Fredrik Søreide

Underwater hyperspectral imagery to create biogeochemical maps of seafloor properties

Abstract: This chapter presents aspects of underwater hyperspectral imaging (UHI) techniques aimed at mapping biogeochemical objects of interest (OOI) on the seafloor. Case examples of instrument-carrying platforms and biogeochemical applications are given. We discuss how to create high resolution, georeferenced, optically corrected digital underwater maps of different habitats, minerals, substrates, and organisms. Corrections for platform speed and direction, inherent optical properties (IOP), optical path length, dynamic positioning, and pitch/roll/yaw are discussed in the context of using UHI-based optical fingerprints (i.e. spectral reflectance in visible wavelengths) of different targets to create maps that can help discriminate, identify, and quantify OOI, and provide statistical information on relevant seafloor features.

Applications of remotely controlled equipment in Norwegian marine archaeology

Since early 1993 the Department of Marine Systems Design and the Department of Archaeology at the University of Trondheim, Norway has worked together on a joint project examining the use of modern technology in marine (underwater) archaeological research. The project seeks to exploit the use of remotely operated vehicles, computer technology and specialised tools such as laser measurement systems, underwater positioning, digital maps etc. to enhance productivity and safety in marine archaeological surveys and excavations. This sort of technology also renders marine archaeological field research possible in depths beyond the reach of diving archaeologists i.e. deeper than 30 meters according to Norwegian work-safety regulations. The projects focus is on the application of existing and new technology, the modification of existing equipment to suit the particular needs of this application and the development of a marine archaeological methodology for this type of operations. The project conducts a number of field trials, and currently work is being carried out at a medieval harbour construction in Agdenes (approximately 110 km north-west of Trondheim), and an 18th century Russian Navy shipwreck called the Jedinorog (the Unicorn) which sank off the coast of central Norway in approximately 280 meters depth. This paper presents the methods and technology used so far and draws some preliminary conclusions as to the appropriateness of these solutions and possible developments in the near future.

Marine archaeology and protection of heritage in deeper water-consequences for future offshore construction projects

In all types of construction projects companies naturally try to keep the costs as low as possible. Only the costs necessary for the safe and legally sound completion of a project are covered. Compared to what is normally the case on land and in shallow water, there has been very little legal or government involvement in most offshore underwater development projects. Besides fisheries, environmental and military interests, there are only rarely other considerations to make. However, recently there has been a change in attitude in several countries. Increased awareness of marine archaeology by the authorities responsible for the protection of cultural heritage has in the past few years led to a requirement that marine archaeological studies must be performed as an important part of commercial projects, also in deep water. This paper presents and discusses some important deep water archaeological projects that have been carried out by the Norwegian University of science and Technology. The paper also presents and discusses the Norwegian law for the protection of cultural remains and compares this with the proposed UNESCO draft convention for the protection of underwater heritage. This draft convention can mean that marine archaeology must be considered by all future deep water construction projects, all over the world. The convention will protect sites in international waters, while at the same time ensure that UNESCO member states provide the necessary protection within their own EEZ. One of the main conclusions of the paper is therefore that companies involved in marine construction projects should start addressing this challenge as soon as possible, creating a win-win situation where our common heritage is protected and the project completed without jeopardizing the reputation of both the project and the company.

Ormen Lange: investigation and excavation of a shipwreck in 170m depth

Final conclusions have not yet been reached. However, it seems likely that the ship is a merchantman of around 40 meters in length that was either trading on the Norwegian coast or passing by. Using the unique new technology developed for this project it is possible to conduct mapping, surveying, sampling and excavation of shipwrecks in deep water. The Ormen Lange project is the most technologically advanced deepwater archaeology project, and first major deepwater archaeological excavation of a shipwreck that has been performed world-wide. The only comparable projects are treasure related salvage operations, but these cannot be called marine archaeology. In fact, this project shows that marine archaeology in deepwater can be carried out with purely scientific goals and without economic motives. 14 shipwrecks have been discovered in the pipeline routes. This clearly shows that the potential of deepwater archaeology is high. Marine archaeological investigations should therefore be an integral part of all industrial development projects in deepwater.

