Science / Tue, 01 Sep 2026 hydro-international.com

New method fills the gaps in coastal tide monitoring

The findings could help improve coastal protection and navigation, particularly in regions where measuring stations are limited or absent. Yet in many coastal regions, that understanding is hard to come by. The newly developed method by researchers at TUM and the University of Oxford also uses satellite data, but in a new way. Previous satellite data could only provide this information at a resolution of about ten kilometres – a difference of a factor of 100. “This also allows us to close the data gap in coastal regions without their own tide gauge stations.” These are currently areas in parts of Africa or Southeast Asia.

Researchers at the Technical University of Munich (TUM) and the University of Oxford have developed a new measurement method that tracks tidal variability more accurately than existing techniques. Applying it to a 90km-long bay, they found tidal differences of up to one metre within that single area. The findings could help improve coastal protection and navigation, particularly in regions where measuring stations are limited or absent.

The tide is a familiar phenomenon along coastlines such as the North Sea, where water levels can shift substantially within a short span of time. Accurate and reliable knowledge of these movements is essential for coastal protection, flood forecasting and safe ship navigation. Yet in many coastal regions, that understanding is hard to come by. Tide gauge stations offer precise data, but only at the specific points where they are installed. Satellite measurements can cover more ground, but near the coast, their resolution is often not sharp enough to fill the gap.

The newly developed method by researchers at TUM and the University of Oxford also uses satellite data, but in a new way. Instead of measuring water depth along the coast, they use the beach itself as a 'ruler'. They combine the visible waterline on satellite images with the known slope of the beach. They can thus monitor sea levels and calculate tidal variations from these observations.

The method provides data accurate to within 100 metres. Previous satellite data could only provide this information at a resolution of about ten kilometres – a difference of a factor of 100. With this level of accuracy, they found, for example, tide differences of nearly one meter along a 90km stretch of coastline on a beach in New Zealand.

Better predictions

Thomas Monahan, one of the study’s authors and a research associate at the University of Oxford, says: “Our research shows that tides can vary significantly even over relatively short distances. This has major implications for the risk of coastal flooding. Small-scale differences in tides can determine whether two neighbouring regions are spared or flooded during the same storm. Once these methods are further refined, they could enable significantly more precise local tide forecasts. People would then no longer just learn about tide patterns in their region, but specifically what to expect on their beach.”

“Our method combines the precision of local tide gauge stations with the coverage of satellite imagery,” says Michael Hart-Davis of the German Geodetic Research Institute at TUM. “This also allows us to close the data gap in coastal regions without their own tide gauge stations.” These are currently areas in parts of Africa or Southeast Asia. This opens up new possibilities, particularly for navigation along the coastline. “ It also offers an opportunity to better assess flood risks involving a combination of factors, such as heavy rain, storm surges and high tides, or to determine when saltwater threatens to seep into the groundwater.”

In developing the method, the researchers relied on satellite imagery spanning more than 40 years, provided by NASA’s Landsat programme and the US Geological Survey. They hope this will enable them to make more reliable forecasts in the future. Additional data from programmes such as Copernicus Sentinel-2 could further increase spatial and temporal coverage in the future.