n value for ponds

Hi Chris,

I had attended your HEC-RAS training at PBS&J. I have a very easy question for you. When you have series of inline ponds along a stream, but not modelled as inline structures, rather just like any regular stream with cross sections cut across it. Can the n value be as low as 0.01 (in the pond area) with the reasoning that the water flowing is experiencing no resistance as the pond water is not moving. Only a layer above the storage is flowing?

Thanks,
Jaspreet Randhawa

Dear Jaspreet :

I greatly enjoyed teaching your group HEC-RAS in beautiful Maryland.

I agree with you. If the flow is modeled through a large body of water with little or no wetted perimeter contact, you can lower the roughness value to represent this.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com

Thank you for replying Chris.

Your course is very useful for our job!