Nalsyau Gad

Nalsyau Gad is a 410 MW storage candidate in the Karnali basin and the best dry-energy performer in the JICA promising-storage set used by this wiki. It is pinned in both Layer: Storage Shortlist and Layer: Priority Watchlist because it contributes the kind of dry-season energy Nepal's run-of-river-heavy system is missing.

Summary

Nalsyau Gad is a 410 MW JICA promising-storage candidate in the Karnali basin and the best dry-energy performer in the JICA shortlist used by this wiki, with 581.8 GWh dry-season energy (41.4% dry share). It is pinned in both the storage shortlist and priority watchlist. The page tracks it as a dry-season portfolio option using the JICA/NEA source set.

Specifications

Storage

Output

Sources

• JICA IPSDP Final Report Annexes (Vol. 2)
• MoEWRI IPSDP Executive Summary

Why It Matters

Nalsyau Gad's value is not just its 410 MW nameplate. The JICA/NEA storage-screening figures give it 581.8 GWh of dry-season energy, equal to 41.4% of annual energy. That is the strongest dry-energy output in the promising-storage shortlist and one of the few project records that directly addresses the Storage Deficit rather than only adding wet-season energy.

Shortlist Context: How Nalsyau Gad Compares

Among the JICA promising-storage candidates in the wiki, Nalsyau Gad occupies a unique position — highest dry-energy share by a significant margin:

What makes the 41.4% figure significant is that it approaches the dry-share range of seasonal-storage projects with much larger reservoirs. Kulekhani Cascade achieves ~50% dry share with only 106 MW. Budhigandaki Hydroelectric Project projects 42% at 1,200 MW with 3,300 MCM of total storage. Nalsyau Gad is delivering comparable dry-energy concentration with less than one-tenth the reservoir volume of Budhigandaki and at a capacity point that is commercially viable for domestic financing.

This is why it appears in the priority watchlist despite being survey-stage. A project can be strategically important before it is construction-ready if it changes the dry-season balance, especially in a system where Kulekhani Cascade is still the only operating seasonal-storage anchor and Tanahu Hydropower Project is the only large storage project in active construction.

Reservoir Economics

Nalsyau Gad's 296.3 MCM effective storage on 410 MW yields a storage-to-capacity ratio of 0.72 MCM/MW — lower than Naumure (2.37 MCM/MW) or Sun Koshi No.3 (1.04 MCM/MW), but the project achieves its high dry share through a different mechanism: favourable basin hydrology in the upper Karnali catchment rather than sheer reservoir volume. The Karnali basin receives reliable monsoon precipitation and has a less flashy dry-season recession than eastern basins like the Koshi, meaning a moderate storage volume can achieve proportionally more dry-season firming.

This hydrological advantage is partly why the Karnali basin dominates the JICA shortlist: 6 of the 9 candidates (Nalsyau Gad, Lower Badigad, Naumure, Madi, Andhi Khola, Chera-1) are Karnali-basin projects. The basin's flow regime is intrinsically more storage-friendly.

Status And Timing

Nalsyau Gad should be read as a planning / promising-storage candidate, not a confirmed near-term build. The IPSDP milestone ladder groups Nalsyau Gad STO in the 2031-2035 project window. That is a planning sequence, not a construction contract.

Near-term milestones that would need to occur:

• Feasibility study update — the JICA IPSDP provides screening-level data; a bankable feasibility study is the next technical gate
• Developer assignment — currently no developer is designated (unlike Dudhkoshi/NEA or Tanahu/NEA). VUCL (Vidhyut Utpadan Company Limited) is the most likely candidate given its mandate for Karnali-basin storage (Mugu Karnali Storage HEP, Phukot Karnali)
• Environmental and social screening — the Nalsyau Gad catchment requires baseline data on resettlement footprint, downstream water-use impacts, and biodiversity
• Financing structure — whether this follows the NEA/AIIB sovereign model (Dudhkoshi), the VUCL/PPP model (Mugu Karnali), or a new structure
• Transmission evacuation — routing from the upper Karnali catchment into the western hill grid and ultimately to the 400 kV backbone. See Nepal Transmission System — 400 kV Landscape & Cross-Border Plan (2025)

