The river Tambaraparani (Now people call Thamirabarani as Thamirabarani) originates on the eastern slopes of Western Ghats in Tirunelveli district of Tamil Nadu. The origins of Tambarabarani and its tributaries are situated at the peaks called "Aduppukkal Mottai", "Agathimalai" and "Cherumunji Mottai", at an altitude of about +2,000m from the mean sea level.

The Tambarabarani basin is situated between latitudes 8.21' N and 9.13' N and between longitudes 77.10' E. Vanatheertham waterfalls (40 m deep) is located close to the origin of the main river. This river joins the Papanasam Reservoir at its 16th km. The river has 4 tributaries called Peyar, Ullar, Karaiar and Pambar upstream of Papanasam Reservoir.

The River Servalar, a main tributary of Tambarabarani joins the main river at a running distance of 22-km. Another tributary Manimuthar originates in the Agathimalai Ranges at an altitude of about +2,000 m above mean sea level. It joins the Tambarabarani at its 36th km near Ambasamudram. Gadana River joins at its 43rd km on the left.

The Tributaries The Gadana River has two tributaries namely Jambunadhi and Ramanadhi. There are six anicuts across Gadana and 7 across Ramanadhi. There is a reservoir across Gadana with a storage capacity of 352 m.cft. The Gadana River irrigates 3,887.09 hectares of wetlands. There is a reservoir of 152 m.cft. capacity across Ramanadhi. This river irrigates 2,023.47 hectares of wetlands.

Pachaiyar, the next tributary joins Tambarabarani at its 61st km near Gopalasamudram. This tributary originates from the Kalakkadu reserve forests at an altitude of about 1,300 m above mean sea level. It has 12 anicuts across and irrigates 6,151.35 hectares of wet and dry lands. Chittar, a tributary of Tambarabarani joins it at its 73rd km, running almost parallel to Tambarabarani till its confluence.

The river Tambarabarani, after the confluence of Chittar, travels another 23-km where it has the Srivaikundam anicut. From thereon, it runs eastwards for 30-km and enters the Gulf of Mannar near Palayakayal.