# Set a non-erodible bottom

**URL:** <https://opentelemac.org/forum/t/set-a-non-erodible-bottom/7880>\
**Category:** GAIA / SISYPHE\
**Created:** [December 17, 2024, 2:11pm UTC](https://opentelemac.org/forum/t/set-a-non-erodible-bottom/7880 "2024-12-17T14:11:50Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![user\_17006](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@user\_17006](https://opentelemac.org/forum/u/user_17006)\
**Post date:** [December 17, 2024, 2:11pm UTC](https://opentelemac.org/forum/t/set-a-non-erodible-bottom/7880/1 "2024-12-17T14:11:50Z")

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Dear [name removed], the form bag concrete is used for slope protection below â–½ 10.0, and the square lattice skeleton is used for slope protection above â–½ 10.0. As shown in the figure, how to set the local non-erodible thickness in this case?

Best wishes

 ![photo.png](https://opentelemac.org/uploads/default/original/2X/c/cd3b336ac0eafb536b0ae8b9aef9a7e1b2b9c764.png)

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**Author:** ![user\_15766](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/9de053/32.png) [@user\_15766](https://opentelemac.org/forum/u/user_15766)\
**Post date:** [December 17, 2024, 6:52pm UTC](https://opentelemac.org/forum/t/set-a-non-erodible-bottom/7880/2 "2024-12-17T18:52:10Z")

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Hi [name removed],

This is a frequent question. The simplest solution I’m aware of is by using user\_bed\_init and a locally modified bottom roughness: [#41943](http://www.opentelemac.org/index.php/kunena/17-sisyphe/14079-accumulation-at-inlet-with-no-sediment-influx#41943)

For sure, a simpler version (such as a LAYER THICKNESS variable that can be added when creating the [name removed]) would be an excellent addition to the GAIA codebase, if it hasn’t been added already in v9p0.

Hope this helps,

[name removed]

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**Author:** ![user\_17006](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@user\_17006](https://opentelemac.org/forum/u/user_17006)\
**Post date:** [December 26, 2024, 9:59am UTC](https://opentelemac.org/forum/t/set-a-non-erodible-bottom/7880/3 "2024-12-26T09:59:33Z")

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Dear [name removed]

Hello, could you tell me how to a layer thickness variable that can be added when creating the selafin? I don’t see the variable layer thickness in bluekenue.

Thank you！

 ![thevariableinbluekenue.png](https://opentelemac.org/uploads/default/original/2X/e/e5e9d32a09b6791c095cd50486239059fb5457d8.png)

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**Author:** ![user\_18214](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/50afbb/32.png) [@user\_18214](https://opentelemac.org/forum/u/user_18214)\
**Post date:** [June 25, 2025, 2:41pm UTC](https://opentelemac.org/forum/t/set-a-non-erodible-bottom/7880/4 "2025-06-25T14:41:54Z")

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It similiar as mesh creat,u can click-new-selafin-add variable,then you

can input the variable’s name as you like.