Bangladesh

The breach in Dhaka’s flood defenses

Water retention ponds shrinking due to urban sprawl
Illegal structures now stand at the Kalyanpur retention pond area. Retention ponds like this are essential to prevent waterlogging, but unchecked urbanisation, jurisdictional overlaps, and negligence threaten their survival, endangering Dhaka’s resilience against floods. Photo: Rashed Shumon

Once the lifelines of Dhaka, the city's canals are now mere shadows of their former selves—clogged with pollution, suffocated by encroachment, and neglected due to flawed urban planning. In this seven-part series, The Daily Star explores the current condition of the capital's canals, botched restoration attempts, and how the sorry state of these waterways is exacerbating the city's waterlogging woes. Together, these stories reveal what it will take to bring Dhaka's dying canals back to life. Here is the third part of the series:
 

Designed to rescue Dhaka from floods, water retention ponds are now in need of rescue themselves. These basins, meant for stormwater management, are shrinking rapidly due to encroachments, unplanned urbanisation, and government neglect.

Just like the capital's canals, these lifelines are now being choked, one illegal grab at a time.

WHAT ARE RETENTION PONDS?

Retention ponds serve as reservoirs for stormwater runoff, preventing flooding and downstream erosion while maintaining water quality. By acting as buffers, they ensure that urban areas can cope with heavy rainfall, particularly during the monsoons. 

Retention ponds act like giant bowls that collect and store excess rainwater during downpours, preventing nearby areas from flooding.

Imagine this: during a storm, instead of rainwater overwhelming streets and homes, these ponds hold the water temporarily. Over time, they release it slowly into nearby rivers or canals, reducing the risk of sudden flooding. 

For example, in Dhaka's Mirpur area, stormwater from nearby roads, homes, and markets flows into the Kallyanpur retention pond through Kalyanpur main canal and its branch canals, which is then pumped out to the Buriganga river, said a Wasa official. If this pond didn't exist, the water would pool on the streets, causing severe waterlogging.

Retention ponds also improve water quality by filtering out pollutants from the runoff before it reaches rivers.

"Retention ponds are indispensable for reducing Dhaka's flood vulnerability. Protecting them is critical for the city's sustainability," said Akter Mahmud, a member of the advisory council of the Bangladesh Institute of Planners. 

 

Photo: Rashed Shumon

WESTERN RETENTION PONDS

The western part of Dhaka is home to three key pump stations – Kalyanpur, Goran Chatbari, and Dholai Khal – each designed with designated retention ponds. However, over the years, these ponds have been encroached upon, drastically reducing their capacity. 

At Dholai Khal, a box culvert constructed in the 1990s by the Dhaka city corporation destroyed the retention area. The pumping station, which requires at least 105 acres for optimal operation, now has just 3.5 acres.

There are three pumps at the Dholaikhal station, each with a capacity of 7.4 cubic metres per second. They are struggling to manage the growing burden. 

At Kalyanpur, the situation is equally dire.

A study by the Japan International Cooperation Agency in 1990 recommended a pumping station with a 20 cumec capacity and 514 acres of retention pond area. However, in over three decades, the government has managed to acquire only 53.004 acres, far short of the requirement.

Despite acquiring only 53.004 acres,  the DNCC has designated 178.82 acres as retention space. This includes 98.35 acres owned by BADC, 6.36 acres by WDB, 11.40 acres of government khash land, and 62.71 acres belonging to Dhaka Wasa. A substantial part of this land is under encroachment.

The BADC recently attempted to fill 11 acres of retention land for a four-storey tissue culture building, violating the Environment Conservation (Amendment) Act 2010. Although legal challenges have stalled the construction, environmentalists warn that the area remains at risk.

"The government's failure to acquire the required land when it was affordable has made the situation worse," said a WASA official. "What could have been done for Tk 50 crore then would now require an exponentially higher budget." 

