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WATER, WATER EVERYWHERE NOT A DROP TO DRINK
By Dr. AB Thapa
English lyrical poet, critic, and philosopher Samuel Taylor Coleridge in his most famous poem “The Rime of the Ancient Mariner,” composed during the autumn and winter of 1790s describes the suffering of a sailor who had committed a crime against the life principle by slaying an albatross “Water, water everywhere not a drop to drink”. But why Kathmandu valley residents amidst the plenty of water should be punished by denying them to quench their thirst with enough water.
It need not be explained that Kathmandu valley at present is suffering from water shortage. There is a great urgency to resolve this problem. Our government has indeed launched a big program. Our program to a great extent is based on method to force the Kathmandu residents to cut down their daily consumption of water by charging them more for water supply. It has been very recently reported that our government has even nominated a foreign firm at an exorbitant cost to accelerate this process. Such demand management is the only recourse in those desert regions where there is not any possibility to augment water supply. How about Kathmandu valley? We have abundant water. We need not cut down the supply to Kathmandu residents to resolve this problem. As explained hereinafter, an enormously large additional quantity of water could be provided to Kathmandu residents almost for free if we linked water supply program with electricity generation. Diversion of regulated Langtang river flow via proposed Melamchi tunnel would provide such opportunity. The super high-head Langtang hydropower stations would be able to produce electricity at an extremely low cost. Unfortunately, we are at present following a very irrational method to resolve Kathmandu water supply problem. There is a need to hold widespread consultations to find best solution to resolve Kathmandu valley’s long term water supply problem.
German Concept of 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 program 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. Fortunately, now the road situation has greatly improved. The decision to build a 28 km long Melamchi tunnel with a capacity to carry a flow of about 15 cubic meters/ sec just to divert about 2 cubic meters/sec Melamchi flow into Kathmandu valley has radically improved the situation and made the Langtang diversion project perhaps the most attractive for implementation in very near future. Intake of the Melamchi tunnel is not far away from the Langtang river. Thus the diversion of the Langtang river into the Melamchi river for power generation would not involve big investment.
Multipurpose Langtang Development
The concept of the Langtang project solely for power generation was developed under the United Nations Development Program 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 Langtang-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.
A New Bagmati River
At present the Bagmati River has virtually turned into city drain. Residents of the Kathmandu valley as well the large multitude of peoples coming to Pashupatinath Temple each day for worshipping from all over the world are appalled at the miserable sight of the holy Bagmati River. It can hardly be denied that the water scarcity is the prime cause of complete deterioration in condition of the Bagmati River. Unfortunately until now we do not have any satisfactory plan to resolve this serious problem. We are pinning our hopes on much publicized Melamchi Project, but it is all eyewash: the Melamchi water will not even reach Pashupatinath Temple area in dry season. According to the Melamchi Project report from 2011 onward the entire Melamchi dry season flow would have to be tapped to meet the growing demand for water supply in the Kathmandu valley.
Fortunately there is a good solution to resolve the Bagmati River conservancy problem. It would be possible to transform the Bagmati into a medium sized river that would be carrying a discharge of about 10 to 15 cumecs even in the driest month. Many of us might be astonished to learn that the proposed Bagmati flow augmentation program would not at all be a financial burden on residents of the Kathmandu valley. Full cost of the project could be recovered from the sale of the cheap hydro electricity. The generation cost of the electricity would be very low, as a result, it might even be possible to lower the present electricity tariff which might be among the highest in our region.
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 absolutely without any additional investment in civil structures and electrical equipments of the Kulekhani dam and hydropower stations.
(Dr. Thapa writes on water resources)
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