Situated in the picturesque state of Kerala, the Idukki Dam stands as a towering testament to human engineering and innovation. It ranks as one of Asia's tallest arch dams and is globally recognized as one of the 22 tallest arch dams worldwide, taking the third spot in India's list of highest dams. Its rich history and geographical significance make it a jewel in Kerala's crown.

Geography and Historical Roots

The Periyar River, originating from the Sivagiri Hills of the Western Ghats in the southeast of Idukki, gracefully cuts across the district, meandering in a northwesterly direction towards Ernakulam district. A pivotal point in the river's journey is the confluence of the Periyar and Mullayar rivers, where the Mullaperiyar Dam stands tall, creating the Periyar Thekkady Lake and Reservoir.

Intriguingly, some of the water from the Periyar Thekkady lake and reservoir is diverted eastwards to Tamil Nadu via a tunnel. After generating power, it flows into the Suruliar River, leading to an inter-basin transfer of water. Downstream of the Mullaperiyar Dam, the Periyar continues its northwestward journey, passing through Vandiperiyar, Elappara, and Ayyappancoil before reaching the Idukki reservoir. This reservoir is formed by the trio of dams: Idukki, Cheruthoni, and Kulamavu, built across the Periyar River in the famous Idukki gorge, nestled between the Kuravan and Kurathi hills.

Further downstream, the Periyar River flows northward in parallel to the western edge of the Idukki plateau. Along the way, it joins forces with its major tributaries, such as the Perinjakutty, Idamalayar, and Muthirapuzha, shaping its course as it enters Ernakulam district at Neriamangalam. This dynamic river eventually joins the Bhoothathankettu barrage.

Every phase of the Idukki project, from its conception to commissioning, has been marked by remarkable events and achievements.

The Idukki Dam: An Engineering Marvel

The Idukki Dam, a double curvature concrete Arch Dam, stretches 555 feet high, ingeniously connecting the 839-meter-high Kuravan Mala and the 925-meter-high Kurathi Mala. This architectural wonder is complemented by two other dams at Cheruthoni and Kulamavu. Together, these dams, along with two saddle dams, have created a vast artificial lake spanning 60 square kilometers.

The stored water from this lake serves as the source of power generation at the underground power station, strategically located 750 meters below the Nadukani Hills in Moolamattom. The power station operates through penstocks, and the tail race water, after electricity generation, flows into the Kudayathur River via a tunnel and open channel.

A Historical Journey

The history of the Idukki Dam dates back to an era when mechanized construction systems were not yet in existence. It was a vision shared by a group of engineers and the hard work of thousands of laborers that transformed this project into a marvel of construction.

The idea of constructing a dam for power generation was initially conceived in 1919 in a report by Italian engineer Jacob, which was, unfortunately, rejected. It wasn't until 1922 when Shri Chemban Karuvellayan Kolumban, the leader of the 'Oorali' tribe, guided W.J. John and AC Thomas Edattu, who were on a hunting trip to the present Arch Dam area. Impressed by the Kuravan and Kurathi Hills legend, they recognized the potential for an Arch Dam at the site.

In 1932, W.J. John submitted a report to the Government of Travancore regarding the feasibility of constructing a dam at Idukki for power generation. The idea gained momentum when assembly member Shri K.A. Narayana Pillai raised the Idukki project's profile in 1935.

Italian engineers Angelo Omedayo and Clantheyo Masele conducted a study in 1937, but progress remained slow. It wasn't until 1947 that a preliminary investigation report was submitted by Sri. P. Joseph John, the Chief Electrical Engineer to the Government of Travancore. The Central Water Commission conducted a detailed investigation in 1956, and the project report was prepared in 1961.

The construction of the Idukki Dam commenced on April 30, 1969, under the leadership of Dr. D. Babu Paul, IAS, who was appointed as the Project Coordinator. With support from the Canadian Government in the form of loans and grants, the project saw assistance from SNC-Lavalin, a renowned Canadian firm of Consulting Engineers, along with construction by the Hindustan Construction Company.

A Technological Marvel

The construction of the Idukki Dam was completed by May 1974, with its underground Power Station standing as a technological marvel. The Power House cavern, measuring 141 meters in length, 20 meters in width, and 34.5 meters in height, is the largest of its kind in the country. Vertical Pelton Turbines are utilized in the station, boasting six generating units, each with a capacity of 130 MW.

The first three units were commissioned by 1976-77, although the initial estimate of the project cost in 1968 was Rs. 63.20 Crores, which later rose to Rs. 115 Crores in a revision in 1976.

A Trailblazing Power Generation Project

The inaugural trial run of the first machine took place on October 4, 1975, and the commercial operation of the Power Station was commissioned on February 12, 1976, by the then Prime Minister, Smt. Indira Gandhi. The second unit was commissioned on June 7, 1976, followed by the third on December 22, 1976, raising the station's capacity to 390 MW by the end of 1977.

The second stage of the project aimed to double the station's capacity, reaching 780 MW. Three units were commissioned in the second stage on January 30, 1985, March 22, 1986, and August 30, 1986, significantly increasing the annual generation potential to 2015 MU. The 220kV Switchyard, located outside the powerhouse cavern, facilitates the transmission of power generated in the station to load centers through seven 220kV feeders. The tail race water, released to the Thodupuzha River through an underground tunnel, serves for power generation in the Malankara Small Hydro Electric station and irrigation purposes.

The Malankara Small Hydro Electric Project taps into the Malankara Dam Reservoir's excess water, ensuring a year-round supply for power generation and irrigation. With its history dating back to 1919, the Idukki Hydro Electric Project remains a true testament to human ingenuity and determination, contributing significantly to Kerala's energy needs.

In conclusion, the Idukki Dam is more than just a monumental structure; it represents the indomitable spirit of those who envisioned it, the dedication of those who built it, and its enduring role in powering the state of Kerala. This engineering marvel continues to stand as a testament.