The Nepal Electricity Authority (NEA) is facing a serious power shortage. It has begun load shedding and we are facing daily interruption of power supply in rotation. The duration of the daily power supply cut is about 2.6 hours. The nature of load shedding indicates that NEA is now experiencing shortage of capacity as well as energy.

The crisis is going to deepen because the demand for electricity in our national grid with a total firm capacity of about 500 MW is expected to grow steadily at an annual rate of at least about five to seven per cent. Except for the 70 MW Middle Marshyangdi Project, other new projects are nowhere near completion. Thus, we are now being dragged into a whirlpool of deep power shortage due to short-sighted planning. However, there might still be a way to soften the impact of the shortage if we launched a programme on war footing to utilise the full potential of the existing Kulekhani storage reservoir and hydropower stations to generate extra power by diverting the surplus flow of Bagmati river from Kathmandu, and later on Melamchi river, into the Kulekhani reservoir. The design of the proposed Kulekhani 3 hydropower should also be reviewed and its capacity has to be raised to about 150 MW to meet the steadily growing demand.

It is reported almost every year that the electricity generation of Kulekhani hydropower stations is going to be reduced by a substantial margin because the storage reservoir is half-empty at the end of the monsoon season, with the result that the NEA would be forced to resort to load shedding in the dry season. This problem would be solved if the surplus water from Bagmati is pumped into the Kulekhani reservoir to be stored for the supply to Kulekhani hydropower stations in the dry season.

The Kulekhani reservoir operation rule for the Kulekhani-1 with an installed capacity of 60MW is framed by a basic discharge pattern of 6.2 cum./sec. in the dry season from December to March and 2.1 cum./sec. in the wet season from April to November. Available water for Kulekhani-2 power station with an installed capacity of 32 MW is comprised of the outflow from the Kulekhani-1 and the runoff of the Mandu river. The maximum Kulekhani-2 discharge is designed to be 13.3 cum./sec. The surplus water from Bagmati could be diverted into the Kulekhani reservoir from a place near Chobhar gorge. Mean flow of Bagmati at Chobhar is quite abundant during the monsoon season. Even in the winter months of the dry season starting from December to the end of March, when the demand for the electricity is high, the average flow of the Bagmati is expected to be over 2 cum./sec. The half empty space of the Kulekhani reservoir (with a storage capacity of 73.3 million cubic meters) could be utilised to accommodate about 20 million cubic metres monsoon season flow of the Bagmati. Thus, the Kulekhani hydropower could be provided additional 4cum./sec. flow throughout the winter months. Out of this total flow, the water drawn directly from the Bagmati would be about 2 cum./sec. and the stored Bagmati water would provide the remaining 2 cum./sec.

The diversion of the surplus Bagmati water from the Kathmandu Valley to Kulekhani reservoir could be a simple and the most cost-effective proposition, though at first glance, it might appear to be a complicated engineering task. The total power generation of Kulekhani 1& 2 hydropower plants would almost be doubled by investing about $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 cum./sec water to a height of about 300m, equivalent in height to the full supply level of Kulekhani storage reservoir. It is equally possible that we might need several small pump stations with a total capacity of about 15 MW if the topography does not allow providing single stage pumping. A 15 km long waterway might be needed to carry the water into Kulekhani storage reservoir out of it and the length of the tunnel could be about nine km. The construction of the proposed Bagmati diversion works could be completed within two years with one additional year for the initial preparatory works. The NEA would not require external foreign investment for this. It could mobilise its own resources to finance this project.

The proposed Bagmati diversion could be implemented within a very short period to meet the ever-growing demand for power. The proposed diversion is going to be perhaps the most economic project because we do not need to invest on construction of the reservoir, power stations and transmission lines. We can utilise the existing power stations, reservoir and other structures. For pumping surplus monsoon period water from Bagmati into Kulekhani reservoir we can use seasonal energy generated by our run-of-the-river hydropower projects. At present the seasonal energy is almost entirely wasted.

Dr Thapa is former member and executive secretary, Water and Energy Commission