×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Still Learning & Need Help-----

Still Learning & Need Help-----

Still Learning & Need Help-----

(OP)

This is probably a simple hydraulics 101 problem but my 75 year old brain is totally blank on how to estimate the flow velocity of water given only the average slope of a river bed  and average water depth.

Any suggestions using calculations with simple algebra  formulas?

 

At 74th year working on IR-One2 - - UHK PhD - - -

RE: Still Learning & Need Help-----

For simple hydraulics, mannings equation would be your best bet. The depth of flow portion of the calculation would be factored into the area component of the equation.

RE: Still Learning & Need Help-----

You can use one of the online calculators to estimate flow:

http://www.flowsizer.com/

RE: Still Learning & Need Help-----

(OP)

Thank You Good People

 

At 74th year working on IR-One2 - - UHK PhD - - -

RE: Still Learning & Need Help-----

If you can approximate the river as a trapezoidal channel Manning's Equation will give you a good first stab at it, but take some pains to try and get your roughness coefficient right.  Also do realize that if the river either changes slope near to your point of interest or there's an obstruction near your point of interest then the normal flow depth assumption won't really be right.

If it's an unusual cross section you can still use Manning's but it's a harder process.  If it's very unusual, or you're dealing with overbank flooding and whatnot, just download HEC-RAS and build yourself a little reach in your model and see what it tells you.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Still Learning & Need Help-----

Oh, one other thing, be aware with Manning's you're dealing with average velocities.  If you're trying to figure out the velocity of a particular streamline in the river then it's more complicated.  Water in the middle flows faster than near the banks / etc.   

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Still Learning & Need Help-----

(OP)

Thanks beej67

Useful addition information
 

At 74th year working on IR-One2 - - UHK PhD - - -

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources