Radar remote sensing aids study of the Great Flood of 1993



Until recently, remote sensing of river floods was constrained by low spatial resolution and cloud cover, which made it impossible to obtain data during the initial stages of most large events. The 1991 launch of the European Remote Sensing (ERS-1) satellite removed both of these constraints. In 1993, ERS-1 put its capabilities to the test, acquiring imagery and a wealth of information about the flooding of the Upper Mississippi Valley.

The cloud-penetrating C-band synthetic aperture radar (SAR) on board ERS-1 produces ground range (cross-track) resolution of approximately 30 m, and azimuth (alongtrack) resolution of approximately 6–30 m. While ERS-1 and its successor, ERS-2, are multipurpose research satellites and their operating systems are not optimal for flood investigations, the satellite's busy operating schedule and its near-global capability have resulted in the chance acquisition of many images of major flood events.