SECULAR SEDIMENT BUDGET OF THE LANGUEDOC-ROUSSILLON SHOREFACE (WESTERN GULF OF LIONS)

This paper presents a shoreface sediment budget est ablished for the 20 th century (1895-1984-2009), along with the results of seismic THR surveys along the microtidal wave-dominated coast of the western Gulf of Lions ( Languedoc- Roussillon, Mediterranean Sea, SE France). The aim o f this study is to link the Large Scale Coastal Behav iour (LSCB) of the western Gulf of Lions littoral prism (expres sed in terms of shoreface sediment budget, shorefac e sediment volume and spatial distribution pattern of cells) t o climatic change, river sediment input to the coast, longshore sediment transport distribution, impact of hard coa stal defence structures and artificial beach nouris hment. The results show a significant reduction of the volume of the l ittoral prism over 114 yr due to (1) the "natural" decrease of river sediment input, (2) the lack of sediment supply by rivers, because the river channels are controlled b y dams and human activities and (3) the littoral prism sand is compo sed of sedimentary reservoirs that are gradually be ing used up.

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