according to the ancient chronicle, "mahavamsa", kantale tank, also named "gangathala vapi", is credited as being built by aggabodhi the ii (606-618) and rehabilitated and developed by parakramabahu the great (1153-1186). 3,750 hectares. constructed for the irrigation of crops in this arid region, its source of water is the mahaweli river, the longest in the island, which flows out to the sea at trincomalee.