Flood

During flood events, rapid mapping of inundated areas guides evacuation and relief efforts.

Sensor: SAR (works through clouds and at night).

Pipeline:

• Collect: SAR image over flood-risk AOI.
• Map: classify pixels as water/non-water using backscatter threshold (water is specularly reflective -> dark in SAR). Compare against pre-flood baseline to identify newly inundated areas.
• Reduce: compute total flooded area, identify affected infrastructure (by overlaying with a stored vector map of roads/buildings). Generate alert.

Alert payload: ~5 KB (flood extent polygon, area km^2, list of affected infrastructure IDs, timestamp).

Feasibility:

• Water/non-water classification in SAR is robust and simple (bimodal histogram thresholding).
• Infrastructure overlay requires storing a lightweight vector map onboard (feasible for a bounded AOI).
• Time-critical during active flood events.