Satellite Coastline Images Enable High-Resolution Tide Mapping

Researchers have developed a technique that uses decades of satellite imagery to chart tidal variations along coastlines with far greater spatial detail than traditional water-level gauges. The method tracks the land-water boundary in thousands of images and combines it with beach slope data, revealing tidal height differences of up to one meter within just a few kilometers. This approach could improve tide predictions in remote regions like Greenland, where gauge coverage is sparse.

The technique leverages more than four decades of Landsat imagery, treating the shifting land-water boundary as a measurable signal rather than data noise. By pairing thousands of coastline observations with beach slope information, researchers can derive local tidal heights with spatial resolution far exceeding that of conventional gauges, which are typically spaced 50 kilometers apart or more.

Published in Communications Earth & Environment, the study involved collaboration between DTU Space, the University of Oxford, the Technical University of Munich, and German space firm OHB. The approach holds particular promise for Greenland, where only a handful of physical gauges exist despite daily tidal swings reaching five to six meters. In contrast, Denmark's dense gauge network and modest tidal range make the method less critical there.