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

 


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Properly setting up DD-boundaries

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Properly setting up DD-boundaries
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Answer (Unmark)
10/10/17 12:43 AM
New user here. I've looked through the documentation and tried (unsuccessfully) to run the example in the repository, and I've seen similar problems posted on the forums but nothing we have tried has solved our issue.

We are attempting to run a 3-domain model of a coastal channel emptying into a large gulf. We have successfully run it as a single-domain model but want to improve the time efficiency. Each of the 3 domains we have split the model into run when tested individually, but when attempting to couple them along DD-boundaries, it just won't work. We have attempted several possible fixes but none so far have worked, so there is obviously a misunderstanding on our part regarding exactly how to define the boundaries.

From the forums we've seemed to get some mixed messages: one post said that dd-boundaries cannot extend into dry cells, but another said that a failed model began functioning when the dd-boundaries were extended further into dry cells. In the manual, it says to change the .ddb file so that each <something>.grd becomes the .mdf file that references that .grd file, which I have done. (The .ddb file was generated in RGFGRID.) But the example in the repository doesn't do that (in the .ddb file, it has zzn.grd but there are no zzn.grd in the folder, only bak_n.grd files).

In most cases we've tried, the errors that we keep getting are all along the grid cells of the dd-boundaries and we are at a loss how to fix it. In a few cases, the cells giving errors were not even part of the grids: they would be shifted one cell outward from the grid, and one cell over from that position. The dd-boundaries we defined in RGFGRID were not along those points so it has confused us.

Our recent approach was to attempt to simply couple two small square grids, but even this is giving us issues.

Kind of lost here, so any help is appreciated.