Archipelago
Near-real-time flood extent from Sentinel-1 SAR
A backend service that turns fresh Sentinel-1 GRD scenes into flood extent rasters on a ~6-hour revisit, built on cloud-native geospatial formats end-to-end.
Placeholder case study. The real writeup lands once the project is built.
Why SAR
Optical sensors don’t see through clouds, and floods live under clouds. Synthetic aperture radar is the only wide-area source that reliably produces signal during weather events, which is exactly when flood maps matter. Sentinel-1 provides free C-band SAR on a six-day revisit globally — the best public-domain starting point for a responder-scale flood map.
Architecture sketch
- Discovery: Element84 Earth Search STAC API for Sentinel-1 GRD items.
- Access: COG HTTP range reads via
rasterio/rio-tiler. No full-scene downloads. - Preprocessing: Lee filter speckle reduction, radiometric terrain flattening with Copernicus DEM.
- Model: A small U-Net trained on the WorldCover flood masks + Sen1Floods11.
- Serving: FastAPI endpoint + PMTiles output for the web viewer.
Current state
Scoping the dataset and infrastructure. Real content lands when the first end-to-end revisit passes.
Colophon
Placeholder — will list data sources, CRS, libraries, model checkpoint, and references when published.