Temporal approaches of historical extreme storm events based on sedimentological archives

Abstract

This paper presents the benefits of multiplying environmental indicators to better understand the impacts of past storm events on the environment. It aims to describe the methodological approaches used to reconstruct past extreme events from washover deposits, at the three main temporal scales used in scientific bibliography: i) the long timescale (Holocene, since 12 000 years BP), ii) the meso timescale (for the last millenary) and iii) the short timescale (Anthropocene, for the last centuries). This methodology is based on a "multiproxy" analysis using sedimentology, geochemistry and various methods of isotope dating. Linking these methods with other disciplines such as history, archaeology and meteorology leads us to confirm with great certainty the existence of these extreme events, and to expose their impacts on the environment and on past coastal societies. These different approaches enable us to enhance and refine our knowledge of coastal hazards, but also to apprehend possible storm influences in the context of climate change.

Depositional environments and historical contamination as a framework to reconstruct fluvial sedimentary evolution

“…Vliet-Lanoe et al, 2014; Pouzet andMaanan, 2020, floods: Jones et al, 2012;Toonen et al, 2015), historical contamination (e.g. Bigus et al, 2014, Dendievel et al, 2020 or other anthropogenic impacts such as pre-historic gullying (Dotterweich, 2005;Vanwalleghem et al, 2006), agriculture intensification (Brooks and Brierley, 1997;Fuller et al, 2015) or river manipulations (Surian and Rinaldi, 2003;Vauclin et al, 2019).…”

Climatological influences on major storm events during the last millennium along the Atlantic coast of France

“…Back barrier lagoons, which are separated from the sea by a sandy barrier, are relevant environments to detect past StE 15 , 21 . The Petite Mer de Gâvres (PMG) and the Traicts du Croisic (TDC) lagoons were selected along the French Atlantic coast as they are environments with a constant natural evolution and with no human impacts 22 . Since the area is threatened by coastal flooding, they are localised in a fitting place to detect past extratropical storms 9 .…”

Spatial Patterns of Macrozoobenthos Assemblages in a Sentinel Coastal Lagoon: Biodiversity and Environmental Drivers

“…The grain size distribution was then treated with the Gradistat© Excel package [27]. Mean, sorting, skewness, kurtosis, decile statistics (including the median used to characterize the sediment type: d50) and clay/silt/sand composition were calculated to precise the textural group of each sample [28,29]. A LECO© carbon analyzer estimated the carbon, CO 2 and CaCO 3 percentages after 1400 • C dioxygen burning and mineral decarbonizing with sulfuric acid solution [30], while the organic matter content was determined by estimating the total organic matter (TOM).…”

“…In opposition to the grain size parameters, carbon content presents lower variation, and only low carbon percentages have been recorded by LECO© for the 68 stations studied. Higher carbon values in stations located nearest channels can be linked to the marine influence providing shell remains in the sands content, whereas the low values (in central and peripheral areas) can be influenced by the continental inputs coming from the watershed and bringing organic matter remains from vegetated areas [29]. The high level of TOM in the center and periphery of the lagoon can be attributed to the presence of fine particles entrapped by the structure of seagrass leaves and the abundance of fragments of dead seagrass encrusted in the sediment [54].…”