This is the largest multi-purpose project of Uttar Pradesh. It involves the construction of a 934 m long and 91 m high (from stream bed 167 m) straight gravity concrete dam across the river Rihand (a Tributary of the Son river) near village Pipri in Sonbhadra district.
The water so impounded is collected in Govind Ballabh Pant Sagar reservoir which spreads over an area of 130 sq. km. (466 sq. km when full) and collects 10,608 m cu m of water. To let down the floods of the Rihand entering the reservoir, the dam is provided with a spill-way of 190 m.
Power House-Downstream of the dam on the right side of spill-way has a power house with installed capacity of 300 mw (6 units of 50 mw each). The power is transmitted through 829 km of 132 km transmission line and 383 km of 66 km transmission line.
It is connected with the U P. power grid and the Obra hydel power station of 99 mw which utilises tail-race waters of the Rihand turbines and with the Obra thermal power station of 25 mw.
The Kanpur thermal power station has also been connected with the Rihand (installed capacity 64 mw). The power is utilised in eastern part of Uttar Pradesh in an area stretching from Bahraich, Kanpur in the west to Ballia in the east.
This power is utilised in cement (at Churk, Dala, Khajuraho), chemical (at Shahpuri), tyre and tube (Naini), fertilisers (at Allahabad and Gorakhpur), aluminium (at Mirzapur), caustic soda, chlorine, porcelain, paper and board, plastic and electrical industries. It is also utilised in running electric trains and energizing tubewells in eastern and central Uttar Pradesh.
Irrigation-the water collected in the Govind Ballabh Pant Sagar reservoir is diverted to the Son canal which irrigates about 2.5 lakh hectares of the agricultural land in Champaran, Darbhanga and Muzaffarpur districts of Bihar.
Other Benefits-Development of fisheries, tourism, water sports, navigatiom, control of floods, afforestation (in Rewa region), and checking soil erosion are other benefits arising out of the project.
The Rihand project has been completed in 1966 with total cost of 375 million rupees. The project is facing problem of water scarcity due to insufficient rainfall in the Rihand catchment area, and silting of the reservoir.