Colombo’s wetlands float to top of flood prevention plan

Sri Lankan officials say the Baddagana wetland park, pictured here on May 9, 2018, is an early example of efforts to revive wetlands as floodwater retention areas in the capital. It is also popular among Colombo residents as a nature trail

By Amantha Perera

BADDAGANA (Thomson Reuters Foundation): On the surface, Sri Lanka’s capital Colombo looks like any other fast-growing South Asian city, with buildings stretching as far as the eye can see and skyscrapers rearing up along its coast.

But beneath the concrete, Colombo hides a wilder and wetter past.

Before it became the nerve centre of Sri Lankan politics and business, the city was a region dotted with wetlands and about 30 km (19 miles) of canals that helped absorb and disperse the massive rains that come in from the Indian Ocean.

In the past four decades, as the island adopted an aggressive development policy, its natural flood protection systems were built over, both by authorised and informal construction.

“Flash flooding is now a frequent thing,” said N.S. Wijayaratne, deputy general manager for wetlands at the Sri Lanka Land Reclamation and Development Corporation, a government body.

Experts say Colombo’s long-neglected wetlands could help alleviate worsening floods - and are set to make a comeback as a key pillar of a major flood prevention program.

Floods occurred in 2016 and 2017 during the monsoon, and smaller deluges have happened this year even before the onset of the monsoon, including in the past few days.

Weather patterns have changed drastically since the 1970s, with rains becoming shorter but more intense, as the planet has warmed. That shift has raised the risk of flooding in the Colombo Metropolitan Area, home to about a quarter of the island nation’s population of 21 million.

In November 2010, heavy rains brought the city to a standstill for a week, causing damage worth as much as $100 million, said World Bank consultant Nadeera Rajapakse Rubaroe.

Fast-shrinking wetlands

The $ 321-million Metro Colombo Urban Development Project - about two-thirds of it funded by the World Bank - aims to strengthen flood protection and urban planning.

Under the plan, what is left of the city’s wetlands are being revived to retain excess water.

Two such areas have been developed in the past three years near a lake close to the city’s parliament building in the eastern suburbs of Baddagana and Diyasaru Thalawathugoda.

Wijayaratne said at least 10 more locations around the lake can be developed into similar parkland.

There is no time to lose, say experts.

“In terms of flood protection and mitigation, the wetlands in Colombo play an indispensable role, and are at an absolutely critical threshold,” the World Bank’s Rubaroe said.

The city has been losing its wetlands at an alarming rate, she added.

Only about 17% of Colombo’s territory consists of wetlands that have not been encroached on, covering some 20 square km combined.

That surface area can retain close to 40% of the rainfall the area receives annually - the equivalent of 27,000 Olympic swimming pools of water.

If Colombo were to lose all its wetlands, flooding would shave off about 1% of its annual gross domestic product of some $53 billion, according to a World Bank study.

Projections by the bank and the government show that without the wetlands, major floods like the one in 2010 – which rose as high as 5 metres (16 ft) in some areas - could be 1.8 metres higher.

People’s parks

To be successful, experts say city communities must have a say in - and gain from - the rehabilitation of the wetlands.

“People have to feel part and parcel of the project - they need to experience that these projects make very real changes to their lives,” said Sameera Premarathana, manager at Baddagana Park, which offers a nature trail for the public.

The plan aims to develop the revivable wetlands around the parliament lake so that they offer recreational, tourist and other benefits, rather than leaving the land unused.

Premarathana said that when Baddagana Park first opened, local people showed little interest, and some even blamed the park for adding to floods in the area.

But after the incidence of flooding reduced to almost nothing, they started to grasp the importance of the park, its manager said.

Local residents have also earned money from running the car park and providing refreshments for visitors, who number some 7,000 a month.

The green space has become popular with school children on educational tours, with some joining the park conservation society.

Premarathana noted the full tourist potential of Colombo’s wetlands has been assessed at about 2 billion rupees ($ 12.7 million) per year.

Wijayaratne of the Land Reclamation and Development Corporation said the wetland restoration projects would incorporate leisure and educational activities while ensuring rainwater run-off can still flow freely through the area.

“The wellbeing of people in Colombo - especially in terms of flood protection - depends on its existing wetlands, and they need to be preserved and used wisely (and) sustainably as part and parcel of city development,” said Rubaroe.