the drains, where silt carried by stormwater can accumulate, preventing it from clogging the main drainage line, Jena said.

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Designed to meet the city’s drainage requirements over the next 30 years, the master plan will be implemented in five years in two phases.

The method aims to reduce waterlogging episodes by 50 per cent in the next three years and flood-related accidents by 30 per cent in the next five years.

The two phases will involve critical flood control and network expansion with priority integration, overhauling the drainage network that runs up to 18,958 km and is overseen by eight agencies.

“The accumulated silt in drains reduces the carrying capacity, which leads to the problem of backflow, and the drainage network we surveyed already is insufficient to handle the stormwater. So if there is a silt trap mechanism then just that chamber will be required to be cleaned as all the silt would be trapped in it and not the drain,” Jena said.

According to the plan, the city has been divided into three basins — Najafgarh Basin, Barapullah Basin, and Trans-Yamuna Basin.

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Across these basins, the drainage system is 50 years old and is no longer capable of catering to rapid urbanisation and patterns of rainfall.

The Public Works Department in 2023 identified 308 waterlogging points.

There are now 445 waterlogging points in the capital.