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

 

 

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Wave & wind input reduction - how to implement in input files?

GL
Gabriel Lim, modified 2 Months ago.

Wave & wind input reduction - how to implement in input files?

Padawan Posts: 32 Join Date: 5/5/18 Recent Posts
Hello,

I am modelling medium- to long-term morphological changes of a beach. I have implemented wave and wind reduction techniques to produce a set of representative wave and wind conditions by seasons. I am running a 2DH simulation with online coupling between FLOW and WAVE modules. See example of representative conditions below:

These are the representative sets of wave and wind conditions for Autumn 2011:
Bin           Rep. Hs (m)    Probabilty    Tp (s)     Dir (deg)    Rep.Wind Spd (m/s)     Wind Dir (deg)
0-0.5              0.37                0.021         15.55         280                    3.21                              170
0.5-1              0.77                0.164           9.94         275                    3.98                              195
1-1.5              1.27                0.219         10.60         279                    7.77                              206
1.5-2              1.75                0.230         11.21         280                    8.16                              208
2-2.5              2.22                0.186         12.82         283                    8.21                              255
2.5-3              2.81                0.098         11.60         282                  11.65                              244
3-3.5              3.19                0.076         11.40         286                  12.13                              245

I want to input the representative wave and wind values with their respective weighting (probability of occurrence per year) into input files, but I cannot see anywhere in the manuals that indicates how this is done. Lesser (2009) who helped develop the Delft3D suite specifies that he used such techniques to implement input reduction techniques and thereby considerably reduced computational costs. If anyone has any idea on how to do this, please advise! Any help would be very much appreciated.

Many thanks in advance for your help and time!

Gabriel
DK
Dmitry Kushnir, modified 1 Month ago.

RE: Wave & wind input reduction - how to implement in input files?

Padawan Posts: 86 Join Date: 11/9/12 Recent Posts
Hi Gabriel,
Have you made a progress in time reduction for Delft3D morphology simulation? I'm not an expert on this, but I think you're probably looking for Morfac technique. See this Msc thesis for more details: https://www.utwente.nl/en/et/wem/education/msc-thesis/2015/wilmink.pdf
Please, post about you findings here, so other could  learn how to do this.
Regards,
Dmitry
GL
Gabriel Lim, modified 1 Month ago.

RE: Wave & wind input reduction - how to implement in input files?

Padawan Posts: 32 Join Date: 5/5/18 Recent Posts
Hello Dmitry,

Thank you for your reply and for sharing the MSc thesis. Yes, I am aware of the morfac technique, and I intend to use it in conjunction with the aforementioned input reduction techniques. As briefly mentioned in my previous post, Lesser (2009) used a representative set of wave and wind data, as well as a morphological tide (representative tide condition) on top of the morfac - further reducing the computational times. Examples of such combinations of input reduction and morfac can also be found in literature (e.g. Luijendijk et al., 2019).

If I found out how to implement these representative conditions into the input files for D3D, I will be sure to share them here also. If anyone has any idea or information, please let me know! Many thanks.

P.s. in case anyone is interested, the references for the publications I cited are as follows:
-Lesser, G. (2009). An approach to medium-term coastal morphological modelling. PhD thesis. UNESCO-IHE, Netherlands.
-Luijendijk, A.P.; de Schipper, M.A.; Ranasinghe, R. (2019). Morphodynamic Acceleration Techniques for Multi-Timescale Predictions of Complex Sandy Interventions. Journal of Marine Science and Engineering, 7, 78.
Adri Mourits, modified 1 Month ago.

RE: Wave & wind input reduction - how to implement in input files?

Yoda Posts: 1224 Join Date: 1/3/11 Recent Posts
Hi Gabriel,That's a so called "wavecon.<runid>" file. This functionality is outdated, not supported and not described in the manual. But it still works. Attached is a set of input files containing a wavecon file. You are free to use it, but support is not guaranteed.Regards,Adri
GL
Gabriel Lim, modified 1 Month ago.

RE: Wave & wind input reduction - how to implement in input files?

Padawan Posts: 32 Join Date: 5/5/18 Recent Posts
Hi Adri

Thank you for your reply and help! I wonder, can this option be used in the online-coupling with FLOW-WAVE? Is there anywhere I can find more information regarding this process and how to carry it out? Ideally I want to include representative values for waves and wind for an online coupled simulation. Do I include the representative wind values in the wavecon file as well instead of the "physical parameters" tab of the FLOW GUI? Or do the values need to be put into the FLOW-GUI separately as well as the wavecon file? The WAVE user manual says in Appendix A.2.8.1, it says:

"To use this Wavecon option, just simply add the <wavecon.rid> file to the working directory and the system will use the file automatically. A WAVE computation is always performed on a certain time point (based on the reference date). If a <wavecon.rid> file exists in the working directory, it will get its wave boundary
conditions (including wind and water level) from that file. The boundary condition values in the default <rid.mdw> file will not be used then. When the time point of the wave computation lies between two prescribed time points in the <wavecon.rid> file, it will interpolate the wave, wind and water level conditions between these two time points."

So I assume any boundary, wind, water level values input into the WAVE-GUI in standalone runs would be replaced by the values in the wavecon file, but what happens in the FLOW-WAVE coupling? Please advise. Thank you!

Kind regards,

Gabriel