Missiaen, T.

Versteeg, W.

Open Marine Archive

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103
Theme 2: A new era in environmental monitoring and assessment: what is at stake?
Missiaen Tine
Ghent University, Dep. Geology
Author(s): Tine Missiaen1 & Wim Versteeg2 
Affiliation(s) :
1 Ghent University, Dep. Geology, Renard Centre of Marine Geology, Ghent, Belgium
2 Flanders Marine Institute (Vlaams Instituut voor de Zee - VLIZ), Ostend, Belgium
Innovative acoustic technique for 3D prospection of intertidal areas
Acoustic studies of very shallow and/or intertidal areas along the North Sea coast pose major 
technological challenges due to the water depth (causing strong multiples), fierce wave action, strong currents, large tidal range, and the presence of biogenic gas in the shallow sediments.  As a result these areas on the land-sea boundary are rarely investigated in a 
structured way. Recently, innovative acoustic investigations have been carried out at Ostend 
and Raversijde for archaeological and environmental prospection of the sub-seafloor. The 
beach area of Raversijde is known for its artefacts and structures dating from Neolithic, 
Roman and medieval times, including old coastal defence structures (e.g. dykes), remnants 
of drowned fishing villages, and intensive peat exploitation. Due to sand suppletion works 
in the ‘70ies all the remains are now covered by a few m of sand. Using a multitransducer 
echosounder system (containing an array of 4 synchronized parametrical transducers with 
a total spread of 1 meter) a 3D sub-seafloor volume could be obtained with a grid cell size 
as small as 25x25x1 cm (x/y/z). This allowed to map the peat and salt excavation pattern at 
Raversijde in the highest detail (cm/dm resolution). The observed features match perfectly 
with the old aerial photographs of the area (before the sand accretion). At the test site in the 
harbour of Ostend a number of small buried objects could be identified within the thick layer 
of fluid mud sediments. The data also allowed a detailed image of the 3D topography and 
internal stratification of the mud layer. This opens new perspectives for detailed prospection 
of the sub-seafloor in nearshore areas.
Keywords: 3D imaging, sub-seafloor, innovative


Innovative acoustic technique for 3D prospection of intertidal areas

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