Hirakud Dam is built across the Mahanadi River, about 15 kilometres (9.3 mi) from Sambalpur in the state of Odisha in India. Behind the dam extends a lake, Hirakud Reservoir, 55 km (34 mi) long. It is one of the first major multipurpose river valley projects started after India’s independence.
Before the devastating floods of 1936, Sir M. Visveswararya proposed a detailed investigation for storage reservoirs in the Mahanadi basin to tackle the problem of floods in the Mahanadi delta. In 1945, under the chairmanship of Dr. B. R. Ambedkar, the Member of Labour, it was decided to invest in the potential benefits of controlling the Mahanadi for multi-purpose use. The Central Waterways, Irrigation and Navigation Commission took up the work. On 15 Mar 1946, Sir Hawthorne Lewis, the Governor of Odisha, laid the foundation stone of the Hirakud Dam. A project report was submitted to the government in June 1947. Pandit Jawaharlal Nehru laid the first batch of concrete on 12 April 1948. The dam was completed in 1953 and was formally inaugurated by Prime Minister Jawaharlal Nehru on 13 January 1957. The total cost of the project was ₹1,000.2 million (equivalent to ₹70 billion or US$1.0 billion in 2016) in 1957. Power generation along with agricultural irrigation started in 1956, achieving full potential in 1966.
The Hirakud Dam is a composite structure of earth, concrete and masonry. 10 km (6.2 mi) north of Sambalpur, it is the longest major earthen dam in India, measuring 25.8 km (16.0 mi) including dykes, and stands across the river Mahanadi. The main dam has an overall length of 4.8 km (3.0 mi) spanning between two hills; the Lamdungri on the left and the Chandili Dunguri on the right. The dam is flanked by 21 km (13 mi) of earthen dykes on both the left and right sides, closing the low saddles beyond the adjoining hills. The dam and dykes together measure 25.8 km (16.0 mi). It also forms the biggest artificial lake in India, with a reservoir holding 743 km2 (287 sq mi) at full capacity, with a shoreline of over 639 km (397 mi). There are two observation towers on the dam one at each side. One is “Gandhi Minar” and the other one is”Nehru Minar”. Both the observation towers present breathtaking views of the lake.
The dam supports two different hydroelectric power houses. Power House I is located at the base (toe) of the main dam section and contains 3 x 37.5 MW Kaplan turbine and 2 x 24 MW Francis turbine generators for an installed capacity of 259.5 MW. Power Station II is located 19 km (12 mi) southeast of the dam at Chipilima. It contains 3 x 24 MW generators. The entire installed capacity of the dam’s power houses is 307.5 MW. Power House I and II were built in three stages. During stage I, four generators were installed at PH I and in stage II, the power channel two and Power House II was constructed. All three generators were installed at PH II along with two more at PH I by 1963. Between 1982 and 1990, the seventh and final generator was installed at PH I.
In the upper drainage basin of the Mahanadi River, centered on the Chhattisgarh Plain, periodic droughts contrast with the situation in the lower delta region where floods may damage crops. The dam was constructed to help alleviate these problems by creating a reservoir and controlling river flow through the drainage system. The dam regulates the flow of the Mahanadi River and produces hydroelectricity through several hydroelectric plants.
The dam helps control floods in the Mahanadi delta and irrigates 75,000 km2 (19×106 acres) of land. Hydroelectricity is also generated. The Hirakud Dam regulates 83,400 km2 (20.6×106 acres) of Mahanadi drainage. The reservoir has a storage capacity of 5.818 km3 (1.396 cu mi) with gross of 8.136 km3 (1.952 cu mi).
It drains an area of 133,090 km2 (32.89×106 acres), more than twice the area of Sri Lanka. The amount of earth, concrete and masonry materials used to build the dam is sufficient to make a road 8 m (26 ft) wide and pave it from Kanyakumari to Kashmir and from Amritsar to Dibrugarh in Assam. With successful irrigation provided by the dam, Sambalpur is called the rice bowl of Odisha.
The project provides 1,556 km2 (384,000 acres) of kharif and 1,084 km2 (268,000 acres) of rabi irrigation in districts of Sambalpur, Bargarh, Balangir, and Subarnapur. The water released by the power plant irrigates another 4,360 km2 (1.08×106 acres) of CCA in Mahanadi delta. The dam can generate up to 307.5 MW of electrical power through its two power plants at Burla, on the dam’s right bank and Chiplima, 22 km (14 mi) downstream from the dam. In addition, the project provides flood protection to 9,500 km2 (2.3×106 acres) of delta area in district of Cuttack and Puri.
Chiplima has gained prominence as the second hydroelectric project of the Hirakud Dam. A natural fall of 80 to 120 ft (24 to 37 m) in the river Mahanadi is used to generate electricity. The place is mostly inhabited by fishermen, whose deity Ghanteswari is very popular in the neighboring area. The state livestock breeding farm and agricultural farm are located here.
These are remnants of temples submerged after the dam was completed in 1957. In the summer season, the receding water of the dam makes the structures become visible. The hidden treasures have finally caught the attention of historians, and steps are being taken to understand the historical significance of these temples, which periodically go under water, only to resurface again. Many temples have been destroyed after 58 years of underwater existence. However, some remain intact.
Interest in these lost temples has been rekindled after two stones, etched with writing (‘Shila Lekha’), were recovered from what is believed to be the Padmasini temple of submerged Padmapur village. The temples located inside the reservoir area were part of the then Padmapur, one of the oldest and most populous in the region prior to the dam construction. More than 200 temples were submerged by the dam, nearly 150 temples have either perished or are underwater and about 50 are visible during summer. The lost temples present excellent opportunities for scuba diving enthusiasts to explore the underbelly of Hirakud Dam. The temple are visible to visitors on boat only during the summer months of May and June.