August 2016


The great mahaweli
August 2016




Mahaweli river basin is spread across a fifth of the total land area of the island (© Prasanna Samarawickrama)

The springs of Agra are the preliminary points that the seeping waters begin to drip to the lower-land, the head waters of the highest Great Open Plains is where the journey of the longest river of Sri Lanka begins.


Words Nethu Wickramasinghe | Photography L. J. Mendis Wickramasinghe


The Mahaweli river basin astonishes with its sheer size and unimaginable amount of vein like tributaries that network across a fifth of the island. It is no wonder therefore that the river has been considered Sri Lanka's lifeblood for thousands of years. The river winds its way through cliffs, plains and valleys cascading across all three major climatic zones, nourishing the driest parts of the island while simultaneously connecting to the wettest parts of the central hills before ending its journey at the bay of Trincomalee. In his descriptions of the island of Taprobane, Ptolemy had referred to a river that drains from Trincomalee as ‘the Ganges'. Sir James Emerson Tennent in his book from the mid-19th century states that the river may have acquired its name ‘Maha-weliya' (meaning ‘the great sandy river') due to the sandy texture of the river, evident by the presence of vast expanses of sand deposits on the valley at many sites. Historical evidence revealed that regionally the river was known by numerous names, for instance in Kotmale it was known as Barakasnadi, in Kandy it was called Maha-ganga and Maha-waluka-nadi, in Mahiyangana as Ma-wali-ganga, in Polonnaruwa as Kalinga ganga, and later on was also reffered to as Rohini. Of the seven major tributaries: Kotmala oya, Hatton oya, Hulu ganga, Loggal oya, Uma oya, Badulu oya, and Amban ganga, that join the main river, the Kotmala-oya streams in from Ulapane located in the Central Province.


From there it takes rapid turns across the hills and cascades in the form of waterfalls from several different points. Some of its famous waterfalls, observed in the hilly terrains are Devon falls, St. Clairs and the Ramboda falls. It trails next, sinuously shaped all around the main city of Kandy. First heading northward passing Gampola then heading towards Peradeniya. The river gushes over the rugged terrain of granite rocks at Gannoruwa, which is also noted to be the narrowest point of the river. The path next takes a brisk turn southward at Katugasthota, a historically important city whose name was derived from "Kadu-gath-thota" which means ‘port where swords were traded'. Since ancient times, Sri Lanka was famous for its steel weaponry and it is evident that the Mahaweli river was used as an essential means of transportation during this time. Subsequently the river heads towards Polgolla, where it runs into a dam. Its volume gradually picks up and heads past the Victoria-Randenigala-Rantambe reservoirs heading North east along a flat terrain towards the sea at Trincomalee. The river then encounters the Manampitiya bridge, which is the second longest bridge in the island. Having been built in the early 20th century it was the only one of its kind that carried both a railway and highway track.


The Mahaweli river has on its journey created a diverse number of ecological zones. From river channels, to islets, to forests and reverine marshes, to villus, to seasonally flooded grasslands, and swamp forests, all teem with a huge diversity of wildlife. Over the years the massive waters that had flushed to the sea had created a geographical barrier separating the Knuckles massif from the Central hills, which had once been an unseperated single entity. This is evident from the very similar species (specifically reptiles and amphibians) that live on both mountain tops. As such Cophotis ceylanica of the Central hills and C. dumbara of the Knuckles massif are quite distinct species yet share similar characteristics.


Being the longest river in Sri Lanka, the Mahaweli also comes in to contact with a large number of protected areas such as; Horton Plains national park, Victoria-Randenigala-Rantambe sanctuary, Maduru-oya national park, Wasgamuwa national park, Flood Plain national park, and Somawathiya national park. The last four were designated under the Mahaweli Development project.


The river is also home to a variety of unique aquatic life that can only be found in the streams of the Mahaweli river basin, and nowhere else. These include the endangered Labeo fisheri, which may even be near extinction, and the endemic barbs Puntius martenstyni and P. srilankensis. The works of art created on the sand deposits by the wild that walked hither and tither are amazing to look at. Striking butterflies flock in to savour the minerals of the sandy banks, while at times even the rare five bar swordtail butterflies become a common sight. These vast sand beds are ideal for recreation that offers a once in a lifetime experience. The breadth and the beauty of this gigantic river system is awe-inspiring as it winds down a long journey and ends at the sea.


Here, the river becomes the beating heart of life to the tiniest of fresh water crustaceans located in the highlands, to large mammals all across Sri Lanka like elephants, sloth bears and leopards and when the river waters mix with the salt of the ocean even the largest animal of them all, the majestic blue whale

 

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    Puna falls, cascading from the Kotmala oya one of the main tributaries of the Mahaweli river

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    Kirigalpotta range as seen from Horton Plains, preliminary source of the Mahaweli river (© Dushantha Wasala)

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    Bio-geographical evidence of (A) Cophotis ceylanica of the Central hills and (B) Cophotis dumbara, which have evolved separated from one another due to the Mahaweli river that has acted as a barrier for a prolonged period of time.

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    An expansive sand bed created by the gushing waters of Mahaweli

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    Calm waters of the Mahaweli river between Randenigala and Mahiyangana

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    The diversity of aquatic life of the river is so vast that even today many species roam the shallow waters that are unknown to science such as this stone sucker species.

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    The Mahaweli river curving its way at Thalatuoya

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    Five bar swordtail butterfly feasting on minerals on the sand beds of Mahaweli

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