Increasing land take in Europe’s land-water interface

Xiang Liu , Tobias Kuemmerle, Matthias Baumann, Shawn Adrian Schneidereit, Sonja C Jähnig

Ecosystems at the interface between terrestrial and aquatic areas are of outstanding ecological and socio-economic importance, yet are under intense pressure due to the concentration of human settlement and agriculture. Despite this, the broader geography of the land-water interface and how it is changing remains poorly understood. Here, we develop an operationalizable definition of the land-water interface and use a fuzzy logic geospatial model to map the land-water interface at high resolution across the European continent. Our results show that the land-water interface covers ~0.87 million km² (~8% of Europe) but is strongly affected by human use: in 2020, about 15% of all built-up areas and more than 8% of all croplands lay within the land-water interface. Analyzing land-cover trends inside the land-water interface since 1992 showed increasing land take: built-up area more than doubled (from 13,752 km² to 29,302 km²), driven primarily by cropland-to-urban conversion. The expansion and densification of built-up areas occurred particularly in lowland river corridors, deltas, and coastal plains. Cropland decline was particularly widespread across Central and Eastern Europe, while cropland expansion occurred in land-water interface regions in northern Europe. Across interface types, the lake land-water interface exhibited the strongest relative increase in built-up areas (>150%) and the sharpest proportional cropland loss compared to riverine and coastal land-water interfaces. Countries inside the European Union had earlier and more intense urbanization trends than non-EU regions, with a slowdown after 2010. More broadly, our results reveal a continental-scale pattern of increasing, and largely irreversible, land take in the land-water interface, likely straining the ecological integrity, buffering capacity, and connectivity of land-water ecosystems. Our land-water interface concept and harmonized maps enable consistent mapping and regional cross-comparisons, support identification of priority areas for conservation and restoration, and provide a baseline to track progress towards flood-risk reduction and restoration targets.