Construction has begun on the 13.1km headrace tunnel which forms a key part of the Sunkoshi Marin Diversion Multipurpose Project (SMDMP) in Nepal.
A double-shield TBM was launched to excavate the tunnel, which will connect to a new surface powerhouse on the Marin River.
The available head between the intake and powerhouse will be used to generate approximately 30MW of energy. Water diverted from the Sunkoshi River to the Marin River through the tunnel will be used to irrigate approximately 122,000ha of farmland in the districts of Dhanusha, Mahottari, Sarlahi, Rauthat and Bara in the Terai Plains.
The multi-purpose project comprises a conventional concrete diversion weir structure (barrage and under sluice bay) across the Sunkoshi River. The diverted water will be passed through a desander to remove silt, before being conveyed via the new headrace tunnel.
SMDMP will combine hydropower and irrigation benefits and has been declared a National Pride project by the Nepalese government.
China Overseas Engineering Co was awarded the tunnelling contract in February last year.
Source: Tunnels and Tunnelling
