How many main rivers are in Tamil Nadu?

There are 17 major river basins found in Tamil Nadu. These are: Palar, Varaha Nadhi, Ponnaiyar, Vellar, Paravanar, Cauvery, Agniyar, Pambar, Kottakaraiyar, Vaigai, Gundar, Vaippar, Kallar, Thamiraparani, Nambiar, Kodayar, PAP. Most of the rivers which drain Tamil Nadu originate from uplands Western Ghats and Eastern Ghats. Among the 17 basins Cauvery river basin is the wider one.