Colombo faces frequent flash flooding, causing inconvenience to the public during rains. 

Multiple stakeholders have identified several factors contributing to this issue, including the inability of the current drainage system to handle rainwater, increase in housing construction, and blocking of waterways and drainage systems. These floods typically last for less than an hour but are disruptive nonetheless. 

According to Colombo Municipal Council (CMC) Director Engineering R.A.T.P. Ranawaka, areas prone to flash flooding include the Armour Street Junction, Norris Canal, Maradana, and Col. T.G. Jayawardena Mawatha. 

He further emphasised the urgent need to improve the city’s drainage system in order to address these recurring issues effectively.

Drainage and staff issues

Ranawaka explained that the previous drainage system had been designed to manage 30 mm of rainwater per hour, which was inadequate given the current intensity of rainfall. Plans are in place to increase the system’s capacity to 102 mm per hour in order to handle higher volumes of water.

He further noted that the drainage network was to be enlarged in the future with the aid of the World Bank. “Critical areas have been prioritised for improvement, with proposals submitted under the CMC’s budget for immediate action,” he said. 

Although regular inspections and maintenance are conducted, Ranawaka noted that current staff levels were insufficient to handle the workload. Requests for additional staff have been submitted to meet the demands of managing the city’s drainage system.

Proposed projects and challenges

Ranawaka further disclosed that several proposals had been made to address specific flood-prone areas. 

In the Armour Street Junction and Norris Canal areas, around eight houses remain occupied despite resettlement programmes offering new housing. Therefore, they have decided to discuss providing high-value houses in Harbour Village to encourage resettlement. 

He noted that, although costly, this initiative was deemed necessary in order to construct a canal through Arnold Ratnayake Mawatha to Beira Lake, a segment that remains incomplete.

Construction at the Armour Street Junction is ongoing and is expected to take 3-4 months, although it faces delays due to the functions of the Sugathadasa Indoor Stadium. However, the Norris Canal project is expected to take at least nine months to complete, according to Ranawaka.

“Even for Col. T.G. Jayawardena Mawatha, proposals and tenders have been submitted for short-to-mid-term construction. Since a long-term solution would require a larger financial cost, it has not been finalised yet,” he said. 

In addition to these major projects, several minor issues have been identified in other areas, with proposals already submitted for their resolution. 

Ranawaka also expressed the need for financial aid to manage these projects. “World Bank aid is crucial for construction efforts, as these projects cannot be managed within our current budget. We are discussing with the World Bank to secure funding for new construction projects.”

Clean SL stance

Speaking to The Sunday Morning, Clean Sri Lanka project member Chaminda Jayasuriya noted their upcoming efforts to solve this issue in the future. He emphasised that Government organisations responsible for these matters would be advised to ensure effective solutions were implemented.

Jayasuriya highlighted that the Battaramulla marsh, which previously absorbed Colombo’s rainwater, had been severely impacted by unregulated housing construction. The loss of this marsh has eliminated a natural area for rainwater retention, worsening the flooding problem. 

He stated that while these issues had been identified along with remedial measures, the solutions outlined in their manifesto would take one to two years to be implemented fully. 

Jayasuriya further pointed out that although developing lakes under previous governments had helped provide rainwater with areas to flow and settle, this alone was not a sufficient solution.

He added that one sustainable solution would involve improving the drainage system and ensuring that rainwater was efficiently conducted to the sea, further noting that there would be collaboration between different Government organisations in order to achieve long-term success.