1. A quick and low‐cost technique to identify layers associated with heavy rainfall in sediment archives during the Anthropocene.
- Author
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Foucher, Anthony, Evrard, Olivier, Cerdan, Olivier, Chabert, Clément, Lecompte, François, Lefèvre, Irène, Vandromme, Rosalie, Salvador‐Blanes, Sébastien, and Dey, Subhasish
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RAINFALL ,RAINFALL frequencies ,SEDIMENTS ,FOREST management ,LAND use ,PALEOHYDROLOGY - Abstract
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 (0·6 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 137Cs‐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. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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