Hirakud Dam is built across the Mahanadi River, about from Sambalpur in the state of Odisha in India. It is the longest earthen dam in the world. Behind the dam extends a lake, Hirakud Reservoir, long. It is one of the first major multipurpose river valley projects started after India's independence. Hirakud Reservoir was declared a Ramsar site on 12 October 2021.
Construction history
On 15 March 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.
In 1952, Mazumdar Committee was appointed by the government to oversee the soundness and technical feasibility of the project. The committee has envisaged costs of 92.80 crore for the project and that the construction of the main dam would be complete by June 1955. It also said that by 1954–55 a total of would be irrigated and that 48,000 kW of electric power would be generated. However, 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 in 1957. Power generation along with agricultural irrigation started in 1956, achieving full potential in 1966.
Technical details
Structure
The Hirakud Dam is a man-made structure of earth, concrete and masonry. north of Sambalpur, it is the longest major earthen dam in the world, measuring including dykes, and stands across the river Mahanadi. The main dam has an overall length of spanning between two hills; the Laxmidungri on the left and the Chandili Dunguri on the right. The dam is flanked by of earthen dykes on both the left and right sides, closing the low saddles beyond the adjoining hills. The dam and dykes together measure . It also forms the biggest artificial lake in India, with a reservoir holding at full capacity, with a shoreline of over . There are two observation towers on the dam one at each side. One is "Gandhi Minar" and the other one is"Jawahar Minar". Both the observation towers present extensive views of the lake.
Power houses
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 southeast of the dam at Chipilima. It contains 3 x 24 MW generators. The entire installed capacity of the dam's power houses is 347.5 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.
Purpose
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 of land. Hydroelectricity is also generated. The Hirakud Dam regulates of Mahanadi's drainage. The reservoir has a storage capacity of with gross of .
It drains an area of , more than twice the area of Sri Lanka.
The project provides of kharif and of rabi irrigation in districts of Sambalpur, Bargarh, Bolangir, and Subarnpur. The water released by the power plant irrigates another 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, downstream from the dam. In addition, the project provides flood protection to 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 in the river Mahanadi is used to generate electricity. The place is mostly inhabited by fishermen, whose deity Ghanteswari is revered in the neighboring area. The state livestock breeding farm and agricultural farm are located here.
Canal system
Hirakud Dam has three canals, namely Bargarh Main Canal, Sason Canal and Sambalpur Canal. Bargarh Main canal has a water discharge rate of .
