Colombo's drainage crisis: how decades of stalled projects left the city exposed

The flooding that paralysed parts of Colombo this week, after 129 millimetres of rain fell in a single hour, has once again exposed how vulnerable the capital's drainage network has become after decades of stalled and half-finished mitigation projects.

Municipal officials have identified around 60 blockages across the city's canals and drains, many caused by unauthorised construction over and around drainage channels. The city council has now launched a joint clearance operation and warned of legal action against illegal structures, while a special task force is being set up to respond to future flooding.

The crisis is not new. Successive governments have announced flood mitigation programmes for Colombo and the Kelani River basin, including a World Bank-assisted city flood mitigation project that opposition parties now urge the government to restart. Several earlier projects were abandoned midway or left incomplete when administrations changed.

The result is a repeating cycle: heavy rain, overwhelmed drains, flooded roads and homes, emergency meetings, and fresh promises. Engineers and planners have long argued that keeping canals clear, completing pumping stations and enforcing planning laws matter more than new announcements.

With more heavy rain forecast during the monsoon, residents and businesses in low-lying parts of the city are asking whether this week's response will finally turn into sustained action, or fade once the water recedes.