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. 




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



Message Boards

Coupling of SWAN with Delft3D-Flow

Tola Lema, modified 8 Years ago.

Coupling of SWAN with Delft3D-Flow

Youngling Posts: 10 Join Date: 12/2/11 Recent Posts
I have a working nested Delft3D-Flow model, I have an overall coarse grid and two nested models (Nested 1 and Nested 2). Now I want to do online coupling of Delft3D-WAVE with Delft3D-Flow. I manged to run the online coupled WAVE-FLOW model using the spiderweb wind field, but what I used is the the overall grid Flow model. In Delft3D-WAVE there is an option to do nesting of various grid , so I nested the overall coarse grid and the nested grids in Delft-WAVE. My question is which Delft3D-Flow model to use with the wave model. Currently I am using the Nested 2 Flow model (Finer model) with the coarse Wave model. I am not sure if I am doing this right or not, do I have to use the overall coarse flow model?. My concern is my Nested 2 grid covers a very small area compared to the Wave grid, I am using the option "Use and Extend " for water level, current, bathymetry, and grid in the WAVE module. It is not clear to me how the "Extend" works, how small can be the Flow grid, and the effect on the results etc. Please advise me the proper way of online coupling of Nested Flow model with overall coarse Wave model (although the wave can be nested).

Thank you in advance
Adri Mourits, modified 8 Years ago.

RE: Coupling of SWAN with Delft3D-Flow (Answer)

Yoda Posts: 1221 Join Date: 1/3/11 Recent Posts
Hi Tola,

If you use nested FLOW grids, you have indeed two options:
  • Use the FLOW data of the coarse grid as input for WAVE. This may lead to too coarse WAVE data in your region of interest.
  • Use the FLOW data of the fine grid as input for WAVE. The "use and extend" option will use values at the boundaries of the small domain and extend that as a constant value outside the small domain. This may lead to unrealistic WAVE data in the coarse domain.

There is one alternative:
If you use DomainDecomposition instead of nesting, you can use all FLOW data of all domains as input for the WAVE domains.

All options have their advantages/disadvantages. You have to decide yourself what option you use.


Tola Lema, modified 7 Years ago.

RE: Coupling of SWAN with Delft3D-Flow

Youngling Posts: 10 Join Date: 12/2/11 Recent Posts
Thank you very much for the reply. I end up using # 1.