When asked about BADC filling up 11 acres of land, Md Mahmudul Hasan, administrator of Dhaka North City Corporation, said BADC still owns significantly more land than what has been filled. BADC uses the land as seed beds.

Rajuk has designated the area as a waterbody in the Detailed Area Plan.

Meanwhile, Goran Chatbari's retention pond, once 619 acres, has also lost 40 acres to the Road Transport and Bridges Ministry to implement one of their projects. Although additional pumps have been installed to compensate, the loss of retention area has strained the system. 

EASTERN RETENTION PONDS

Dhaka's eastern retention ponds are also struggling to survive.

Two critical areas – one at the confluence of the Gobindopur and Bouthar canals at the Uttar Khan and Dakkhin Khan areas on the bank of Balu River, and another at the ending points of the Dumini and Norai canals at Nagdarpara and Kayetpara – are also being filled up in the name of housing projects.

"These areas are earmarked in the Drainage Master Plan, Dhaka Metropolitan Development Plan (DMDP), and Detailed Area Plan (DAP)," said Akter Mahmud.

Without intervention, the government risks losing these crucial areas, jeopardising future drainage projects, he said.

WHO IS TO BLAME?

Encroachment, negligence, and a lack of coordinated government action are at the heart of the crisis, according to experts.

Overlapping jurisdictions between Wasa, DNCC, and the Ministry of Agriculture have resulted in a lack of accountability and enforcement, they added.

"The government must take immediate steps to protect these areas," said Iqbal Habib, an urban planner. "Canals and retention ponds are integral to the city's drainage system. Any disruption could lead to a total collapse." 

Despite the grim outlook, there are, however, some promising initiatives.

DNCC Chief Engineer Brig Gen Md Moin Uddin revealed plans for a hydro-eco park at Kalyanpur. The project envisions a retention pond surrounded by trees to increase water-carrying capacity while maintaining ecological balance. 

However, a large portion of BADC's land is essential for this project.

Meanwhile, administrator Mahmudul said both the DNCC and LGRD Ministry support the project, but an inter-ministerial decision is required for the land.

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The breach in Dhaka’s flood defenses

Water retention ponds shrinking due to urban sprawl
Illegal structures now stand at the Kalyanpur retention pond area. Retention ponds like this are essential to prevent waterlogging, but unchecked urbanisation, jurisdictional overlaps, and negligence threaten their survival, endangering Dhaka’s resilience against floods. Photo: Rashed Shumon

Once the lifelines of Dhaka, the city's canals are now mere shadows of their former selves—clogged with pollution, suffocated by encroachment, and neglected due to flawed urban planning. In this seven-part series, The Daily Star explores the current condition of the capital's canals, botched restoration attempts, and how the sorry state of these waterways is exacerbating the city's waterlogging woes. Together, these stories reveal what it will take to bring Dhaka's dying canals back to life. Here is the third part of the series:
 

Designed to rescue Dhaka from floods, water retention ponds are now in need of rescue themselves. These basins, meant for stormwater management, are shrinking rapidly due to encroachments, unplanned urbanisation, and government neglect.

Just like the capital's canals, these lifelines are now being choked, one illegal grab at a time.

WHAT ARE RETENTION PONDS?

Retention ponds serve as reservoirs for stormwater runoff, preventing flooding and downstream erosion while maintaining water quality. By acting as buffers, they ensure that urban areas can cope with heavy rainfall, particularly during the monsoons. 

Retention ponds act like giant bowls that collect and store excess rainwater during downpours, preventing nearby areas from flooding.

Imagine this: during a storm, instead of rainwater overwhelming streets and homes, these ponds hold the water temporarily. Over time, they release it slowly into nearby rivers or canals, reducing the risk of sudden flooding. 

For example, in Dhaka's Mirpur area, stormwater from nearby roads, homes, and markets flows into the Kallyanpur retention pond through Kalyanpur main canal and its branch canals, which is then pumped out to the Buriganga river, said a Wasa official. If this pond didn't exist, the water would pool on the streets, causing severe waterlogging.

