An improved method for paleoflood reconstruction and flooding phase identification, applied to the Meuse River in the Netherlands

Abstract

This study investigates Holocene floodplain evolution and flooding phases as experienced in the Lower Meuse catchment, primarily based on grain-size distributions of channel-fill and floodplain deposits in sediment cores. The presence of post-depositional FeeMn concretions and resistant organic particulate materials impedes the direct use of grain-size data. By combining end-member modelling results with laboratory observations, we have constructed a Flood Energy Index (FEI), which allows identification of phases of past increased flooding from the grain-size signal. Since concretions and organic-rich sediments regularly occur in floodplain sediments, we emphasize that the quality of a grain-size dataset should be assessed prior to its use for reconstruction of flood events. We suggest that the new approach has potential to become standardized within paleoflood research. The temporal variation of FEI in Meuse sediment cores highlights multi-centennial flooding phases occurring at c. 8500, c. 8000, c. 7600, c. 7000 and c. 5900 cal BP within the fluvio-lacustrine environment (early-middle Holocene). The record of low flood activity in the Subboreal is attributed to a cooler and dryer climate anomaly after the Holocene Climatic Optimum. In the late Holocene, the first flooding phase occurring at c. 2800 cal BP can be linked to the 2.8 ka climate anomaly. During the last two thousand years, the variation of FEI index reveals oscillating flood regimes in the Lower Meuse floodplain. The last three recorded flooding phases most likely coincide with the Roman Period (c. 12 BCE-250 CE), the Medieval Warm Period (c. 950-1400 CE) and the Little Ice Age (c. 1400-850 CE). Despite uncertainty in the age-model, the rapid accumulation rate and amplified flood magnitudes imply increased fluvial instability during the late Holocene, indicating that humans exerted a profound influence on fluvial dynamics in the Meuse.

Slackwater sediments refine the timing of Late Holocene Icelandic canyon-carving floods and confirm they were smaller than reported

“…We also employed End-Member Modeling Analysis (EMMA) to decompose sample Grain Size Distributions (GSDs) after e.g. 66 ; this approach has shown signi cant promise to derive information about the magnitude of past oods 83 . To this end, we relied on the AnalySize tool by 84 in version 9.3 of MATLAB.…”

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

“…However, like floodplain sedimentary archives (e.g., Toonen et al, 2015;Peng et al, 2019), the alternating coarser and finer levee sediments can in principle be used to infer flooding regime changes, if other factors (i.e., tectonic movements, channel migration and incision) can be ruled out or constrained by additional data. The relative contributions of finer and coarser deposits can be determined by performing end-member modelling analysis on grain size distributions in vertical sections (e.g., Toonen et al, 2015;Peng et al, 2019).…”

“…However, like floodplain sedimentary archives (e.g., Toonen et al, 2015;Peng et al, 2019), the alternating coarser and finer levee sediments can in principle be used to infer flooding regime changes, if other factors (i.e., tectonic movements, channel migration and incision) can be ruled out or constrained by additional data. The relative contributions of finer and coarser deposits can be determined by performing end-member modelling analysis on grain size distributions in vertical sections (e.g., Toonen et al, 2015;Peng et al, 2019). End-member modelling analysis has been successfully applied to the various sedimentary systems, including floodplain deposits, to understand their source, transport mechanism and depositional environment (i.e., Weltje and Prins, 2003;Prins et al, 2007;Toonen et al, 2015;Peng et al, 2019).…”

“…The relative contributions of finer and coarser deposits can be determined by performing end-member modelling analysis on grain size distributions in vertical sections (e.g., Toonen et al, 2015;Peng et al, 2019). End-member modelling analysis has been successfully applied to the various sedimentary systems, including floodplain deposits, to understand their source, transport mechanism and depositional environment (i.e., Weltje and Prins, 2003;Prins et al, 2007;Toonen et al, 2015;Peng et al, 2019). These studies indicate that the end-member modelling approach is capable of distinguishing the different contributing components that reflect the corresponding depositional processes.…”

Landscape changes and human–landscape interaction during the first millennium AD in the Netherlands

“…The strongest trends are observed in the lowest areas (Bommelerwaard, southern part of the delta). This area was initially dominated by the Meuse which had relatively low flooding activity between AD 250 and 950 (Peng et al, 2019). Around AD 450 the Waal (Rhine) branch became more dominant in this area, likely bringing higher and more frequent floods.…”