Hirakud Dam Project

Conception and Construction

The Hirakud Dam, built across the Mahanadi River at about 15 kilometres upstream of Sambalpur town, is a monument to post-independence India’s vision of harnessing its rivers for development. The idea of a dam on the Mahanadi was first mooted by Sir M. Visvesvaraya in the 1930s as a flood control measure for the Mahanadi delta, which had experienced devastating floods, notably in 1937. Pandit Jawaharlal Nehru, India’s first Prime Minister, laid the foundation stone on 12 April 1948, and he personally described dams as the “temples of modern India”. The project was completed in 1957, and the dam was inaugurated by Pandit Nehru. The construction involved the displacement of approximately 26,000 families from about 300 villages submerged under the reservoir — one of the earliest large-scale instances of development-induced displacement in independent India.

Engineering and Technical Specifications

Hirakud is the longest earthen dam in the world, with a total length of 25.8 kilometres including the main dam and the dykes. The main dam spans 4.8 kilometres across the Mahanadi valley, while two earthen dykes — the left dyke (10.5 km) and the right dyke (10.5 km) — extend on either side across low saddles to contain the reservoir. The dam is a composite structure of earth, concrete, and masonry, with a maximum height of 60.96 metres above the riverbed. The spillway, situated in the main dam section, has 64 radial gates and can discharge up to 42,450 cubic metres of water per second — one of the highest spillway capacities in India. The reservoir, named the Hirakud Reservoir (or the Mahatma Gandhi Reservoir), has a total storage capacity of 8,136 million cubic metres at Full Reservoir Level (FRL), a live storage of 5,818 million cubic metres, and a water spread area of about 743 square kilometres at FRL — making it the largest artificial lake in Odisha.

Irrigation and Command Area

The primary purpose of Hirakud is irrigation. From the dam, water is released into three main canal systems serving the districts of Sambalpur, Bargarh, Bolangir, Sonepur, and Subarnapur. The Bargarh Main Canal, the largest of the three, takes off from the left bank and runs for about 86 kilometres, serving the fertile Bargarh plain. The Sason Main Canal on the right bank irrigates the Sambalpur-Bolangir tract. The Sambalpur distributary serves areas close to the dam. The total length of the main and branch canals is approximately 900 kilometres, and the designed irrigation potential is 2.54 lakh hectares (kharif). The Hirakud canal system transformed the central Odisha tablelands from a drought-prone subsistence agriculture region into one of the most productive rice-growing belts in the state. Bargarh district, in particular, emerged as the “Rice Bowl of Odisha”, a direct consequence of Hirakud’s water. The project also provides regulated releases downstream for the delta canals below Naraj, benefiting the rice and cash crop cultivation in Cuttack, Puri, Jagatsinghpur, and Kendrapara.

Power Generation

Though irrigation is the primary function, the Hirakud project includes a hydroelectric component with a total installed capacity of 347.5 megawatts distributed across three powerhouses. Burla Powerhouse I (on the left bank), with 5 units totalling 67.5 MW, was commissioned in 1957. Burla Powerhouse II (also on the left bank), with 3 units of 37.5 MW each (112.5 MW), was added later. Chiplima Powerhouse, located about 35 kilometres downstream, uses the waters released from the dam through a second dam at Chiplima (the Mahanadi’s water is diverted through a power channel) with 5 units totalling 72 MW. Together, these power stations provide valuable peaking power to the Odisha grid and were among the first major hydroelectric installations in eastern India.

Flood Moderation

Flood control was the original rationale for Hirakud, and the dam has substantially moderated the flood regime in the Mahanadi delta. By storing a portion of the monsoon inflows and releasing them in a regulated manner, the dam prevents the simultaneous arrival of flood peaks from the upper and lower catchments at the delta head. Critics, however, point out that the reservoir’s siltation — estimated at nearly 25 per cent of its original capacity — has reduced its flood absorption capacity, and that the dam cannot prevent floods when heavy rainfall occurs in the lower catchment below the dam (as in the 2001 and 2008 floods). The dam also provides municipal water supply to Sambalpur, Bargarh, and Jharsuguda towns.

Social and Environmental Impact

The Hirakud reservoir submerged approximately 743 square kilometres of prime agricultural and forest land, displacing over 26,000 families, predominantly tribal and traditional Odiya agrarian communities. The rehabilitation and resettlement experience was deeply unsatisfactory — compensation was meagre, alternative land was often of poor quality, and communities were scattered and socially dislocated. The reservoir has also experienced rapid siltation, primarily due to deforestation and agricultural expansion in the upper catchment in Chhattisgarh and within Odisha, reducing its capacity more rapidly than anticipated. The ecological impact includes the drowning of the Satkosia gorge’s upper extension, the fragmentation of wildlife corridors, and changes in the downstream riverine ecology (reduced sediment and nutrient flows to the delta). Despite these costs, Hirakud remains the most important piece of water infrastructure in Odisha and is integral to the state’s agricultural, energy, and flood management systems. The dam is also a notable tourist attraction, with the Gandhi Minar at the dam site and the Cattle Island in the reservoir serving as popular points of interest.