Mahaweli River

The Mahaweli River (Sinhala: මහවැලි ගඟ, literally "Great Sandy River"; Tamil: மகாவலி ஆறு [mahawali gangai]),^[2] is a 335-kilometre-long (208-mile) river, ranking as the longest river in Sri Lanka. It has a drainage basin of 10,448 km² (4,034 sq mi), the largest in the country, which covers almost one-fifth of the total area of the island.^[3] The Mahaweli Ganga starts at Polwathura (in the Mahawila area), a remote village of Nuwara Eliya District in bank Nawalapitiya of Kandy District by further joining of Hatton Oya and Kotmale Oya. The river reaches the Bay of Bengal on the southwestern side of Trincomalee Bay. The bay includes the first of a number of submarine canyons, making Trincomalee one of the finest natural deep-sea harbours in the world.^[4]

Native name

• මහවැලි ගඟ (Sinhala)
• மகாவலி ஆறு (Tamil)

CountrySri Lanka

locationHorton Plains National Park^[1]

MouthBay of Bengal

Quick facts Native name, Location ...

Mahaweli River
Mahaweli River flowing through Thennakumbura
Native name	මහවැලි ගඟ (Sinhala) மகாவலி ஆறு (Tamil)
Location
Country	Sri Lanka
Physical characteristics
Source
• location	Horton Plains National Park[1]
Mouth	Bay of Bengal
• location	Trincomalee Bay
• coordinates	08°27′34″N 81°13′46″E
Length	335 km (208 mi)
Basin size	10,448 km2
Basin features
Tributaries
• left	Amban Ganga
• right	Kotmale Oya

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As part of Mahaweli Development programme, the river and its tributaries are dammed at several locations to allow irrigation in the dry zone, with almost 1,000 km² (390 sq mi) of land irrigated.^[5] The production of hydroelectricity from six dams in the Mahaweli system supplies more than 40% of Sri Lanka's electricity needs. One of the many sources of the river is the Kotmale Oya.^[6]

There is a misconception in Sri Lanka that the Mahaweli starts at Sri Pada Mountain. The Mahaweli gets its source waters from Horton Plains in Kirigalpoththa and the Thotupola mountain range.