HydroCad weir width restriction 1

[yazoo]

why does hydrocad restrict you to a 999.99ft weir width and how do you get around it? I am trying to route a breach that flows thru a box culvert and the roadway above will act as a trapezoidal weir but the overall with is much larger than 999.99 ft. How do i get around this or do i use another method? I need expert help please.
Thanks

 

[psmart]

The upper limit on most parameters is designed to prevent accidental entry of unlikely values. However, each limit can be adjusted as required:

Open the Settings|Units screen
Click the Custom button
Scroll down to the CrestLen parameter and check the box
Enter a larger maximum value, as desired
Click OK twice

The custom parameter is stored in the specific project file.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

Did i tell you that "you da man". Thanks i am going to give it a try.

 

[yazoo]

It still won't let me go over 999.99. ? What am i doing wrong?

 

[psmart]

If you're using a Vee/Trap weir, you'll need to adjust the CrestLen0 parameter.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

Did that- still won't let me.

 

[psmart]

What type of weir are you using in HydroCAD?

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

Trapezoidal. 275 ft weir crest width at 0 head. 3033 ft width at 13.6 ft head

 

[psmart]

It sounds like you're actually using a Custom Weir/Orifice, which uses different parameters...

What is the exact title on the outlet screen?


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

That is correct. Custom weir/orific. I didn't know i had another choice?

 

[psmart]

To increase the limit for a Custom Weir/Orifice you would need to adjust the "BotWidth" parameter.

If you use the Vee/Trap Weir you need to adjust CrestLen0.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

Ok Now i tried v/trap and now the notch angle can't be less than 20 degress.

 

[psmart]

The adjustments for the notch angle are not valid for angles below 20 degrees. But remember that the notch angle is the total included angle between the two sides, not the angle from horizontal. (See Help for details.)

Given your previous post, I believe your notch angle is quite large - nearly 180 degrees - so the 20 degree minimum isn't a problem. But you'll probably find it easier to use the Custom Weir/Orifice option so you can enter the top width directly, rather than having to calulate the notch angle.




Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

Ok. I think i got it.
On Breaches:
The help info for MODELING A DAM BREAK says that i should also include any other normal outlet structures that will continue to function.The primary outlet will be insignificant for my breach which will begin at the crest esw elevation. Do i strip it out of the routing (also removing esw) and insert a breach trapezoidal section?

 

[psmart]

You want to be sure you don't double-count the flow area. If the breach "overlaps" the normal spillway area (which I assume it does), then you should remove the normal spillway outlet - or just set it's discharge multipler to zero.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

ok. I guess i can set multiplier on the principle to zero also or just strip it.
I have a TR 60 breach routing i want to input. Is hydrocad using the same t and q formulas. Cant i just link my outflow data directly and bypass my subcatchment runoff for the original routing. I am trying to get to my inundation mapping portion of the project.
Thanks

 

[psmart]

By "t and q formulas" do you mean runoff? You will need to compare the two models carefully to be sure you are using the same runoff parameters and procedures. If you already have an inflow hydrograph, you could enter this directly into HydroCAD using a link.

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[yazoo]

Im sorry I mean Tr66 Breach Hydrograph. Flowrate vs time data.

 

[psmart]

If you want to enter a predefined hydrograph into HydroCAD, you can use a link.



Peter Smart
HydroCAD Software

http://www.hydrocad.net