Project

Dendrogeomorphology; Alpine topography; Hillslope-Channel Connectivity; Surface Erosion; 10Be-based erosion rates

Lead
Lay summary
The response of the sediment routing system to the sculpting of the Alpine landscape during the Last Glacial Maximum (LGM) has been a major scope in the geomorphic community recently. We address this topic by analyzing patterns and rates of sediment transfer in two study catchments located on both sides of the Alps (the 2.5 km2-large Schimbrig catchment in Switzerland, and the 40 km2-large Zielbach drainage basin in Italy). Both sites are characterized by transient geomorphic features related to LGM glaciations. In these basins, we aim to quantify the timescales of the hillslope-channel coupling relationship in order to understand how differences in this parameter have controlled the mechanisms and the rates of sediment transfer in these basins. At Schimbrig where sediment transport has occurred through landsliding, debris flows and floods, we quantify geomorphic timescales with dendrogeomorphic data collected from more than 500 trees. The preliminary results indicate that the hillslope-channel coupling mechanisms have operated at decadal and centennial time scales, but that processes in the channel network are not implicitly related to those on the hillslopes over shorter time spans. In a second and third task, we measure the variability of 10Be concentrations of stream, soil and debris flow samples in a formerly glaciated drainage basin (Zielbach, Südtirol, Italy). In this basin, erosion and sediment transfer has been accomplished by either supply-limited fluvial or transport-limited debris flow processes. Based on our preliminary results, we find a large variability of sediment transfer rates in the debris flow dominated catchments, but a nearly uniform pattern of 10Be concentrations in the supply-limited network of bedrock channels. We proceed by completing the following tasks. (i)  measure 10Be concentrations of the last six samples, and (ii) analyze and interpret the 10Be dataset. In particular, we recently had the unique opportunity to sample a 30 m-long core for both 10Be analyses of riverine quartz, and 14C dating of paleo-floodplains, allowing us to trace the variability of 10Be concentrations and related debris flow transfer rates back in time since. We anticipate that the quantitative assessment of the mechanisms, the rates and the timescales of sediment transfer in the study catchments will advance our understanding of how the glacial inheritance has imprinted on the Holocene development of a sensitive Alpine landscape.

Direct link to Lay Summary

Last update: 21.02.2013

Number	Title	Start	Funding scheme

The response of the sediment routing system to the sculpting of the Alpine landscape during the Last Glacial Maximum (LGM) has been a major scope in the geomorphic community recently. We address this topic by analyzing patterns and rates of sediment transfer in two study catchments located on both sides of the Alps (the 2.5 km2-large Schimbrig catchment in Switzerland, and the 40 km2-large Zielbach drainage basin in Italy). Both sites are characterized by transient geomorphic features related to LGM glaciations. In these basins, we aim to quantify the timescales of the hillslope-channel coupling relationship in order to understand how differences in this parameter have controlled the mechanisms and the rates of sediment transfer in these basins. At Schimbrig where sediment transport has occurred through landsliding, debris flows and floods, we quantify geomorphic timescales with dendrogeomorphic data collected from more than 500 trees. The preliminary results indicate that the hillslope-channel coupling mechanisms have operated at decadal and centennial time scales, but that processes in the channel network are not implicitly related to those on the hillslopes over shorter time spans. In a second and third task, we measure the variability of 10Be concentrations of stream, soil and debris flow samples in a formerly glaciated drainage basin (Zielbach, Südtirol, Italy). In this basin, erosion and sediment transfer has been accomplished by either supply-limited fluvial or transport-limited debris flow processes. Based on our preliminary results, we find a large variability of sediment transfer rates in the debris flow dominated catchments, but a nearly uniform pattern of 10Be concentrations in the supply-limited network of bedrock channels. We need resources to (i) complete the measurements of 10Be concentrations of the last six samples, (ii) analyze and interpret the 10Be dataset, and (iii) to write the last paper and to finalize the PhD project of S. Savi. In particular, we recently had the unique opportunity to sample a 30 m-long core for both 10Be analyses of riverine quartz, and 14C dating of paleo-floodplains, allowing us to trace the variability of 10Be concentrations and related debris flow transfer rates back in time since. We anticipate that the quantitative assessment of the mechanisms, the rates and the timescales of sediment transfer in the study catchments will advance our understanding of how the glacial inheritance has imprinted on the Holocene development of a sensitive Alpine landscape.