Dense shelf water cascades in the Cap de Creus and Palamós submarine canyons during winters 2007 and 2008

The Cap de Creus and the Palamós submarine canyon heads were instrumented during two consecutive winters to study their respective role in the dynamics of the sediment transport on the north-western Mediterranean Sea. Several events of dense shelf-water cascading (DSWC) were identified simultaneously at both canyons and compared between them. DSWC events were characterized by abrupt drops of temperature, increases of current speeds, and peaks of high suspended-sediment concentrations (SSC). Concentrations up to 170 mg l− 1 were recorded in both studied winters at the Cap de Creus Canyon coinciding with the first DSWC event of the winter concurrent with an eastern storm. Overall, the amount of sediment transported during the DSWC events was one order of magnitude greater at the Cap de Creus Canyon than at the Palamós Canyon. Results from this study have identified for the first time the presence of DSWC events also in the Palamós Canyon head, south of the Gulf of Lions (GoL), and corroborated previous findings that the Cap de Creus Canyon is the main pathway for DSWC and the associated sediment transport from the GoL down to the deeper regions of the north-western Mediterranean.

Research Highlights
► DSWC events take place at the Palamós Canyon concurrent with the ones occurring at the Cap de Creus Canyon.
► At the Palamós Canyon northern storms enhance DSWC without significant effect at the Cap de Creus Canyon.
► Different sediment transport patterns have been observed in both submarine canyons.
► High-concentrated transport events coincide with the first long-lasting DSWC event concurrent with a moderate eastern storm.
► The amount of sediment transported during DSWC events is one order of magnitude greater at the Cap de Creus Canyon than at the Palamós Canyon.