Billy, J., Robin, N., Certain, R., Hein, C. and Berné, S., 2013. Barrier shoreline evolution constrained by shoreface sediment reservoir and substrate control: the Miquelon-Langlade Barrier, NW Atlantic. The Saint-Pierre-et-Miquelon Archipelago (France) is located in the NW Atlantic Ocean, proximal to the Cabot Straight outlet of the Gulf of Saint-Lawrence, and 50 km south of Newfoundland (Canada). The Miquelon-Langlade Barrier is a 12-km-long, 100–2500-m-wide, north-south–oriented isthmus connecting two bedrock islands (Miquelon to the north; Langlade to the south). This study aims to improve our understanding of shoreface-shoreline sediment exchange processes by comparing medium-term (1949–2011) shoreline changes, determined from aerial photographs and differential GPS data, with total shoreface sediment reservoir volumes estimated using seismic along the west coast of the Miquelon-Langlade Barrier. Spatial variability between the northern and southern sectors of the study site are seen both in...

River mouths are highly dynamic environments responding very rapidly to changes in wave energy or river floods. While the morphological response during floods or during marine storm events has been widely documented in the literature, little is known about the mechanisms acting during the co-occurrence of fluvial and marine hazards. This concomitance of river flood and marine storm is quite common in the western Mediterranean Sea, and was the case for the Gloria event, considered to be the most extreme event in recent decades. During this event, monitoring of hydrodynamics and morphological evolution was implemented, making it possible to better understand the impact of concomitant marine storm and fluvial flood during an extreme meteorological event on spit breaching of a small Mediterranean river mouth. Monitoring using a combination of high-resolution hydrodynamic measurements, topographic and bathymetric surveys, and sediment cores was used before, during, and after the storm “Gloria”. The results suggest an amplification of the morphological impact of the events and a different morphogenic response than if each of the events had acted independently on the system. The marine storm, occurring first, weakened the spit and initiated its breaching, which was continued by the extreme fluvial flood, thus leading to the complete destruction of the mouth. The destruction of the spit acted as a sediment source for subaqueous large delta deposition amounting to 50% of the total volume. The contribution of the river, estimated at 30%, was quite low for an exceptional event, showing the importance of locating rainfall in a catchment area controlled by a dam. For this event, extreme morphological evolution was observed, as well as the importance of water levels in the river mouth, which probably increased flood hazards, demonstrating the importance of including the compounding effect of extreme coastal water levels in river flood risk management.

Robin, N.; Billy, J.; Castelle, B.; Hesp, P.; Laporte-Fauret, Q.; Nicolae-Lerma, A.; Marieu, V.; Rosebery, D.; Bujan, S.; Destribats, B., and Michalet., 2020. Beach-dune recovery from the extreme 2013-2014 storms erosion at Truc Vert Beach, Southwest France: New insights from ground-penetrating radar. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 588–592. Coconut Creek (Florida), ISSN 0749-0208.Foredunes are efficient natural coastal defenses acting as protective barriers during storm events. A striking example is the response of coastal dunes along the Aquitaine Coast (SW France) to the 2013-2014 winter, which was the most energetic winter since at least the mid-20th century in most of the NE Atlantic. The aim of this study is to analyze the (partial) foredune recovery from the 2013-2014 winter at Truc Vert beach using ground-penetrating radar (GPR) and through the coastal dune internal structure. Geophysical data was compared with semi-monthly DGPS topographic data of the beach, UAV-photogrammetry and Airborne LiDAR surveys of the coastal dune. Three main recovery phases were identified from the 2013-2014 winter: (i) aggradation of the upper-beach and dune front-crest during the post-storm summer; (ii) distinct phases of incipient dune-foot development with dune-crest stability during the following year, and (iii) since 2016, aggradation of both dune-foot and dune front-crest tending towards an equilibrium profile. This study shows that GPR surveys, combined with chronological topographic data, is an efficient tool to provide comprehensive understanding of the beach-dune system evolution at a decadal scale. This approach opens new perspectives to document foredune recovery timing and magnitude along sandy coasts.