Transmission & Grid Integration

Nalsyau Gad's location in the upper Karnali catchment presents a transmission challenge. The western Karnali region has limited 220 kV connectivity; the nearest 400 kV infrastructure is the proposed Karnali corridor. A 410 MW storage plant in this location would require:

• A dedicated 220 kV transmission line from the powerhouse to the nearest substation
• Integration with the planned Karnali basin transmission backbone (linked to Upper Karnali and Mugu Karnali Storage HEP evacuation plans)
• Possibly a collector substation serving multiple Karnali storage projects (Nalsyau Gad, Lower Badigad, and Madi are all in the same general catchment)

The transmission constraint is not a deal-breaker — 410 MW is within the range of standard 220 kV double-circuit capacity — but it adds a material cost component that the JICA screening-level cost estimates may not fully capture. Transmission costs for western hill storage are consistently higher per km than eastern corridor equivalents.

Geological & Site Character

The Nalsyau Gad site is in the upper reaches of the Nalsyau Gad river — a Karnali tributary draining the southern flank of the Saipal Himal range in far-western Nepal. The JICA screening identifies the site as having suitable dam-axis topography for a storage reservoir with ~420 MCM total capacity, suggesting a relatively wide valley section upstream of a constriction — the classic storage-dam site geometry.

Key geological considerations include:

• Himalayan foothill geology — sedimentary and metamorphic rock formations typical of the Lesser Himalayan zone, with potential for weak interbedded shales
• Seismic zone 4+ — within the active Himalayan deformation front
• Sediment load — the Nalsyau Gad drains steep terrain; sediment management in the reservoir design will be critical for maintaining active storage volume over the project life. See Sediment as Design Constraint
• GLOF exposure — lower than the Dudh Koshi or Arun basins, but the upper Karnali has glacially-fed tributaries that require assessment

Limitations & Controversies

• Survey-stage data only. The JICA IPSDP figures are screening-level, not bankable. A full feasibility study could shift capacity, energy, or storage numbers materially.
• No developer assigned. Unlike Dudhkoshi (NEA), Tanahu (NEA), or Mugu Karnali (VUCL), Nalsyau Gad has no institutional sponsor moving it forward.
• Transmission cost uncertainty. The western hill grid is less developed than the eastern and central corridors. Evacuation from a remote Karnali tributary adds cost.
• Competing Karnali priorities. The Karnali basin has multiple storage candidates vying for limited development bandwidth: Mugu Karnali (1,902 MW, pre-construction), Phukot Karnali (426 MW, survey), Upper Karnali (900 MW, stalled), Karnali Chisapani (10,800 MW, conceptual). Nalsyau Gad must compete for developer attention, financing, and transmission capacity with larger projects.
• Downstream water-use impacts. The Nalsyau Gad feeds the Karnali main stem; flow alteration could affect downstream ecosystems and, potentially, cross-border flows into India's Ghaghara system. See Hydro-Geopolitics.

Map Interpretation

The map marker is a river-aligned project reference derived from the registry/project point. It is suitable for basin-level and corridor-level comparison, but it should not be treated as a final dam-axis coordinate.

Registry note

• JICA/NEA storage master plan volume 2

See also

• Karnali Basin
• Storage Deficit
• Firm Power
• IPSDP Milestone Ladder 2022-2040
• Layer: Storage Shortlist
• Layer: Priority Watchlist
• Mugu Karnali Storage HEP — the largest Karnali storage project
• Sediment as Design Constraint
• Nepal Transmission System — 400 kV Landscape & Cross-Border Plan (2025)
• Map Inventory