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

DELFT3D Wave height decreases incredibly fast (Urgent)

Joao Morim, modified 7 Years ago.

DELFT3D Wave height decreases incredibly fast (Urgent)

Youngling Posts: 3 Join Date: 4/10/13 Recent Posts
Hello guys,

I have built my model and it is running on a curvilinear grid using spectral data from WW3 last version. I created a spectral file for each location, which were subsequently uploaded into DELFT3D-WAVE GUI using segments (a file per segment).

The model runs and does not present any errors, however, the results are physically impossible. My boundaries (where the files were uploaded) are sufficiently far away from the coast (>2000m of water depth) as you can see in Fig 1 (attached). When I run the model for 5 hours the results are not how they should be. My boundaries conditions are around 3.5/4m at the boundaries, however, as soon as they start to propagate through the model they decrease incredibly fast in very deep water....where waves do not yet feel the bottom. As we can see in Fig 2 and 3 as soon as they get into the domain, they loose immediately 2m without any explanation. Plots of the energy transport also show the same as in Fig 4. I have compared to wave buoy records and waves should have around 1.9 m near the buoy, however, they presented 0.6 m without any reasons.

I have tried a lot of different approaches to get around this, however, I was not well succeeded. I attached my mdw file, spectral files, grid and depth to this email. If you guys could give a quick look into it and give any hint about what is going on I would be deeply appreciated.

Very appreciated...looking forward to see your opinions!
Arjen Luijendijk, modified 7 Years ago.

RE: DELFT3D Wave height decreases incredibly fast (Urgent)

Padawan Posts: 38 Join Date: 2/22/11 Recent Posts
Dear Joao,

The problem lays in the fact that you run a non-stationary simulation. In case you make stationary simulations, the results look very realistic. If you do want to make a non-stationary simulation (in case of storms this is often advised), you should select a smaller time step than 60 min (try 10 min), AND you should activate that you want to use the hotstart file option. Else, each SWAN computation will start from scratch again, and the wave propagation in 60 minutes period is not fully resolved yet. By using the hotstart file option, the results of the previous hour are given as initially field for the next SWAN computation which corresponds to reality...

Good luck, Arjen