Lead


Lay summary

The evolution of the alpine landscapes is a result of the composite effects of climate, tectonics and erosion. In order to understand the landscape evolution it is necessary to establish erosion or denudation rates. However, it is known that denudation rates are variable over time and space, but it is largely unknown to what extend this variability exists, can be quantitatively constrained and what induced these variations. Specifically, after the last glaciations (e.g., in the European Alps), geomorphic processes and denudation rates must have adjusted to the new interglacial condition. The main questions hereby - amongst others - are: 1.) Did denudation rates first increased and later decreased since the retreat of the glaciers? 2.) What impact has a Holocene climate change on denudation rates? 3.) How does a climate change affects permafrost areas and thus processes in this region? 4.)What is the influence of episodic events (thunderstorms, floods) on short, medium and long term denudation rates, that occur rather infrequent but with high magnitude? 5.) Are their lag times of cause and effect? 6.) Can we quantify climate change (e.g., increasing numbers of heavy rainstorms and floods, landslides and debris flows) and the related change of denudation rates, and thus study natural hazards and try to better perform on predicting natural risks?

The projects tackles these questions by trying to establish time series of denudation rates using terrestrial cosmogenic nuclides, in combination with field work and GIS analysis. We will use multiple cosmogenic nuclides (10Be 14C, 21Ne, 26Al) in sand from modern rivers and from lake archives for resolving Holocene denudation rates in various catchments of the European Alps. These rates are furthermore evaluated in the light of denudation rates obtained by other methods (sediment yield or thermochronology) that will enable us to have an idea about the steadiness or variability of denudation rates over various temporal and spatial scales. Furthermore we will compare the results of the European Alps with data from the Chilean-Bolivian Andes in South America. This region is characterized by a different climatic and tectonic setting and we thus expect different rates over different integrating timescales. Finally, in combination of the data from the Alps and the Andes we hope to get a better understanding of geomorphic processes, their rates and their driving forces.