Only 19 out of 41 gates fully operational

More than 55 per cent of Dhaka's sluice gates are either fully or partially out of service, significantly weakening the city's ability to drain rainwater and worsening waterlogging during heavy downpours, according to city engineers and urban planning experts.

Officials from Dhaka's two city corporations said only 19 of the city's 41 sluice gates are fully operational. The remaining 22 are either non-functional or operating below capacity, including six that are completely out of order and 16 that are only partially functional.

The latest spell of torrential rain once again exposed the vulnerabilities of Dhaka's ageing drainage system. According to the Bangladesh Meteorological Department (BMD), the capital received 192 millimetres of rainfall over two days, inundating major roads and residential areas, including Nilkhet, Jigatala, Motijheel, Shantinagar, Kakrail, Kamalapur, Shahjahanpur, Gendaria, Old Dhaka and Mirpur.

In many neighbourhoods, knee- to waist-deep water persisted for several hours, disrupting transport, business activities, healthcare services and daily commuting.

Engineers said the recurring flooding is not solely the result of intense rainfall but also reflects years of inadequate maintenance, ageing drainage infrastructure, encroached canals and weak institutional coordination.

Dhaka's drainage network relies on only eight major outfalls to discharge stormwater from nearly 306 square kilometres of urban area inhabited by around 25 million people. Officials acknowledged that the network has not expanded in line with the city's rapid urbanisation.

The situation has been further aggravated by mechanical failures at key pumping stations. At the TT Para Pump Station near Kamalapur Stadium, one of the station's three high-capacity pumps has remained out of service for nearly one and a half years, reducing pumping capacity during peak rainfall.

DSCC Executive Engineer (Electrical) Nur Mohammad said procurement of a replacement pump has been completed and installation is expected soon, although it is unlikely to become operational during the current monsoon season.

He said the Dhaka South City Corporation currently operates two major pumping stations with a combined discharge capacity of about 5,000 litres per second. Our drainage system is designed to handle around 50 millimetres of rainfall, which normally clears within two hours. But recent rainfall far exceeded that capacity, overwhelming the entire network, he told The Daily Observer.

Engineers also said plastic bags, rubber, foam and other solid waste continue to clog drains and canals despite regular cleaning operations, significantly slowing the flow of stormwater. DSCC Superintending Engineer Rajib Khadem said routine drain cleaning is ongoing, but indiscriminate waste dumping remains a major challenge.

He added that a study by the Institute of Water Modelling (IWM) is evaluating long-term solutions, including modernising the drainage network, repairing damaged sluice gates, shortening drainage routes, increasing pumping capacity and installing additional suction machines.