Flood Playback

What did the 2022 Assam floods look like from space, day by day?

Flood Playback is a viewer for the June 2022 floods in Assam and nearby northeast India. It plays a locally generated sequence built from NASA GIBS MODIS flood observations, with the original imagery and false-color satellite views available for comparison.

ForAnyone curious about how satellite flood observations change over the course of an event, and people who want to see the limits of that data.

SolvesSatellite flood products are published as daily tiles with caveats attached, and it is hard to watch an event unfold or tell observation from inference.

What is Flood Playback?

Flood Playback lets you scrub through the June 2022 flooding in Assam using NASA’s MODIS flood product. The default viewer plays a sequence generated locally from the observations, and you can switch to the original flood imagery or to false-color satellite imagery to compare.

The data comes with important caveats, and the viewer keeps them visible. NASA’s flood product uses a rolling three-day observation window. The results are categorical observations, not water depth and not a forecast. Clouds and gaps in coverage can hide water, so a transparent pixel must not be read as dry land.

How the sequence is built

Combined playback keeps each day’s valid observations and fills missing pixels only from the latest original observation in the preceding two days. Gaps that remain are drawn with a faint hatch. Six-hour frames between days blend adjacent combined maps using premultiplied alpha; they are a visual transition, not an estimate of water movement. Every combined or interpolated frame is labeled as derived, and the original mosaics, source hashes and per-pixel age maps stay in the bundle for provenance.

A Python pipeline using numpy and Pillow downloads the tiles for June 12 to 30, 2022, caches them, and caps each run at 64 MiB. A manifest file describes the published sequence and its method.

Playback

The local bundle covers northeast India at Web Mercator zoom 8. Playback preloads nearby frames and keeps the current frame on screen until its replacement is ready. The basemap, from OpenFreeMap and OpenStreetMap contributors, and the satellite mode still need an internet connection.

An older synthetic depth demonstration remains available behind a query flag for testing the depth-raster pipeline.

Imagery is provided by NASA’s Global Imagery Browse Services.