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| Last Updated:: 15/02/2022



Basin area, km2



Basin area in Kerala State, km2



Basin area in neighbouring State, km2


114 (Tamil Nadu )

District of Kerala in which basin are located


Idukki, Eranakulam

Origin of River


Sivagiri Elevation. m : 1830

Length of main stream, km



Main tributaries


Muthirapuzha Ar, Perinjankutty, Idamalayar, Mangalapuzha

Average annual rainfall, mm



Average annual streamflow, Mm3



Important rainguage stations marked on the map (with code numbers)


1.     Kodungallur (1)

2.     Perumbavur(2)

3.     Irumpupalam (3)

4.     Odakkali (4)

5.     Adimali (5)

6.     Perinjankutty (6)

7.     Devikulam (8)

8.     Kokkayar (7)

9.     Malayattur(9)

10.   Kumily (10)

11.   Chinnar(11)

Important discharge stations marked on the map (with code numbers)


1.     Marthandavarma (1)

2.     Panniar (2)

3.     Kalady (3)

4.     Bhuthathankettu (4)

5.     Idamalayar (5)

6.     Rajakad (6)

7.     Kallar (7)

Water requirement for wetland for three crops, Mm3



Water requirement for gardenland , Mm3



Water requirement for domestic use (2021 AD), Mm3



Water requirement for industrial use  (2021 AD), Mm



Existing major/medium irrigationproject (commissioned)


Periyar Valley

Major/medium irrigation projects under construction



Existing Hydroelectric project


Sengulam, Neriamangalam, Panniar, Idukki

Hydroelectric project Under Construction


Perinjankuztty, Neo Pallivasal, Lower Periyar, Idamalayar, Puyamkutty, Erattayar, Kallar

Navigable length of river, km




(Note: The Periyar River is the longest river in the state of Kerala, India, with a length of 244 km. The Periyar is known as The lifeline of Kerala; it is one of the few perennial rivers in the region and provides drinking water for several major towns. The Idukki Dam on the Periyar generates a significant proportion of Kerala's electrical power. It flows north through Periyar National Park into Periyar Lake, a 55 km² artificial reservoir created in 1895 by the construction of a dam across the river. Water is diverted from the lake into the Vaigai River in Tamil Nadu via a tunnel through the Western Ghats. From the lake, the river flows northwest through the village of Neeleswaram into Vembanad Lake and out to the Arabian Sea coast. Its largest tributaries are the Muthirapuzha River, the Mullayar River, the Cheruthoni River, the Perinjankutti River and the Edamala River. Through the Periyar Lake dam and tunnel, the river serves as the major water source for five drought-prone districts in the state of Tamil Nadu, including Theni, Madurai and Ramanathapuram.)