hardlayer option

[victor quilfen]

Hi all,

I'm using XBeach to study nearshore currents and sediment transport on
elliptic beaches. The model works fine, but there is a significant
erosion in the corners.
In natural beaches, these "corners" are often rocky outcrops or rocky
points (for example pocket beaches).

So I would like to know if it's possible to use the hardlayer option
implemented in XBeach for taking into account this phenomenon.

Generally speaking, does the option "hardlayer" can "imitate" semi-
submerged rocky platforms?

Thanks for any suggestions!

Kind regards,

Victor

[M.Onur Kürüm]

Hi Victor,
you can enable the hardlayer option by adding the lines (if you don't
already have them)
struct = 1
ne_layer = hardlayer.dep (you can have different file name)

basically hardlayer.dep file should be the same size as your grid.
This file will tell Xbeach where to limit the erosion.
so as an example, if you have a bed.dep file 4x6

-5 -4 -3 -2 -1 0 1
-5 -4 -3 -2 -1 0 1
-5 -4 -3 -2 -1 0 1
-5 -4 -3 -2 -1 0 1

your hardlayer.dep file might look like this:

10 10 10 10 10 10
10 10 10 0 0 10
10 10 10 0 0 10
10 10 10 10 10 10

0 will tell xbeach that that cell is not erodible, so you can do this
where you have your rocky platforms. just be careful that your bed.dep
file and hardlayer.dep files match. I suggest experimenting with it
first with a very basic case so that you can easily see the effects on
the outputs. There is a simple example in the testbed but I don't
remember its name for now.

10 in the example I gave you above means that that cell will be
"allowed" to erode 10 meters. At least, that's what I call it.

good luck
Onur

[victor quilfen]

Hi Onur,

Thanks for your reply.
I ran a simulation using the "hardlayer" option, I await the results.

Otherwise, I asked myself if the deposit of sediments was possible on
non-erodible surfaces or if the sediments were lost?

Thanks for your help,

Best,
victor