intro story Coast / Estuary

Coast / Estuary

Coastal systems are among the most dynamic physical systems on earth and are subject to a large variety of forces. The morphodynamic changes occurring to coastlines worldwide are of great interest and importance. These changes occur as a result of the erosion of sediments, its subsequent transport as bed load or suspended load, and eventual deposition. 
 
Estuaries are partly enclosed water bodies that have an open connection to the coast. Estuaries generally have one or more branching channels, intertidal mudflats and/or salt marshes. Intertidal areas are of high ecological importance and trap sediments (sands, silts, clays and organic matter).
Within the Delft3D modelling package a large variation of coastal and estuarine physical and chemical processes can be simulated. These include waves, tidal propagation, wind- or wave-induced water level setup, flow induced by salinity or temperature gradients, sand and mud transport, water quality and changing bathymetry (morphology). Delft3D can also be used operationally e.g. storm, surge and algal bloom forecasting. 
 
On this discussion page you can post questions, research discussions or just share your experience about modelling coastal and/or estuarine systems with Delft3D FM. 
 

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Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 

 

Message Boards

How to specify a concentration in a cell without complete mixing?

Javier García Alba, modified 5 Years ago.

How to specify a concentration in a cell without complete mixing?

Youngling Posts: 12 Join Date: 1/4/12 Recent Posts
Hi,

We want to specify a concentration value in a cell (surface discharge). When we run the delwaq, the model do a complete mixing in the cell ((discharge flow*discharge concentration + cell concentration*volume cell)/(discharge flow+volume cell)), but we want to impose the concentration value in the whole cell without a complete mixing process. Actually, we want to impose initial dilution concentration directly in the cell. Is it possible?

Javi
Christophe Thiange, modified 5 Years ago.

RE: How to specify a concentration in a cell without complete mixing?

Jedi Knight Posts: 125 Join Date: 11/15/12 Recent Posts
Hi Javi,

You cannot use a simple load to impose a concentration on a particular segment because there will always be other fluxes to/from that segment.

The user-defined wasteload functionality (Appendix E of the user manual) allows you to program a load based on the concentration in a given segment at each time step. If the volume of your target segment does not change, you could define such a wasteload to add (or remove) the required mass to obtain the desired concentration in your segment.
As far as I know, there no way to access a segment's volume from the user-defined wasteload routine, hence if the volume of your segment does change over time you'll have to be creative (like hardcoding a time series of that segment's volume in your wasteload routine).

Can I ask why you want to impose a concentration inside a segment? Maybe there are other means to that end.

Regards,
Christophe
Javier García Alba, modified 5 Years ago.

RE: How to specify a concentration in a cell without complete mixing?

Youngling Posts: 12 Join Date: 1/4/12 Recent Posts
Hi Christophe,

Thank you for your quick response. I want to couple the results of a initial dilution model with the far-field (using delwaq). The problem is that delwaq model calculates a complete mixing in the dicharge cell and I want to impose the obtained concentration with the initial dilution model.

I think it could be an improvement, if the user can impose a fix concentration directly in the discharge cell with the GUI.

Regards,

Javi