Gadananathi originates from Agasthyamalai Biosphere Reserve. The towns Ambasamudram and Kallidaikurichi are located respectively on the left and right banks of Thamiraparani, after which the river meets the tributary Gadananathi River at Tiruppudaimaruthur. Before the Gadananathi's entry into the Thamirabarani, the Gadananathi is joined by the rivers Kallar, Karunaiyar and Veeranathi or Varahanathi which joins the river Gadananathi about 1.5 kilometres (0.9 mi) north-east of Kizha Ambur. The Gadananathi is fed by the Jambunathi and Ramanathi Rivers. The Gadananadhi has 6 anicuts and a reservoir of 9,970,000 cubic metres (8,080 acre·ft), and irrigates 38.87 square kilometres (15.01 sq mi) of wetlands.The anaicuts are Arasapattu anaicut, Alwarkurichi Thenkal anaicut, Manjapalli anaicut, Kakkavallur anaicut and Kangeyan anaicut. Gadananathi joins Tamariraparani at Tiruppudaimaruthur.Length of the river is 43 kilometres (27 mi).This river flows on many villages like Sambankulam, Sivasailam, Karuthapillaiyur, Poovankurichi, Kizha Ambur.
Gadana Nathi Reservoir is located at the foot of the western Ghats in Sivasailm village near Alwarkurichi which is one of the important tourist places of Tirunelveli district. Nowadays many tourists visit the dam and park. During the Courtallam season and Sabarimalai season more number of tourists visit this place.