Dikau Richard

Paraglacial Sediment Storage Quantification in the Turtmann Valley, Swiss Alps
Quantifizierung paraglazialer Sedimentspeicher im Turtmanntal, Schweizer Alpen

Project Number: CH-4399
Project Type: Dissertation
Project Duration: 01/01/2003 - 11/30/2006 project completed
Funding Source: other ,
Project Leader: Prof. Richard Dikau
Department of Geography
University of Bonn
Meckenheimer Allee 166
DE-53115 Bonn
Phone: +49 228 737234
FAX: +49 228 739099

related to this project.
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Research Areas:

environmental sciences

Turtmann Valley, sediment storage, landform

Sediment flux plays a central role within evolution of land surfaces and Earth's biogeochemical system. Within sediment flux systems, the role of sediment storage is often the least understood part. This study analyses the spatial distribution of sediment storage and quantifies sediment volumes in the high Alpine Turtmann Valley, Swiss Alps. A detailed geomorphological mapping provided information on the distribution structure of storage landforms. Geophysical methods were used to derive sediment thickness of single landforms in one hanging valley that have been used to model the storage volume for different landform types in all hanging valleys. The remaining sediment stores were quantified using different, subsystem specific GIS approaches.
A total sediment volume of 780 - 1,030 x 106 m3 is stored in the Turtmann Valley. More than 70 % of the material is located in the hanging valleys, resulting from a de-coupling and closure of the hanging valley subsystem. Within the hanging valleys, moraine deposits store the greatest volumes (70%), while slope landforms cover the largest areas (> 50%). Thus, the spatial distribution of stores emerges from the system behaviour, process intensity and land surface structure of the hanging valleys.
Average denudation rates for the Turtmann Valley vary between 0.9 and 1.25 mm a-1, calculated for a time period of 10 ka. Single landform denudation rates vary from 0.2 – 3.1 mm a-1 for talus slopes and cones to 0.1 – 1.8 mm a-1 for active rock glaciers. These values lie within the ranges of comparable values for the Alps.
The spatial pattern of landforms is used to infer a relative model of paraglacial landform evolution. A reworking of glacial deposits in the hanging valleys was accomplished mainly by glacier derived rock glaciers. Their distribution hints on three phases of paraglacial evolution since the End of the Pleistocene. Since most of today’s active rock glaciers are talus-derived, the reworking of paraglacial deposits is most probably completed and the paraglacial period in the hanging valleys of the Turtmann Valley is considered to be terminated.
This study presents a method to quantify landform volumes in a meso-scale alpine catchment. For the first time volumes are quantified for different landform types. Thus, a gap is closed between previously performed small scale studies and large river catchment investigations that provide non differentiated sediment volumes. A comparison of denudation rates indicates that the quantified volumes lie within a realistic range of previous studies. Finally, the importance of rock glaciers in the paraglacial evolution of the valley and the sediment storage distribution stresses the role of periglacial processes in the sediment flux system of high alpine environments.

Leading questions:
  • What is the distribution structure of sediment storages in the Turtmann valley?

  • What kind of functional relationships exists between these landforms in terms of sediment flux?

  • How much sediment is stored in the Turtmann Valley?

  • Wich landform types store the largest quantities of sediment?

  • How is the sediment flux system of the Turtmann Valley affected by sediment storage?

  • What does the distribution of sediment storages reveal about the landscape evolution of the Turtmann valley?

    Otto, J.-C. (2006): Periglacial sediment storage quantification in the Turtmann Valley, Swiss Alps. Bonner Geographische Abhandlungen, Heft 124. 2009. Bergisch Gladbach.
    pdf Dissertation

    Last update: 7/18/17
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