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intro story DELWAQ

DELWAQ

DELWAQ is the engine of the D-Water Quality and D-Ecology programmes of the Delft3D suite. It is based on a rich library from which relevant substances and processes can be selected to quickly put water and sediment quality models together.

The processes library covers many aspects of water quality and ecology, from basic tracers, dissolved oxygen, nutrients, organic matter, inorganic suspended matter, heavy metals, bacteria and organic micro-pollutants, to complex algae and macrophyte dynamics. High performance solvers enable the simulation of long periods, often required to capture the full cycles of the processes being modelled.

The finite volume approach underlying DELWAQ allows it to be coupled to both the structured grid hydrodynamics of the current Delft3D-FLOW engine and the upcoming D-Flow Flexible Mesh engine (1D-2D-3D) of the Delft3D Flexible Mesh Suite (or even other models such as TELEMAC).

'DELWAQ in open source' is our invitation to all leading experts to collaborate in further development and research in the field of water quality, ecology and morphology using Delft3D. Feel free to post your DELWAQ related questions or comments in this dedicated forum space. If you are new to DELWAQ, the tutorial (in the user manual) is a good place to start. A list of DELWAQ related publications is available here.

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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 4 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.
CT
Christophe Thiange, modified 4 Years ago.

RE: Problems with nutrient flowing

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

Is the emersion process active?
FA
Fernando Aguilar, modified 4 Years ago.

RE: Problems with nutrient flowing

Youngling Posts: 22 Join Date: 2/7/13 Recent Posts
Yes, it is activated.
CT
Christophe Thiange, modified 4 Years ago.

RE: Problems with nutrient flowing

Jedi Knight Posts: 125 Join Date: 11/15/12 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)