Melamchi Water Supply Project

Melamchi Water Supply Project (MWSP) is a project to supply drinking water to Kathmandu Valley by diverting of water per day. The project started in 1998 and completed in 2021. The intake of this project is located in Melamchi, Nepal. Ministry of Physical Infrastructure and Transport (Nepal) is the executing agency for the Project and Melamchi Water Supply Development Board is the implementing agency.
This project is mainly financed by Japan and the Asian Development Bank. About 57% of the project cost is loan, 16% is grant and 26% is financed by the Nepalese government.
Project description.
The intake of the project lies in the Melamchi valley in the gorge below Ghwakan, just upstream of the confluence of Melamchi River and Ribarma Khola. The main structure is the diversion weir, river-training structures, and sediment exclusion basin. A gravity concrete weir is 5 to 7 m high with the crest at an elevation of 1,425 m asl. The control system and the sediment exclusion basin have a design capacity of 6m3/s. The sediment exclusion basins are double-chambered with a length of 80 m each. 
The tunnel intake is at an elevation of about 1416m and the outlet is about 1,408 m asl.
The length of the tunnel from the intake to the water purification facilities in Kathmandu Valley at Sundarijal is about 26 km. The tunnel is longest water supply tunnel of South-asia and second longest water supply tunnel of Asia. The tunnel is being excavated from adits at Ambathan, Gyalthum, Sindhu and Sundarijal waterfall. The diversion flow in 6m3/s. The tunnel has a cross-sectional area of 12.7 m2 and lined with shotcrete in most of the section; concrete lining is done only in the weak rock formation. The tunnel is excavated by drill and blast method. The geology of the areas consists mainly of gneiss with mica schist and laminated quartzite.
The distribution work has nine service reservoirs at various locations in the Kathmandu (Mahankalchaur, Bansbari, Paani Pokhari, Balaju, Khumaltar, Arubari, Tigni, Katunje and Kritipur). The water from Sundarijal to service reservoir is supplied by a Bulk Distribution System (BDS). The distribution to household is done by a network of pipes about 670 km long. About 540 km of sewerage network will also be upgraded in this project.
Delays.
The project has a serious history of delays.