Ponnaiyar River flows across the boundary between
Cuddalore and Villupuram Taluks (also called
as Taluka) and joins with the Bay of Bengal about 3 miles north of
The Gadilam River, which starts in eastern part of Tirukkoyilur Taluk of Villupuram district flows through Cuddalore Taluk. In Cuddalore Taluk, Malattar joins it on the right and then it flows into the Bay of Bengal at a point, just north of Cuddalore.
The Ponnaiyar and the Gadilam are connected by a river course called "the Malattar", which serves to carry the surplus water from Ponnaiyar to Gadilam.