Global Coastal Satellite-Derived Bathymetry

Coastal zones are home to about 40% of the world's population and include key infrastructure and ecosystems. These regions are crucial for economic activities like maritime transport or the deployment of offshore renewable energy, are vital for human settlement and contain unique habitats. Erosion, sediment transport, climate-change, and human activities exert pressure on coastal zones and make them highly dynamic. Accurate mapping of shallow water bathymetry is essential for effective and sustainable management, yet many areas remain unmapped or have outdated bathymetry data. A pivotal technology facing the challenge of bathymetry mapping on a large scale is Satellite-Derived Bathymetry (SDB), which has become a game-changing method for understanding and managing coastal areas by delivering accurate information about underwater topography. SDB leverages data from Earth Observation (EO) satellites, such as the Copernicus Sentinel-2 satellites. EO technologies enable continuous, global-scale observations across expansive and often inaccessible areas, democratizing data access and allowing regions with limited resources to benefit from these advancements without significant financial investment. The extensive archives of EO data establish robust baselines that facilitate the analysis of long-term environmental changes, aiding in the creation of informed management strategies. The immense potential of EO has been recognized by diverse stakeholders, including the European Commission, which enlisted Mercator Ocean International to collaborate with EOMAP (as lead), Deltares, and GGSgc to deliver a global coastal satellite-derived bathymetry dataset. This initiative employs state-of-the-art methodologies - including the inversion of the radiative transfer equation, intertidal bathymetry, wave kinematics, and active satellite LiDAR measurements – to reach the greatest possible coastal bathymetry coverage from the shoreline down to a maximum depth of -35 m. The dataset will be made publicly accessible in a 100m spatial resolution grid within the Copernicus Marine Service. Our presentation gives an overview of the technological processes involved in creating this dataset, shares initial results and findings and demonstrates the potential of very high-resolution SDB grids for coastal zone monitoring using the identical techniques. Fundamental to achieving the UN Ocean Decade goals, this shared comprehensive global dataset not only advances our scientific understanding of coastal zones but is also essential for promoting international cooperation in coastal conservation and for collective sustainable ecosystem management. The results can contribute to the Nippon Foundation-GEBCO Seabed 2030 Project, which aims to provide a global 100m resolution bathymetry grid by 2030. The project positions EO instruments at the forefront of fostering innovative monitoring solutions, driving scientific discovery, and crafting resilient management frameworks necessary for adapting to and mitigating the impacts of climate change on coastal ecosystems. As such, this project embodies a pivotal advancement towards sustainable ocean management and more resilient coastal communities, together with understanding the blue planet more comprehensively.