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Analysis and modelling framework for sediment production and yield in mountain basins

Applicant Molnar Peter
Number 144515
Funding scheme Project funding (Div. I-III)
Research institution Institut für Umweltingenieurwissenschaften ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.10.2012 - 31.03.2013
Approved amount 27'272.00
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All Disciplines (2)

Discipline
Geology
Hydrology, Limnology, Glaciology

Keywords (5)

debris flows; sediment cascade model; Illgraben; sediment dyanamics; landslides and rockfalls

Lay Summary (English)

Lead
Lay summary

Recent investigations of erosion in the Illgraben make it quite clear that the processes by which sediment is generated on hillslopes (landslides, rockfalls) and transported downstream (debris flows, floods) are stochastic with complex interactions dependent on the extent of hillslope erosion and its connectivity to the channel system downstream. Our research hypothesis is that it is both the state of sediment stored in a sediment cascade and the stochastic variability in the triggering mechanisms that contribute to sediment dynamics which can be described in a probabilistic framework. We have proceeded to develop this concept by first building an understanding of the driving processes in the Illgraben, and generating a new database to build a sediment budget for this site. The main goals of our research are:

a) to generate a new dataset of landslides in the Illgraben and describe it statistically with extreme event analysis of individual failures as well as to estimate average erosion rates over decadal scales;

b) to analyze the temporal change in the erosion of hillslopes and channels and their sediment residence times and to relate the observed changes to hydroclimatic variables in the basin;

c) to develop a coupled hillslope-channel sediment cascade model for the Illgraben and simulate the dynamics of landslide-debris flow interactions in a stochastic framework;

d) to generalize the results to hillslope-channel coupled sediment cascades and quantify the uncertainty in erosion rates estimated from short sampling windows as a function of the system parameters.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Patterns and controls of sediment production, transfer and yield in the Illgraben
Bennett G. L., Molnar P., McArdell B. W., Schlunegger F., Burlando P. (2013), Patterns and controls of sediment production, transfer and yield in the Illgraben, in GEOMORPHOLOGY, 188, 68-82.
Erosional power in the Swiss Alps: characterization of slope failure in the Illgraben
Bennett G. L., Molnar P., Eisenbeiss H., McArdell B. W. (2012), Erosional power in the Swiss Alps: characterization of slope failure in the Illgraben, in EARTH SURFACE PROCESSES AND LANDFORMS, 37(15), 1627-1640.

Collaboration

Group / person Country
Types of collaboration
Fritz Schlunegger, University of Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Brian McArdell, WSL Birmensdorf Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Associated projects

Number Title Start Funding scheme
120467 SedyMONT - Analysis and modelling framework for sediment production and yield in mountain basins under climate change (IP6) 01.10.2009 Project funding (special)
120467 SedyMONT - Analysis and modelling framework for sediment production and yield in mountain basins under climate change (IP6) 01.10.2009 Project funding (special)

Abstract

Slope failures are a critical process in mountain basins - they are a key source of sediment, eroding hillslopes and delivering substantial quantities of sediment to the heads of mountain channels. In many mountain basins, debris flows subsequently transport this sediment, and deliver it to the downstream fluvial system. The quantification of the volumes of sediment removed by rock-slope failure and transferred by debris flows, and the identification of their coupling and controls are pertinent to understanding landscape evolution at the heads of mountain basins and mountain basin sediment yield (e.g., Hovius et al., 1997, Hungr et al., 1999; Jakob & Hungr, 2005; Korup et al., 2010). The evolution of mountain ranges includes the role of tectonics, climate and erosion history. The identification of the response of mountain basin topography and sediment yield to climate change in particular is still an open issue, lacking good field datasets and a solid modelling framework to interpret the data and find generalities. The SedyMONT project (TOPO-Europe), within the ESF Eurocores programme, aimed to build such a dataset for key sites in the European Alps and Norway, with different glaciation histories. In addition, the particular role of our project funded by the SNSF was to develop a conceptual modelling framework for the Illgraben which was one of the key sites in our study.Recent investigations of erosion in the Illgraben make it quite clear that the processes by which sediment is generated on hillslopes (landslides, rockfalls) and transported downstream (debris flows, floods) are stochastic with complex interactions dependent on the extent of hillslope erosion and its connectivity to the channel system downstream (Schlunegger et al., 2009; Berger et al., 2011). Our research basis in this project is that it is both the state of sediment stored in a sediment cascade and the stochastic variability in the triggering mechanisms that contribute to sediment dynamics which can be described in a probabilistic framework. We have proceeded to develop this concept by first building an understanding of the driving processes in the Illgraben, and generating a new database to build a sediment cascade model for this site. We are now in the process of generalizing the findings to coupled hillslope-channel systems in mountain settings. The main goals of our research are:- to generate a new dataset of landslides in the Illgraben and describe it statistically with extreme event analysis of individual failures as well as to estimate average erosion rates over decadal scales;- to analyze the temporal change in the erosion of hillslopes and channels and their sediment residence times and to relate the observed changes to hydroclimatic variables in the basin; - to develop a coupled hillslope-channel sediment cascade model for the Illgraben and simulate the dynamics of landslide-debris flow interactions in a stochastic framework;- to generalize the results to hillslope-channel coupled sediment cascades and quantify the uncertainty in erosion rates estimated from short sampling windows as a function of the system parameters.By the time of our official project end (1.10.2012) our research will complete to about 80% and we request with this proposal a 6-month extension of the project to complete the research tasks for the PhD student Georgina Bennett to defend her PhD degree in the form of a paper dissertation. The progress obtained so far is described in detail in this proposal.
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