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Variabilité et devenir des apports sédimentaires par les fleuves côtiers: cas du système Têt - Littoral roussillonnais dans le golfe du Lion

Abstract : The Gulf of Lions is a continental margin with deltaic construction subjected to the impact of the sedimentary contributions (1) of the Rhone, one of the largest Mediterranean rivers, with seasonal hydrological cycle; (2) as well as series of torrential coastal rivers. Temporary deposit areas of the fine-grained sediment develop directly front of these rivers around 30 m water depth corresponding to the storm wave base. The dynamic of these zones subjected to the impact of the extreme events plays an important role in (1) the dissemination of the fine sediments and the associated contaminants from sources (catchment) to the sea, and (2) the water quality of the littoral zone. An automatic high frequency and long-term monitoring station was installed on the Têt River, example of mediterranean torrential coastal rivers and on its prodelta in order to estimate the variability, the impact of the hydro-climatic events on the behaviour of fine sediments in the littoral zone. Flash-floods generated by marine winds are the principal sources of fine sediments at the littoral zone. Storms associated to floods create redistribution of this material towards the circa-littoral mud belt around 50 m of water depth and the shelf edge where are located the underwater canyons. The succession of these extreme events during the year determines the preservation of the fine material in the littoral zone or its export towards the shelf. A strong interannual variability also exists in the Gulf of Lions between wet years with strong floods and storms supplying and redistributing great quantities of sedimentary material on the shelf and, dry years characterized by intense currents originating from dense water cascading descending and eroding the shelf to the underwater canyons. The extreme hydro-climatic events (flash-floods, storms, dense water cascading) are the principal actors who shape the bottom sediments of the Gulf of Lions. The impact of the human activities and climatic change plays an important role on the frequency of these extreme events and on the variability of littoral water quality and the fine-grained sediments and contaminants dispersal.
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https://tel.archives-ouvertes.fr/tel-00383233
Contributor : François Bourrin <>
Submitted on : Tuesday, May 12, 2009 - 2:58:27 PM
Last modification on : Friday, April 5, 2019 - 8:05:19 PM

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  • HAL Id : tel-00383233, version 1

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François Bourrin. Variabilité et devenir des apports sédimentaires par les fleuves côtiers: cas du système Têt - Littoral roussillonnais dans le golfe du Lion. Océan, Atmosphère. Université de Perpignan, 2007. Français. ⟨tel-00383233⟩

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