Colombo's wetlands: how the 'lungs' of Sri Lanka's capital are being restored

The wetlands of Colombo – described by one expert as "the lungs and kidneys" of Sri Lanka's capital but long since neglected and polluted – are being restored, helping to manage floods and boost biodiversity.

Once "used as trash dumps", the wetlands have been "remade as flood-buffering parks", said the Bulletin of the Atomic Scientists , but despite recent progress, the ecosystems continue to face threats from urban development.

Troubled history

Sri Lanka's ancient kingdoms "thrived in a well-managed wetland system", where the marshes were used for transport and to grow food, said the BBC . But in the British colonial period from the late 18th century, the wetlands were drained to build housing and businesses.

The situation deteriorated further in the decades following independence in 1948. Some wetlands were claimed for housing and used to dump "everything from food waste to solid waste", chemicals and sewage .

It was only after a series of calamitous floods in 2010, which affected nearly 700,000 people and submerged the country's parliament, that government policy began to shift.

Colombo is located in a river basin, so the city is "naturally prone to floods", but wetlands "act as a flood buffer", with 40% of floodwater draining into wetland areas. These are not their only benefits: they also "sink carbon, purify the air and control temperatures".

A cautionary tale

In 2016, the government introduced a new management strategy for the ecosystems, which sets out to include wetlands in urban planning, prevent further wetland loss, restore the areas and inspire communities to play a part in their conservation.

Colombo now has four wetland parks and a number of other recreational spaces linked by wetlands. So although the city's recent history is a "cautionary tale" of what can happen when authorities are "prioritising urban growth" over "life-saving natural resources", the wetlands "could soon become the area's greatest strength".

Flooding in Sri Lanka is "getting worse", said the Bulletin, and climate change, coastal erosion and urbanisation are "magnifying the impact of floods ". If Colombo can "harness" its nearly 5,000 acres of wetlands to "limit destruction wrought by floods", the city's victory would "provide valuable lessons for cities around the world".

For now, the sight of "couples taking daily sunset walks through mangrove forests and schoolchildren's delighted shrieks when a monitor lizard pulls itself out of the water are a sign" that wetlands are becoming "a fixture of Colombo's psyche".