Integrated geomatics for seamless coastal mapping: a vulnerable coastline in the central Adriatic Sea

The dynamic interface between land and sea - often referred to as the ‘white ribbon’ by the British Geological Survey - remains one of the most challenging zones for high-resolution surveying due to its inaccessibility to both traditional marine and terrestrial methods. Yet, this intertidal and nearshore region is critical for assessing coastal vulnerability, sediment dynamics, and erosion risk, especially under climate change pressures. This study presents an integrated geomatics-based approach to generate a seamless, high-resolution digital elevation model (DEM) for the vulnerable coastline of Sirolo (Central Adriatic Sea, Italy), characterized by steep cliffs and dynamic sedimentary processes. A suite of complementary datasets - including GNSS-derived elevation points, single- and multibeam echosounder data (via Autonomous Surface Vehicle and survey vessel), and UAV-based photogrammetry - were harmonized to bridge the coastal data gap. The resulting DEM supports numerical simulations to evaluate the effectiveness of adaptation measures and nature-based coastal defense strategies.