Satellite imagery breakthrough enables high-resolution coastal tide mapping

Researchers from the University of Oxford and Technische Universität München have developed a new method to map coastal tides at a 100-meter resolution using satellite imagery. This technique addresses the limitations of traditional tide gauges, which provide data only at specific locations, and satellite radar, which often lacks fine detail.

The method utilizes decades of shoreline data from NASA and the US Geological Survey’s Landsat program. By treating the beach as a measuring tool, scientists can observe how the waterline shifts along a sloping shore as tides rise and fall. This allows for the calculation of sea-level changes with unprecedented precision.

Testing the method on Pacific coastlines revealed significant tidal variations over short distances. For instance, in New Zealand’s South Taranaki Bight, tidal levels varied by nearly one meter across a 90-kilometer stretch. These findings suggest that local tidal conditions can differ substantially from broader models, which is critical for predicting how sea levels will impact specific coastal areas.