The Sunkoshi-Marin Diversion Multipurpose Project envisages diverting water from the Sunkoshi River to the Bagmati River to irrigate 122,000 hectares of farmland in Rautahat, Dhanusha, Mahottari, Sarlahi and Bara districts in the Tarai.

As per the detailed project report (DPR), water will be redirected at Paurai in Chandrapur Municipality-1 in Rautahat via the Marin River in Sindhuli. The scheme is part of the Bagmati Irrigation Project, and is slated to be completed in five years.

The multipurpose project will draw 77 cusecs of water from the Sunkoshi by constructing a 180-metre-long dam.

The water from the Sunkoshi will first be diverted to the Marin River in Sindhuli through a 13.1-km-long and 7-metre-wide tunnel before being channelled into the Bagmati River. The water will then be collected at a barrage and distributed to irrigate fields. A powerhouse will be built on the Marin River to generate 40.8 MW of electricity. The DPR is being reviewed by ETech Consultant, according to Mitra Baral, director of the project.

A tunnel, decanting basin, headrace tunnel, surge shaft, penstock pipe, powerhouse, water source point, turbine and switch pad will be constructed.

The project is estimated to cost Rs36.37 billion.

Low water flows in the Bagmati River have caused severe difficulties for farmers in Rautahat and Sarlahi districts to irrigate their fields. In the dry season, irrigation facilities are not available.

The flow rate in the Bagmati River is just 5-6 cusecs. Bhaktapur Lal of the project said, “If water can be drawn from the Sunkoshi, there won’t be irrigation problems at any time of the year.”

The Bagmati Irrigation Project has been providing irrigation facilities in various packages with assistance from Saudi Arabia. The project has constructed a 500-metre weir that can hold 122,000 cusecs of water. The project aims to supply 48 cusecs to farmers in Rautahat and 64 cusecs to farmers in Sarlahi.

The project built various branches and sub-branches from 1977 to 1984 with the assistance of the Saudi Development Fund. The west irrigation channel and Bhalohiya branch were constructed in June 1978. Under the project, there will be 21 main and 109 secondary branches. The project office said that 28,000 hectares out of the total 46,600 hectares were irrigated under the first stage of the project.

The planned generation of electricity under the Bagmati Irrigation Multipurpose Project was delayed for over three decades as the construction of the first phase of the irrigation scheme was held up.

Project officials said that prioritising electricity generation would be a good idea as demand for power has surged across the country. The project had planned to generate 140 MW of electricity by erecting a 117-metre-tall dam in 1979. Japanese Project Nippon Koei has conducted a survey to produce energy by building a dam.