Mahaweli Ganga | Longest River in Sri Lanka Mahaweli Ganga (Sinhala: මහවැලි ගඟ; Tamil: மகாவலி ஆறு) is the longest and largest river system in Sri Lanka (Arumugam, 1969). It is 335 km long and is longer than the combined length of any other two rivers in the country (Bandara, 1985; Vithanage, 1988). It conveys the largest volume of water in Sri Lanka amounting to one-seventh of the total runoff (Hewavisenthi, 1997). The headstreams of the river originate at altitudes of over 1,340 m above sea level and they form the main river before it flows through lowland plains and enters the Indian Ocean through Koddiyar Bay, south of Trincomalee (Bandara, 1985). The Dick Oya, Dambagastalawa Oya, Agra Oya and Nanu Oya originate in Marlborough estate, Ambawela hills, Horton Plains and Pidurutalagala respectively are the four streams that form the river (Arumugam, 1969). Dambagastalawa Oya flows into Agra Oya and these two meet Nanu Oya at Talawakelle to form Kotmale Oya (Arumugam, 1969). Dick Oya meet Kotmale Oya at Mahavilla (Arumugam, 1969)…
