The salient features and the various benefits from Sapta Kosi High Dam Multipurpose Project are as follows:
Hydropower Generation
A 269 m high storage dam on river Sapta Kosi is proposed about 1.6 km upstream of Barahakshetra, Nepal with an underground powerhouse having installed capacity of 3000 MW at 50% load factor i.e. annual power generation of 15,732 Million Units and availability of peaking power. Also, three canal power houses of installed capacity of 100 MW each along the power canal are proposed with annual generation of 1,875 Million Units.
Irrigation Development
A re-regulating barrage is proposed at Sisauli about 12 km downstream of the dam site with a network of canals on eastern and western sides of river Sapta Kosi for irrigation development of 5.46 Lakh Hectares (tentative and may change upon completion of Irrigation studies) of tarai area in 7 districts i.e. Mahottari, Dhanusha, Siraha, Saptari, Sunsari, Morang and Jhapa in Nepal and 10.53 lakh hectare of area in Bagmati-Adwara, Kamla-Balan basin and Mahananda basin in Bihar (India). Further, There is an existing command of 1,67,750 ha in Nepal from various existing irrigation projects in which irrigation is envisaged to be stabilized.
Flood Control/Management
A flood cushion of 3.0 m has been proposed in the reservoir of Sapta Kosi High Dam for flood control of tarai area in Nepal and flood prone areas of Bihar.
Navigation
A sea route to the land-locked country Nepal is also proposed through Kosi Inland Waterways from Chatara (downstream of Barahakshetra) to its integration with India's Inland Waterways No. 1 at Kursela, where Kosi meets river Ganga.
Besides Sapta Kosi Project, Sun Kosi Storage cum Diversion Scheme and Kamla Multipurpose Project are integrated schemes, which have considerable benefits enumerated as below.
Hydropower Generation
A 49 m high diversion dam on river Sun Kosi is proposed to divert 72 cumecs of water to river Kamala, through 21.5 km long diversion tunnel, to augment its discharge during non-monsoon period. A surface powerhouse is proposed at the end of the diversion tunnel with an installed capacity of 61 MW. The annual generation proposed from this powerhouse at Khadikhop is 511 Million Units.
A 51 m high Rock-fill dam on river Kamala with a dam toe powerhouse with installed capacity of 32 MW is proposed having annual power generation of 121 Million Units.
Irrigation Development
A barrage at Uttarayani around 7 km downstream of Kamala Dam is proposed with a network of canals for irrigation development of 1.75 lakh hectare (tentative and may change upon completion of Irrigation studies) in tarai area in Nepal comprising 7 districts i.e. Saptari, Siraha, Dhanusha, Mahottari, Sarlahi, Rautahat, Bara and Parsa. Further, there is an existing command of 1,12,678 ha in Nepal from various existing irrigation projects in which irrigation is envisaged to be stabilized.