Structure
The Hirakud Dam is a composite structure of earth, concrete and masonry. Ten km north of Sambalpur, it is the longest major earthen dam in the world, measuring 24km including dykes, and stands across the river Mahanadi. The main dam has an overall length of 4.8 km spanning between two hills; the Lamdungri on the left and the Chandili Dunguri on the right. The dam is flanked by 21 km 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. It also forms the biggest artificial lake in Asia, with a reservoir holding 743 km² at full capacity, with a shoreline of over 640 km.
Purpose and Benefits
In the upper drainage basin of the Mahanadi River, centered on the Chattisgarh 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 7,500,000 hectares of land. Hydroelectricity is also generated. The Hirakud Dam regulates 83,400 km² (32,200 mi²) of Mahanadi's drainage. The reservoir has a storage capacity of 5.818 km³ with gross of 8.136 km³.It drains an area of 133,090 km², 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 meters 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 Orissa. Here photography is strictly prohibited.
The project provides 1,556 km² of kharif and 1,084 km² of rabi irrigation in industries of Sambalpur, Bargarh, Bolangir, and Subarnapur. The water released by the power plant irrigates another 4360 km² 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 downstream from the dam. In addition, the project provides flood protection to 9500 km² 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 feet (25 to 40 m) in the river Mahanadi is used to generate electricity. The place is mostly inhabited by fisherman, whose deity Ghantlei is very popular in the neighboring area. The State Livestock Breeding Farm and Agricultural Farm are located here.
Cattle Island
Cattle Island exists in one of the extreme points of Hirakud Reservoir, a natural wonder. It is near Kumarbandh village of Belpahar-Banharpali range which is about 90 km from Sambalpur. By motor launch from Hirakud Dam, it is closer by 10 km via the river. The island is nothing but a submerged hill, and prior to Hirakud Dam construction, it was a developed village. Only cattle inhabit the island. During the resettlement period, villagers left some of their cows and bulls behind; when the dam construction was over, the cattle settled on the hilltop. With the passage of time, the nearby area filled up with the reservoir water, turning the hilltop into an island. Being away from mankind, the cattle are now wild, very swift and not easily caught. Living on a hilltop with dense forest, they are larger than tame cattle. Almost all are white in colour. Nearby residents attempt to hunt these animals from time to time, but these hunts are rarely successful. Though descended from tame cattle, these animals provide a contrasting picture of this breed of animal returning to life in the wild.