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SUMMARY:On modeling hyporheic dissolved oxygen\, temperature and nitrogen 
 dynamics in gravel bed rivers
DTSTART:20130416T161500
DTEND:20130416T171500
DTSTAMP:20260414T105933Z
UID:b58a45377e738124ef18aecbe1c0b0894ca7b13c1f8e9696b2d1e50a
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Alberto Bellin\, Department of Civil\, Environmental and Me
 chanical Engineering\, University of Trento\, IT\nDissolved inorganic nitr
 ogen (DIN)\, naturally a limiting element in pristine watersheds\, has rec
 eived recently great attention because of its increasing concentrations in
  water bodies due to anthropic activities. DIN concentrations regulate riv
 erine ecosystems and organisms’ metabolism with important processes occu
 rring in hyporheic\, riparian and parafluvial zones\, whose biochemistry i
 s influenced by subsurface flow patterns. Although a large body of experim
 ental evidences confirms this\, most of the models used to represent nutri
 ents cycling in fluvial ecosystems lump these processes in a single diffus
 ion-type exchange term. In this seminar I discuss a new modeling approach\
 , which overcomes this limitation. In particular\, I will discuss a three-
 dimensional semi-analytical process-based model that couples hyporheic flo
 w patters with dissolved oxygen and DIN biochemical processes within the s
 treambed sediment. Flow patterns\, are obtained analytically\, with a few 
 simplifying assumptions\, from the streambed topography and solute transpo
 rt is modeled within a Lagrangian framework chiefly as an advective proces
 s with temperature-dependent reaction rate coefficients derived from field
  experiments.  In addition\, I will discuss the application of this model
  to investigate the role of hyporheic flow induced by alternate bars - an 
 ecologically important and ubiquitous bed form in both regulated and natur
 al streams - on DIN dynamics.  This modeling approach allows to investiga
 te the effect of bedforms\, alluvium depth\, hyporheic water temperature a
 nd relative abundance of ammonium and nitrate in stream waters on DIN dyna
 mic.  Published results demonstrate how the model can be used to estimate
  nitrogen gas emissions from rivers.
LOCATION:GR A3 32 http://plan.epfl.ch/?room=GR%20A3%2032
STATUS:CONFIRMED
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