Sediment budget and morphodynamics of an alpine talus cone on different timescales

摘要

The sediment budget and morphodynamics of a single talus sheet-debris cone complex in an Alpine glacial valley of the Northern Calcareous Alps is analysed on three different time scales. The undercutting, truncation and dissection of this sedimentary storage system caused by a high-magnitude event in August 2005 is documented and analysed using multitemporal geodetic surveys. On an intermediate timescale, the erosion or redistribution of sediment by debris flows is analysed by means of multitemporal orthophoto interpretation. Finally, the dissection of the talus sheet by debris flows is estimated to have started in the second half of the 19(th), century, based on estimations of debris flow magnitude and frequency. It seems to be caused by a change in catchment size rather than by climatic change at the end of the Little ice Age alone. The most recent persistent change in system behaviour has been initiated by the August 2005 high-magnitude event, the consequences of which will be monitored in the future.