Flood Mapping Using Synthetic Aperture Radar Sensors From Local to Global Scales

Synthetic aperture radar (SAR) sensors have emerged as the preferred mode of flood monitoring due to their all-weather, all-day imaging capabilities. Current and upcoming SAR satellites provide high-resolutions and shorter revisit times, which can facilitate effective resource allocation during emergency response. However, the sensitivity of microwaves to surface roughness and the side-looking imaging geometry often result in ambiguity in flood detection. This chapter provides an overview of the challenges and opportunities associated with operational SAR-based flood mapping at multiple scales. The principles of SAR imaging are outlined with reference to flood detection problems, and the state-of-the-art solutions proposed in literature to eliminate these effects are critically discussed. Finally, a few selected case studies that demonstrate the potential of SAR-derived extents for operational flood mapping are presented.