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

RE: Difficulty with transport boundary conditions: free outlet

AC
Adrian Csibran, modified 3 Years ago.

Difficulty with transport boundary conditions: free outlet

Youngling Posts: 2 Join Date: 9/9/15 Recent Posts
Dear All,

I have some difficulty with open boundary conditions in case of transport processes. I have a lake with 2 open boundaries: an inflow (total discharge) and an outflow (water level). I know the concentration at the inflow, but I have no information about it near the outflow. I would like to adjust an open boundary with free outflow, without adding any transport boundary condition. I tried to adjust zero concentration for outflow, but it reversed back on the domain. I also tried to use the Thatcher-Harleman lag, though this function was not designed for this kind of condition, but it didn’t solve the problem either. As the exact concentration near the outflow is very important to me, I am looking for a way to overcome this problem. Does an option exist in Delft3D-Flow which provides free outflow for transport, or could you suggest me any other method to fix this problem?

Thank you in advance,

Adrián Csibrán
AC
Adrian Csibran, modified 3 Years ago.

RE: Difficulty with transport boundary conditions: free outlet (Answer)

Youngling Posts: 2 Join Date: 9/9/15 Recent Posts
Dear All,

The answer for my question can be found in the Flow Manual, I have not noticed it before. In case someone would face a similar problem:
„When you specify a negative value for the time lag (Thatcher and Harleman time lag) the boundary treatment for constituents, salinity and temperature will be the same as at outflow, but now for all times. Thus, the solution for these parameters will be fully determined by the processes inside the model area. „

Best regards,

Adrián Csibrán
Qinghua Ye, modified 3 Years ago.

RE: Difficulty with transport boundary conditions: free outlet

Jedi Council Member Posts: 612 Join Date: 3/2/11 Recent Posts
Hi Adrián,

Great you find the answer from the Manual.

Cheers,

Qinghua
VM
Vahid Mohammadian, modified 2 Years ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 5 Join Date: 1/29/16 Recent Posts
Hello and thank you for your helpful solution about outflow!

I have more or less the same issue with modeling of salinity intrusion into an estuary.

The problem is that I have to define a constant salinity at the mouth of the estuary. During the flood tide, there is no problem and the saline tides intrude into the estuary from the bay. But the issue is that during ebb tide, the free outflows should be flushed out from the estuary into the bay/ocean. But the fixed constant value for the salinity (let say 30 ppt) does not allow us to have a free outflow with real salinity. In the other word, the salinity value at the mouth is confined to be constant and does not change freely, while I expect to have less saline ebb tides at the mouth.

I highly appreciate if anybody can help with comments.
GK
Gowtham Krishna, modified 7 Months ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 7 Join Date: 8/13/19 Recent Posts
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GK
gangakaur kaur, modified 4 Months ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 1 Join Date: 11/19/19 Recent Posts
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Python Pool, modified 1 Month ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 6 Join Date: 2/7/20 Recent Posts
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Tayla Evie, modified 1 Month ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 1 Join Date: 2/21/20 Recent Posts
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henk123 nic, modified 18 Days ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 1 Join Date: 3/12/20 Recent Posts
An outflow boundary, also known as a gust front, is a storm-scale or mesoscale boundary separating thunderstorm-cooled air (outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature and a related pressure jump dqfanfeedback
MN
mia novah, modified 4 Days ago.

RE: Difficulty with transport boundary conditions: free outlet

Youngling Posts: 2 Join Date: 3/27/20 Recent Posts
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