The Guduvaiyar River (sometimes pronounced Kuduvaiyar) flows through the Cuddalore and Villupuram districts of Tamil Nadu and Puducherry Union Territory.
It is a stream originates near Valavanur. It generally gets flooded during the monsoon season. Few bed dams exists in its course, one at Kizhur is the major one. This river joins Sankaraparani River near Chunnabar Bridge (NH-45A) at Ariyankuppam. It form border between Tamil Nadu and various enclaves of Puducherry.
References
Guduvaiyar River Wikipedia(Text) CC BY-SA