| Mapping gradients in seafloor characteristics in the Belgian Part of the North Sea: MBES bases classification of the diverse sediment types and sediment plume dispersion due to sand extraction: detection and delimiation of sediment plumes with the MBES |
Period: 2021 till 2023
Status: Completed
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| Institutes (5) | Top | - Instituut voor Landbouw-, Visserij- en Voedingsonderzoek (ILVO), more, organiser
- Koninklijk Belgisch Instituut voor Natuurwetenschappen (IRScNB/KBIN), more, partner
- Vlaams Instituut voor de Zee (VLIZ), more, partner
- Universiteit Gent (UGent), more, partner
- Federale Overheidsdienst Economie, KMO, Middenstand en Energie; Algemene Directie Kwaliteit en Veiligheid; Afdeling Kwaliteit en Innovatie; Dienst Continentaal Plat (COPCO), more, partner
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| Abstract | Both research projects are part of the continuous study of the impact of human
activities on the seabed and water column in collaboration with ILVO and RBINS/OD
Nature, and are essential for the sustainable management of sand and gravel
extraction on the Belgian Continental Shelf and in the Belgian territorial sea.
1. Over the last 20 years, multibeam echosounder (MBES) bathymetry and
backscatter data and sediment samples have been acquired at regular
intervals to monitor the impact of marine aggregate extraction in the Belgian
part of the North Sea (BPNS). Although very valuable to monitor changes in
seabed characteristics, no systematic and repetitive classifications of the
seafloor were produced with these data until now. Anticipating on the next
era in multibeam monitoring with the new RV Belgica and RV Simon Stevin, a
specific approach will be developed to (1) classify gradients in seafloor
characteristics based on MBES data acquired at different frequencies and (2)
identify gradual changes in seafloor characteristics over time. To achieve this,
a detailed characterization of the acoustic, sedimentological, geotechnical and
macrobenthic properties of archetypal morpho-sedimentological
environments of the BPNS is required on reference areas.
During the cruises predefined reference area’s will be studied in detail: multifrequency acoustic mapping with EM2040D multibeam echosounder and
sedimentological definition of the elementary sediment types through
multiple sampling and imaging/video recording with accurate positioning on
the seafloor. The location of the ground truthing positions will be defined on
the basis of the backscatter and acoustic classification maps, constructed
onboard after the initial multibeam survey. The quantitative acoustic approach
requires a prior quality evaluation and calibration of the acoustic
measurements with the EM2040D with surveys on the Kwinte reference zone.
2. The planned sustainable adaptation of the fees for sand extraction in the
Belgian part of the North Sea will take into account the specific environmental
impact of each extraction activity. In order to determine this objectively and
scientifically based, additional and innovative research into the impact by
means of sediment plumes is necessary, in particular into the range and
nature of the impact. In this study, acoustic measurements are planned with
the EM2040D and Norbit on board the Simon Stevin and Zeekat. In addition,
water samples in the sediment plumes and continuous measurements of the
sediment concentration in the water column are planned. This specific
experiment with sediment plumes from sand extraction activities fits in
seamlessly with the objectives of the TURBEAMS project in which VLIZ,
RBINS/OD Nature and Continental Shelf Service are already working together.
The research is part of the tasks of the Continental Shelf Service: to carry out
continuous research into the influence of the exploitation of non-living resources of
the territorial sea and the continental shelf on the sediment deposits and the marine
environment (Law of 13 June 1969 on the exploration and exploitation of non-living
resources of the territorial sea and the continental shelf), and aims to enhance the
scientific knowledge and expertise on this subject.
The regular (and legally required) monitoring of the impact of sand extraction is
carried out with RV Belgica. These specific projects, for which we work together with
ILVO, RBINS/OD Nature and VLIZ (TURBEAMS), will be carried out both with RV
Belgica and RV Simon Stevin. The measurements and results of the research with
both research vessels can be combined to a large extent, and will contribute to a
comprehensive common quality evaluation and optimally promote the future
interchangeability of the acoustic measurements. |
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