GSI's Ground-truthing (Sampling)
hugely important aspect of the National Seabed Survey is the Groundtruthing
Programme. Groundtruthing or sampling is important because the various
features being imaged using the multibeam technique cannot be fully
understood and interpreted without groundtruth data. The groundtruthing
data will in turn feed into an innovative seabed classification system
the software for which GSI has been helping to develop with a Canadian
firm, Quester Tangent.
The principal objective
of the programme is
to obtain a broad distribution of box core sediment samples for
use in seabed classification of multibeam data, and to form a baseline
geological, geochemical, geotechnical, and biological database of
the Irish seabed. Seabed samples are gathered from various locations,
photographed, described, and then sub-sampled for post-survey biological,
chemical, geotechnical, and sediment distribution laboratory analysis.
Video profiles are also taken On right is an image of deep-water
Atlantic coral (lophelia) taken from the Logachev.
May and July 2002 the GSI carried out the first portion of its Seabed
Sampling Programme concentrating on sediments rather than rock cores.The
programme includes seabed sampling, video runs and still photography
and, in 2002, involved three separate contractors
- the R/V
Akademic Boris Petrov, the S/V
Professor Logachev and the R.V. Ocean Seeker - with
results being achieved from approximately 100 sites throughout the
Zone 3 deepwater area. For further information on the 2002 programme
Programme - Logachev Cruise - 31 August-14 September
VICTOR ROV © IFREMER 2003
| Last year's Groundtruthing
Programme was deemed a successful one and shortly after its conclusion
plans were in train for a further programme in 2003. This year three
vessels - Explorer, Logachev and the Polarstern - have been used in
further exploring the physical make-up of our seabed.
last year's successful use of the Logachev in the Groundtruthing Programme
it was decided this year to use her again for a further programme.
Investigation of the 2002 multibeam survey data identified the West
Porcupine at the edge of the continental margin as a potentially interesting
area in terms of its substrata and morphological features. The objective
was therefore to carry out high resolution detail mapping on the area
by use of side-scan sonar, sediment sampling and video lines.
trip was a successful one with 21 sites sampled and 5 video lines run
amounting to between 10-15 hours of footage. The samples have been sent
to the laboratory for analysis
for geotechnical, geochemical and biological properties.
German research vessel, the Polarstern, was also used in this year's
programme and a review of her cruise is posted here.
and biological analysis of last year's samples has been conducted
and reports have been received which are now being studied. A presentation
at the 2003 Annual Seabed Seminar will outline the results from
last year's sampling programme.