The Ponnaiyar is a river which originates in the southeastern slopes of the Chennakesava hills, north west of Nandidurg, in Karnataka
, at an altitude of 1000 m above
mean sea level. Alternately called the South Pennar or the Dakshina Pinakini, the river flows south and then east for 400 km (250 miles) through Karnataka
and Tamil Nadu
, emptying into the Bay of Bengal
Ponnaiyar river basin is sandwiched between Cauvery river basin in the west and south and Palar and Tondiar basins in the east and north. The Ponnaiyar River is an ephemeral stream and usually flows only for a few weeks during the rainy season.