Mapping a Salt Marsh, Centimetre by Centimetre

Mon, 28 Sep 2026 00:00:00 +0000

Near the village of Wierum, on the Frisian coast of the Wadden Sea, a drone flies over the salt marsh every few months. Each flight becomes an orthophoto at 1.4 cm per pixel: about 222,000 by 98,000 pixels, more than 20 billion in total. For CODAP, the Coastal Data Portal we built with Rijkswaterstaat and Lumax AI, a segmentation model labels every one of those pixels as mudflat, salt marsh, macro-algae, shells, dike grass or asphalt, so that coastal managers can compare surveys in a browser.

Watching a Coastline Move, Centimetre by Centimetre

Mon, 28 Sep 2026 00:00:00 +0000

A salt marsh protects the dike behind it only as long as it keeps up with the sea. Whether it does comes down to a sediment budget measured in centimetres: mud settling on the flats in front of the marsh, and the marsh edge crumbling where waves attack it.

At Wierum, on the Frisian coast of the Wadden Sea, we measured those changes across the whole site for CODAP, the Coastal Data Portal we built with Rijkswaterstaat and Lumax AI. Between January 2024 and March 2026, half of the site rose by 11 cm or more, and the fields between the brushwood groynes by up to about half a metre. Along the marsh edge, a narrow band dropped by up to about 50 cm.

Geospatial on earthtoolsmaker

Mapping a Salt Marsh, Centimetre by Centimetre

Watching a Coastline Move, Centimetre by Centimetre