Stages of sedimentary infilling in a hypertidal bay using a combination of sedimentological, morphological and dynamic criteria (Bay of Somme, France)

Abstract

In the context of rising sea level, many estuaries and bays show an overall trend to sedimentary infilling. Among these coastal environments, the Bay of Somme is a hypertidal tide and wavedominated estuary, filled in by marine sands, with a superficy of 70 km 2 . This study proposes a spatial zonation of the intertidal area of the bay based on the combination of information on sediments, seabed morphology and dynamics. Data come from a surficial sediment sampling campaign and six airborne LiDAR topographic surveys, acquired over the period 2011-2013, providing information on grain size, carbonate content, bedform occurrence and seabed dynamics. The Main Map shows the morpho-sedimentary and -dynamic zonation used as a basis to describe infilling stages in the bay. ARTICLE HISTORY

Morphodynamics of intertidal dune field in a mixed wave-tide environment: Case of Baie de Somme in Eastern English Channel

“…The variation of the dune geometry is associated with clockwise/counter-clockwise changes in the orientation angle and positive/negative changes in the elevation of dunes, respectively. Such variation of geometry involves the dune migration which is mainly produced towards NE in Baie de Somme following its polarity (Michel et al, 2017).…”

“…1). As documented by Michel et al (2017), the intertidal sandy area of the bay of 42.5 km 2 is covered by more than 4 000 hydraulic dunes with different sizes. The mean height, wavelength and sinuosity of the dunes are 0.375 m (s.d.…”

“…The bay is classified as a mixed wave-tide dominated estuary (Michel et al, 2017). It is fed by two rivers with small mean flow rates of around 1.5 m 3 /s for the Maye river and 32 m 3 /s for the Somme river.…”

“…Averaged over the entire observation period, dunes have shown a varying asymmetric shape with a polarity changing from NE to SW according to the hydrodynamic conditions (Michel et al, 2017) . Contrary to the previous studies (e.g.…”

Satellite-Derived Topography and Morphological Evolution around Authie Macrotidal Estuary (France)

“…A mutual interaction takes place between the morphology and the current patterns. Thus, the deposition of sediment from the sea changes the morphology of the estuary, which in turn modifies the tidal currents and the sediment import, leading to a morphodynamic feedback [3,4]. Since sea level rise is expected to hamper estuary infilling, the morphological response of estuaries is uncertain and may depend on the size of the estuary [5].…”