Rooftop runoffg Local drainsg Secondary canals gMain canal ringsgRiver or Sea
Urban leadership today depends not only on what is visible above ground but on how effectively a city manages that lies beneath it. Elections are won on streets and in neighbourhoods, but public trust is sustained through invisible systems - drains, canals, culverts and pumping stations that quietly carry away rainwater. When these fail, even the most ambitious political mandates are submerged in public frustration. Probably former President Ziaur Rahman knew it very well envisioning canal-digging programme during his time in power between 1976 and 1981. The Ulashi-Jadunathpur at Barabaria Bazar in Jashore was the first canal President Ziaur Rahman dug.
Now his son Prime Minister Tarique Rahman is reworking on the BNP's flagship project shelved for a long time. Over these years, Bangladesh has been exposed to water aggression by upper riparian country like India. Government has earmarked 31.57 crore taka to identify and classify the 30,000 canals and the move is likely to criminalise the canal encroachers. The cumbersome job have been started through opening Shahapara Canal in Kaharole upazila in Dinajpur and the countrywide programme is likely to 3600 canal and river grabbers in the country. And for the first time in Bangladesh's history of Parliamentary democracy that Leader of the Opposition Dr Shafiqur Rahman eloquently eulogized the canal digging project reinitiated by Prime Minister Tarique Rahman. This was a rare gesture which was really rare in the political landscape of the deltaic land before July Uprising.
Digging of thirty thousand canals is a national government activities but if it is handled in an isolated way, it may spell disastrous result. There should be a synchronization between drain, canal and river or sea. The disaster will be felt harder in the cities, metropolitans and towns - be it Dhaka or Chattogram or Jashore- where clogged drains are a perennial concern.
Dhaka's chronic water-logging during monsoon seasons is not merely an engineering problem; it is a structural and governance failure. Lessons from global canal-based cities - particularly the London, Amsterdam, Seoul and Bangkok - offer important insights into how drains and canals can function as integrated, climate-resilient infrastructure.
Dhaka's Drainage Reality: Dhaka historically evolved as a deltaic settlement interwoven with natural canals (khals), wetlands and distributaries of the Buriganga-Turag-Balu river system. Mid-20th-century surveys suggest that the city once possessed more than 60 functioning canals forming several hundred kilometres of natural drainage corridors.
Today, although thousands of kilometres of drains exist under different agencies, hydraulic performance remains weak. The stormwater system was originally designed to handle rainfall intensities of approximately 20-25 mm per hour. However, contemporary downpours frequently exceed 30 mm per hour, overwhelming drains that were never engineered for current runoff volumes.
Several interrelated factors need to be addressed including encroachment and narrowing of canals, solid waste blocking tertiary drains, extensive concretisation reducing soil infiltration and fragmented institutional responsibility.
The problem is not merely insufficient length of drains; it is broken connectivity. Drains often end in clogged canals; canals lack adequate outfalls; and pumping stations operate reactively rather than as part of a coordinated hydraulic network.
London: Layered Infrastructure and Long-Term Vision: London's drainage transformation began after the "Great Stink" of 1858. Engineer Joseph Bazalgette designed a network of intercepting sewers that redirected waste eastward along the Thames. The system was deliberately over-engineered to accommodate future growth - a foresight that allowed the network to support more than a century of expansion.
Key lessons from London include: Metropolitan-scale planning - Infrastructure was conceived for the entire city, not neighbourhood fragments.
Layered underground zoning - Roads, utilities, sewers and rail systems coexist through spatial coordination.
Future-proofing design capacity - Oversizing pipes ensured resilience to population growth.
Modern upgrades - The Thames Tideway Tunnel demonstrates continuous adaptation.
London shows that drainage systems must evolve with climate change and urban density rather than remain static.
Amsterdam: Living with Water, Not Against It: Amsterdam, much of which lies below sea level, integrates canals directly into daily urban life. Rather than burying water, the Dutch expanded floodplains under the "Room for the River" approach.
Amsterdam's system operates hierarchically
Rooftop runoffg Local drainsg Secondary canalsg Main canal ringsg Pumped discharge to sea
Distinct features include separated stormwater and wastewater lines, automated pumping stations, regional water boards with unified authority.
The Dutch model demonstrates that water governance must be basin-wide rather than fragmented across competing agencies. Canal width preservation and retention capacity are non-negotiable for hydraulic efficiency.
Seoul: Ecological Restoration with Hydraulic Reinforcement: Seoul's restoration of the Cheonggyecheon stream illustrates how buried waterways can be revived as both drainage channels and public spaces. Once covered by highways, the stream was reopened and redesigned to function as a flood-control corridor.
Key features include: Variable channel depth to absorb storm surges, Integration with upstream culverts, Automated flood gates and pumping systems, Urban cooling and biodiversity gains, Following severe flooding in 2011, Seoul invested in deep underground storage tunnels to temporarily hold excess rainwater. The city demonstrates that restoration is not merely aesthetic; it enhances hydraulic resilience.
Bangkok: Pump-Canal Synchronisation in a Monsoon Delta
Bangkok, historically dependent on klongs (canals), faces seasonal monsoon floods and river backflow. After the devastating floods of 2011, the city strengthened canal dredging, expanded pumping capacity and introduced retention basins known as "monkey cheeks."
Bangkok's three-tier system operates as:
Local drainsg Secondary channelsg Primary canalsg River discharge
When river levels rise, floodgates prevent backflow and pumps evacuate stormwater. The Bangkok case highlights the importance of coordinated pump operation, canal re-excavation, legal protection against encroachment, temporary water storage zones.
Relevance for Dhaka: Dhaka's hydrological challenge resembles a combination of Bangkok's monsoon stress and Amsterdam's low-lying vulnerability. However, governance fragmentation remains a critical barrier. Responsibilities are divided among Dhaka WASA, city corporations and development authorities, resulting in maintenance gaps and slow disaster response.
A systems-based reform should include a single metropolitan body responsible for drains, canals and retention basins under one hydrological command structure. GIS-based canal inventories, depth measurements, encroachment tracking and rainfall simulation models must guide planning.
Neighbourhood drains must connect efficiently to widened secondary drains, which in turn discharge into re-excavated primary canals leading to rivers. Low-lying parks and wetlands should function as temporary storage during peak rainfall.
Trash screens and sediment traps at drain-canal junctions are essential to prevent blockages. Mixed systems amplify contamination and overload during heavy rainfall.
International experience shows that hydraulic success depends on institutional clarity. Amsterdam's water boards, Singapore's centralized PUB authority and London's regulated utility model ensure accountability.
Dhaka must move beyond reactive desilting campaigns toward long-term capital planning, climate-adaptive design standards, transparent public dashboards on canal status, strict enforcement against encroachment. Re-excavation alone is insufficient unless hydraulic continuity is restored from rooftop to river.
Cities such as London, Amsterdam, Seoul and Bangkok demonstrate that drains and canals are not obsolete relics but dynamic urban infrastructure. Their success rests on five shared principles including integrated metropolitan planning, multi-level hydraulic layering, upstream retention capacity and technological monitoring.
Unified governance: Dhaka's flooding crisis is not inevitable. It is the cumulative outcome of encroachment, fragmented authority and outdated design assumptions. Reclaiming the city's blue-green network requires restoring gravity flow, protecting canal corridors and treating water infrastructure as a central pillar of urban governance. For a deltaic capital facing intensifying monsoons and rapid urbanisation, integrating drains and canals is not optional - it is existential.
The writer is senior journalist, Daily Observer
