Paleoflooding reconstruction from Holocene levee deposits in the Lower Meuse valley, the Netherlands

Abstract

This study investigates the Holocene levee deposits and paleoflooding history of the Lower Meuse in the Netherlands based on archeological investigations and sedimentary analyses (grain size, end-member modelling, magnetic susceptibility and thermogravimetric analyses). The levee on the left bank in the study area near Ooijen contains a continuous sedimentary record in the NW downstream part. The archeological evidence and sedimentary results, including a grain size based flood energy index (LFEI), indicate that the Lower Meuse experienced a quiescent flooding period and low sedimentation rates during the mid-late Mesolithic when the levee was low and human influence was minor. Deposition during the Mesolithic shows a fining-upward trend and a highly-developed soil containing abundant artefacts. During the Neolithic and Bronze Age, the flooding intensity was low but gradually increased to a moderate level probably because of deforestation and increased runoff. Limited Bronze Age findings may reflect decreased human activity because of the increased flooding. Starting from the Iron Age, the Meuse experienced a generally enhanced flooding regime, which is reflected by erosion and coarsened sedimentation in the Iron Age and Roman Period. The high peak discharges during the Iron Age may have re-opened a low-lying paleochannel near to the levee during the intensified floods. This general increasing trend is interrupted by the lower flooding phase in the early Middle Ages (Dark Ages). From the middle to the late Middle Ages, the floods intensified again. The coarsening deposition and higher sedimentation rates since the Iron Age resulted from increased floods and higher sediment supply by deforestation and soil erosion. The findings of this study agree with a recent paleoflood reconstruction for the Lower Meuse by using a floodplain archive, implying that levee sediment records have potential in paleohydrological studies if the completeness of the record and chronological information is guaranteed.