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| Titel |
Rainfall events as landslide triggers -- implications for the evolution of
the SW-German cuesta landscape |
| VerfasserIn |
Jan Henrik Blöthe, Joachim Götz, Hannah Berger, Daniel Jäger |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152577
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| Publikation (Nr.) |
 EGU/EGU2017-17430.pdf |
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| Zusammenfassung |
| The cuesta landscape of southwestern Germany (Swabian Alb) is characterized by layered
sedimentary rocks (Jurassic) of variable strength. Due to this geologic preconditioning, where
porous limestone (Malm) is underlain by impermeable claystone (Dogger), and the deeply
incised valleys of the Rhine river system, landslides play an important role in the landscape
evolution of the region, continually eroding the slopes of the Swabian Alb and displacing the
escarpment further backwards. One of the largest (well documented) landslides happened in
April 1983, when an estimated volume of 6 x 106 m3 (∼0.5 x 106 m2) was mobilized at the
Hirschkopf close to Mössingen, after 1/3 of the mean annual precipitation was
delivered in only a few days. The historic record holds further evidence of at least
four landslides of similar size (>0.25 x 106 m2) in the past 250 years, most of
which have been attributed to high-intensity and/or long-duration precipitation
events.
During summer 2013, at least eight landslides have been initiated in the vicinity (<10 km
distance) of the Hirschkopf, all on June 2nd and 3rd. Again, the period before these events
was very wet, suggesting that high-intensity and/or long-duration precipitation plays a key
role in the evolution of the SW German cuesta landscape. We take this opportunity to a)
quantify the volume of material mobilized during the events and b) to estimate the sediment
output from the affected catchments.
By comparing post-event digital elevation models (DEMs) obtained from UAV/SfM and
TLS surveys with a pre-event DEM (ALS), we estimate that at least 2.5 x 106 m3have been
mobilized by these landslides, with the largest of them accounting for >1 x 106 m3 of
material. Assessing data from more than 20 rainfall stations in the region (<40 km distance)
reveals the June 2013 precipitation to exceed the 95th percentile of the past decade by far, in
six locations constituting the maximum of the ten-year record. Preliminary results of
suspended sediment export that we estimate from sediment-discharge rating curves indicate
that high-intensity long-duration rainfall events govern the total sediment delivery from the
region. |
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