Silent Witnesses for Torrential Processes

Kaitna, Roland; Huebl, Johannes

doi:10.1007/978-94-007-4336-6_7

Cited by 16 publications

(7 citation statements)

References 14 publications

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“…The mud lobes (RML) (Figs. 6F-E) were deposited as thin, cohesive, fine-grained debris flows (i.e., mudflows), which bypassed most of the fan and came to a halt on the low-gradient distal domain, possibly as late-stage, more fluidal phases of main debris-flow events (Pierson, 1986;Wells and Harvey, 1987;Blair and McPherson, 1998;Kaitna and Huebl, 2013). Individual (Carling and Reader, 1982;Bluck, 1987;Zielinski, 2003), (ii) well-developed microforms such as gravel clusters (e.g., Brayshaw et al, 1983;Brayshaw, 1984) or transverse clast dams (Bowman, 1977;Church and Jones, 1982;Bluck, 1987), and (iii) reworking of fine sediments to leave a clast-supported bed distally associated with coarse sandy to fine pebbly deposits where flow competence was decreased.…”

Section: Processes Of Long-term Fan Aggradationmentioning

confidence: 99%

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

et al. 2014

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. (2014) 'Debris-ow dominance of alluvial fans masked by runo reworking and weathering. ', Geomorphology., Further information on publisher's website:http://dx.doi.org/10.1016/j.geomorph.2014.04.028Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Geomorphology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be re ected in this document. Changes may have been made to this work since it was submitted for publication. A de nitive version was subsequently published in Geomorphology, 217, 2014Geomorphology, 217, , 10.1016Geomorphology, 217, /j.geomorph.2014 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractArid alluvial fan aggradation is highly episodic and fans often comprise active and inactive sectors. Hence morphology and texture of fan surfaces are partly determined by secondary processes of weathering and erosion in addition to primary processes of aggradation. This introduces considerable uncertainty in the identification of formative processes of terrestrial and Martian fans from aerial and satellite imagery. The objectives of this study are (i) to develop a model to describe the sedimentological and morphological evolution of inactive fan surfaces in arid settings, and (ii) to assess the relative importance of primary processes of aggradation and secondary processes of weathering and reworking for surface morphology and sedimentology and for the stratigraphic record. We studied an alluvial fan characterized by a recently active sector and a long-abandoned, inactive sector along the coast of the hyperarid Atacama Desert. Here, rates of primary geomorphic activity are exceptionally low because of extreme aridity, whilst weathering * Corresponding author. Tel.: +3130 2532778, E-mail: t.dehaas@uu.nl Preprint submitted to GeomorphologyJune 2, 2014rates are relatively high because of the effects of coastal fogs. Long-term processes of fan aggradation and reworking were determined through sedimentological facies analysis of stratigraphic sections. Ground surveys for textural and morphological patterns at the fan surface were integrated with remote-sensing by an Unmanned Airborne Vehicle (UAV). Discharges and sediment-transport capacities were calculated to estimate the efficiency of secondary runoff in reshaping the inactive fan sector. Stratigraphic sections reveal that the fan was dominantly aggraded by debris flo...

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Section: Processes Of Long-term Fan Aggradationmentioning

confidence: 99%

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

et al. 2014

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“…The individual application of either control mechanism for flood protection has drawbacks and advantages. The reliability of mechanical control depends on the size of the transported sediment or large wood, but size estimates of expected sediment or wood (e.g., based on deposits from former floods) are associated with high uncertainty (Kaitna & Hübl, 2013;Shima et al, 2015Shima et al, , 2016. Mechanical control is preferable when the main objective is to retain coarse sediment and minimize the retention of fine sediment.…”

