October 2014


Diyawanna Oya: A Suburban Wetland to Savour
October 2014




“Green swathes and waterways”

Words Richard Boyle Photography Indika De Silva and Damith Wickramasinghe


During the 15th Century the Kingdom of Kotte flourished in Sri Jayawardenepura Kotte, now the location of the Island's parliament and the administrative capital, just a short drive from the centre of Colombo.The ancient capital of Kotte was a jala durgha (fortress surrounded by water), triangular in shape, with the stream-formed ‘lakes' and associated marshes known as the Diyawanna Oya and Kolannawa Oya forming two sides, and a moat the third.

Apart from the Kotte fortress, the crocodile infested waters edged by extensive mudflats, the nearby swampy terrain and thick wetland jungle-not to mention the perils of the "Pass of Mosquitoes"-provided near-perfect security. Thus the varied wetland eco-system of the area, dominated by the Diyawanna Oya, has played a fundamental role in Kotte's remarkable history.

The wetland environmental value attached to the Diyawanna Oya is incalculable
Over the centuries much change has occurred in the extent and shape of the Diyawanna Oya wetland, the most recent being when part of the lake was dredged to create the five-hectare island of Duwa to house the New Parliament Complex, opened in 1982. The shape of the lake today is long and thin, with protrusions and depressions, the most predominant being the artificial island south of centre with its causeway to the shore.


The wetland environmental value attached to the Diyawanna Oya is incalculable. Most of the area surrounding the parliament complex and elsewhere consists of low-lying freshwater marshland. Habitats as diverse as lily-filled ponds, outcrops of shrub land, grasslands lightly flooded during the monsoon, and the grey mudflats of old, can be found here, particularly in the Beddagana urban wetland.


The Diyawanna Oya is well-populated with aquatic birds, but Beddagana is considered the best spot for viewing them close to Colombo (together with the nearby Thalangama Wewa). The Beddagana wetland was gazetted as a Wildlife Sanctuary by the Department of Wildlife Conservation in 1984 due to its bird life. And, as I write, a Beddagana Biodiversity Park is being created that contains a bird sanctuary.


However, to begin at the beginning of the most probable visit to the Diyawanna Oya, you will be travelling from Colombo on the Parliament Road when the lake's nearby western end becomes visible on the left behind a tree-studded, shaded and cool strip of land of comparatively recent creation, which is the Diyawanna Oya Park. It is evidence of the enhancement to the greening of the area, a good place-encouraged by friendly seating-to get an impression of this part of the lake. At the tip, apartment blocks overlook the calm waters, yet the vegetation on the further side is dense. It's where the city of Colombo ends, and the stunning suburban wetlands of the Diyawanna Oya begin.


Beyond, over the blue-arched bridge that crosses the lake, is the Diyatha Uyana, the market and restaurant hub of the Diyawanna Oya in its function as an increasingly important recreational site in the greater Colombo area.On the opposite shore is a new addition, a vintage train engine with a complement of assorted wagons.


But the natural beauty lies near the Diyatha Uyana edge of the lake, where the wetland is dominated by a small tree with pretty white flowers, the South Indian Plum (Syzygium caryophyllatum), known in Sinhala as dan. It is a threatened species according to the IUCN (International Union for Conservation of Nature), yet found in abundance here. It stands in water surrounded by myriad water plants such as reeds, ferns and lilies, an excellent example of aquatic flora diversity.


To proceed to the parliament area, take the Japan-Sri Lanka Friendship Road to view the architectural wonder within the Diyawanna Oya. But to experience the best of the wetlands at Beddagana, on your return journey turn left at the blue-arched bridge down Nippon Mawatha and you will enter a more rustic area, with the tree-shrouded Diyawanna Oya on one side and the extra archaeological benefit of glimpses of the fortress rampart, made from brown laterite or kabook, on the other. Farther on, the lake gives way to accessible rush and reed studded wetlands, a bird's and birder's paradise.


