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. 
 

** PLEASE TAG YOUR POST! **

 

 

Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 

 

Message Boards

trachytopes example or manual

RC
Rafael Casares, modified 7 Years ago.

trachytopes example or manual

Youngling Posts: 17 Join Date: 12/9/11 Recent Posts
Hi,

I need to use trachytopes in Delft3D in order to calculate roughness coefficients dependent on local water depth and submerged vegetation, but the FLOW User Manual does not explain well enough how to implement it, i.e., it says nothing about file extensions.

I wonder if someone has an example, manual or procedure to read and try to implement this feature.

I hope someone can help me,

Thanks in advance.
Richard Measures, modified 7 Years ago.

RE: trachytopes example or manual

Jedi Knight Posts: 178 Join Date: 3/23/11 Recent Posts
Hi Rafael,

I don't think the file extensions matter. I managed to implement vegetation trachytopes based on the information in the manual section 9.11.2 and B.17. I chose to use file extension *.tdf for the trachytope definition file and *.taf for the trachytope area file. As my vegetation resistance was the same in both directions I only used one area file but referenced it for both Trtu and Trtv.

The relevant part of my *.mdf file is:
Trtrou= #Y#
Trtdef= #VegDefinition_001.tdf#
Trtu  = #VegArea_001.taf#
Trtv  = #VegArea_001.taf#
TrtDt = 2.0


I used two trachytopes for different vegetation types, hence my trachytope definition file (VegDefinition_001.tdf) has two lines:
1 154 3 1.15 1.00 35.4
2 154 8 1.60 1.00 35.4


Hope that helps,

Richard
RC
Rafael Casares, modified 7 Years ago.

RE: trachytopes example or manual

Youngling Posts: 17 Join Date: 12/9/11 Recent Posts
Thank you Richard, sure I will be trying it.

By the way, I have 2 conceptual questions about the mechanisms by which Delft3D processes bottom roughness:

1. If I use a FormulaNr=52 (constant Chezy value) for trachytopes, what would the advantage of using trachytopes be instead of assigning Chezy values directly in the GUI (physical parameters) without trachytopes? I think both cases operate the same way, giving the same result.

2. I understand that the model calculates Chezy values from Manning coefficients assigned in the GUI (physical parameters), without trachytopes, through the formula C=(h^1/6)/n. Is this process iterative depending on the value of h at each time-step? Or is this iterative process only possible by using trachytopes with a FormulaNr=53 (constant Manning value)?

Regards,

Rafael
Qinghua Ye, modified 7 Years ago.

RE: trachytopes example or manual (Answer)

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

I won't expect anything different between FormulaNO 53 and a constant Manning coef set in GUI. Both are iterated every (half) time step varying with the total water depth.

Regards,

Qinghua
RC
Rafael Casares, modified 7 Years ago.

RE: trachytopes example or manual

Youngling Posts: 17 Join Date: 12/9/11 Recent Posts
Thank you Qinghua, very kind on your part.

Rafael