Augmenting Water Supply To Kulekhani

By AB THAPA

It is reported in a local newspaper that the electricity generation of the Kulekhani hydropower stations is going to be reduced by 40%, with the result that the NEA would be forced to resort to load shedding in the coming dry season. The newspaper explains that in this year the rainfall is below normal. Thus the reservoir has not yet been filled up though we are already at the end of the monsoon season.

Unfortunately the water shortage problems are too frequently plaguing the Kulakhani hydropower plants. Luckily there is a good solution to resolve the Kulekhani water shortage problem. Several articles have already been published to explain how the Kulekhani water shortage problem could be resolved. It should be stated with deep regret that nobody appears to be truly concerned to find a way to resolve this problem.

A New Approach

It would be possible to augment substantially the flow of the Kulekhani river by diverting into the Kulekhani storage reservoir the Langtang and Melamchi river waters in surplus to the need of Kathmandu valley and other adjacent places. The proposed plan could provide excellent opportunity to Kathmandu residents to be supplied with abundant waters from the Langtang and Melamchi rivers for free. Full cost of the proposed Kulekhani water supply augmentation project could be recovered from the sale of the cheap hydro electricity. Generation of power would be adequate to meet the nation’s demand for electricity for the coming decade. The generation cost of the electricity would be very low, as a result, it would even be possible to lower the present electricity tariff.

From Langtang to Kulekhani

It would greatly help to enhance the feasibility of the Kulekhani and the proposed Melamchi Project if theses projects are linked with the modified Langtang Project which is not at all a very big project. The whole plan would comprise of the following three steps. (1) Diversion of the Langtang River into the Melamchi for generation of cheap electricity. (2) The 28 km long proposed Melamchi Project tunnel would deliver the combined flows of the Langtang and the Melamchi rivers into the Bagmati River near Sundarijal. It would not be necessary to enlarge the size of the already finalized Melamchi tunnel earmarked for the diversion of the solely Melamchi river to deliver the combined flow of the Melamchi and Langtang rivers. The cross-sectional size of the proposed Melamchi tunnel is too large It can easily carry the combined flow of the Melamchi and the Langtang rivers. The augmented Bagmati River would be able to flush wastes held in suspension across the Kathmandu city zone to Chhobar. (3) A big proportion of the augmented Bagmati flow would be picked up at Chobbar for diverting it into the Kulakhani storage reservoir. As a result, the electricity generation of the existing Kulekhani No.1 and Kulekhani No.2 power stations, and the proposed Kulakhani No.3 Project could be tripled. The proposed new plan is described hereinafter.

Rationale Behind Melamchi- Langtang Interconnection

The concept of the Melamchi-Langtang interconnection is based on the combination of independent studies of various projects carried out at different time. The main impetus to such interconnected project is provided by the concurrence of the views of the government as well as the donors to acknowledge the need to implement the 28 km long tunnel to deliver Melamchi water to Kathmandu valley to meet the growing demand for water supply in the valley until 2011. There after the water of the Yangri and Larke rivers would have to be further added. There is one serious drawback in building the 28 km long Melamchi tunnel project exclusively for water supply. The project would be too expensive and thus the financial burden on the people of Kathmandu would be too heavy. Each customer ultimately might have to pay every month perhaps about Rs. 5000 for water supply unless the government decides to pay it in the form of subsidy. Thus an overwhelming majority of the people living in the valley would not be able to afford to bear such an extremely high cost of water supply.

Langtang River Diversion

The diversion of the Langtang river for water supply to Kathmandu valley is not a new concept. Initially it was thought to effect diversion from the catchments area instead of the river. A study of such diversion was made by GTZ in 1977. The study provides the following information.

The idea to augment the limited water resources of the Kathmandu valley by diversion of water from the Langtang / Gosaikund massif in the North was first mentioned by Peter Aufschnaiter in 1960. In 1976 /77 the project was studied on a very preliminary level by Dr. Ing. Cristian Kleinert. This project, originally not listed by HMG of Nepal under the projects to be investigated for possible cooperation with the Germany had been included into the study programme on the initiative of the German Government Mission itself because of the fascinating concept and promising objects. The Mission report points out that at that time the high cost of the project mainly caused by difficult access and transportation would not make it viable to undertake this project for further detailed study. Now the road situation has greatly improved.