Section: Introductionmentioning

confidence: 99%

Design of sediment detention basins: Scaled model experiments and application

Moldenhauer-Roth

Piton

Schwindt

et al. 2021

International Journal of Sediment Research

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“…Juvenile and mature fan deltas essentially differ in the following structural components: fan and catchment geometry and their connectivity, slope, vegetation cover, and the ruggedness of the terrain. The 7.9 % sediment delivery ratio of the juvenile fan indicates high connectivity between the small catchment and the fan delta, which enables a greater intake of rock debris (Kaitna and Huebl, 2012) and facilitates high throughput towards the lake. 550…”

Section: Terrestrial and Subaqueous Depositional Patternsmentioning

confidence: 99%

“…Low-magnitude debris flows terminate in dry, coarse sediments at the flow margins. Abundant coarse clasts spread over the entire cross-section at the foot of the apron are remnants of this zone of high frictional resistance 570 (see Kaitna and Huebl, 2012). However, the massive subaquatic volume of the fan delta shows that over time, the largest portion of debris-flow sediment accumulates in the lake basin, and the onshore fan thickness represents only part of the total transported volume.…”

Section: Terrestrial and Subaqueous Depositional Patternsmentioning

confidence: 99%

A 4,000 year debris-flow record based on amphibious investigations of fan delta activity in Plansee (Austria, Eastern Alps)

Kiefer

Oswald

Moernaut

et al. 2021

Preprint

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Abstract. The frequency of debris flows is hypothesized to increase in recent decades with enhanced rainstorm activity. Geological evidence to test this tendency for prehistoric times is scarce due to incomplete sediment records, complex stratigraphy, and insufficient age control especially in Alpine environments. In lacustrine archives, the link between onshore debris-flow processes and the depositional record in lake depocentres is poorly investigated. We present an amphibious characterization of alluvial fan deltas and a continuous 4,000 year debris-flow record from Plansee (Tyrol, Austria) combining Light detection and ranging (LiDAR) data, swath bathymetry, and sediment core analyses. The geomorphic investigation of two fan deltas in different developmental stages revealed a sediment delivery ratio of 7.9 % for the juvenile fan and no sediment transport into the lake on the mature fan within a 3-month summer period (May 2019–August 2019). Event deposits were dated and categorized according to their causal mechanism in a transect of four sediment cores. Debris flow-induced turbidites feature a more gradual fining-upward grain-size trend and higher TOC and δ13C values compared to earthquake-induced turbidites. Over the last 4,000 years, the record containing 138 debris flow-induced turbidites reveals four different debris-flow activity phases. Phase 1 (2050–1960 before the common era; BCE) depicts the second highest observed event frequencies. Phase 2 (1960 BCE–1550 common era; CE) shows large recurrence intervals. Phase 3 (1550–1905 CE) displays a gradual increase of event frequency. Phase 4 (1905–2018 CE) exhibits a debris-flow frequency increase between 1908 and 1928 CE, followed by the overall highest debris-flow frequency between 1928 and 1978 CE, and lower debris-flow frequencies since 1978 CE, which still exceed those of phase 1 to 3. Most remarkably, we find a ~7-fold increase of debris-flow frequency compared to the reference period 1700–1900 CE. The triggering of debris flows is more controlled by short intense rainstorms than for any other mass movement process and we demonstrate that lacustrine debris-flow records provide a unique inventory of hazard-relevant rainstorm frequencies over decades, centuries, and millennia. In a calibration period of 7 decades, we can show that the debris flow-induced turbidite record matches with the previously published debris-flow volume increase derived from aerial photography coincident to a pronounced rainstorm frequency increase. Here we show a millennium-scale debris-flow record that documents a ~7-fold increase in debris-flow frequencies in the 20th and 21st century coincident to 2-fold enhanced rainstorm activity in the Northern European Alps and provide a novel basis for systematic non-stationary estimation of future debris-flow frequencies in a changing climate.

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Silent Witnesses for Torrential Processes

Cited by 16 publications

References 14 publications

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

Design of sediment detention basins: Scaled model experiments and application

A 4,000 year debris-flow record based on amphibious investigations of fan delta activity in Plansee (Austria, Eastern Alps)

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