User Forum of Software BASEMENT

BASEMENT
Basic Simulation Environment for computation of environmental flow and natural hazard simulation
Laboratory of Hydraulics, Hydrology and Glaciology (VAW)
ETH Zurich
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#1 2017-04-20 08:42:48

alaquas
User
Registered: 2015-08-27
Posts: 9

reach equilibrium with multigrain sediment transport

Hi,

I am trying to model a morphological equilibrium state using sediment transport (constant sediment rate, constant inflow, multigrain). I did several runs using restart files for hydraulics and morphology. Even after several hundred days of total_run_time not even half of the sediment reaches the end of the model, there appears to be reached no equilibrium state at all: while in section A the sediment input is 0.06 m3/s the sediment output after 125 days is 0.025 m3/s, section B has a sediment input of 0.03 m3/s and the sediment output after 320 days (!) is 0.01 m3/s. I already reduced grain sizes of the sediment mixture to a minimum (compared to observation). I also checked the relation between inflow and sediment rate.

Is there any sense in continuing modelling using the same conditions? Has anyone already reached an equilibrium condition using multigrain sediment transport in BASEMENT?

Thanks in advance!

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#2 2017-04-21 16:01:09

Lukas Vonwiller
Developer
Registered: 2014-09-04
Posts: 127

Re: reach equilibrium with multigrain sediment transport

Hi alaquas

If you start with an active layer with same grain size distribution (GSD) as in sublayer this might take a while until you reach equilibrium condition!
You would face a similar problem in laboratory experiments using non-uniform sediment.
However, in BASEMENT you can define a top layer with coarser GSD using the same thickness as the active layer thickness.
This will decrease simulation time until you reach equilibrium state.
To determine the GSD of static armor layer you could for example follow the ASCE Manual 54 on Parker's webpage.

Hope this helps!
Best, Lukas

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