HydroCAD Tc Line Method for Dry Swales

[Serene111]

Hello,

I was wondering what method I should use when Tc line is going to a dry swale? There is an underdrain pipe, but I don't think it is proper to select the "pipe channel" method because the grass cover on top would provide some detention.

Thank you for your time.

Best,
Serene

 

[Ekenny_G]

which route would be most conservative approach? I would use the overland flow thru the swale with the grass cover, not the underdrain pipe.

 

[Serene111]

Thank you for the suggestion. I was also trying to model the dry swale using "Pond", but my swale as a 4% longitudinal gradient and I can't find any outlet device that can describe it.

Thanks again,
Serene

 

[psmart]

Sounds like a segment of channel flow.

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[Serene111]

Hello Peter,

Do you mean the Tc line? Would the shallow concentrated flow work as well?

 

[psmart]

Yes, I was referring to a Tc segment for channel flow. For very small depths you could use shallow concentrated flow. Or try both and compare the results.

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[Serene111]

Thanks Peter, I'll try both. What about the to model the dry swale using "Pond"? I'm using a pond storage with outlet "exfiltration" and "broad-crested weir", what should be the conductivity in the "exfiltration"? The current model is giving me very small exfiltration at the 100-year storm event I gave a very large conductivity (a random number). I also attached the HydroCAD file here. Please let me know if you have any questions.

 

[psmart]

If you have free flow through the swale then you should model it as a reach or a Tc segment of channel flow. A pond node would apply only is you have level pool storage controlled by one or more outlet devices.

If you don't know the conductivity value I suggest you specify a constant velocity instead. Click help on the exfiltration screen for details.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[Serene111]

Got it. Thank you, Peter!