IP 4 - Project

Sediment budgets of glacier forefields (Pasterze & Obersulzbachkees, Upper Tauern, Austria) - quantification and temporal variability.

Motivation
In the context of Global Climate Change, magnitudes and frequencies of geomorphic processes are subject to climatic controlled variations leading to significant modifications in land surface topography. Sediment budgets identify, differentiate and quantify sediment transfer processes, sediment storages and clarify to what extent these system components are coupled to each other. The relationship between sediment storage volumes and present-day sediment transfer rates can contribute to both, an understanding of previous (postglacial) landscape development and to the prediction of future topographic evolution.
As retreating Alpine glaciers expose landscapes with unconsolidated, loose and potentially unstable landforms (e.g. moraine slopes), which are not in equilibrium with changing environmental conditions, glacier forefields react very sensible to climate change and therefore are susceptible to rapid topographic modification. Due to this accelerated (paraglacial) geomorphodynamic, sediment budget studies on relative short time scales within glacier forefield landsystems are of specific scientific interest. Furthermore, this study will have implications to an improved water reservoir management for the Margaritze reservoir (study site Pasterze).

Research scopes

  • Description of the sediment routing system and quantification of sediment fluxes.
  • Comparison of glacier and sediment dynamics (e.g. Pasterze, for the last 50 years).
  • Contribution to the understanding of the model of paraglacial landscape response.
  • Prediction of future sedimentation trends with regard to glacier retreat and changing sediment fluxes due to changed environmental conditions

Research methods

  • Spatial distribution of sediment storage types (area):
    • geomorphological mapping
    • orthophoto interpretation
    • morphometric digital terrain analyses
  • Quantification of single landform- and catchment storage (volume/mass):
    • field geophysics (GPR, ERT, RST)
    • morphometric analyses
    • GIS analyses
  • Present day sediment fluxes:
    • repeated terrestrial laser-scanning (slope & channel)
    • measurement of discharge; bed-, suspended- and solute load (channel)
Preliminary studies
Within the scopes of three diploma theses the sandur in the glacier forefield of the Pasterze was investigated in 2006/2007. A first geomorphological map of the sandur area and the adjacent slopes was designed to identify sediment storages, sediment transfer processes and the major paths of the sediment routing system. Discharge, suspended load and the concentration of solutes were measured during the ablation period of 2006 and the sediment transfer through the sandur system was calculated. In addition, geophysical investigations were carried out to determine the sediment thickness of the sandur.
 
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