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

Water Depth Exceeds 5%, can we change?

SS
Syamsidik Syamsidik, modified 7 Years ago.

Water Depth Exceeds 5%, can we change?

Youngling Posts: 2 Join Date: 7/6/11 Recent Posts
I tried to couple Delft3D-FLOW and Delft3D-Wave to simulate morphology changes.
I used 15 days tidal cycle with Astronomic forcing types (M2,S2, K1, and O1).

With MORFAC of 2 and Time Steps 0.5 minutes, the simulation gave errors. The Tri-diag file gave this:

"Water Depth Exceeds 5%........."

My questions:
*(1) what does it mean?
(2) can we change the limit of 5%, and if yes, how?

Thank you,
Adri Mourits, modified 7 Years ago.

RE: Water Depth Exceeds 5%, can we change? (Answer)

Yoda Posts: 1212 Join Date: 1/3/11 Recent Posts
Hi Syamsidik,

The message
*** WARNING Bed change exceeds 5% of waterdepth after ? timesteps, location (m,n) = (?,?)
is a warning and will not cause an abort of the calculation. This message will be written a limited number of times.

The message
*** WARNING Velocity change too high > 5.0 m/s (per 0.5 DT) after ? timesteps in the following points:
is also a warning and will not cause an abort of the calculation. This message can be supressed by adding the following line to the mdf-file:
UgrThr = 99.0
Default value is 5.0

The message
*** ERROR Water level change too high > 25.0 m (per 0.5 DT) after ? timesteps in the following points:
is really an error and does cause a direct abort of the calculation. This message can be supressed by adding the following line to the mdf-file:
SgrThr = 99.0
Default value is 25.0

All these message are related to a calculation that is about to become unstable. There are 3 possible causes:
  • The Courant number is too big.
    You should reduce the timestep and/or MORFAC. If the Courant number is just a little bit too big, supressing the messages above may result in a not aborting calculation, but then you do have to inspect the results very carefully. If the Courant number is much too big, supressing the messages above will avoid the calculation to abort directly, but it will probably crash a few time steps later due to NaNs in the calculation. In this case you have to reduce the time step (or simplify your model).
  • The input files contain an error.
    Supressing the messages above will not solve this. You have to investigate the results just before the abort to find out where the eror is.
  • Delft3D-FLOW contains an error
    If all other options fail, there might be a bug in the code. You can try to solve it yourself or report it to Deltares.


Regards,

Adri
MH
Md Habib, modified 5 Years ago.

RE: Water Depth Exceeds 5%, can we change?

Youngling Posts: 2 Join Date: 10/16/15 Recent Posts
Dear Adri,

I am getting the same error message while running delft3d flow module

*** ERROR Water level change too high > 25.00 m (per 0.5 DT) after 154896 timesteps in the following points: (m,n) = (118,99), s0, s1, abs(s0-s1): 0.759E+02 , 0.105E+03 , 0.294E+02
*** ERROR Flow exited abnormally

Reducing time step solved this problem but then it takes too much time to complete the run.
Exactly which flow results should I check at the time just before the abort to find out where the error is ?

Thanks
Ahsan Habib
JR
Janay Reis, modified 25 Days ago.

RE: Water Depth Exceeds 5%, can we change?

Youngling Posts: 1 Join Date: 4/13/21 Recent Posts
Md Habib:

Dear Adri,

I am getting the same error message while running delft3d flow module

*** ERROR Water level change too high > 25.00 m (per 0.5 DT) after 154896 timesteps in the following points: (m,n) = (118,99), s0, s1, abs(s0-s1): 0.759E+02 , 0.105E+03 , 0.294E+02 five nights at freddy's
*** ERROR Flow exited abnormally

Reducing time step solved this problem but then it takes too much time to complete the run.
Exactly which flow results should I check at the time just before the abort to find out where the error is ?

Thanks
Ahsan Habib
I am also a master student working on sediment transport. I tried the space varying wind as you mentioned below but still i am getting some errors like "error in accessing quantity3". can you please attach your space varying wind file and modifications to be made in mdf file if any....if possible please attach mdf file as well.