Which is the longest river of Sri Lanka, with the largest river basin in the country?

The Mahaweli Ganga (Mahaweli river) is the longest river in Sri Lanka, about 335 km long. Its basin is the largest in the country, covering roughly one-sixth of the island's area. "Ganga" here simply means "river" in Sinhala.

Course of the Mahaweli:

• It rises in the central highlands of Sri Lanka, in the area around Horton Plains and the Adam's Peak (Sri Pada) range, where several streams join to form it.
• It flows north and then north-east through the hill country, passing near the city of Kandy, the last royal capital of Sri Lanka and home of the Temple of the Tooth Relic (Sri Dalada Maligawa).
• The Royal Botanical Gardens at Peradeniya lie in a bend of the river near Kandy.
• It finally empties into the Bay of Bengal at Koddiyar Bay, near Trincomalee, on the east coast.

Importance:

• The Accelerated Mahaweli Development Programme, begun in the late 1970s, is the largest multipurpose development project in Sri Lanka's history.
• It includes major dams and reservoirs such as Victoria, Kotmale, Randenigala and Rantembe, which generate a large share of the country's hydroelectric power.
• Water diverted from the Mahaweli irrigates large areas of the dry zone in the north-central and eastern parts of the island, helping rice cultivation.

Other rivers of Sri Lanka:

• Sri Lanka's rivers flow outward from the central highlands in a radial pattern.
• The Kelani Ganga flows into the sea at Colombo and supplies much of the capital's water.
• The Kalu Ganga flows to the west coast at Kalutara and is known for floods; it has a high discharge due to heavy rainfall.
• The Aruvi Aru (Malvathu Oya) is the second longest river, flowing to the north-west coast near Mannar; the ancient capital Anuradhapura lies near it.

Why not the other options?

• ✗The Kelani Ganga is important but much shorter, ending at Colombo.
• ✗The Kalu Ganga is shorter and lies in the wet south-west.
• ✗The Aruvi Aru is the second longest river.