A measure of Sri Lanka's extraordinary biodiversity is that the total number of bird species recorded in the Island is 492, of which 219 are breeding residents. The rest are migrants that settle in Sri Lanka from September to April to escape the winter of their northern breeding grounds. Thirty-four resident species use Beddagana as a breeding site, and 18 migrant species have been identified in the area.


Resident species to be seen at Diyawanna Oya include the spectacular Spot-billed Pelican (Pelecanus Philippenses), with the characteristic long bill and large throat pouch. Of note is that Colombo's pelicans are descendants of members of the species released by the National Zoological Gardens at Dehiwela in the 1970s.


The Indian Pond Heron (Ardeola grayii) has a streaked olive and brown plumage and has the habit of standing very still for long periods while hunting fish. The Purple Heron (Ardea purpurea) is also an inhabitant of the Diyawanna Oya.


The large White-throated Kingfisher (Halcyon smyrnensis) has the species' typical short-tail and large-head profile, with a bright blue back, wings and tail. The Common Kingfisher (Alcedo atthis), on the other hand, is a smaller species with blue upperparts, orange underparts and a long bill.


The Diyawanna Oya is home to both the Little Cormorant (Phalacrocorax niger) and the slightly larger Indian Cormorant (Phalacrocorax fuscicollis). Visitors who take a boat ride may, if they are lucky, witness a cormorant making its headlong dive into the water.


In addition, you may see the White-breasted Waterhen (Amaurornis phoenicurus), which makes loud and repetitive croaking calls after rain; the small, squat Little Grebe (Tachybaptus ruficollis); or the gregarious Lesser Whistling Duck (Dendrocygna javanica).


To see migrants, keep an eye out for the Blue-tailed Bee-eater (Merops philippinus), a richly coloured, slender bird; the Brown Shrike (Lanius cristatus), which has a distinctive black ‘bandit-mask'; the Barn Swallow (Hirundo rustica), with blue upperparts and a long, deeply forked tail; and the beautiful Indian Pitta (Pitta brachyura), a small stubby-tailed bird with green upperparts, buff underparts and a bright red belly.


Several environmentalists I know assert that there are a few mugger or marsh crocodiles (Crocodylus palustris) that frequent these waters and emerge once in a while.


Where reptiles are concerned you are more likely to encounter the smaller but still awesome-looking water monitor (Varanus salvator), better-known as kabaragoya in Sinhala. You may well witness them in the water-they are excellent swimmers, using the raised fin on their tails as a rudder-or lumbering in dinosaur fashion on the water's edge, their long forked tongues flicking in and out.


The Beddagana Biodiversity Park is currently being created to preserve the wealth of the wetlands for the benefit of future generations. The 18-hectare park, which abuts the Diyawanna Oya, will include an orientation centre, bird watching hides and decks, nature trails, boardwalks, and an introduced wetland forest patch.


In general, much has been achieved in preserving the Diyawanna Oya while the Beddagana Park, together with a second project, the Kotte Rampart Park, will in particular address the problems of proposed infilling and development that causes flooding, unauthorised encroachment, and other pressures. Thus the Diyawanna Oya will continue to be a suburban wetland to savour.

 

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    Map of the Kingdom of Kotte showing the environmental aspects of waterways and marshland

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    The South Indian Plum: a tree that dominates part of the wetland

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    The delicate flower of the South Indian Plum

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    A lily of the genus Nymphaea about to bloom

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    The calm waters of the Diyawanna Oya at dusk

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    A vintage train, yet to be refurbished, is a new arrival

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    Environmental asset: A typical well maintained embankment

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    The tree-embowered road to Parliament

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    Newly-planted trees: the green future

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    A wetland patch encircled by a jogging track

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    Black-crowned Night Heron (Nycticorax nycticorax)

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    Little Egret (Egretta garzetta)

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    Diyawanna Oya marshland

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    Casting shadows: the Indian Sugar Plum tree is endangered

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