Multipurpose Langtang Development

The concept of the Langtang project solely for power generation was developed under the United Nations Development Programme supported Gandak Basin Master Plan study. This project can be easily linked with the Melamchi project tunnel. The interconnection of these two projects could open up whole new vistas for the most cost effective development of hydropower in near future. The diversion of the Melamchi- Langtang flow into the Kulekhani could be regarded as one of such possibilities. It can be roughly said that after the full development of the Lantang-Melamchi-Kulekhani interconnected projects it could be possible to generate about 2500 million KWh peaking power at a cost of about 2 US Cents per KWh. Three hydropower projects each operating at a head of about 1000 m or more with a total installed capacity of about half a million KW could be built at a cost of about US $ 1000 per KW. After the completion of the above projects the Melamchi tunnel could be expected to run in full capacity of about 15 cumecs throughout the year though the Melamchi river alone would be able supply only about 1.5 cumec or even less in dry months when the demand for water supply in the Kathmandu valley is the highest.

Diversion from Kathmandu to Kulekhani

The diversion of the surplus Melamchi and Langtang waters from Kathmandu valley to the Kulekhani reservoir could be a very simple and at the same time the most cost effective proposition despite the fact that at first glance it might appear to be a highly complicated engineering task. Let us take a hypothetical case that we are going to draw only 4 cumecs water somewhere near Chobar out of the combined flow of the Bagmati. Melamchi and Langtang rivers. It is explained hereinafter that the benefit accruing to the NEA could be as high as US $ 22.5 million per annum by investing only about US $ 20 million in the construction of the proposed diversion structures.

We might have to build a 15 MW pump station at Chobar to lift 4 cumecs water to a height of about 300 meters which might be equivalent in height to the full supply level (FSL) of the Kulekhani storage reservoir. It is equally possible that instead of one big pump station we might need several small pump stations with a total capacity of about 15 MW that would be completely dependant on topography. A 15 km long waterway might be needed to carry the water into the Kulekhani storage reservoir out of it the length of the tunnel could be about 9 kilometers. The total cost of such diversion could be about US $ 20 million

After the completion of the above described Langtang diversion into the Kulekhani reservoir, there would be a net increase of about 250 GWh firm power in annual generation of the Kulekhani Nos 1,2&3 hydropower stations even after taking into consideration the energy spent on pumping. Thus the additional generation of the Kulekhani hydropower stations after the Langtang diversion would be two times greater than the present annual generation of Kulekhani No 1 Station. It would be possible to increase to such a great extent the electricity generation without any additional investment in civil structures and electrical equipments of the Kulekhani dam and hydropower stations.

At present the NEA is paying to the private developers at an average rate of about US Cents 6 per KWh. Out of such purchase, the firm energy is only about 50% and the rest is secondary energy. The purchase rate of the exclusively firm energy could be about US Cents 9 per KWh if it is presumed that 3 KWh secondary energy would be equivalent 1 KWh firm energy though in the World Bank supported Upper Karnali Project feasibility study the seasonal energy has been valued only at 10% of the firm energy based on the expected net value of such energy for the thermal fuel displacement. Thus even a small scale Langtang diversion into the Kulekhani could help to increase the annual income of the Kulekhani hydropower stations by a wide margin of US $ 22.5 million whereas the total investment in the pumping system to deliver the water into the Kulekhani reservoir could be only about US $ 20 million.

Threat To Langtang Melamchi Interconnection

Within the past decade our power development plans have been thrown into a complete disarray by foreign developers who were virtually given free hand to do as they wish. The task of regulatory body even now is nothing more than a mere formality. The 60 MW Khimti hydropower, the first project in private sector, has opened a Pandora's box. The Khimti project had disastrous consequences for the economy of the Nepal Electricity Authority. The seasonal energy procured from the Khimti is completely wasted though NEA is made to pay about US $ 9 million per annum for such seasonal energy. Many other developers were also quick to follow. Some of them are already building hydropowers. Few have recently got permission to carry out detailed study but they are not yet ready to start the construction works. Mini Langtang project appears to be one of such projects.

We would have to sacrifice the big Langtang Project if it is decided to implement this mini Langtang project because they are mutually exclusive. The mini Langtang project operating at a head of about 200 meters is in the lowermost reaches of the Langtang river. The water supply to the mini Langtang project would have to be completely cut off to divert the Langtang river into the Melamchi. So all the arrangements made with the private developer must be annulled before it is too late to save the big Langtang Projects from having to wage legal battle later on against the private developers.