Disaster Data Releases from Planet Labs PBC

# Planet Crisis Response — Bhote Koshi–Trishuli Outburst Flood, Nepal (2026)

> STAC catalog of Planet imagery covering the 26 August 2026 glacial outburst flood on the
> Bhote Koshi–Trishuli river corridor, Nepal and Gyirong County, Tibet Autonomous Region,
> China. 16 scenes from two sensors in three collections, split by event date.

STAC root: `catalog.json`. Base URL:
`https://data.source.coop/planet/disasterdata/nepal-flash-flood-2026-08-26`

## Contents

- 16 scenes as STAC Items, from two sensors at very different resolutions
- `pre-event/2026-05-27` — 5 PlanetScope (`PSScene`, ~3.8 m), 2026-05-27 05:32 UTC, satellite `254a`
- `post-event/2026-08-26` — 9 PlanetScope (`PSScene`, ~3.8 m), 2026-08-26 05:01 UTC (`255f`, 5
  scenes) and 05:45 UTC (`251f`, 4 scenes)
- `post-event/2026-08-27` — 2 SkySat (`SkySatCollect`, ~0.8 m), 2026-08-27 02:00 UTC, satellite
  `SSC1`, over the Rasuwagadhi border crossing and Syabrubesi
- Spatial extent: 84.894 to 85.648 E, 27.795 to 28.659 N
- Temporal extent: 2026-05-27 to 2026-08-27
- Asset keys vary by sensor: `visual` everywhere; `analytic_sr` (pre-event PlanetScope),
  `analytic` (post-event PlanetScope), `pansharpened` (SkySat); `udm2` (PlanetScope), `udm`
  (SkySat); `thumbnail` everywhere
- STAC GeoParquet indexes at `<phase>/items.parquet` and `<phase>/<collection>/items.parquet`

## Caveats that affect analysis

1. **Cloud cover is significant and varies by collection.** Pre-event PlanetScope 5–52% cloud
   (35–93% clear); post-event PlanetScope 62–93% cloud (2–14% clear); SkySat 50% cloud (~8%
   clear). Monsoon season. Filter on `eo:cloud_cover` and consult the mask asset. Reported
   clear fractions understate usable ground — much of the loss is thin haze through which
   terrain remains interpretable. Least obscured: `20260527_053226_41_254a` (pre-event),
   `20260826_050125_99_255f` (post-event PlanetScope), `20260827_020055_ssc1_u0001` (SkySat,
   Rasuwagadhi).
2. **Mixed analytic processing levels within PlanetScope.** Pre-event items carry `analytic_sr`
   (surface reflectance); post-event items carry `analytic` (top-of-atmosphere radiance).
   Surface reflectance was not yet published for the post-event scenes at assembly time.
   Pre/post analytic bands are not directly differenceable without atmospheric correction. The
   `visual` assets are comparable.
3. **13 of 14 PlanetScope scenes are `quality_category: test`**, not `standard`, in Planet's
   Data API. Only `20260527_053217_72_254a` is `standard`. Both SkySat collects are `standard`.
4. **Footprints do not fully coincide.** The post-event PlanetScope swaths extend further west
   and east than the single pre-event strip, so some post-event area has no matching baseline.
   The SkySat collects cover two focal points only, not the full corridor.
5. **Mask assets differ by sensor.** PlanetScope carries `udm2` (multi-class with confidence);
   SkySat carries `udm` (single-band). Code consuming masks must handle both.
6. **Resolution spans nearly 5×** (0.79–3.8 m GSD). Do not assume a uniform pixel size across
   the catalog; read `gsd` per item.
7. Casualty figures in the description are provisional as of 26 August 2026.

## License

CC-BY-NC-4.0 — attribution required, non-commercial use only.
https://creativecommons.org/licenses/by-nc/4.0/

Imagery © Planet Labs PBC via the Planet Crisis Response Program
(https://www.planet.com/disasterdata/).

## Related

Umbrella dataset: https://source.coop/planet/disasterdata