Sri Lanka, Nov. 11 -- Only around 20 kilometres of Colombo's 469-kilometre canal and drainage network have been upgraded since 2014 to cope with heavy rainfall, Cabinet Spokesman and Minister Dr. Nalinda Jayatissa said.

Speaking at the weekly Cabinet decisions press briefing, the Minister said the recent flooding in several parts of Colombo was mainly caused by exceptionally heavy rainfall, with between 129mm and 150mm of rain falling within one to two hours.

The Minister explained that Colombo's existing drainage network was designed to accommodate rainfall of around 30mm per hour.

Of the city's total 469-kilometre canal and drainage network, only around 20 kilometres have been upgraded since 2014 to withstand rainfall intensities of...