Automatic Flood Extent and Depth Estimation Using Alos-2 and Flood Simulation Data

The all-weather, day-and-night imaging capability of synthetic aperture radar (SAR) has become essential for flood disaster monitoring. This study developed a SAR-based flood monitoring method that automatically estimates flood extent, floodwater depth, and their changes. The flood extent was estimated from a Bayesian probabilistic model using ALOS-2 SAR data (amplitude and coherence) and hydrodynamic simulation data provided by Today's Earth (TE). The floodwater depth was calculated using the SAR-derived flood extent and high-resolution digital elevation model (DEM). We examined our methods using ALOS-2 data for the 2015 flood in Japan.