Kulekhani I

60 MW · operating · on the Kulekhani · in Makawanpur district.

Summary

Kulekhani I is Nepal's 60 MW upper reservoir hydropower plant and the anchor of the country's only operating storage cascade. The page documents its seasonal-shifting role, FY 2081/82 operating data, and sedimentation evidence.

Specifications

Sources

• NEA Annual Report FY 2024/25

Specifications (NEA FY 2081/82)

Kulekhani I is Nepal's only reservoir-type hydropower station — a dam-and-reservoir facility that stores monsoon runoff and releases it for generation during the dry months when the RoR fleet collapses. Two 30 MW Francis units operate as a peaking plant, also supporting voltage and system stability for the central grid.

The reservoir has a 65 m uncontrolled spillway and two radial gates designed for operation at EL. 1530 masl. On 12 Ashoj 2081, heavy rainfall caused the water level to rise beyond the spillway's capacity — both radial gates were opened at 1,530.20 masl to stabilize the reservoir, a reminder that even Nepal's only reservoir must handle extreme inflow events that RoR headworks simply pass through.

The Seasonal Shift in Practice

Kulekhani I takes the water that RoR plants must spill during monsoon surplus and converts it into dry-season generation from Mangsir through Baisakh (November–May). The NEA report states the plant "stores monsoon water and operates mainly during the dry season to meet peak demand." The reservoir level data confirms this cycle: a 45.2 m drawdown between the post-monsoon peak (1,531.5 masl in Ashoj) and the dry-season trough (1,486.28 masl in Baisakh/Chaitra).

This seasonal shifting is categorically different from the 4–6 hours of "peaking" pondage that PRoR plants like Marsyangdi and Kali Gandaki A use for daily load-smoothing. Those plants cannot store water across months — when the river drops in January, so does their output. Kulekhani I can.

The 64.5% year-over-year increase in generation (FY 2080/81 to 2081/82) tells the other half of the story. A reservoir plant is still governed by the monsoon that fills it. In a good monsoon year, the reservoir fills early and generation rises; in a drought year, the drawdown deepens and dry-season output collapses. The 279.8 GWh combined cascade generation in FY 2081/82 was a function of heavy monsoon filling, not a guaranteed floor.

Why 106 MW of Storage Is Not Enough

The cascade page notes that 106 MW across Kulekhani I + II + III is Nepal's entire reservoir hydropower base against a fleet of 3,400+ MW — a ratio of roughly 3%. Kulekhani I's operational data makes this concrete.

The NEA's own Large Generation O&M Department data (page 21 of the FY 2024/25 report) shows that seven plants totaling 465 MW generated 2,487 GWh in FY 2081/82 — about 86% of NEA's total annual generation. Kulekhani I's 170.56 GWh represents only 6.9% of that large-plant subtotal.

In dry-season months, when the RoR fleet output collapses to 25–40% of monsoon peak, Kulekhani I is the only facility that can meaningfully offset the shortfall. At 60 MW, it cannot close the gap alone. The reservoir can shift water across months, but the plant's capacity puts a hard ceiling on what shifting can accomplish. See Storage Deficit for the system-level arithmetic.

Sedimentation — Quantified

Kulekhani I was commissioned in December 1982 (Unit 1) and May 1987 (Unit 2), with a reservoir storage volume of 85.3 MCM. Sediment monitoring began in June 1989 and has been conducted continuously since. Multiple post-2010 Differential GPS bathymetric surveys and RUSLE modelling studies provide updated capacity loss figures.

Capacity loss trajectory

A declining rate — but irreversible accumulation

While the absolute capacity loss has deepened, the rate of sedimentation entering the reservoir has steadily declined due to improved watershed management, afforestation, and land-use changes in the upstream catchment:

This is evidence that watershed-level sediment control works — the rate has dropped by nearly two-thirds over 16 years. But because sedimentation is cumulative and largely irreversible without economically paralyzing dredging operations, the total volumetric loss has continued to deepen even as the inflow rate slowed. Physical DGPS bathymetric surveys (Sangroula, NTNU/Hydro-Lab, 2009/2010) measured cumulative total storage loss at 20.4 MCM out of 85.3 MCM original — 23.9% gross loss, 19.1% active live storage loss. Separate InVEST/RUSLE spatial catchment modeling (Bokan et al., 2021–2024) tracked the declining watershed sediment delivery rate (13.3→4.8 t/ha/yr) but does not directly measure reservoir volume.

