[cameron]

how did you set up the junction for the model? did you try the different options in the junction editor?

[cameron]

Have you tried adjusting the mixed flow options or adding more cross-sections in trouble spots?

[cameron]

This can be done in the mapper program in HEC-RAS 5.0 quickly. You just select to export the cross-sections as a surface and it will create one for you.

[cameron]

It all depends on what flow you are modeling. Is the flow going to over top the banks of the river and act as if the channel doesn’t exist (common at very high flows) or is it going to follow the meanders of the river?

[cameron]

In HEC-RAS 5.0 you can export the bank lines or points as a shapefile from Mapper.

[cameron]

What bridge method is used for both geometries, does it change from one to another when solving?

[cameron]

Did you set a projection for RAS Mapper?

[cameron]

I would say HEC-RAS 5.0 could replace those models for a lot of applications, but it does not currently have all of the features of the other models (rainfall, infiltration, and a few others). The biggest benefit over HEC-RAS would be support and development of the software. HEC does not provide support unless you have a contract with them usually. The release cycle of the software is not as often as commercial models so bugs and new features are not fixed/added as often.

[cameron]

Do you have a projection set up in ArcMap before you try to import?

As for the second message about XS interpolation surfaces not stored, that is normal message. are there any other messages?

[cameron]

If you open the *.P01.hdf file in an HDF viewer, you can get the cell minimum elevations from Geometry|2D Flow Areas|”Project Name”| Cells Minimum Elevation.

The values will be based on an id number that can be found in the HDF file.

[cameron]

What is the timestep for the model? Try lowering it to see if the model becomes stable. Have you tried using a minimum flow for the inflow hydrographs, adjusting the HTAB parameters, adjusting ineffective areas so the active top width have a smooth transition between cross-sections, or pilot channels?

[cameron]

a few things I noticed,

1. XS 90883.06 does not appear to be in the correct location in plan view. As I scrolled through past this cross-section it jumped (skipped) multiple cross-sections.
2. There should probably be some ineffective flow areas added to the model, the locations I noticed were around 71602. This will help increase the water surface elevation which should also help stabilize it.
3. you should add weir stationing at HW cross-sections in the lateral structure options as the locations where the cross-sections intersect the lateral structure should be based on actual location and not the reach length.
4. A better initial guess for the split flow in the flow options might help
5. The last thing you could try is to run the model in unsteady mode with a constant hydrograph. This is more stable sometimes and also has the option of adjusting stability coefficients to make it more stable if needed.

[cameron]

I have tested and compared it to other 2D models and will say this about HEC-RAS 2D:

In it’s current form, I would would not use it for detailed in-channel hydrodynamics for the items you mentioned. I would probably use either SRH-2D, RiverFlow2D, or TUFLOW FV.

Mesh development in HEC-RAS 2D is lacking currently and very time consuming if you want to add a lot of detail. This is going to be fixed eventually, but not sure how soon.

I would recommend only using HEC-RAS 2D for Floodplain and Dam/Levee Break studies.

[cameron]

You can change the trigger to how the dam fails to time instead of water surface elevation. Set the dam to fail 1 hour (or something else) into the simulation run and at 1 hour, the dam fails.

[cameron]

You should contact Chris, me, or anyone else at WEST Consultants about providing training if you are interested. The cost of each training depends on multiple factors and so the fee varies from training to training.

The link below has basic info about the training and how to contact WEST.

[Author]

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