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October 2024
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29 Reads
The ice-sheets and valley glaciers of the Pleistocene glaciations dammed rivers up into lakes filling up entire valley systems, diverted water bodies or directed the surface flow along more or less temporary ice-marginal valley systems. Some of the lakes were continental in extent and their outburst floods completely reshaped the entire landscape.
October 2024
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2 Reads
The preceding chapters have shown how diverse the history of floods on Earth is. On the one hand, the presentations touched on the classification of current flood dimensions in the historical context and, on the other hand, also listed the attempts to locate the oldest flood description ever using the example of the Flood myth. In the geological record, numerous large megafloods occurred in Pleistocene times and exceed recent events by several magnitudes. First flood traces date back up to billion of years.
October 2024
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12 Reads
The refill of oceanic basin in the Earth’s recent history since the end of the Tertiary represent floods of a special magnitude. Such floods do not manifest themselves through a temporarily increased discharge, but as a rule represent a distinct event. Compared to the lake outbursts described before, the direction of flow is reversed due to the inflow into the basin instead of draining it. At the same time, the duration of the floods also changes, which is typically measured in years according to the size of the basin. Questions also arise not only about the cause of the flood when it fills, but also about how, when and why a previous emptying occurred in the first place.
October 2024
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21 Reads
Insofar as written records have been compiled, one can find records of floods from historic times from all parts of the world (cf. Table 3.1). Often, these descriptions are related to weather records, namely for extraordinary events. As expected, the oldest flood records are from the ancient civilisations in China and Egypt and thus date back to the time before the birth of Christ.
October 2024
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16 Reads
In contrast to floods, which are controlled by meteorological causes such as precipitation or snowmelt, lakes can empty suddenly and unexpectedly without warning or external signs. Depending on the volume of water released, extreme peak discharges can occur that exceed floods caused by precipitation by several orders of magnitude. Although reservoirs may be associated primarily with man-made dams, there are many forms of natural reservoirs whose abrupt emptying due to dam failure is referred to as a lake outburst.
October 2024
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9 Reads
Floods are among the most frequent and consequential natural disasters on Earth. They occur in all environments at all times. They frequently surprise with unexpected magnitudes and the damage they cause. Characteristics such as floods of the century and millennium including comparisons with the biblical deluge are quickly on everyone's lips, but what do we really know about the floods of the past?
October 2024
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14 Reads
In principle, the same parameters can be used to describe the dimensions of historical floods as for recent floods. However, as they cannot usually be recorded as precisely as for recent events, one usually has to live with estimates of magnitudes or be satisfied with incomplete representations. Nevertheless, contemporary descriptions have often survived that allow an astonishingly accurate reconstruction of the water level height.
August 2024
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75 Reads
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6 Citations
Global and Planetary Change
May 2024
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27 Reads
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2 Citations
International Journal of Sediment Research
March 2023
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124 Reads
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4 Citations
Local scour holes are erosional bed structures that are related to different scientific disciplines in Earth science and hydraulic engineering. Local scouring at naturally placed boulders is ubiquitous, but many competing factors make it difficult to isolate the effects of a given variable. This is especially true for local scouring at natural instream obstacles that are exposed to unsteady flow conditions in the course of flood hydrograph experiments. Experimental investigations in laboratory flumes offer the advantage that boundary conditions can be systematically varied. We present novel experimental data on the impact of the submergence ratio, hydrograph skewness, and flow intensity on local scouring at boulder-like obstacles during unsteady flow and evaluate the effect of discharge chronologies. In total, 48 flume experiments on subcritical clear-water conditions and channel degradation were performed. The experimental results reveal that local scouring dominantly occurred at the rising limb when flow depth was comparable to the obstacle size, so the obstacle was unsubmerged. The steeper the rising limb, the quicker the local scour hole matured. The experimental results are relevant for the hydraulic interpretation of local scour holes found at boulders in the field. They may be utilized as a proxy for the minimum duration of the beginning stage of a flood.
... On July 13 and 14, 2021, enormous rainfall amounts of 100 to 150 mm fell over western Germany and in parts of Belgium and Luxembourg. Most of the precipitation fell within 15 to 18 h [20], which led to extreme peak runoff conditions along the Ahr river and its tributaries, exceeding mean discharge by factor 150 [28,29]. Severe geomorphological changes such as mass movement and bank erosion, channel displacement and widening, and the deposition of material on the floodplains were among the consequences [14,23,31] (Fig. 1). ...
August 2024
Global and Planetary Change
... Local scour holes develop around objects such as wrecks or boulders due to sediment mobilization caused by flows around the obstacle (Schlömer and Herget, 2023). Various experimental studies (Hong et al., 2013;Cui et al., 2019;Ferraro et al., 2021Ferraro et al., , 2022 have demonstrated the formation of features on the seabed induced by ship propellers. ...
March 2023
... In the Lower Rhine, the largest flood is dated to 1374 CE (Toonen 2013;Cohen et al. 2016). Hydraulic modelling based on historical (non-) exceedance levels (Ngo et al. 2023) and flood wave propagation (Bomers et al. 2019) estimates the peak discharge to have been c. 25% larger than the 1926 CE flood, the largest event in the gauged record. ...
December 2022
Journal of Hydrology
... Attributing current extreme floods to human impact is only persuasive if forced flood variability by human GHG emissions can be shown to be larger than unforced variability, and here we summarise historical and palaeoflood data from the Lower Rhine, upland and lowland catchments in the UK, and the Valencia region of eastern Spain that constitute some of the longest and complete event-based fluvial records currently available in Western and Southern Europe, to show that this is often not the case. These studies are part of a larger focussed research programme to better understand the nature of past flood events worldwide (Baker et al. 2022). ...
