River, central Kerala state, southwestern India.
It is 140 mi (225 km) long and rises in the Western Ghats range near the border with Tamil Nadu state. It flows north to Periyar Lake, an artificial reservoir created by damming the river. A tunnel carries water from the lake eastward through the mountains to the Vaigai River, where it is used for irrigation. From the lake it flows northwest and empties into the Arabian Sea.