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: Bed Layer in(.inb) file work

Zhina Mohammed, modified 3 Years ago.

Bed Layer in(.inb) file work

Youngling Posts: 23 Join Date: 12/14/15 Recent Posts
Hello everyone,
I wanted to make a post about working of the bed layer inial bed file in morphology file.
I did several simulations with different bed division

Run1
3 layer: transport layer+ 1 under layer+base layer
my transport layer consist of spatial distribution of 6 fractions and define it by(.frc) file

in one part 1 have
1 for frac-1(frac 1: is the finest particles I have in the model which is mud)
0 for other fraction

when simulation starts see what happen
----------------------- layer1-frc1-------------- layer-2-frc1-------------- Layer-3-frc1
----------------------- SedMass ------------- SedMass----------------- SedMass kg/m2
at time =0----------- 2000 -------------- 0.00---------------------------0 (2000=vol fraction*density of sediment* bed thickness at that layer)
at time=1------------1500 -------------- -- 500---------------------------0
-
-
at end siml.----------500-------------------------275-------------------------- 0 to find the thickness that has been removed from bed=(dry bed density/ sediment mass)

sed thickness--------2m ---------------------- 0.45m------------------------

sumation=2.45m =the erosion I have at the end of simulation when I look at cumulative erosion and deposition till now it is somehow fine although it will not scour first from the first layer and if the thickness of first layer finish after that go to 2nd layer. as you see I have 2000 mass sediment in layer 1 after starting sediment calculation automatically 500 mass sediment go to 2nd layer. why this happen I did not put this fraction in the second layer

Another interesting thing I saw when I looked at the other fraction
-----------------------------------------------------------------------------------------------------------------
for fraction 5/ sand particle
----------------------- layer1-frc1-------------- layer-2-frc1-------------- Layer-3-frc1
----------------------- SedMass -------------- SedMass ----------------SedMass kg/m2
at time =0--------------0-------------------------3200-------------------------0
-
-
-
at end siml -----------1600 ----------------------1600-----------------------0

sed thickness-------1m (add)------------------1m(remove) ----------------------------------------------which it looks like the from layer 2 go layer 1

---------------------------------------------------------------------------------------------------------------
or fraction 6/ sand particle
----------------------- layer1-frc1-------------- layer-2-frc1--------------Layer-3-frc1
----------------------- SedMass -----------------SedMass-------------------SedMass kg/m2
at time =0 -------------- 0 ---------------------------3200------------------------12000

-
-
at end siml. --------------1600 -------------------1600--------------------------12000

sed thickness------------1m (add)---------------1m(remove) ---------------------------which it looks like the from layer 2 go layer 1

I do not know why this happen, I appreciate if someone can give me some explanation on what is going on here

====================================================================================================
Run2/
making 2 layer as you see from the file I attached, (transport layer+Base layer)both layer put spatial fraction distribution

in this part that I am analysing both transport and the base layer I put the same fraction

for fraction 1/mud
----------------------- layer1-frc1---------------layer-2-frc1
----------------------- SedMass-----------------SedMass
at time =0---------------2000 ---------------------3750
at time =1---------------1500----------------------4250
-
-
at end siml.-------------1500 ---------------------2750

sed thickness-----------0m--------------------------3m(remove) which it looks like the from layer 2 all the erosion occurs

=======================================================================================================

I hope someone helps me with this , why the sediment from the first layer first not removed after that go to sediment in layer 2?


your help is appreciated
Thank you
Zhina







I have read this discussion also
https://oss.deltares.nl/web/delft3d/coast-/-estuary/-/message_boards/view_message/377337
EC
Eduardo Cordeiro Gonçalves, modified 3 Years ago.

RE: Bed Layer in(.inb) file work

Youngling Posts: 7 Join Date: 10/19/13 Recent Posts
Hi, Zhina,

In Delft3D, only sediments of top layer is avaible for erosion, after this next layer become the top. At the case you described the process of sediment transport along the time. So, erosion and deposition occurs and if you look carefully at the end, only a erosion process occurs, because the model reach the stability.

Best Regards, Eduardo