By Hayden Close, Tiago Silva and Freya Goodsir (Cefas)
Globally historic wrecks from WWII are reaching the end of their structural lives and starting to release oil from their ballast or cargo tanks. In a project funded by Defra’s Earth Observational Centre of Excellence (EOCOE), Cefas’s Earth Observation Team have developed a tool to help assess the impact of these wrecks.
Leaks from wrecks leave a surface sheen that can be observed by satellite (either visible or Synthetic Aperture Radar (SAR)). The team has developed a tool that searches ESA Sentinel 1 and 2 satellite images looking for the distinctive pattern of releases from a known wreck site. The tool developed in Google Colaboratory using Jupyter notebooks and python extracts the tracks of the oil plume indicating the frequency of release, the magnitude of release and the potential landfall of the oil. This forms the basis of a risk based management approach in prioritising the high risk vessels in the “sunken fleet” and forming the evidence base for management options e.g. through oil removal (via hot tapping) or allowing natural dispersion.
In a recent workshop, colleagues from MOD, MCA and Defra learnt how to use the scripts to create their own maps of leaks from wrecks such as the War Mehtar (North Sea), HMS Royal Oak (Scapa Flow) and HMS Repulse (Far East) and is available on GitHub.
Figure 1 – Example showing the GIS output for HMS Royal Oak in Scapa Flow, Shetlands analysed for a 3 month period between June and September 2023
The image above is from ESA sentinel 1 ( ie Synthetic Aperture Radar) and the main feature image is from ESA Sentinel 2 – visible. The red dot is the position of the wreck (in this HMS Repulse).
+44 (0)7436 140185