Long-term records are needed to investigate the impact of extreme events in the current framework of global change. Sedimentary reconstruction with a high resolution remains difficult without conducting expensive, destructive and/or time-consuming analyses. In this study, high resolution CT-scan profiles (0 center dot 6 mm resolution) were used to investigate their potential for detecting flood deposits induced by heavy rainfall events. This method was applied to a sediment core dated with fallout radionuclides - covering a 120 year period - collected in a pond draining a small forested catchment (French Massif Central - Central France). Between 1960 and 2017, 28 layers were deposited. Seventy-six percent of these deposits were correlated to the occurrence of heavy rainfall (>50 mm) recorded during one or two consecutive days. The remainder of the deposits detected with the Computer Tomography (CT) scanner (n = 5) were not correlated to weather events. They mainly occurred in response to landscape management operations (for example, afforestation works as a result of the major 1999 storm). This period was indeed characterized by an increase in the delivery of Cs-137-enriched sediment, demonstrating a greater topsoil contribution to sediment during major forest management operations. The intensity of detrital layers has significantly decreased throughout time after a major land use change that took place in 1948 and land abandonment. The frequency of heavy rainfall and associated detrital deposits has nevertheless increased by 60% and 75%, respectively, between the years 1960 and 2017. These results outline the potential of CT-scan for reconstructing long-term flood deposits associated with heavy precipitation.
1.UVSQ, CEA Saclay Orme Merisiers, LSCE, IPSL,CEA,CNRS,UMR 8212, F-91191 Gif Sur Yvette, France 2.Univ F Rabelais Tours, Fac Sci & Tech, Lab GeoHydrosyst Conlinentaux GeHCO, EA 6293, Parc Grandmont, F-37200 Tours, France 3.Bur Rech Geol & Minieres, Dept Risques & Prevent, 3 Ave Claude Guillemin, F-45060 Orleans, France 4.Ctr INRA Val Loire, Plateforme Chirurg & Imagerie Rech & Enseignement, Serv Imagerie, UMR PRC, F-37380 Nouzilly, France
Recommended Citation:
Foucher, Anthony,Evrard, Olivier,Cerdan, Olivier,et al. A quick and low-cost technique to identify layers associated with heavy rainfall in sediment archives during the Anthropocene[J]. SEDIMENTOLOGY,2019-01-01