New platform for plumbing the sea depths
Bathymetry is the measure of water depth, the underwater equivalent to topography. Just as topographic maps represent the altitude of Earth's surface at different geographic points, bathymetric maps represent the sea depth depending on geographic coordinates. Up-to-date bathymetric data is vital for producing navigation products such as nautical charts for facilitating safe and efficient navigation of ships. In addition, it underpins almost every other activity associated with the sea, including port and offshore construction, maritime defence and security, coastal zone management, fishery, cruising, and tourism. The EU-funded project BASE-platform addressed the lack of available up-to-date, high-resolution bathymetric data in many areas of the world. With the increasing number of Earth observation satellites, just like ESA’s Sentinel fleet, ocean imagery data is now widely available. BASE-platform’s ambition was to use this satellite data for creating bathymetric maps and supplying them to end users. Harmonised bathymetric data Partners from five different countries combined their expertise to create an advanced commercial platform for a broad range of users that derives images from multiple remote sensing technologies to create bathymetric products. These include optical, synthetic aperture radar and altimetry satellites, where each technology applies to a different depth range. Additional input is gathered from crowd-sourced echo sounding data provided by a large number of ships and boats. While all of these technologies have been used separately before, BASE-platform refined methods and tools for merging these data sources, thus allowing for wide data coverage and high accuracy. “Within the project, existing data generation processes have been automated to become part of a processing chain that requires minimal human intervention. The BASE-platform data portal is a cost-efficient bathymetric product that provides high-resolution data,” says Dr Stefan Wiehle. Data was also integrated with tidal modelling for reducing depths to local chart datums. Exploring the seas in-depth To date, less than half of the coastal waters are deemed to be adequately surveyed to modern standards or have not been surveyed at all. The picture gets worse when considering that 80 % of oceans still remain unexplored, and there is an enormous amount we do not know about them. “We actually know more about the surface of the Moon than the depths of our oceans,” Dr Wiehle points out. Sea depths were measured already by the ancient Greeks and Romans, but bathymetric charts only became frequently produced from the middle of the 19th century onwards. Over this period, methods and equipment for depth measurements have evolved tremendously, from single lead line depth soundings to modern multibeam sonars. However, “Depending on the source, bathymetric data can either be of little value to users as it comes in low-resolution and some depths may have been calculated with interpolation, or can be too expensive to obtain,” explains Dr Wiehle. BASE-platform addresses the need to provide the maritime and other industries with accurate bathymetric data at substantially lower costs than data from multibeam surveys. The new bathymetric data portal provides high-accuracy data on a global scale covering the whole range of sea depths and is ideal for oil and gas exploration, fishing or coastal engineering. A major achievement, satellite-derived optical bathymetry data has already been included in official sea charts.
Keywords
BASE-platform, bathymetric data, sea depth, bathymetric products, ocean, satellites, portal, Earth observation