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

spherical and geographical coordinates

RC
Rodrigo Carballo, modified 8 Years ago.

spherical and geographical coordinates

Youngling Posts: 19 Join Date: 5/27/11 Recent Posts
Hi,

I am trying to run a model in geographical coordinates.
I ran the same model in geographical coordinates in the cartesian system and it works well, instead the same model choosing spherical coordinates does not work well.
The following error occurs after
first simulation (I am using a file with different conditions):
"...rem exit
>>...End of SWAN run
*** ERROR: SWAN file PRINT contains ERRORS

The strange thing is that convergence is achieved in the simulation but it is not saved any file data.

Thanks in advance
Bert Jagers, modified 8 Years ago.

RE: spherical and geographical coordinates

Jedi Knight Posts: 201 Join Date: 12/22/10 Recent Posts
Hi Rodrigo,

CARTESIAN model = grid locations in metres relative to some reference point. Check the validity of the coordinate system that you want to use; far away from the origin distortions may occur in the metric. Furthermore, in Cartesian models the curvature of the earth is ignored in this coordinate system, as is variability in the Coriolis force (in FLOW models). So, a Cartesian model should only be used for local to small regional models.

SPHERICAL model = grid locations in degrees east and degrees north. A spherical model should be used for large regional to global models.

Geographical coordinates may refer to either latitude/longitude in degrees, or to metric coordinates in e.g. a UTM zone. I assume that you refer to latter in which case your model is referred to as CARTESIAN in the context of Delft3D.

Note that coordinates are processed in double precision throughout the Delft3D system with one exception: coordinate data (as any other data) on the output files is stored in single precision. If the distance between the grid points and the origin is large in a Cartesian model, or if you're looking at a high resolution model in spherical coordinates, you may encounter some optical distortion of the grids in the post processing. It's something that we would like to solve in 2012.

Best regards,

Bert
RC
Rodrigo Carballo, modified 8 Years ago.

RE: spherical and geographical coordinates

Youngling Posts: 19 Join Date: 5/27/11 Recent Posts
Hi again,

Thank you very much for your reply.
The problem is that I would like to implement a model in lat, long coordinares (thus spherical model) of a not very large region (it could be adequated also to implement it in metric UTM coordinates). The problem is that in the simulations, after the first run (that apparently simulated properly), the following error occurs (and no output file is storaged):

>>...End of SWAN run
*** ERROR: SWAN file PRINT contains ERRORS

I tried with different models and in spherical coordinates, always occurs the same; instead in metric coordinates (thus cartesian model) all models works properly.

Do you know if there exist any limitation with spherical models? (I am using grid sizes of approximately 200 m, I do not know if this has something to do...)

Thanks in advance,

Regards,

Rodrigo
Bert Jagers, modified 8 Years ago.

RE: spherical and geographical coordinates

Jedi Knight Posts: 201 Join Date: 12/22/10 Recent Posts
Hi Rodrigo,

Please look in the simulation directory. It should contain all input and output file of the SWAN run including the file called "PRINT". According to Delft3D-WAVE there is an error message in that file. Check whether you can determine what's the problem from that file. If not, please post the PRINT file or the error message that it contains.

Success,

Bert