Nepal Flood 2026: fAIr Damage Assessment, Upper Trishuli and Bhote Koshi

OpenStreetMap and Overture Maps vector layers for the area flooded in the 2026 Bhote Koshi and Trishuli flood in Nepal, and the ground immediately around it. The area of interest is the observed flood extent of 27 August 2026 widened by 200 metres. The extent itself was mapped from drone, Landsat, PlanetScope and Sentinel imagery and is published here as its own resource, so the water line can be separated from the margin around it. That margin brings in buildings and roads beside the water, so a feature being in this dataset is not evidence that it was flooded or damaged. Clip to the Flood Extent resource when you need figures for the water itself. The area follows the river from Rasuwagadhi to the Narayani confluence, across Bagmati and Gandaki Provinces and the districts of Rasuwa, Nuwakot, Dhading, Gorkha and Chitawan. Every layer holds what is standing and what has been lost, so buildings and roads do not vanish from a download once mappers record them as destroyed. `status` says Standing, Damaged or Destroyed, and the Destroyed and Damaged Features layer gathers everything marked destroyed or damaged in one place. Layers are rebuilt straight from OpenStreetMap through the day, so they carry volunteer work as it lands. Buildings, schools, health facilities and points of interest also come in an Overture version, which fuses Microsoft, Google and OpenStreetMap and reaches ground volunteers have not mapped yet. Overture follows its own release cycle and will not show mapping done during this response, so for damage work prefer the OpenStreetMap layers and use Overture where their coverage is thin. Mapping task boundaries from the Tasking Manager campaign show where volunteers are being asked to map. The bridge damage assessment is reported from the ground by volunteers and lists road bridges with their condition after the flood, deck length where measured, and administrative codes from the same boundaries as the other layers. For the wider 1 km river corridor under assessment, use Nepal Flood 2026 River Corridor. AI-scored building damage from post-event imagery is published separately as Nepal Flood 2026: fAIr Damage Assessment. Subscribe to the dataset for updates as mapping progresses. - Source: OpenStreetMap, Overture Maps, NAXA and volunteer field reports - Part of HOT disaster response exports on HDX by HOT

OpenStreetMap and Overture Maps vector layers for the full Bhote Koshi and Trishuli river corridor in Bagmati and Gandaki Provinces, Nepal, for the 2026 flood response. The area of interest is a 1 km buffer around the river centrelines, running from Rasuwagadhi on the China border to the Narayani confluence at Devghat in Chitawan, across Rasuwa, Nuwakot, Dhading, Gorkha, Tanahu and Chitawan. It merges the original partner shapefile for the upper reach with OCHA's HPCS corridor downstream. This is the wide planning view, the whole corridor under assessment rather than the ground that flooded. For data limited to the flooded area, use Nepal Flood 2026 Flood Affected Area, which clips every layer to the observed inundation footprint of 27 August 2026 and a 200 m margin around it. Every layer holds what is standing and what has been lost, so buildings and roads do not vanish from a download once mappers record them as destroyed. `status` says Standing, Damaged or Destroyed, and the Destroyed and Damaged Features layer gathers everything marked destroyed or damaged in one place. Layers are rebuilt straight from OpenStreetMap each day, so they carry volunteer work as it lands. Buildings, schools, health facilities and points of interest also come in an Overture version, which fuses Microsoft, Google and OpenStreetMap and reaches ground volunteers have not mapped yet. Overture follows its own release cycle and will not show mapping done during this response, so for damage work prefer the OpenStreetMap layers and use Overture where their coverage is thin. Subscribe to the dataset for updates as mapping progresses. - Source: OpenStreetMap, Overture Maps - Part of HOT disaster response exports on HDX by HOT

Overture building footprints and IHME population estimates in the identified impacted area from the 26 August flash flood in Nepal. - 37 sq km impacted - 4,977 intersecting Overture building footprints - IHME 2026 Population Estimate 10,203.8

satellite imagery by Vantor, acquired 2026-08-26 to 2026-08-26, 37.4 cm per pixel, published on OpenAerialMap.

Building footprints across the area: every feature tagged `building=*`, from residential homes to hospitals, schools, and places of worship. Useful for population estimation, damage assessment, and urban planning. Coverage reflects where volunteer mappers have been active. Urban areas are usually well represented, remote areas may be sparse. Cross-check critical decisions with local field knowledge. - Source: OpenStreetMap, a free, collaborative world map - Tags: building - Part of the country exports on HDX by HOT

This dataset provides a rapid damage screening assessment for the 26 August 2026 Nepal flash flood and debris-flow event using 10-m Sentinel-1 Synthetic Aperture Radar (SAR) data. A post-event radar acquisition acquired on 28 August 2026 was compared with a one-year pre-event Sentinel-1 baseline to identify unusually strong changes in radar backscatter. The resulting damage proxy was spatially averaged using a 50 m neighbourhood and restricted to a built-environment search domain (residential and non-residential) defined from pre-event Overture building footprints and a 30 m surrounding buffer. A conservative operational threshold (K50 absolute z-score ≥ 1.60) was used to identify high-confidence likely-damage/change areas. The resulting layer was visually reviewed at post-processing level to remove identified artefacts. Across the assessed area, approximately 245.13 ha of high-confidence change were identified within approximately 4755 ha of assessed built-environment domain across 58,557 ha of assessed AOI. Admin-3 summary statistics are provided for 16 municipalities intersecting the analysis area. The product is a likely-damage / unusual-change proxy and not proof of structural or building-level damage. It is intended to support rapid geographic prioritisation, complementary imagery review and field assessment.