The Thamirabarani River originates from the peak of the Pothigai hills on the eastern slopes of the Western Ghats at an elevation of above sea-level. The river is joined by its headwater tributaries Peyar, Ullar, Pambar before it flows into the Karaiyar Dam reservoir, where it meets Karaiyar. The river forms the Paanatheertham waterfalls, high, as it enters the Kariyar reservoir. Servalar joins the Thamirabarani before it enters into the Papanasam lower reservoir, which was built for the Papanasam Hydroelectric station. The river descends down the mountains near Papanasam, where it forms the Kalyanatheertham falls and Agasthiar falls.