Trishuli Valley Glacial Collapse Impact & Hydropower Flow Simulator

Simulation Parameters

Glacial Ice-Rock Mass 14.5 M m³

Baseline collapse volume estimate above Langtang / Trishuli origin.

Meltwater / Slurry Ratio 48%

Slurry fluidity directly governs downstream mud-wall velocity.

Downstream Warning Lead Time 12 min

Time available for tunnel evacuations and dam gate drops.

Riverbed Geomorphology

Comparative Scenarios

⚠️ Ground Observation Record

On August 26, an immense ice and rock mass broke loose high above Nepal's Trishuli valley, precipitating a catastrophic debris flow. Hydropower engineer Kabir Maharjan and hundreds of dam site personnel were submerged in turbine tunnels and powerhouse excavations. Over 1,300 confirmed deceased with thousands still unrecovered along the upper cascades.

Impact Data & Briefing

Peak Discharge (Q_max)

8,500 m³/s

8.2× normal monsoon flood

Wave Front Velocity

16.4 m/s

59 km/h alpine surge

Time to Upper Trishuli-3A

38 mins

Distance: 37 km from collapse

High-Risk Workforce

450 crew

Est. 1,300+ valley deaths

Elapsed Time: T+38 min

Trishuli Basin Features

Glacier Collapse Origin (Peak Crest)

Trishuli River Flow Channel

Hydropower Station / Dam Intake

Mud-Ice Surge Front Location

Cascading Wave Front Progression Along Trishuli Hydro Corridor Wave Front: Overtopping Upper Trishuli-3A Dam

Hydropower Station Vulnerability Audit 6 Major Facilities

Facility	Km	Wave Arrival	Workers	Inundation	Status

Casualty & Rescue Zone Triage Estimator Empirical GLOF Matrix

Upper Gorge (Mailung - UT3A): Catastrophic Impact (450+ workers)

Mid Basin (Betrawati / Dhunche confluence): High Inundation (Bridge Washout)

Lower Basin (Trishuli Bazar & Bidur): Secondary Mud Sedimentation

*Model accounts for lead evacuation alert time, tunnel subterranean depth, and sudden tailrace flooding experienced by Kabir Maharjan's crew during the August 26 event.