Department of Geography Seminar: Georgie Bennett, ETH, Zurich
The Illgraben is a debris flow catchment in the Swiss Alps characterised by several debris flows each year. We quantify sediment transfer through the upper catchment over a 42 year period following a huge rockfall of 5x106 m3 that choked the channel with sediment. This is achieved through the extraction and morphometric analysis of DEMs from historical aerial photographs.
We extracted an inventory of 2500 bedrock failures spanning 6 orders of magnitude in volume from a 1km² rockface at the head of the catchment. Magnitude-frequency and volume-area scaling relationships that indicate a mixed rockfall/landslide inventory are presented.
The upper channel behaves both as a reservoir and conveyor of the failed sediment over the study period. Channel sediment residence times are presented along with statistical analysis of the hillslope and channel fluxes with hydroclimatic variables that indicates the transport limited nature of sediment transfer by debris flows.
Georgie is a former Durham graduate (BSc and MA). She moved to Switzerland in 2009 to take up a PhD position at ETH Zurich to work on the Sedymont/TopoEuropo project which aims at understanding sediment transfer in mountain basins under a changing climate.
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