Bhote Koshi & Trishuli flood

31.7 km² of water, observed 27 August 2026, inside a 90.1 km² area of interest.

Source HOT · HDX / Rebuilt daily / checking…

Only the blue extent is water. Everything else is the 200 m margin around it.

Satellite: whole corridor

None Sentinel-2, after Sentinel-2, before Sentinel-1 radar

10 m, covering the whole corridor including the reach through Dhading and Nuwakot.

Photos & footage

Show located media

Event media only. No photos exist of individual damaged buildings.

Official incident reports

BIPAD portal, NDRRMA

Reports, not a survey. No dot means no report.

Bridge condition: ground reports

Click a bar to filter. Click a bridge to fly to it.

Source of the flood

Show source & seismic events

26 Aug, 08:37 NPT. Glacial collapse and debris flow, upper Lhende Khola. USGS M5.2.
26 Aug, 11:45 NPT. Second landslide, M4.2.
27 Aug. Flood extent observed from satellite and drone imagery.

Not an earthquake. First reported as M4.4, then reclassified by USGS as a glacial collapse. The shaking was the result, not the trigger.

Ongoing risk: barrier lake

About 2 million m³ pooled behind debris near the border, already overflowing. China expects 3 million m³ more by 30 August. A breach would follow the same gorge.

Forecast, not observed. Nothing on this map shows it.

Where the mapping stops

Mapping ends at Devghat. The flood did not. Bodies were recovered downstream through Chitwan and both Nawalparasi districts.

Unmapped, not unaffected. No open data covers the reach below Devghat.

AI building damage: fAIr

Show scored buildings

Min confidence0%

Preliminary AI from satellite imagery, not field checked. Scored only inside the yellow outline.

Flood extent

Show water line

Wider context

River corridor

1 km buffer along the river to Devghat. 317 km², six districts, 97,640 features.

Volunteer mapping tasks

District boundaries

Eight districts, classed by how far the survey reached.

Context only, not an impact assessment.

Data source

The same ground mapped twice. Flip to compare coverage.

Layers

Basemap

Satellite is a Sentinel-2 cloud free mosaic for 2024, so it shows the valley before the flood. Pair it with the water line to see what stood on the ground that flooded. It is not post event imagery and shows no damage.

Corroborating estimates

Microsoft AI for Good Lab: 37 km² impacted, 4,977 buildings, about 10,200 people. Their files cannot be loaded cross-origin, so the figures are quoted, not drawn.

Mapped data: HOT / HDX flood-affected area and fAIr damage assessment, ODbL. Seismic events from USGS. Barrier lake and downstream casualty figures reported by Kathmandu Post and Al Jazeera. © OpenStreetMap contributors, Overture Maps, volunteer field reports.

Rendered in browser from a 4.1 MB PMTiles archive, no backend

Loading flood layers…