Detecting shipwrecks from space

A paper published in Journal of Archaeological Science by Dr Rory Quinn (Geography and Environmental Sciences) and colleagues from the Royal Belgian Institute of Natural Sciences (Dr Matthias Baeye and Dr Michael Fettweis) and the Flemish Hydrographic Service (Dr Samuel Deleu) reports a new technique to detect fully submerged wreck sites using satellite remotely sensed data.

Locating and characterizing shipwreck sites is important for a number of reasons. Historic wrecks are unique time capsules of our past, modern wrecks are point sources for toxic pollutants, and wrecks in general are hotspots for marine biodiversity, often acting as hard substrate in a ‘sea’ of soft sandy sediments.

Sansip DEM

Multibeam echosounder (sonar) image of the Sansip wreck site showing distinctive scour areas around the wreck structure

Shipwrecks, ocean acidification and the dumping of waste into oceans are among the biggest sources of marine pollution (Council of Europe Parliamentary Assembly, 2012). Greater than 70% of sunken wrecks in European waters date back to WW1 and WW2; their metal structures are ageing and their metal plates are deteriorating, thus threatening to release their contents into the ocean due to the effects of corrosion. The North Atlantic Ocean contains 25% of the potentially polluting wrecks in the world. These wrecks are estimated to contain nearly 38% of the total volume of oil trapped in sunken vessels. The warships used in the world wars also carried munitions which have corroded to the point where they are liable to start leaking significant quantities of toxic substances. Some of these toxic substances, such as mercury, are not biodegradable and can cause chemical contamination of the food chain (Council of Europe Parliamentary Assembly, 2012).

Rory explains “Detecting submerged wrecks is time consuming and expensive, made more difficult in turbid coastal areas by navigation hazards, shallow water and poor water clarity. Established waterborne and airborne remote sensors are compromised as search tools because their effective swath is a function of water depth, necessitating very close survey line spacing in shallow water, increasing cost accordingly. Additionally, in turbid coastal waters, bathymetric LiDAR is ineffective as it relies on clear (non-turbid) water.”

In this study, the authors report a new methodology to detect the presence of submerged shipwrecks using ocean colour satellite imagery. For the first time, they demonstrate that wrecks generate Suspended Particulate Matter (SPM) concentration signals that can be detected by high-resolution ocean colour satellites such as Landsat-8. The findings of this study are likely to be of interest to government agencies, oceanographers, archaeologists, environmental scientists, biologists and heritage managers.

Funding: This work was supported by the HIGHROC project (HIGH spatial and temporal Resolution Ocean Colour products and services), funded by the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 606797.

 

Citation: Baeye, M, Quinn, R, Deleu, S, Fettweis, M, 2016, Detection of shipwrecks in ocean colour satellite imagery, 66, 1-6. doi:10.1016/j.jas.2015.11.006

Journal of Archaeological Science, 7/235, Archaeology, SCImago Journal Rank 2014