GREAT-ER Class Concept

Frederik Verdonck frederik.verdonck at
Tue Aug 24 08:47:56 CEST 2004

Dear Frank,

Not sure if I understand your question correctly but letting the user
decide between "class parameters" and "environmental parameters" may not
be straightforward as the user will probably not know what you mean with
"class parameters" and "environmental parameters". You may want to use
more TGD-wording as "site-specific" and "generic" or "local" and
"regional" parameters.

I would even argue it may be helpful to encourage/guide the user to use
distinct parameter sets (if sensitive to PEC) for different types of
stretches in a catchment (if allowed by data availability) because what
is the added-value of using a GIS-system if no georeferenced data are

Just some thoughts, hope this helps,

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> -----Oorspronkelijk bericht-----
> Van: great-er-list-bounces at 
> [mailto:great-er-list-bounces at] Namens Frank Koormann
> Verzonden: maandag 23 augustus 2004 11:13
> Aan: great-er-list at
> Onderwerp: GREAT-ER Class Concept
> Dear all,
> as you may have noticed a new CEFIC LRI Project has started 
> to add a first and rather simple sediment component to 
> GREAT-ER: Simple equilibrium concentration in sediment as 
> described for the WATER model (which is implemented by GREAT-ER). 
> The parameters needed for this approach are already in the 
> GREAT-ER database, as fields in the stretch class table. Some 
> of these have to be made editable by the user. I will 
> illustrate our plans from the 
> parameter editing point of view, describe some consequences to the 
> class concept and I would like to ask for your comments on this:
> The class concept 
> (implemented by GREAT-ER 2.0 as well as 1.0) allows to define 
> distinct parameter sets for different types of stretches in a 
> catchment. However, in personal communication it always has 
> been considered as somewhat experimental and not of much use 
> since the parameters have to be defined during catchment 
> preprocessing. They cannot be changed/displayed later on.
> For the sediment module at least the suspended solids concentration
> (SS_RIVER) has to be editable by the user, we will add this to the 
> environmental parameters. As a consequence a single SS_RIVER 
> probability density function will be applied for the entire 
> catchment. We are planning to add also the other parameters 
> needed for the equilibrium calculation to the environmental 
> parameters:
>         f_oc:    Organic carbon fraction of suspended solids in river
>         rho_sed: Dry sediment density
>         eps_sed: Volumetric water fraction of the sediment
> As for all environmental parameters default values will be 
> defined which will overwrite the values from river classes. 
> For users who really want to work with classes will will add 
> a choice to the model mode dialog:
> - Use class parameters
> - Use environmental parameters
> Your thoughts?
> Thanks in advance,
>         Frank
> -- 
> Frank Koormann                             
> <frank.koormann at>
>  Professional Service around Free Software       
> (
>  FreeGIS Project                     
>             (
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