November 2021
... The morphology of local scour holes at boulder-like obstacles is consistent over a range of spatial scales from a small-scale laboratory (10 −2 m) to scour holes at boulders (10 m) [33] (Figure 1a,b). The local scour hole forms at the luv side of the approaching flow upstream of the obstacle. ...
February 2021
... In terms of ancient dammed lakes, especially those formed during geological history, attentions concentrate on lacustrine deposits, chronology, and paleo-environment and geomorphology Fan et al., 2020;Liu et al., 2018;Lord & Kehew, 1987;Xu et al., 2020). However, few researches about paleohydraulic reconstructions of landslide-dammed lake outburst floods (LLOFs) were reported due to the great challenges of long-history ages (Baker, 2013;Benito et al., 2023;Herget & Fontana, 2019;Ma et al., 2022). ...
January 2020
... As a result, the thesis as a whole as well as some of the individual chapters combine physical geography and geology with archaeology and historical geography to answer an ultimately hydrological question. Multidisciplinarity is increasingly being recognized as very important in palaeoflood hydrological research (Woodward et al., 2010;Fontana et al., 2020a), and this thesis underlines that idea. ...
February 2020
Quaternary International
... Similar dune-like features elsewhere have also been termed mega dunes, mega ripples, giant ripple marks, giant current ripples, whaleback dunes, gravel waves etc. (Pardee, 1942;Bretz et al., 1956;Baker, 1973;Rudoy and Baker, 1993;Maizels, 1997). Obstacle marks formed on the lee-side of icebergs or boulders that were transported during the flood and subsequently arrested as the flood levels waned (Russell, 1993;Fay, 2002;Herget, 2005;Baker, 2009;Herget et al., 2013;Weckwerth et al., 2019;Schlömer et al., 2020). The features, which are considered diagnostic for high-energy glacial floods, are often identified as a lee-side scour and/or depositional ridge behind a kettle hole or a boulder, and the orientation of the features allow reconstruction of local flow patterns (Høgaas and Longva, 2016). ...
January 2020
... Massive and sudden releases of meltwater have repeatedly taken place in the history of the Earth (Carrivick and Rushmer, 2006), triggered by the melting of continental ice sheets (Clague and Evans, 2000;Kershaw et al., 2005;Murton et al., 2010;Baker, 2020) or alpine glaciers (Herget et al., 2020;Turzewski et al., 2020). The last (i.e., Weichselian) glaciation in particular generated many glacial lake outburst floods (GLOFs) (Carling et al., 2009;Margold et al., 2018;O'Connor et al., 2020;Wells et al., 2022) that left distinct landforms in the formerly glaciated areas. ...
October 2019
Earth-Science Reviews
... En el cas d'Europa, destaquen investigacions relacionades amb el context climàtic per tota l'etapa (Wanner et al, 2022), l'impacte de les erupcions volcàniques en l'origen de la PEG (Miller et al, 2012), l'ús de fonts escrites per documentar la variabilitat en les temperatures (Dobrovolny et al, 2010) o la estacionalitat de les inundacions (Brazdil et al, 2012;Mesmin et al, 2024) així com la importància dels episodis de sequera i els seus impactes socioeconòmics (Brazdil et al, 2020;Pfister i Brazdil, 2006;Wetter, 2014) Pel que fa a l'estat espanyol, existeixen estudis de climatologia històrica des de les dècades dels 70 i 80 del segle passat, encara que la recerca sobre aquesta temàtica assoleix el seu moment més destacat a les darreries del segle XX, amb estudis dendroclimatològics, sedimentològics, geomorfològics i geoquímics. Es combinen doncs fonts d'informació documental (arxius municipals, parroquials, correspondència) amb mètodes d'anàlisi a laboratori a partir de mostres obtingudes mitjançant feina de camp. ...
January 2014
Climatic Change
![(a) Local scour hole at a boulder in ephemeral Rambla de la Viuda, NE Spain, 2019. (b) Local scour hole at a cube generated in a flume. (c) Plan view of a local scour hole at a cuboid obstacle at laboratory scale (cm) indicating local scour hole (red isolines) and sediment ridge (blue isolines). Arrows indicate direction of flow. Reprinted from Schlömer et al. [29].](https://www.researchgate.net/publication/368978267/figure/fig1/AS:11431281410332956@1745870353294/a-Local-scour-hole-at-a-boulder-in-ephemeral-Rambla-de-la-Viuda-NE-Spain-2019-b_Q320.jpg)
![Simplified flow field in the vicinity of a submerged cuboid obstacle. Adapted from Schlömer et al. [29].](https://www.researchgate.net/publication/368978267/figure/fig2/AS:11431281410342911@1745870355717/Simplified-flow-field-in-the-vicinity-of-a-submerged-cuboid-obstacle-Adapted-from_Q320.jpg)
![Upstream cross-sectional profile of the frontal scour hole indicating internal differentiation and positions of primary horseshoe vortex (HV1) and secondary horseshoe vortex (HV2) (not to scale). Adapted from [29].](https://www.researchgate.net/publication/368978267/figure/fig3/AS:11431281410265593@1745870356891/Upstream-cross-sectional-profile-of-the-frontal-scour-hole-indicating-internal_Q320.jpg)
