Koyna Dam

Context:

Recently, the Comptroller and Auditor General (CAG) of India informed about the delay in the grant of Revised Administrative Approval to an incomplete hydroelectric project in Maharashtra. The delay resulted in the funds being blocked for more than six years.

About Koyna Dam:

• The Koyna dam is one of the largest dams in Maharashtra, India.
• It is a rubble-concrete dam constructed on the Koyna River that originates in Mahabaleshwar, a hill station in the Sahyadri ranges. It is located in Koynanagar, Satara district, in the Western ghats on the state highway between Chiplun and Karad.
• The construction of the dam began in 1956 and it was opened in 1964.
• It is the 2nd largest completed hydroelectric project in India.
• After the first world war, a hydroelectric project on the Koyna river was built by the Tata group.
• This dam has experienced various tremors in the past due to which some cracks had appeared on it but later on it has been strengthened and it is believed to be strong enough to tolerate any tectonic activities in the future.

What is the purpose behind its construction?

The main purpose of the dam is hydroelectricity with some irrigation in neighbouring areas. Today the Koyna Hydroelectric Project is the largest completed hydroelectric power plant in India having a total installed capacity of 1,920 MW. Due to its electricity generating potential Koyna river is considered as the ‘lifeline of Maharashtra’.

The spillway of the dam is located at the center. It has 6 radial gates. The dam plays a vital role in flood control in the monsoon season. The catchment area dams the Koyna river and forms the Shivsagar Lake which is approximately 50 km (31 mi) in length. It is one of the largest civil engineering projects commissioned after Indian independence. The Koya hydro-electric project is run by the Maharashtra State Electricity Board.

Key Facts about the Koyna River

• The Koyna River is a tributary of the Krishna River which originates in Mahabaleshwar, Satara district, Western Maharashtra.
• Unlike most of the other rivers in Maharashtra which flow East-West direction, the Koyna River flows in North-South direction.
• It covers an area of 2,036 km² in the Deccan terrain of the district of Satara in the state of Maharashtra.
  • With an elevation range of 550 – 1,460 m above mean sea level it typically represents a physiographic setup characterized by the Deccan plateau in the Western Ghats region.
• It is dammed by the Koyna Dam at Koynanagar forming the Shivsagar reservoir.
• Koyna River is supported by four tributaries. They are Kera, Wang, Morna and Mahind. Among these rivers Kera, Wang and Morna are dammed.

Krishna River System

• The Krishna is the second-largest east-flowing river of the Peninsula.
• Krishna river rises at Mahabaleshwar at an altitude of I336 m near the Jor village in the extreme north of district Satara, Maharashtra in the west, and meets the Bay of Bengal in Andhra Pradesh, on the east coast.
• Ecologically, this is one of the disastrous rivers in the world, in that it causes heavy soil erosion during the monsoon season.
• It is bounded by the Balaghat range on the north, by the Eastern Ghats on the south and the east, and by the Western Ghats on the west.
• The total length of the river from origin to its outfall into the Bay of Bengal is 1,400 km.
• The major part of the basin is covered with agricultural land accounting to 75.86% of the total area.
• The Krishna forms a large delta with a shoreline of about 120 km. 
• Almatti Dam, Srisailam Dam, Nagarjuna Sagar Dam, and Prakasham Barrage are some of the major dams constructed on the river.
• Because it is fed by seasonal monsoon rains, the river’s flow undergoes great fluctuation during the year, limiting its usefulness for irrigation.
• Satara, Karad, Sangli, Bagalkot. Srisailant, Amaravati, and Vijayawada are some of the important urban and tourist centers on the bank of the river.

Tributaries of Krishna River

• Right bank: Venna, Koyna, Panchganga, Dudhganga, Ghataprabha, Malaprabha and Tungabhadra are the major right-bank tributaries
• Left Bank: Bhima, Dindi, Peddavagu, Halia, Musi, Paleru, and Munneru are the major left-bank tributaries
• The Koyna is a small tributary but is known for Koyna Dam. This dam was perhaps the main cause of the devastating earthquake (6.4 on Richter scale) in 1967 that killed 150 people.
• The Bhima originates from the Matheron Hills and joins the Krishna near Raichur after for a distance of 861 km.
• The Tungabhadra is formed by the unification of the Tunga and the Bhadra originating from Gangamula in the Central Sahyadri. Its total length is 531 km.
• At Wazirabad, it receives its last important tributary, the Musi, on whose banks the city of Hyderabad is located.

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