Autonomous underwater vehicles as a platform for underwater hyperspectral imaging

During an expedition to the Atlantic Mid-Ocean ridge in August 2016, an underwater hyperspectral imager (UHI) was utilized. The target was to investigate its applicability to exploration for marine minerals. The imager was deployed on both an autonomous underwater vehicle (AUV) and a remotely operated vehicle (ROV). To the authors knowledge, this is the first time a full scale hyperspectral imager has been mounted on an AUV. This new platform comes with many advantages and drawbacks which will be discussed, both in terms of future potential and observed data quality.

Underwater hyperspectral imaging as an in situ taxonomic tool for deep-sea megafauna

Identification of benthic megafauna is commonly based on analysis of physical samples or imagery acquired by cameras mounted on underwater platforms. Physical collection of samples is difficult, particularly from the deep sea, and identification of taxonomic morphotypes from imagery depends on resolution and investigator experience. Here, we show how an Underwater Hyperspectral Imager (UHI) can be used as an alternative in situ taxonomic tool for benthic megafauna. A UHI provides a much higher spectral resolution than standard RGB imagery, allowing marine organisms to be identified based on specific optical fingerprints. A set of reference spectra from identified organisms is established and supervised classification performed to identify benthic megafauna semi-autonomously. The UHI data provide an increased detection rate for small megafauna difficult to resolve in standard RGB imagery. In addition, seafloor anomalies with distinct spectral signatures are also detectable. In the region investigated, sediment anomalies (spectral reflectance minimum at ~675 nm) unclear in RGB imagery were indicative of chlorophyll a on the seafloor. Underwater hyperspectral imaging therefore has a great potential in seafloor habitat mapping and monitoring, with areas of application ranging from shallow coastal areas to the deep sea.

Deepwater archaeology - status and potential

This paper will discuss the Ormen Lange deepwater archaeology project.

Data fusion on the Ormen Lange shipwreck project

An archaeologists primary interest is to extract as much information as possible from a sunken ship. An archaeological investigation should therefore not rely on one single method but utilize sensor fusion as much as possible. Various survey equipment complement each other and by combining more than one tool the archaeologists capability for interpretation is enhanced. This paper presents the use of sensor fusion on the Ormen Lange deepwater archaeology project, where a number of sensors were combined to document the site with improved precision and standards as a result

ROV based drilling for deep sea mining exploration

Exploring for minerals on the seabed is challenging — and the ability to collect representative sub surface samples is essential. The research project MarMine led by NTNU has together with Seattle based Williamson and Associates developed and tested an ROV-based drill rig for mineral (seafloor massive sulfides) and rock sampling. The ROCS system is a single stroke drill and is simple, robust and possible to use from various larger ROVs. For the vehicle to provide a stable platform, the vertical bollard pull of the ROV and the vehicle mass are important variables. The developed drill uses a thin wall drill bit and barrel and operates at high RPM to reduce the required down weight and drilling moments. The system also contains an emergency release to be used if the core barrel is stuck. The drill is hydraulically powered with cylinders operating the tower and a rotation unit. It can rapidly be modified to provide samples from softer samples like unconsolidated material. At the Arctic Mid Ocean Ridge, a work class ROV was deployed with the drill mounted for testing at 2700 m depth in basalt rock. The recovery from the system was above 80%. Such core samples can be used for chemical analyses of metal and mineral grades, mineralogy and rock mechanical testing. The system provides a probing tool for marine mineral exploration, with low cost, low operational complexity and low risk. Proper resource estimation requires drilling deep into the deposit, but the one meter deep core samples provided by the ROCS will provide valuable a priori information planning for more extensive drilling campaigns.

Marine biological baseline study in Igaliku fjord, Greenland

This paper will discuss the results of a marine biological baseline study in the Igaliku fjord, Greenland.