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The devastating flood in the Bhotekoshi River has damaged more than a dozen hydropower projects, putting additional pressure on the Kulekhani Hydropower Project to maintain electricity generation.

The Bhotekoshi flood on August 26 disrupted more than 400 MW of power generation, increasing the burden on other hydropower plants across the country.

All three Kulekhani hydropower projects are currently operating around the clock. Of the two generators at Kulekhani-I, one is undergoing maintenance while the other remains in operation. Kulekhani-I has an installed capacity of 60 MW. Once Kulekhani-I is in operation, Kulekhani-II and Kulekhani-III also generate electricity.

Pralhad Raut, chief of Kulekhani Hydropower Project-I, said that all three Kulekhani projects have been brought into operation because the flood damaged hydropower plants in Rasuwa and Nuwakot, halting electricity production from those areas.

According to Raut, the shutdown of more than 400 MW of generation due to the flood has placed additional pressure on Kulekhani and other hydropower projects nationwide.

The Kulekhani reservoir, which serves as a backup facility for the Nepal Electricity Authority, is currently losing 20 to 25 centimeters of water daily due to power generation. Meanwhile, the reservoir receives only 15 to 18 centimeters of water inflow each day.

The water level of Indrasarovar Reservoir, the storage reservoir of the Kulekhani Hydropower Project, reached 1,522.46 meters above sea level as of 2:00 PM on Friday.

The reservoir still needs about 7.5 meters of additional water to reach its full capacity. Indrasarovar can store water up to a maximum elevation of 1,530 meters above sea level.

The 2015 earthquake caused cracks in the Kulekhani dam, prompting the Nepal Electricity Authority (NEA) to take precautionary measures whenever the reservoir level reaches 1,527 meters.

Following the earthquake, a study conducted by Japanese experts concluded that water could be safely stored in the reservoir up to an elevation of 1,527 meters.

“Had the project not been operated during the monsoon season as it is now, the Kulekhani reservoir would already have been full by this time,” said a senior official at Kulekhani-I. “After the Bhotekoshi flood, all three Kulekhani projects have been generating electricity around the clock.”

In previous years, electricity from Kulekhani was generated primarily during the dry season. Continuous rainfall in the catchment area has increased water inflow into the Indrasarovar Reservoir, although water is also being consumed for power generation.

Electricity generation becomes impossible once the reservoir’s water level falls below 1,483 meters.

The 47-meter usable water head of the Kulekhani Reservoir can be utilized for electricity generation.

Kulekhani-I generates 60 MW, Kulekhani-II 32 MW, and Kulekhani-III 14 MW, giving the Kulekhani system a combined installed capacity of 106 MW. All three projects generate electricity using water stored in the reservoir.

The Kulekhani Reservoir, which is approximately 300 meters wide and seven kilometers long, has already submerged the lower parts of the Markhu area as water levels continue to rise. Kulekhani is one of Nepal’s major hydropower generation facilities.

Power Generation Declining

A report published by the Nepal Electricity Authority (NEA) five years ago stated that rising sediment levels on the bed of the Kulekhani reservoir, located in Indrasarovar Rural Municipality of Makwanpur, have reduced electricity generation by 63.3 million units (kWh).

The declining water storage capacity of the Kulekhani Reservoir has led to a reduction in electricity generation.

Initially, the water stored in the reservoir was capable of generating 211.1 million units (kWh) of electricity. However, that capacity has now declined to 144.7 million units, reflecting a significant drop in power generation potential.

The reduction is primarily due to the reservoir’s shrinking storage capacity. Every year, rivers carry stones, soil, sand, leaves, and other debris from the catchment area into the reservoir. The accumulation of these materials has gradually raised the reservoir bed, reducing the amount of water it can hold.

According to the Nepal Electricity Authority (NEA), the reservoir originally had a storage capacity of 85.3 million cubic meters of water. Five years ago, that capacity had fallen to 59.99 million cubic meters.

When the Kulekhani-I Hydropower Project began operation in 1982/83, about 57 meters of the stored water could be utilized for electricity generation. After the major flood of 1993, only 50 meters of water remained usable for power generation. At present, only about 46 meters of water can be effectively used to generate electricity.

The continuous accumulation of debris has steadily reduced the volume of water available for power production. The 1993 flood alone raised the reservoir bed by six meters. Since then, the reservoir floor has continued to rise each year.

An engineer at Kulekhani-I said that approximately 170,000 cubic meters of debris have now accumulated in the reservoir.

Kulekhani-I, Kulekhani-II, and Kulekhani-III were constructed with the objective of utilizing the water stored in the Indrasarovar Reservoir.

As the rising reservoir bed has reduced its water storage capacity, all three Kulekhani powerhouses are likely to be affected. Experts have estimated the reservoir’s lifespan at 50 years.

The reservoir would have to be completely drained to remove the stones, soil, and silt accumulated at the bottom.

The Indrasarovar Reservoir was constructed at a cost of US$12 million.

Kantipur