Colombo under water: Is drainage system ready for challenges of changing climate?
By Eng. Thushara Dissanayake The floods that inundated several parts of Colombo on November 06, 2026 have once again exposed the vulnerability of Sri Lanka’s commercial capital to heavy rainfall. This incident highlights the urgent need for a comprehensive assessment of the capacity and adequacy of the existing urban drainage system, particularly its ability to […]
On November 6, 2026, Colombo was submerged by heavy rainfall, exposing the city's vulnerability to extreme weather. The floods left several areas inoperable, prompting questions about the drainage system's capacity and preparedness in changing climate conditions. The rain recorded was 129 mm within a short period, far exceeding the system's original design for 30 mm per hour. Some claim the system has been strengthened, while others argue it's inadequate.
The root cause of urban flooding is often debris and solid waste in drainage channels, supported by recent discussions. However, inadequate infrastructure, poor maintenance, and unplanned urban development also play significant roles. Improper waste disposal and the removal of natural drainage systems contribute to increased flood vulnerability.
Urban development without considering natural drainage systems exacerbates the problem. The Colombo region has lost 40% of its wetlands due to urbanisation, leading to increased surface runoff. The city's drainage system, managed by several agencies, requires integrated planning and maintenance. Citizens can help by adopting flood mitigation measures like rooftop rainwater harvesting and green roofs.
Written by urgent.news from The Island Sri Lanka's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
