Question about the sediment erosion

1

Hello everyone,I have a question about the mass erosion.
I know that cohesive bed erosion occurs in mass(bulk) erosion and surface erosion.
Because I simulated suspended sediment transport during the high flow in the large estuary, I checked the mass erosion in the model. And I thought the TSS concentration would higher than the one without checking,but it didn’t.
In the model, total bed stress was almost higher than 10 N/m^2 in the period.I tried to calculate the Taus by using Hwang and Mehta (1989) relationship (Taus=9.808*rhob - 9.934; rhob is bulk density).If the bulk density is 1.7, Taus is 7.16 N/m^2 in the formula.The value seems lower than total bed stress, but the mass erosion don’t happen. How could I solve this problem? Thank you!

2

Hello, yuxuan0117

Thanks for your question about the sediment mass erosion option. We will investigate the issue you are experiencing. In the meantime, would you let us know which version of EEMS and EFDC+ you are using for this modeling work? This information would be helpful for us to find the solution to your issue. Thank you.

Sincerely,

-Jeffrey

3

Hello, Jeffrey
Thanks for your reply. My version is EEMS10.3.5.

4

Thanks for letting us know the version you have. We are looking into the issue and will let you know soon.

Sincerely,

-Jeffrey

5

Dear yuxuan0117

Thanks for your patience in waiting for our response.

Regarding your question, we identify that the “Mass (bulk) Erosion” option has been deactivated in the EFDC+ source code so that the sediment transport model does not simulate the mass (bulk) erosion. This was why the model results did not change when you toggled on/off the “Mass (bulk) Erosion” option for your model.

We also recognize that the EEMS GUI interface and the efdc input file should have removed the “Mass (bulk) Erosion” option or at least should have notified that this function does not work. We apologize for the misleading interface and will modify the associated interface for the following EEMS release.

I hope our response addresses some of your concerns. Please feel free to let us know if you have more questions. Thank you.

Sincerely,

-Jeffrey

6

Okay, I see.Thank you.

7

Hi, I have another question.
Is it possible to make sediments in some grids not to erode and deposit?
Thank you.

8

Thanks for your question.

You can use the hard bottom option to activate (or deactivate) specific cells for erosion and deposition simulations. Please visit the video link below to see how you can use the hard bottom option with EEMS 10.3 LTS version.

I realized that the video keeps losing the audio, so please let me know if it is difficult to follow the process in the video without audio. Thanks for your understanding in advance.

Sincerely,

-Jeffrey

9

Thank you so much.I’ll try it.