[A Atkinson]

Hi Libby,

I’ve never used Delft3D, but I know RAS does have some options for modeling turbulent flow and eddies. They are in the Computation Options and Tolerances section of a Plan. If you google “RAS eddy viscosity” and “2D Computation Options and Tolerances RAS” then you can get the RAS help pages to come up. Sorry for some reason I can’t get the links to work here.

Thanks,
A

[A Atkinson]

Hi Netra, another thing you can try is to make the Google Satellite layer transparent. That way you can see both the terrain and the satellite layer at the same time. In RAS Mapper, right click the Google Satellite layer and click “Properties”. Then, on the Visualization and Information tab, slide the Opacity scale to whatever transparency you would like the layer to be.

[A Atkinson]

Hi Zain –

I don’t believe there has been any updates on this topic since 2019; that is, there isn’t a way to change Manning’s n values as the simulation is running.

I suppose a work around would be to break up your simulation into smaller time frames and use a different land cover file or Manning’s n values for each of the smaller simulations. So, for example, if you had a simulation you need to run from June to December, you could break it into a June – October simulation and an October – December simulation. For the June-October simulation you could use a geometry file that had Manning’s n values associated with the summer, and for the October – December simulation you could use a geometry file that had Manning’s n values associated with the fall/winter.

Also, I know you can assign a Manning’s n value to Open Water, but I’m not sure if simulated flow gets that n value or if that value is only assigned to areas where Land Cover = Open Water.

– A

[A Atkinson]

Hi Maria,

Is the water surface in the pond reaching an elevation above 1230.4? If the culvert is large enough and you haven’t “blocked” it in some way, then water will keep flowing through the culvert until the WSEL in the pond has reached 1230.4. Once the WSEL has reached 1230.4, water will exit the pond through the culvert AND the overflow structure.

If you want to see how the overflow structure is performing in a situation where, for example, the culvert is blocked, try creating a geometry that doesn’t include the culvert. That way, the only way water can exit the pond is by the overflow structure.

– A

[A Atkinson]

Hi Eric,

Thanks for your response!

I tried running the model with a longer boundary condition line. You’re right, lengthening the line did have some effect, but as my calibration point is a few miles upstream of the downstream boundary condition, it didn’t have much effect.

So, this answered my question. Thanks again for your help and for the explanation.

A Atkinson

[A Atkinson]

Hi Luis (and others) – how did you end up solving this problem? I am having this issue too. I’ve tried lengthening my bridges using the Move Points tool and by adding additional length on the Deck Editor. The ends of the bridges appear to line up with cell borders. Do you just have to delete and recreate the bridges?

Thanks!

[Author]

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