Sri Lanka has 103 rivers & streams. Most of these rivers flow down from the mountainous regions. The longest river of Sri Lanka is “Mahaweli”. The “Mahaweli” river starts from Adam’s peak, and after traveling for 333 kilometers it makes its way to the Indian Ocean, at the Koddiyar Bay, located at Trincomalee. This is the only river which is perennial, and also crosses the dry zone. The perennial rivers in Sri Lanka are referred to as Ganga, which the other associated streams are addressed as Oya in the Sinhala language. In Tamil, Oya is referred to as Aru. Rivers have been developed at a larger scale, in order to facilitate power and irrigation. One such power project is “Victoria”, which is the largest power project of Asia, and is located on Mahaweli Ganga. There are other power projects as well which are located on Mahaweli, these are Rantambe, Kothmale, and Randenigala. Kala is an Oya, which originates from the reservoir of Kalawewa. This reservoir was built in the 5th century.
List of the rivers which are longer than 100 kilometers in descending order.