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

submerged sills in delft 3d

Gabriel Ruiz, modified 7 Years ago.

submerged sills in delft 3d

Padawan Posts: 59 Join Date: 9/30/11 Recent Posts
Hi modelers,
I’m using the delft 3d in order to simulate the effect of different schemes of coastal defenses has in a littoral system. For this reason, I have done simulations where I use breakwaters, groins and beach nourishments. This task has been a nice opportunity to learn about how to use dry points, thin dams and porous plates in delft 3d.

All my simulations have been done, taking into account the structures as emerged. But now, I would like to use submerge structures to simulate a perched beach and artificial reefs.

On the other hand, to give the height of my submerged sills, I was thinking that in some cells I should need to do a bed level variation and with this, the obstacle height will be done. But, thinking about this idea, I had one question: how should I tell to delft 3d that my structure is impermeable and the cells with this level variation do not change during the morphodynamic evolution?
Taking about artificial reefs, I have other problem: how could I change the porosity in the structure?

With these doubts in mind… if I used structures as “local weirs”, these hydraulic structures would solve my problems? I’m not 100% sure of this! Because I have understood well, we should use this special hydraulic structure in rivers and channels.

What kind of special structure in delft 3d, I should use?
Any idea about it?

Thanks and regards.

Richard Measures, modified 7 Years ago.

RE: submerged sills in delft 3d (Answer)

Jedi Knight Posts: 178 Join Date: 3/23/11 Recent Posts
Hi Gabriel

It's possible to set cells as in-erodible by setting the sediment thickness as zero. You can do this by using an initial bed composition file (*.inb) and spatially varying sediment thickness file (*.thk). (These files are described in the delft3d-flow manual Appendix emoticon. With sediment thickness set to zero no erosion below the initial bed level is possible.

I can't answer the other parts of your question as I haven't much experience with the hydraulic structures functionality in Delft I'm afraid.

Gabriel Ruiz, modified 7 Years ago.

RE: submerged sills in delft 3d

Padawan Posts: 59 Join Date: 9/30/11 Recent Posts
Hi Richard!

Thank you Richard, I got it. Let me try it and if I have any problem, I will write other post in this thread.
Do not worry of my questions about the hydraulic structures. I hope that other delft 3d user can give me some ideas.

Again, thanks and regards!

Arjen Luijendijk, modified 7 Years ago.

RE: submerged sills in delft 3d (Answer)

Padawan Posts: 38 Join Date: 2/22/11 Recent Posts
Hi Gabriel,

Master students of TU Delft have applied Delft3D for submerged breakwaters. The most recent study is of Jos van der Baan. You can find his report here for inspiration:


Hope this gives you insight in how we can simulate such structures. The porosity of the breakwater can not be included explicitly. Through the transmission coefficient in SWAN you could indirectly include this characteristic in the wave propagation.

Regards, Arjen
Gabriel Ruiz, modified 7 Years ago.

RE: submerged sills in delft 3d

Padawan Posts: 59 Join Date: 9/30/11 Recent Posts
Hi Arlen!

Thank you for share the link.
Definitely, this report will give me some ideas about how to simulated perched beaches.

Thank you Arjen for your post, it has been very useful.