Source: JICA Nationwide Master Plan Study on Storage-type Hydroelectric Power Development in Nepal, Vol. 1 (2014), pp. 72–73, citing Sangroula (2007); Sangroula, D.P., Sedimentation and sustainability of the Kulekhani Reservoir: A Himalayan Case, NTNU doctoral dissertation (2006, DGPS surveys 2009/2010); Bokan, L.T. et al., Potential Sedimentation Rate and its Prioritization in Kulekhani Watershed Using InVEST Model (2024, modeling 2002–2018 data).

What this means

A ~24% gross capacity loss over ~30 years (20.4 MCM of 85.3 MCM original, per DGPS bathymetry) means current total storage is approximately ~65 MCM. However, the critical metric for generation is active live storage: with 14 MCM of live storage lost (19.1%), effective seasonal-shifting capability is reduced to roughly ~59 MCM. The "106 MW of storage" claim in planning documents remains misleading — not because the absolute loss is higher, but because even a 19% active storage loss materially reduces the system's dry-season peaking capacity.

This has two structural implications:

1. Kulekhani's own future. Every year of continued sedimentation — even at the declining rate — further reduces capacity. The reservoir will eventually reach dead storage (capacity below which intake gates cannot function) unless dredging or flushing interventions are deployed at scale. The sloping intake structure and sediment control dam (see Countermeasures below) have slowed but not stopped this trajectory.

2. Template for future storage. Tanahu (140 MW), Dudhkoshi (635 MW), and Budhigandaki (1,200 MW) are all proposed reservoir projects in catchments with comparable or higher sediment yields. The ERC's 2026 reservoir directive mandates a 50-year design life for new storage projects. Kulekhani's ~19% live storage loss over 30 years — in a catchment with aggressive afforestation and sediment control dams — suggests that without aggressive watershed management and sediment bypass systems from day one, a 50-year reservoir will lose more than half its capacity before its design life expires — and the cost-plus tariff written at commissioning will not cover the mid-life capacity that no longer exists. See Sediment as Design Constraint and Storage Deficit.

Countermeasures deployed

Following the flood damage, Japan-supported disaster prevention projects implemented three sediment management measures at Kulekhani:

• Sediment control dam constructed upstream on the Kulekhani River and at the river mouth in the reservoir to trap sediment before it reaches the main reservoir body.
• Sloping intake structure to prevent clogging of the intake by sediment and enable water withdrawal even as sedimentation levels rise.
• Hydrosuction Sediment Removal System (HSRS) under examination — uses the water head between upstream and downstream to suck sediment from the reservoir bottom and discharge it downstream through a pipeline.

These measures, combined with watershed afforestation, have reduced the annual sedimentation rate from 13.3 t/ha/yr (2002) to 4.8 t/ha/yr (2018). But the cumulative capacity loss continues — and no intervention deployed to date has reversed it.

Limitations & Controversies

Kulekhani I is well documented relative to many entity pages, but its storage-loss figures come from multiple measurement and modeling frames that should not be casually merged. Current live storage, sedimentation rate, operating rule curves, dredging feasibility, and climate-era inflow reliability require updated technical verification before using the page for project-design benchmarking.

See also

• Kulekhani Cascade — full three-plant system overview (106 MW combined)
• Kulekhani II — downstream cascade plant (32 MW, commissioned 1986)
• Storage Deficit — why 106 MW against 3,400 MW defines Nepal's energy problem
• Firm Power — what reservoir generation provides that RoR cannot
• Seasonal Mismatch — the monsoon-to-drought cycle Kulekhani partially offsets
• Sediment as Design Constraint — reservoir sedimentation dynamics
• Tanahu Hydropower Project — next proposed reservoir (140 MW, under construction)
• Dudhkoshi Storage Hydroelectric Project — long-term storage development (635 MW)