TINY INPUT AND GIANT OUTPUT: Marshyangdi Project
By Dr. AB Thapa
It has been reported in a local newspaper on March 20, 2007 that the Marshyangdi Hydel Project, which had been shut down for 10 days, resumed its operation. After the renovation, the project has been able to generate 4 MW more electricity. The project is now generating 73 MW power. The news helped to refresh our past memory: how we were able to bring about a gigantic enhancement of the scope of the Marshyangdi Hydel Project without any additional investment only by simply spending a week time to conduct hydraulic calculations. Our recalculations carried out on behalf of the Ministry convinced the German consulting team, who had done the final design works in Frankfurt, Germany, that the ultimate capacity of the proposed civil structures involving about 2/3 of the total project cost can be considered to be adequate to generate up to 75 MW against the originally adopted 63 MW capacity. Thus, our tiny input contributed to a giant output.
Marshyangdi Project Cost
In early 1980s the final design works of the 63 MW Marshyangdi Hydel project had been completed. The LAHMEYER International of the Germany was the consulting firm that had done the design works. At that time the global economy had not still been able to recover from the shock of the past high inflations. The authorities in the World Bank were worried that the total amount pledged to implement the civil work component of the Marshyangdi Project might not be adequate. However, the consulting firm LAHMEYER International was found to be absolutely certain that the final civil works cost would not exceed the estimated amount. Certainly the Government was in a dilemma. At that time I had joined the Ministry of Water Resources to look after the Project Monitoring Section.
A New Exercise
I spent about a week time to go through the final reports of the Marshyangdi Project to explore the possibility to find out some way to bring down total project cost. I finally came to the conclusion based on the full study of the feasibility and design reports that the size of the Marshyangdi Project tunnel to be provided to deliver water to the power house from the head pond could easily be reduced by about 20% without adversely lowering the installed capacity of the hydropower station originally fixed at 63 MW.
The head office of the LAHMEYER International at Frankfurt Germany was responsible for design works on the Marshyangdi Hydel Project. My revision calculation sheet was sent to Germany for the opinion of the consultants. At first the LAHMEYER was not prepared to agree that there is any room to justify to amend the finalized design. In subsequent next phase of correspondence they agreed that there might slight be a possibility to make variations but its net effect would be dismal. Finally they yielded to my suggestion.
Consensus on Increased Capacity
By this time it had become clear that the cost estimate of the Marshyangdi Project prepared by LAHMEYER is more or less accurate. There was no need for seeking additional fund to meet the civil works cost. The LAHMEYER forwarded us a new proposal. Why not we decide to raise the installed capacity of the hydropower instead of reducing the size of the conveyance tunnel? It was decided to raise the installed capacity to 69 MW though it would have been possible to raise further the installed capacity up to 75 MW. It was agreed to provide electro-mechanical equipments with enough excess capacity to generate 69 MW.
We are very much impressed by the sincerity of the German consultants. They on their own further raised the capacity of the electro-mechanical equipments to generate 75 MW totally following our suggestions.
The Marshyangdi Hydropower Project was able to generate 75 MW power immediately after the completion of project. At the beginning some hydro-dynamical problems were observed at higher velocities in the draft tubes. It is a normal phenomenon that vortexes are formed in the draft tube leading to instability in electricity generation if the shape of the draft tubes are not properly designed. It was later reported that the consultant rectified this problem with the help of the manufacturer.
Nowadays Public Interest Is Unashamedly Sacrificed
The Melamchi Water Supply Project is in the focus since a long time because this project is lifeline for more than a million people living in the capital Kathmandu and its environs. It is quite unfortunate that even such a strategically important project has not been spared from being mishandled.
The Melamchi Project feasibility study report prepared with the assistance of the UNDP explains that around the time 2011 the total system demand for water supply ( in Kathmandu valley) is expected to reach the total supply from in-valley surface sources and Melamchi. Thereafter the next stage of the development of the Melamchi will be required. This entails diversion from the YANGRI and LARKE rivers that flow to the east of the Melamchi. Water would have to be diverted by tunnels to a point upstream of the Melamchi intake. The total length of the delivery tunnels is expected to be over 12 kilometers.
The Larke and the Yangri are the main tributaries of the Indrawati River. After the diversion of the Yangri and Larke rivers into the Melamchi there would hardy be any flow in the upper reach of the Indrawati River during the dry season.
It saddens any common Nepalese to learn that the Indrawati River has been recently leased out to private developers to build a cascade of hydropower. One hydropower is already completed and the others are at planning stage. We see no justification for the decision to lease the Indrawati River to private developers to build a cascade of hydropower. Could not we find some other suitable rivers any where in Nepal to be leased out to private hydropower developers?
Please Save Hydropower Component
There exists a big potential to generate cheap electricity by using the diverted flow of the Melamchi River The elevation of the Melamchi intake weir is 1715 m and the inlet to the treatment works near Sundarijal is 1409 m. Thus there is an enormously big gross head of 306 m. The UNDP report has clearly stated that the net increment in investment ( the cost of the powerhouse located near Sundarijal with electromechanical equipment) needed to implement the hydropower element is relatively small as the intake headrace tunnel and penstock are already in place for conveying water to the treatment works. According to the feasibility report of the Arun-3 Project operating at a head of about 300 meters ( same as the Melamchi Hydropower ) the cost of electromechanical equipments and power station civil works is only about 30% of the total project cost. The UNDP study has concluded that it would be worth constructing the hydropower and it could make a contribution to reducing the cost of drinking water to Kathmandu. The UNDP report explains that even before the diversion of the Yangri and Larke rivers the total annual generation of the Melamchi hydropower would be 60 GWh and out of it the firm power generation would be 40.5 GWh.
The Melamchi hydroelectricity generation would be close to 50% of the annual generation of the Kulekhani No.1 hydropower project. After the diversion of the Yangri and Larke the electricity generation of the Melamchi hydropower plant would have been further increased.
It surprises anyone to learn that the Melamchi hydropower component has been dropped. Even the alignment of the tunnel has intentionally been slightly modified to preclude the inclusion of the hydropower component later on. The Planning Commission should seriously look into this matter to find out why the power component of the Melamchi project was allowed to be dropped despite the fact that the UNDP report has concluded that the power station would be worth constructing and could make a contribution to reducing the cost of drinking water to Kathmandu residents. It is still not too late to reintroduce the hydropower component.
(Dr. Thapa writes on water resources)
