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

Problems with nutrient flowing

FA
Fernando Aguilar, modified 5 Years ago.

Problems with nutrient flowing

Youngling Posts: 22 Join Date: 2/7/13 Recent Posts
Dear all,

We are running ECO model coupled to Delft3D to simulate water quality in a reservoir from April to October. The hydrodynamic model (Z-Model, 35 layers, 5 tributaries configured as discharges and 2 outflows, time step is 5 minutes) show no continuity problems and the water level follows fairly well the real data.

But when running the ECOWAQ model, the top layers are always visible, showing substances values, although these layers become dry in the FLOW model. Also we can appreciate that a continuous and very high load of nutrients (substances concentrations 6 magnitude orders over the real ones) is entering the lake during all the simulation time, aparently coming from these (4) top layers and their boundary cells in these, saturating with nutrienst all the simulation domain.
AA
Anonymous Anonymous, modified 5 Years ago.

RE: Problems with nutrient flowing

Jedi Master Posts: 333 Join Date: 7/30/20 Recent Posts
Hi Fernando,

Is the emersion process active?
FA
Fernando Aguilar, modified 5 Years ago.

RE: Problems with nutrient flowing

Youngling Posts: 22 Join Date: 2/7/13 Recent Posts
Yes, it is activated.
AA
Anonymous Anonymous, modified 5 Years ago.

RE: Problems with nutrient flowing

Jedi Master Posts: 333 Join Date: 7/30/20 Recent Posts
Hi Fernando,

If the water level drops relatively quickly, it could be that mass remains trapped in inactive surface layers. The high concentrations you see could be due to the small segment volumes in the surface layer. Transport from the upper layer can still occur with dispersion.

Hard to guess what is going on without more details. Uploading your model or at least the inp and lst files may help.

In any case, some workarounds you can try:
  • Use the no dispersion if flow rate is zero option (to avoid dispersion from the upper layer)
  • Aggregate the top layers vertically, so that the top layer never runs dry (drawback is that you will loose resolution near the surface, obviously)