[Luis Partida]

You can do 2 SA connections outfalling into a single storage area which will act as the DS boundary condition of both the main channel and the tributary. In the SA connections the culvert data can be entered. While this goes against the cross section rules for modeling bridges/culverts, it is your best option.

[Luis Partida]

You can assign a boundary of ND, but you are running the simulation under mixed conditions for which i assume you have assigned an upstream boundary condition of critical depth. I do know that if you have run a model with a DS BC of ND and it ends in critical depth something is incorrect and boundary conditions should be re-evaluated. There is a blog on this see website – website.https://therassolution.kleinschmidtgroup.com/ras-post/downstream-boundary-normal-depth/

[Luis Partida]

This is not really a problem. The RAS errors warnings and notes are just there to guide you in what occurred in the back end while solving. It is up to you to decide if the solution provided makes sense or if the model needs to be adjusted. But fyi, you can open almost every single FEMA model and there will be those same warnings.

[Luis Partida]

No, I have not had any issues with this, however you can create it in 5.0.7 and then use the “add existing land use RAS layer” and load it in the newer version

[Luis Partida]

I explain the problem and potential solution in the following post I authored. Its up to you to determined if terrain modifications is more efficient. https://therassolution.kleinschmidtgroup.com/the-ras-solution-forum/topic/modeling-2d-bridges-ras-60-elevated-terrains/

• This reply was modified 3 years, 2 months ago by Luis Partida.
• This reply was modified 3 years, 2 months ago by Luis Partida.

[Luis Partida]

By default, RAS 6.0 geometries created in RAS Mapper are by default set to Horizontal Variations in Manning’s n. To allow the modeler to enter a manning’s n value, the user must be in the cross section editor and select “options” and turn off horizontal variations in Manning’s n for each cross section.

[Luis Partida]

The upstream and downstream end of a single reach is not allowed to be connected to the same 2D domain in 5.0.7. This was fixed in version 6.0 see RAS release notes #13 for “Problems Repaired for Version 6.0”

1D Reach connected to same 2D Area (upstream and downstream). If you had a 1D river reach directly connected to the same 2D Flow Area, both at the upstream end and downstream end, the program was getting confused on what to set for the initial conditions.

[Luis Partida]

Rhys, a 0.3 sec d(t) should almost never be required especially for that mesh and cell sizes. I would re-evaluate that model

[Luis Partida]

Send me a link i will upload my model

[Luis Partida]

Rhys, again, it is not meant to be done with breaklines. You must use refinement regions. I just did it with a 15×15 refinement region and the results of both are the same. Again do not use breaklines. Open RAS Mapper and under geometry expand your 2D flow area>Refinement region. Then edit and draw the polygon, then open the properties and for the dx dy enter 15. Close, right click refinement region “Enforce All Regions”

[Luis Partida]

Rhys, i solved the problem. Thank you for providing the model for review. The issue is your break line spacing being 5 and 5 on a 50×50 meter mesh. While i cannot explain why the results differ, when i removed those breaklines the results are the same and your error is resolved.

I would instead try and utilize a refinement region rather than breaklines, this can be done in RAS Mapper. You have to remember that your time step and cell spacing are variables within satisfying the courant condition. If you have a variance from 5 to 50 i would expect to see issues. I see no reason the resolution would require that small of a cell size but i dont know the scope of your project. Anyways, hope this helps.

[Luis Partida]

12 m is very very coarse. But if you see the terrain in Mapper then it should show values. Prior to cutting XS’s you must right click on geometries (bolded word) and associate your geometry with the terrain. Then, RAS will recognize the terrain and geometry together as one.

[Luis Partida]

I have never seen this happen. One option is to put a link here with the model zipped up and i would be happy to give it a look

[Luis Partida]

The other option is too extend your 2D mesh outside of the study area such that you can add a culvert and actually send it away from your focus region

[Luis Partida]

Use a pump that replicates the culverts efficiency

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