Periyar is the longest river in Kerala with a length of 244 Km, and has the largest discharge capacity. It is one of the few perennial rivers in this region, and it supplies drinking water to several large cities. It flows through industrial and commercial zones and generates a significant portion of Kerala’s electricity via the Idukki Dam.
It has thus been referred to as the “Lifeline of Kerala.”. 25% of Kerala’s industry is placed on its banks. Muthirapuzha, Mullayar, Cheruthoni, and Perinjankutti are the river’s primary tributaries.
Origin of Periyar River
Periyar originates in the Sivagiri hills of the Western Ghats. The river starts from the Idukki district’s southeastern boundary. Its source is located in the Periyar Tiger Reserve’s distant woods; Chokkampatti Mala, a peak on the southern border of the Tiger Reserve, is said to be the river’s origin, according to many sources.
According to specific non-governmental sources, the river is believed to have originated in the Sivagiri peaks of Sundaramala, Tamil Nadu. However, in its ruling on the Mullaperiyar case in 2014, the Supreme Court of India stated unequivocally that Tamil Nadu could not claim to be the original state of the river Periyar. A 350 square km jungle sits below the river’s origin. The forest’s highest reaches remain inaccessible and untouched.
The river has many major as well as minor tributaries. It eventually flows into the Periyar Lake. At an elevation of 850 metres, the Periyar Lake is 31 square kilometres in size and serves as a dam’s artificial reservoir. It is surrounded by a nature sanctuary and is situated between mountain peaks. Some water is redirected to the Vagai River for agriculture through a tunnel.
Map of Periyar River
It flows north from the ghats, eventually merging with a westward flowing tributary, Mulllayar, in Mullakudy. This river runs through various spots of the Periyar Tiger Reserve.
It forms a border between the Periyar area of the reserve in the east and the Sunderamala section in the west as it flows lower downstream. Further east, it forms a boundary with Moolavaigai and Thannikudy, and in the west, it creates a border with Ummikuppan, Mlappara, and Aruvoida. It empties into Periyar Lake. The Lake is formed by a Mulliyarpriyar dam erected at the confluence of the Periyar and Mulliyar rivers. Some water is diverted into the Nirar, a Tamil Nadu tributary. Some water is redirected through a tunnel and meets the Suruliar River, a tributary of the Vaigai River.
It flows downstream for 35 km from the lake to the north. It flows through Vandiperiyar, Elappar, and Aiyyappankoil to Idukki, a reservoir built by three dams: Idukki, Cheruthoni, and Kulamava. These dams help the state generate hydroelectricity. It flows north-westwards, down the mountains, and westwards to the coastal plains. It reaches Aluva when it splits into two sections: Marthanadavarma and Mangalpuzha. At Munambam, the Magalaphuza section meets the Chalakudy River before falling into the Lakshadweep Sea. The other area, the Marthanavarma, travels south, passing through the Udhyogamandal district before joining the Cochin backwater at Varapuzha.
The Periyar basin covers a total area of 5,398 square Km, with the majority of it located in central Kerala. It is situated between 9°15’30″N, 76°08’38″E and 10°21’00″N, 77°24’32″E.
The river drains parts of Kerala’s Idukki, Ernakulam, Thrissur districts and Tamil Nadu’s Coimbatore district. The basin is shaped like an inverted “L,” with the intersection the widest point.
6:1 is the length-to-width ratio. The majority of the streams flow through deep gorges with steep slopes in the basin’s highlands. The Periyar river flows west after emerging from the hills. Its basin encompasses the northern portion of the Ernakulam district. Stretching from the Periyar is an eighth-order stream with a well-developed tributary system. The basin’s average drainage density is 2.46 km/km2, with 15,773 first-order streams. The basin’s total stream length, including all orders, is 13,291 kilometres.
The river originates in the Western Ghats’ high hills, and the stream pattern and existence of structural valleys show the influence of tectonism. Forests cover almost 1,500 square kilometres (28 per cent) of the basin’s surface, while cardamom and mixed tree crop settlements cover 322 square kilometres and 2,176 square kilometres, respectively. The basin has a delicate biological ecosystem.
Approximately 80% of the total land in the high ranges is vulnerable to erosion and mass movements. The highest point in the basin is Anamudi, which stands at 2,695 metres and is the highest peak in South India.
Periyar is the longest river In the Indian state of Kerala. It is 244 km long. It originates in the Sivagiri hills of the Western Ghats. The river starts from the Idukki district’s southeastern boundary and runs through the Periyar Tiger Reserve. Some water is diverted into the Nirar, a Tamil Nadu tributary. Some water is redirected through a tunnel and meets the Suruliar River, a branch of the Vaigai River. It flows downstream for 35 km from the lake to the north. It flows through Vandiperiyar, Elappar, and Aiyyappankoil to Idukki. Then it flows down the mountains and westwards to the coastal plains. It reaches Aluva when it splits into two sections: Marthanadavarma and Mangalpuzha.