The Kosi River, because of its frequent floods, is called the ‘sorrow of Bihar’. The Kosi project is an outcome of the joint agreement between the governments of Bihar (India) and Nepal reached in 1954. Its main objective is to construct a barrage near Hanumannagar in Nepal, to build embankments (length 270 km) along both the banks of the river to control floods, to lay down canals for irrigation, and to generate cheap hydel power. The project involves two-stage construction.
The first stages includes a 1,140 m long concrete made dam across the Kosi River near Hanumannagar (Nepal); about 270 km long embankment along both the banks of the river; to control floods; eastern Kosi canal irrigating about 5 lakh hectares of land in Nepal and Purnea and Saharsa districts of Bihar.
The second stage of the Kosi project involves the construction of: (a) the Kosi power house with installed capacity of 20 mw on the Eastern Kosi canal and related transmission lines, (b) 112 km long Western Kosi canal to irrigate about 3.25 lakh hectares of land in Darbhanga district of Bihar, and 12,120 hectares in Saptari district of Nepal, and (c) 9.6 km long Rajpur canal taking off from the Eastern Kosi main canal to irrigate 1.6 lakh hectares of area in Saharsa and Munger districts of Bihar, and (d) extension of the eastern flood embankment by 25.76 km and of the western embankment by 4 km to protect an area of 15,190 hectares from floods.
The full potentiality of the project is to irrigate about 8.48 lakh hectares of area and generate 5.8 lakh kw of electricity. This power has been linked with the D.V.C. grid. The project will lead to all round development of Darbhanga and Muzaffarpur districts of Bihar.