A Holocene palaeoflood chronology of the Lower Rhine

Abstract

Sedimentary records of the Lower Rhine in Germany and the apex of the Rhine Delta in the Netherlands provide an excellent archive for reconstructing the chronology and magnitudes of Holocene palaeofloods. The sedimentary product of floods that exceeded bankfull discharge are well preserved as individual layers in local floodplain depressions, such as abandoned channels (Toonen et al., 2012a). From eight primary research locations holding sedimentary records that partially overlap in time, cores were retrieved to construct a 5000-year palaeoflood chronology of the Lower Rhine. Flood magnitudes were reconstructed, based on ~3000 grain size analyses of individual flood layers. End member statistics were used to characterize the coarsest tail of grain size distributions, which is indicative for large discharges; comparison of grain-size based discharge reconstructions with truly measured discharges of the last centuries confirms the suitability of sedimentary archives (and the end member modeling approach) for palaeoflood magnitude reconstructions (Toonen et al., 2012b).