Alos-2/4 Automatic Flood Detection Algorithm: Updates and Recent Results

The all-weather, day-and-night imaging capability of synthetic aperture radar (SAR) has become essential for flood monitoring. We have developed and implemented a fully automatic flood detection algorithm using SAR data from Advanced Land Observing Satellite-2 (ALOS-2). The algorithm rapidly processes ALOS-2 and ancillary data (flood simulation, hazard map, and other geographical information) and provides damage information less than an hour after the input data are entered. The algorithm has been operational since 2022 for disaster response users and is still being improved for better accuracy and robustness. During the two years of operation, our algorithm has responded to 15 flood events, demonstrated superior performance, and provided information used in disaster response activities.