Arasalar River is a branch river of Cauvery which split into 5 different rivers when it enters into Thanjavur district from Tiruchirapalli. At a village named Pullambadi the River Cauvery has been stopped by Lower Anaicut or the Grand Anaicut (Anaicut in Tamil means Dam in English) and from Thiruvaiyaru (the name of the town refers separation of 5 rivers) the Arasalar River separates from River Cauvery. This river enters into the Sea of Bay of Bengal at Karaikal.