Although Colombo is one of the most populous cities in Sri Lanka, there are a number of ecologically important sites in and around the commercial capital. Especially in such a densely populated city of Colombo, it is noteworthy that there are several ecological zones designated as Ramsar Wetlands.
It was in 1992 that Sri Lanka signed the Ramsar Convention. It currently has 170 member countries.
Until now, only ecologically important wetlands have been designated as Ramsar wetlands. Among the wetlands in Sri Lanka are, Bundala and the Maadhu Ganga. In addition to them, the city of Colombo has been declared as a wetland city, considering the environmental importance of the wetlands around Colombo.
This is the first time the Ramsar Convention has implemented the wetland city concept. Accordingly, 18 cities in six countries have been declared as wetland cities. Apart from Colombo, six cities in China, four cities each in France and Korea, one city each in Hungary, Tunisia and Madagascar have been declared as urban wetlands. Among them, Colombo was the first capital to become a Ramsar wetland in the world.
According to environmentalists, the wetlands in Colombo consist of seven major vegetation areas including marshy plants, shrubs, grasslands, rivers and mangrove forests.
Two-hundred-and-nine species of aquatic animals are recorded in this region. It is important to note that 17 of these are endemic species, while another 26 species have been identified to be endangered nationally.
These include dragonflies, two species of butterflies, four species of snails, two species of freshwater fish, and four species of mammals. About 252 plant species are recorded in the Colombo wetlands including nine endemic plant species. Most of these wetland species are endangered by human activities.
Many wetlands such as the Thalawathugoda Diyasaru Park, Beddagana Wetland Park, Thalangama Lake Environmental Protection Zone, Bellanwila - Attidiya Sanctuary are located in the vicinity of Colombo city.
These locations go a long way in reducing the risk of floods in the city, protecting the environment as well as enhancing biodiversity.
Diyasaru Park
Diyasaru Park, (formerly known as Thalawathugoda Wetland Park or Thalawathugoda Biodiversity Study Park), is a 60-acre urban wetland park located in Thalawathugoda of Sri Jayewardanepura. It comprises a range of wetland habitats such as marshes, flooded woodlands, lakes, and ponds.
Originally in the 1980s, the area was a paddy field. Part of the land was used to build the Parliament Lake in the late 1970s, while the other part was used to deposit dredge material. Gradually, the land became heavily covered with invasive species and transformed to a wetland. During the flood in 2010, the Government began to reconstruct and modify the area as a wetland. The land was divided into several small islands and artificial canals were made.
Currently, park premises serve as a flood detention area by absorbing flood water during heavy storms and reducing inundation of the Parliament area.
The park offers many Eco touristic activities as well as recreational and leisure activities. It is divided into several sections such as a bird watching tower, bird hide, butterfly garden, organic agriculture area, open study area, green buildings, boardwalks, plant nursery, ecology laboratory, a herbarium, children’s pond, rush and reed pond and audio video room.
Diyasaru Park is home for more than 250 species of animals across all ranges including molluscs, arthropods and vertebrates.
Many rare and migrant birds, butterflies, dragonflies, mammals, many types of fishe including endemics, amphibians, and reptiles are abundant. Numerically, there are about more than 80 species of wetland birds including 50 species of migratory birds, 15 species of fish including three endemics, 40 species of butterflies, 28 species of dragonflies, 28 species of reptiles and seven species of mammals.
Beddagana Wetland Park
Beddagana Wetland Park is another highest biodiversity hotspot in Colombo.
This is a land belonging to the Sri Jayewardenepura Sanctuary which was opened in 1985. It was developed as an urban wetland park in 2006 and opened to the public.
It covers an area of 18 hectares. Beddagana Wetland Park is a beautiful place with swamps, natural ponds, waterways and scrubland. Bird watching towers and bird watching sites too have been set up here. Many migratory birds also flock to Beddagana from May to October every year.
Talangama Wetlands
Located just a few kilometres away from Colombo, the Thalangama wetlands are an environmental protection area and biodiversity hotspot in a rapidly urbanising environment.
The wetland is home to two man-built reservoirs (tanks) namely Thalangama Tank and Averihena Tank, both just 300 metres apart.
The Thalangama Tank spanning about 28 acres (11 ha) is comparatively larger and much older than the recently constructed Averihena tank (8 acres or 3.2 ha) and serves today mainly as a source of irrigation water supply for about 100 acres (40 ha); maintained by the Department of Irrigation.
The tanks are also important for flood water retention and have a high scenic and aesthetic value, which attracts many visitors.
The area is particularly rich in biodiversity with a remarkable Avifauna (bird population), which is well-known among local and foreign wildlife enthusiasts.
The wetland is also in high demand for educational purposes, fishing, biking, bathing and the collection of flowers and water lily leaves for ceremonial purposes.
Both tanks thus constitute multi-purpose urban freshwater resources with different stakeholder interests that govern its use and management.
The three graphics in this section show how the local residents value the lake and paddy fields and what they see as major problems based on a survey of 145 local residents.
Due to rapid urbanisation of the area, the land value has increased significantly leading to excessive land filling and the reclamation of paddy lands for housing, despite the fact that this activity is illegal.
This is accompanied by indiscriminate (over-night) garbage and construction waste disposal, next to the volume of litter and bottles left by the daily lake visitors.
Given the overall garbage challenges in the country, authorities are struggling with a way to address these issues.
The 449.2 hectares of wetland centred around the Diyawanna Oya around the Kotte Parliament was declared a sanctuary on January, 9, 1985. Due to later developments, only a small area of land remains at present.
The area around Diyawanna Oya and Parliament is currently left as a sanctuary. A large portion of the wetland to the left of Parliament has been cleared to make way for the Diyatha Uyana Urban Park.