Analysis of erosion rates and geomorphological processes on Little Ice Age lateral moraines

Kurzfassung/Abstract

The rapid glacier recession in the European Alps exposes high amounts of unconsolidated sediment, especially in the form of moraines. Several processes are involved in the reworking of this sediment on steep lateral moraines, e.g. small slides on the steep upper slopes, sheet erosion by snow gliding and debris flows. The temporal development of the morphodynamics after deglaciation depends on the abundance of loose sediment, the presence of dead ice in the slope, the slope gradient, moisture availability and the altitude a.s.l. of the respective slope, amongst others.
To gain deeper insight into the dependence of the morphodynamics on lateral moraines on the time since deglaciation, we analyse erosion rates and geomorphological processes occurring on small test areas situated at different distances from the present-day glacier termini. Moreover, we assess the significance of parameters like initial slope gradient, moisture availability and the presence of dead ice for the morphodynamics and examine whether their impact can surpass and thereby obscure the influences of the distance from the glacier tongue and the altitude a.s.l.
For our analyses, several moraine tracts of 10 glaciers in the German, Austrian, and Italian Alps are investigated. The glacier forefields not only differ in their location within the Alps, but also regarding their altitude a.s.l. and size.
For the long-term detection of sediment reworking, we use a series of historical aerial images to generate Digital Elevation Models (DEM) by photogrammetric analyses. In order to detect recent geomorphological processes in detail, we derive highly accurate DEMs from our own UAV-surveys conducted in summer 2017 and 2018.