Full Momentum: An HEC-RAS Vodcast (Ep.7). Manning's Roughness for 1D Models

Episode 7: Manning's n values for 1D models
Edenville/Sanford Dam Failures (2:45), Manning's n theory and application (23:00), horizontal variation in n values (28:00), vertical variation in n values (34:15) and how to choose your n values/references (46:00)!
Ben Cary and Chris Goodell discuss special HEC-RAS topics, cool project applications, and new developments in the H&H engineering world!
Want to submit a question, interested in sponsoring, or just want more information on the Vodcast? Email us at [e-mail]
RAS Mapper, HEC-RAS, Hydraulic Modeling, 1D Modeling, 2D Modeling
Thank to to our sponsor for this episode Kleinschmidt Group! Visit our website at: www.kleinschmi...

[@ksmasmaaa21]

Very useful vodcast. Thanks a lot. God bless you.

[@gkdarkwah]

I like the way Chris referred to Manning's n as the ignorance coefficient.

[@tarmak968]

Dude you have an A/C hanging on the wall behind you! Nice video and conversation on the failure!!

[@TheRASSolution]

Ha...gotta stay cool when recording vodcasts! That's Ben's. Maybe it's a heater?

[@yarinj5373]

Hi. Thanks for sharing useful information. Setting the boundary conditions of HEC-RAS in unsteady flow analysis is really overwhelming to me. I don't know how to adjust the simulation time with start and ending times. I would appreciate if you could guide me how to get rid of this problem. thanks

[@qabdelal]

Thanks guys for a great talk.... Can you go above the 0.2 for very low flow in ephemeral stream in steep mountainous area (.15 slope)? Model instability becomes a serious issue there!

[@TheRASSolution]

Absolutely! i believe there is plenty of reference material out there that would support using higher Manning's values for very low flow in steep mountain streams. However, if you ever find yourself getting outside of suggested ranges for Manning's its a important to provide justification and be able to show that your model is calibrated.

[@qabdelal]

@@TheRASSolution any pointers on specific references?

[@TheRASSolution]

We cover a number of them at the end of this episode!

[@javelina34]

Question from a newbie: can I use shapefiles to assign n values in a 1D model or is this only for 2D?

[@panagiotisdimas6925]

Hi Chris, I am really interested in automating a HEC-RAS unsteady flow model by altering the inflow hydrograph. For example I would like to run 100 different inflow hydrographs and save the results in a table for every XS. I have bought the "Breaking the HEC-RAS code" book but I cannot trace a similar application. Your help and/or tips would be highly appreciated. Panos

[@sonertuglu1485]

👏👏👍👍