[sktse]

This sounds like a good match for what I’m seeing here. I looked up the v4.1 Hydraulic Reference Manual and I noticed the note on 8-11.

However, it uses an equation here Q = CLH^(3/2) that has parameters I have not entered.

C = Weir Coefficient
L = Length of spillway Crest
H = Upstream energy head above the spillway crest (in this case it would be 714.75 m – 712.62 m = 2.13 m i suppose?)

If I assume that C = 1.4 and L = 7.2 m based on the values that I enter on the inline structure (but that don’t necessarily apply to the gate openings), then I get:

Q = (1.4)*(7.2 m)*(2.13 m)^(3/2) = 31.33 m3/s

This does appear to be in the right ballpark. I’ll have to do more playing around with this.

[sktse]

If I’m understanding your question right, you’re exploring either alternatives in the geometry of your model (i.e. the effect of construction on the model), or alternatives in flow scenarios.

The way that HEC-RAS is structured allows both of these possibilities to be explored within a single project file.

A project file consists of geometries, flow scenarios, and plans (among other things).

A geometry file (*.g01, *.g02, etc.) will describe the physical features in your model, such as hydraulic structures and the channels in your model.

A steady/unsteady flow file (*.f01, *.f02, or *.u01, *.u02, etc.) describe the different flow scenarios (1:10 year return period, PMF scenarios, etc.).

A plan file (*.p01, *.p02) pairs a geometry file with a flow file to create the model that you want. So for example:

MyProject.p01 might consist of a pre-construction geometry (MyProject.g01) with a 1:60 year return period (MyProject.f01)

To see how construction might affect this, you would create a post-construction geometry file (MyProject.g02), and run it through your original 60-year flow file (MyProject.f01). You can save this to a new plan (MyProject.p02). That way, you can refer to both your original plan (p01) and your new plan (p02) without having to load an entirely new project file each time.

Organizing your alternatives along plans this way allows you to cross-section information that compares the two on a single plot (by going up to Menu Bar > Options > Plans… and checking off the appropriate plans).

If you are saving your geometries in separate projects, that’s okay — the HEC-RAS geometric data editor allows you to import HEC-RAS geometry files (*.g01, *.g02, etc.) into your project (by going to the Menu Bar > File > Import Geometry Data > HEC-RAS Format…)

At least that’s how I understand it. I hope that this helps you out.

Shawn

[Author]

Posts