Box culvert obstructing Kallyanpur canal flow, raising waterlogging risks

As Dhaka grapples with clogged canals and authorities work to remove illegal structures obstructing water flow, some infrastructure projects are undermining these efforts.

One such obstruction is a box culvert constructed by Dhaka North City Corporation in 2023 over the Kallyanpur "Cha" canal as part of the Syed Mahbub Morshed Road development.

The culvert has significantly narrowed the canal, raising concerns over drainage, waste accumulation, and environmental degradation.

The Kallyanpur Cha canal, which runs from the National Parliament area to Kallyanpur, previously had a wider culvert at this location.

Experts argue that a bridge, rather than a box culvert, was needed to preserve the canal's flow. Instead, the culvert has created a bottleneck, allowing silt, plastic waste, and sludge to accumulate, blocking the canal's mouth and preventing proper drainage.

During a recent visit to the site, stagnant water was seen in several sections, with plastic waste piled up along the canal. The area near the culvert was particularly clogged, with thick layers of sludge and overgrown weeds emitting a foul odour.

The canal flows behind the National Orthopaedic Hospital and Rehabilitation Institute, and residents report that mosquito and insect infestations have worsened, further deteriorating the living conditions of both locals and patients at the hospital.

"This canal has not been cleaned for the past year. Last monsoon, the water overflowed into our homes. We had to clear the canal's mouths ourselves to allow drainage," said Nesar Alam, a resident living along its banks.

Zakia Begum, a resident of a nearby slum, said waste collection services had stopped in recent months, forcing residents to dispose of garbage directly into the canal.

"If it rains for even an hour or two, water enters our houses because the culvert blocks the flow," she added.

The Syed Mahbub Morshed Road project, completed at a cost of Tk55 crore, expanded a 1,400-metre stretch from the Agargaon intersection in Sher-e-Bangla Nagar to the Shishumela intersection in Shyamoli.

The six-lane road features bus bays, passenger shades, bicycle lanes, and roadside parking.

The box culvert, built under this project for Tk2 crore, was meant to facilitate road construction, but experts argue that the funds could have been used to build a high bridge instead, allowing the canal to remain unobstructed.

"This project was planned in 2016, and we received the drainage system around 2021. Before that, Dhaka Wasa had already built a box culvert over this canal," said Faruque Hassan Md Al Masud, superintending engineer (civil) of Dhaka North's Drainage Circle.

"As a result, the culvert was retained in our project. But a high bridge was needed here," he added.

Masud, also the project director for the road development, acknowledged that obstructed canal flow is a widespread issue in Dhaka.

"The interim government is prioritising canal restoration, and we are also working on it. However, demolishing box culverts and replacing them with high bridges is expensive. While it is part of our long-term plan, immediate action is not possible," he further added.

Dhaka North's waste management department has pledged to remove garbage from the canal and ensure regular maintenance.

However, urban planners argue that more decisive steps are needed.

"The city corporation does not conduct proper planning when building roads over canals," said Sheikh Muhammad Mehdi Ahsan, general secretary of the Bangladesh Institute of Planners.

"The canal should have been taken into account before constructing the culvert. Even if it was costlier, a high bridge was essential to maintaining water flow."

As a temporary solution, Mehdi suggested that Dhaka North regularly clear waste from the canal while planning for a long-term fix.

"The box culvert should eventually be demolished, and a bridge should replace it. If the city corporation is serious, it could restore the canal's network within one and a half years."

For now, residents of Kallyanpur continue to bear the consequences of the flawed design, as the canal, once a natural drainage channel, remains clogged with waste and stagnant water.