Utilizing 3D Optical and Acoustic Scanning Systems to Investigate Impacts from the Oil Spill on Historic Shipwrecks

Abstract

The U.S. Bureau of Ocean Energy Management (BOEM) and Bureau of Safety and Environmental Enforcement (BSEE) are required to consider the effects of their permitted actions on cultural resources, per the National Historic Preservation Act (1966). After the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, BOEM, BSEE, and study partners implemented a multidisciplinary approach to assess micro- to macro-scale impacts from the spill on a select number of previously investigated deepwater shipwrecks. The Gulf of Mexico Shipwreck Corrosion, Hydrocarbon Exposure, Microbiology, and Archaeology (GOM-SCHEMA) Project collected microbiological, geochemical, and archaeological data at wooden- and metal-hulled shipwrecks within and outside of the spill-impacted area for a comparative analysis. Archaeologists documented the selected shipwrecks’ post-spill state of preservation using 3D optical and acoustic scanning systems for comparison with existing geophysical and visual data collected prior to the spill. Marine archaeologists are using 3D scanning systems as new tools for recording and interpreting shipwreck sites and analyzing site formation processes in the marine environment. The GOM-SCHEMA Project combined 3D laser data from an Autonomous Underwater Vehicle (AUV) with 3D sonar data collected by a Remotely Operated Vehicle (ROV) as a first step toward monitoring efforts that will inform BOEM and BSEE of the spill’s long-term impacts on deepwater shipwreck preservation. Employing microbial ecological analyses and laboratory-based corrosion experiments that identified micro-scale impacts, scientists gained a better understanding of how the spill affected the natural processes of metal corrosion and wood degradation. 3D imaging creates a permanent digital record that allows scientists to study minute details and also serves as an important outreach tool by allowing the public to virtually explore archaeological resources. By comparing 3D scans collected repeatedly at the same sites over time, especially the sub-centimeter-accurate 3D laser data, archaeologists can quantitatively analyze changes occurring on these sites as a result of enhanced corrosion or degradation. Collectively, these datasets can inform archaeologists and submerged cultural resource managers about site stability, formation processes such as sedimentation and scouring, and the long-term impacts of a major oil spill on submerged cultural resources.