Abstract. A 2600 yr long composite palaeoflood record is reconstructed from high-resolution delta plain sediments of the Hasli–Aare floodplain on the northern slope of the Swiss Alps. Natural proxies compiled from sedimentary, geochemical and geomorphological data were calibrated by textual and factual sources and instrumental data. No fewer than 12 of the 14 historically recorded extreme events between 1480 and the termination of the Hasli–Aare Correction in 1875 were also identified by coarse-grained flood layers, log(Zr/Ti) peaks and Factor 1 anomalies. Geomorphological, historical and instrumental data provide evidence for flood damage intensities and discharge estimations of severe and catastrophic historical floods. Spectral analysis of the geochemical and documentary flood series and several climate proxies (TSI, δ18O, tree-rings, NAO, SNAO) identify similar periodicities of around 60, 80, 100, 120 and 200 years during the last millennia, indicating the influence of the North Atlantic circulation and solar forcing on alpine flood dynamics. The composite floodplain record illustrates that periods of organic soil formation and deposition of phyllosilicates (from the medium high catchment area) match those of Total Solar Irradiance maxima, suggesting reduced flood activity during warmer climate pulses. Aggradation of clusters of flood layers with increased contribution of siliciclasts from the highest catchment area (plutonic bedrock) (e.g., 1300–1350, 1420–1480, 1550–1620, 1650–1720 and 1811–1851 cal yr AD) occurred predominantly during periods with reduced solar irradiance, lower δ18O anomalies, cooler summer temperatures and phases of drier spring climate in the Alps. Increased water storage by glaciers, snow cover and snow patches susceptible to melting processes associated with rainfall episodes and abrupt rises in temperature substantially increased surface run-off on slopes and discharges of alpine rivers. This interpretation is in agreement with the findings that the severe and catastrophic historical floods in the Aare since 1670 occurred mostly during positive SNAO pulses after years or even decades dominated by negative SNAO and cooler annual temperatures.
Abstract. A 2600-year long composite palaeoflood record is reconstructed from high-resolution delta plain sediments of the Hasli–Aare floodplain on the northern slope of the Swiss Alps. Natural proxies compiled from sedimentary, geochemical and geomorphological data were calibrated by textual and factual sources and instrumental data. No fewer than 12 of the 14 historically recorded extreme events between 1480 and the termination of the Hasli–Aare river channel correction in 1875 were also identified by coarse-grained flood layers, log(Zr / Ti) peaks and factor 1 anomalies. Geomorphological, historical and instrumental data provide evidence for flood damage intensities and discharge estimations of severe and catastrophic historical floods. Spectral analysis of the geochemical and documentary flood series and several climate proxies (TSI, δ18O, tree-rings, NAO, SNAO) identify similar periodicities of around 60, 80, 100, 120 and 200 years during the last millennia, indicating the influence of the North Atlantic circulation and solar forcing on alpine flood dynamics. The composite floodplain record illustrates that periods of organic soil formation and deposition of phyllosilicates (from the medium high catchment area) match those of total solar irradiance maxima, suggesting reduced flood activity during warmer climate pulses. Aggradation with multiple sets of flood layers with increased contribution of siliciclasts from the highest catchment area (plutonic bedrock) (e.g. 1300–1350, 1420–1480, 1550–1620, 1650–1720 and 1811–1851 cal yr AD) occurred predominantly during periods with reduced solar irradiance, lower δ18O anomalies, cooler summer temperatures and phases of drier spring climate in the Alps. Increased water storage by glaciers, snow cover and snow patches susceptible to melting processes associated with rainfall episodes and abrupt rises in temperature substantially increased surface runoff on slopes and discharges of alpine rivers. This interpretation is in agreement with the findings that the severe and catastrophic historical floods in the Aare since 1670 occurred mostly during positive SNAO (Summer North Atlantic Oscillation) pulses after years or even decades dominated by negative SNAO and cooler annual temperatures.
PurposeThe multidisciplinary Fluvalps‐3000 research project focuses on the variability of the Late Holocene and historical fluvial dynamics in alpine catchments. The purpose of this paper is to examine the potential of a 3,600 year‐long record composed from fluvial deposits for flood hazard assessment.Design/methodology/approachThe research is based on a multi‐proxy approach integrating methods of various disciplines as sedimentology, geochronology, pedology, geomorphology, palynology, history, and archaeology. This paper considers particularly the sedimentological and geocronological methods applied to the fluvial records of several key sections of the Lütschine and Lombach fan deltas.FindingsThe sedimentary data of the high‐resolution fan delta record show up to seven major aggradation pulses from 3,600 cal yr BP to present. Furthermore, 19 minor burial episodes occur between 3,600 and 1,050 cal yr BP at average intervals between 113 years (Lütschine) and 105 years (Lombach) suggesting that aggradation during the focused period was triggered by centennial flood events. Nine coarse‐grained flood layers of the Lütschine record, deposited during the last 3,350 years by catastrophic flood events at a recurrence interval of 370 years, coincide with positive radiocarbon anomalies and cold phases in the Alps. The solar influence on regional hydrological regime is proposed as the main factor triggering the flooding events. However, the impact of land‐use changes in the region since 2,300 cal yr BP was detected by pollen and geochemical proxy data from fluvial deposits.Originality/valueAccording to the results, the 2005 flood may not be considered as one of these mayor catastrophic events, thus providing useful data for future risk assessment by regional and local authorities. The 3,600 year flood history derived from fan delta proxies, presented in this paper, is unique in the European Alps.
Both natural and documentary evidence of severe and catastrophic floods are of tremendous value for completing multidimensional flood calendars, as well as for mapping the most extreme riverine flooding phenomena in a river basin, over centennial and millennial time scales. Here, the integration of multi-archive flood series from the Hasli-Aare, Lütschine, Kander, Simme, Lombach, and Eistlenbach catchments in the Bernese Alps constitutes a unique approach to
Nature 451, 437-440 (2008) In Fig. 3a, the descriptions of the continuous and dotted curves were inadvertently swapped. The continuous line corresponds to the modified synthetic thermal profile (storms reaching the 60 mbar level). The dotted line corresponds to the Cassini CIRS thermal profile (storms reaching the 160 mbar level). The experiment measures the differential laser transmission through the quantum dot between the on-and off-exciton resonance condition. As a result, the origin in Fig. 2a-h corresponds to the zero of the measured differential transmission and does not exclude the existence of constant background absorption. It is therefore important to note that the undershoot in the Fano spectra does not correspond to a negative absorption (that is, an optical gain), but is consistent with the continuum broadband background absorption, as analysed in our observation of the nonlinear Fano effect. Similarly, the theoretical graphs in Fig. 2i-n are also given for the differential transmission. CORRIGENDUM
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.