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| Titel |
Modelling bottom trawling-generated sediment flows in La Fonera submarine canyon (Northwestern Mediterranean Sea) |
| VerfasserIn |
Marta Payo-Payo, Ricardo Silva Jacinto, Galderic Lastras, Miquel Canals, Pere Puig, Jacobo Martin, Anna Sanchez-Vidal, Marina Rabineau |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111560
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| Publikation (Nr.) |
 EGU/EGU2015-11693.pdf |
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| Zusammenfassung |
| Bottom-trawling is one of the anthropogenic activities with a stronger and more widespread
impact on the seafloor. Physical processes involved in sediment resuspension due to trawling
and the resulting sediment-laden flows are not fully understood. The amount and fate of
remobilized sediments are of the utmost relevance for establishing present-day continental
margin sediment budgets. Resuspension by bottom trawling leads to massive transfer of
sediment from shallower to deeper areas practically worldwide. La Fonera submarine
canyon is a large, deeply-incised active canyon in the Northwestern Mediterranean
Sea. It presents complex sediment transport dynamics associated to littoral drift
and extreme events such as dense shelf water cascading and severe storms. Recent
studies have revealed recurrent peaks in near-bottom current speed and suspended
sediment concentration in the northern flank of the canyon synchronously with
trawling.
Aiming at simulating sediment-loaded fluxes triggered by trawling and their interaction
with the seafloor in La Fonera canyon, we have implemented a numerical process-based
model developed to reproduce such flows. Mooring data have been used both to calibrate the
modelled sediment fluxes. Good agreement between model and monitoring data has been
found, with modelled peaks of suspended sediment concentration values exceeding
120 mg/
l-1 and current speed measurements of up to 40 cm/
s-1 at the mooring
site.
Moreover, we have quantified fishing activity over the canyon flanks through modelling
and have obtained the propagation pattern of sediment flows from the fishing ground
downward the canyon. Our results confirm the value of numerical models to complete and
enlarge our understanding of the sedimentary transfer processes from shallow to deep in the
ocean. Besides, they allow establishing quantitative comparisons between trawling impact
and natural forcing on the sediments dynamics of La Fonera submarine canyon. |
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