[huesmann]

Thanks. It looks like somehow terrains get de-linked. Right clicking on Results in the layer list, and selecting Manage Geometry Terrain Associations allows a user to re-link the appropriate terrain with the layer.

[huesmann]

Someone at my firm had the idea to just change the global datum by 2 or 3 feet and re-run the model, which seems to have worked.

[huesmann]

Are you talking about weir flow above a culvert?

[huesmann]

Incorrect on a couple of counts.

1. HEC-2 will run on Windows 7, but I think the restriction is 64-bit hardware. I needed to run HEC-2 and it complained about my work computer being 64-bit. I dragged in an old 32-bit laptop with Windows 7 and it works just fine in a CMD window.

This may be your issue with HEC-HMS too…

2. Prince George’s County, MD accepts HEC-2 models (welcome to the 20th Century). They may be doing modeling of new floodplains in HEC-RAS, but a crapton of their old models haven’t been converted (and I suspect never will be).

[huesmann]

What do you do about it though?

[huesmann]

Hence the “weirdness” in the thread title. 🙂

[huesmann]

Hope this works.

I was able to insert 3 obstructions at 516.2 but could not at 516.3.
WMATA_JD.zip

[huesmann]

4.1.0.

Using:

Tried even using 581 instead of 580 to ensure no overlap, but no dice!

[huesmann]

Model as a single bridge? Are they at same elevations?

[huesmann]

When you enter your bridge data, click on the Bridge Modeling Approach button on the left and select Energy (Standard Step). (This applies only to modeling it as a bridge.)

[huesmann]

Cross sections and abutments are same for both bridges?

[huesmann]

I would agree with Randy’s point 1, above. On the high side, if the channel n-value is the same all the way up, using a high bank elevation makes sense.

You do have the option of horizontally varying n-values too…

[huesmann]

The problem is that the culvert is basically at the confluence of two streams–the major one I’m modeling, and a minor one that adds a little flow.

How does one add lateral inflow? I’ve only done lateral outflows.

[huesmann]

The culvert is about 360′ long; the junction box is at about the mid-point. I know I could bump up the Manning’s, but have no idea how much would be appropriate.

As far as the bend losses with lidded cross sections, can’t one input minor losses into HEC-RAS (Geometric Data–>Tables–>Minor Losses–>Minor Loss Coefficient), into the section immediately upstream (or downstream?) of the junction?

[huesmann]

Is the excavated area going to have the same Manning’s n as in existing conditions? Maybe you can justify your n change that way?

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