Dhaka’s persistent waterlogging is driven by fragmented management, the lack of an integrated master plan, unchecked urbanisation, and the steady disappearance of wetlands and canals, according to experts.

Officials said the two city corporations spent more than Tk 262 crore between 2021 and 2024 to construct 334.19km of drains and box culverts after taking over responsibility for the capital’s drainage system from Dhaka Water Supply and Sewerage Authority (Wasa) on December 31, 2020.

Yet many parts of the city continue to go underwater after heavy rain.

The problem was laid bare again on Sunday when more than 100mm of rainfall inundated large parts of the capital, including many areas not previously identified as waterlogging hotspots. Many parts of the city also went under water yesterday.

Experts say the city corporations have continued implementing drainage projects without an integrated citywide plan.

Adil Muhammed Khan, executive director of the Institute for Planning and Development, said the city’s biggest problem is the absence of a comprehensive drainage master plan.

“The city corporations have been carrying out scattered, isolated works -- receiving some funds and making improvements in a few locations. This is not an integrated approach, and it cannot solve the waterlogging problem.”

Officials of both city corporations said they are now preparing a drainage master plan.

Experts also blamed decades of unplanned urbanisation for steadily eroding the city’s natural capacity to absorb and drain rainwater.

A 2023 study by the Bangladesh Institute of Planners (BIP) found that Dhaka has lost 17.67 percentage points of its wetlands and 15.4 percentage points of its green and open spaces since 1995 due to rapid, unplanned urbanisation. During the same period, built-up areas expanded from 43 percent to 76.78 percent of the city’s land, sharply increasing concrete coverage.

Adil said weak development control has allowed drainage channels, wetlands and green spaces to disappear in the name of urban development.

“If urban expansion continues without proper regulation, there is no reason to expect waterlogging to decrease,” he said.

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Earlier this year, Dhaka North City Corporation (DNCC) and Dhaka South City Corporation (DSCC) identified 141 waterlogging hotspots -- 108 under DNCC and 33 under DSCC.

The city corporations resorted to pre-monsoon cleaning of drainage systems there to curb waterlogging.

But Sunday’s downpour, however, inundated several additional areas, indicating that the drainage network lacks the capacity to quickly discharge increasingly intense rainfall.

Adil warned that flooding would spread to more areas and the crisis would deepen if Dhaka’s remaining floodplains and water retention areas continue to disappear.

“Areas around Aminbazar and Madhumati that were meant to function as floodplains and retention zones are being filled up. Once these are gone, Dhaka will face an even more severe crisis,” he said.

Urban planner Akter Mahmud said the city’s natural drainage system has become increasingly disconnected as canals have narrowed, retention areas have shrunk and solid waste continues to choke drains and waterways.

“Roadside catch pits are frequently blocked by polythene and other waste, reducing drainage capacity at the very first stage,” he said. “The drains leading to canals are also obstructed because solid waste is not properly managed.”

Akter, a former BIP president, said rainwater now runs off much faster because expanding concrete surfaces leave little room for it to seep into the ground.

“When the pathways to canals, wetlands and retention areas are blocked, water cannot move efficiently. It creates water congestion similar to traffic congestion,” he said.

He said key recommendations of the Drainage Master Plan prepared by Wasa in 2015 were never implemented.

Among the examples, he cited the Goran-Chandbari water retention area, which originally covered about 615 acres but has already lost around 40 acres to development. In Kallyanpur, more than 200 acres had been earmarked for water retention, but only about 30 to 35 acres remain.

He also said three proposed water retention ponds intended to drain runoff from Gulshan, Badda, Merul Badda and Nikunja into the Balu river have all been lost to land filling.

“Wetlands are disappearing, ponds are vanishing, lakes are shrinking and canals are narrowing. Combined with changing rainfall patterns caused by climate change, this is exactly the scenario experts had predicted,” Akter said.

Iqbal Habib, vice-president of Bangladesh Poribesh Andolon, said climate change is increasing the frequency of intense rainfall, making it even more urgent to update the city’s drainage strategy.

He also said sewage continues to flow into stormwater drains and canals, clogging drainage channels and polluting water bodies.

“A lasting solution requires restoring wetlands, protecting canals from encroachment, improving solid and liquid waste management, redesigning roads where necessary and implementing a comprehensive drainage master plan,” Iqbal said.

LGRD and Cooperatives Minister Mirza Fakhrul Islam Alamgir told parliament on June 16 that the government was implementing short-, medium- and long-term measures to tackle waterlogging in Dhaka.

These include regular desilting of drains and canals, installing additional catch pits, deploying portable pumps and ward-level emergency response teams.

The medium-term plan focuses on restoring major canals and expanding drainage infrastructure, while long-term measures include developing nearly 50km of canals, constructing new pump stations and utility ducts, improving drainage and modernising solid waste management.