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SUMMARY:Stochastic modelling of the sediment cascade in the Illgraben
DTSTART:20131029T161500
DTEND:20131029T171500
DTSTAMP:20260601T083231Z
UID:9a215d13395d22be76f80091107e718e2bb72a2ce9418906eaa17535
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Peter Molnar\, Chair of Hydrology and Water Resources Ma
 nagement\, ETH Zurich\nAbstract:\nFluvial systems generally exhibit sedime
 nt dynamics that are strongly stochastic. This stochasticity comes from th
 e randomness involved in sediment production\, sediment transport pathways
 \, and the transport triggering process\, e.g. heavy rain or overland flow
 . Fully deterministic models of fluvial systems\, even if they are physica
 lly realistic and very complex\, are likely going to be unable to capture 
 this stochasticity and as a result will fail to reproduce important featur
 es of long-term sediment dynamics. In this presentation I will show instea
 d a simplified conceptual approach to modelling based on the notion of the
  sediment cascade and will apply it to the Illgraben. The model conceptual
 izes Illgraben as a spatially lumped cascade of connected reservoirs repre
 senting interconnected hillslope and channel storages where sediment is st
 ochastically generated and goes through multiple cycles of storage and rem
 obilization by surface runoff. All relevant hydrological processes that le
 ad to runoff in an Alpine basin are included. Despite its simplicity\, the
  model produces complex sediment discharge behaviour which is driven by th
 e availability of sediment and antecedent moisture (system memory) as well
  as the triggering potential (climate). The argument will be made that thi
 s modelling approach has greater potential for statistical predictions of 
 debris flow occurrence than methods based on a single rainfall threshold. 
 I will conclude by arguing that in the context of stochasticity\, traditio
 nal notions of stability and equilibrium\, of the attribution of cause and
  effect\, and of the timescales of process and form in geomorphic systems\
 , become increasingly difficult.Dr Peter Molnar is professor of hydrology 
 and fluvial systems at ETH Zurich. His main research aim is to describe an
 d quantify the propagation of stochasticity from rainfall into water and s
 ediment fluxes on a river basin scale and the resulting effects on river m
 orphology and processes in the riparian environment. He places high import
 ance on high quality education in hydrology and water resources problems\,
  both as a service to developing countries as well as in the graduate prog
 ramme at ETH.
LOCATION:GR A3 31 http://plan.epfl.ch/?room=GR%20A3%2031
STATUS:CONFIRMED
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