Retention ponds also improve water quality by filtering out pollutants from the runoff before it reaches rivers.

"Retention ponds are indispensable for reducing Dhaka's flood vulnerability. Protecting them is critical for the city's sustainability," said Akter Mahmud, a member of the advisory council of the Bangladesh Institute of Planners. 

 

Photo: Rashed Shumon

WESTERN RETENTION PONDS

The western part of Dhaka is home to three key pump stations – Kalyanpur, Goran Chatbari, and Dholai Khal – each designed with designated retention ponds. However, over the years, these ponds have been encroached upon, drastically reducing their capacity. 

At Dholai Khal, a box culvert constructed in the 1990s by the Dhaka city corporation destroyed the retention area. The pumping station, which requires at least 105 acres for optimal operation, now has just 3.5 acres.

There are three pumps at the Dholaikhal station, each with a capacity of 7.4 cubic metres per second. They are struggling to manage the growing burden. 

At Kalyanpur, the situation is equally dire.

A study by the Japan International Cooperation Agency in 1990 recommended a pumping station with a 20 cumec capacity and 514 acres of retention pond area. However, in over three decades, the government has managed to acquire only 53.004 acres, far short of the requirement.

Despite acquiring only 53.004 acres,  the DNCC has designated 178.82 acres as retention space. This includes 98.35 acres owned by BADC, 6.36 acres by WDB, 11.40 acres of government khash land, and 62.71 acres belonging to Dhaka Wasa. A substantial part of this land is under encroachment.

The BADC recently attempted to fill 11 acres of retention land for a four-storey tissue culture building, violating the Environment Conservation (Amendment) Act 2010. Although legal challenges have stalled the construction, environmentalists warn that the area remains at risk.

"The government's failure to acquire the required land when it was affordable has made the situation worse," said a WASA official. "What could have been done for Tk 50 crore then would now require an exponentially higher budget." 

When asked about BADC filling up 11 acres of land, Md Mahmudul Hasan, administrator of Dhaka North City Corporation, said BADC still owns significantly more land than what has been filled. BADC uses the land as seed beds.

Rajuk has designated the area as a waterbody in the Detailed Area Plan.

Meanwhile, Goran Chatbari's retention pond, once 619 acres, has also lost 40 acres to the Road Transport and Bridges Ministry to implement one of their projects. Although additional pumps have been installed to compensate, the loss of retention area has strained the system. 

EASTERN RETENTION PONDS

Dhaka's eastern retention ponds are also struggling to survive.

Two critical areas – one at the confluence of the Gobindopur and Bouthar canals at the Uttar Khan and Dakkhin Khan areas on the bank of Balu River, and another at the ending points of the Dumini and Norai canals at Nagdarpara and Kayetpara – are also being filled up in the name of housing projects.

"These areas are earmarked in the Drainage Master Plan, Dhaka Metropolitan Development Plan (DMDP), and Detailed Area Plan (DAP)," said Akter Mahmud.

Without intervention, the government risks losing these crucial areas, jeopardising future drainage projects, he said.

WHO IS TO BLAME?

Encroachment, negligence, and a lack of coordinated government action are at the heart of the crisis, according to experts.

Overlapping jurisdictions between Wasa, DNCC, and the Ministry of Agriculture have resulted in a lack of accountability and enforcement, they added.

"The government must take immediate steps to protect these areas," said Iqbal Habib, an urban planner. "Canals and retention ponds are integral to the city's drainage system. Any disruption could lead to a total collapse." 

Despite the grim outlook, there are, however, some promising initiatives.

DNCC Chief Engineer Brig Gen Md Moin Uddin revealed plans for a hydro-eco park at Kalyanpur. The project envisions a retention pond surrounded by trees to increase water-carrying capacity while maintaining ecological balance. 

However, a large portion of BADC's land is essential for this project.

Meanwhile, administrator Mahmudul said both the DNCC and LGRD Ministry support the project, but an inter-ministerial decision is required for the land.

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