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

Sediment diameter and *.d50 file

MK
Manuela König, modified 2 Years ago.

Sediment diameter and *.d50 file

Youngling Posts: 14 Join Date: 3/31/17 Recent Posts
Hey,

I have a question concerning the sediment diameter.

I have grain size distribution from the sediment and want to split it up in a silt/cohesive and a sand/non-cohesive fraction.
Should I use the d_50 of my whole distribution or just from my sand fractrion part (what seems more logical to me).

Would be quite helpful to get some tips and learn from your experience.

Thanks
Manuela
Qinghua Ye, modified 2 Years ago.

RE: Sediment diameter and *.d50 file

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Manuela,

It depends on what kind of detail you want to resolve. If you only focus on the total sediment transport, morphology change and so on, one or two representative fractions are good enough. If you are interested in sediment transport of different fractions (e.g., mud and sand) and so on, you may use different settings.

Delft3D offers both options. You can implement as many as 99 fractions in the model, if it is really necessary.

Hope this may help a bit?

Greetings from Qinghua
MK
Manuela König, modified 2 Years ago.

RE: Sediment diameter and *.d50 file

Youngling Posts: 4 Join Date: 6/12/17 Recent Posts
Hej Qinghua,

thanks for helping emoticon

I have another question you might help with. I would be very glad.

I am trying to build a D50 file to specify my grain size diameter for my sand fraction.
I followed all the discribed steps but getting the ERROR message: *** ERROR Sediment diameters must be positive!

I checked my d50 file, but there are no negative values in it.

Hope you might help.
Attached you find my .d50 and .sed file.

Thanks,
Manuela
Qinghua Ye, modified 2 Years ago.

RE: Sediment diameter and *.d50 file

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
HI Manuela,

I checked your D50, which is ok in my opinion. But there might be mismatch with grid. Can you also post the grid?

Greetings,

Qinghua
MK
Manuela König, modified 2 Years ago.

RE: Sediment diameter and *.d50 file

Youngling Posts: 4 Join Date: 6/12/17 Recent Posts
Hej Qinghua,

thx for your quick answer. Attached you find my grid.

Thanks
Manuela
Qinghua Ye, modified 2 Years ago.

RE: Sediment diameter and *.d50 file (Answer)

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Manuela,

Indeed. This is a known "feature" that we cannot use the spatial varying diameters and more than 1 sediment fraction. Refer to Delft3D-Flow Manual, the first remark under table B.3, "The SedDia parameter may only be specified as a file if the simulation includes only one sediment fraction.".

If you remove the mud fraction, it should work.

Greetings,

Qinghua