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Civil engineering - manning's equation through channel

  1. Sep 1, 2010 #1
    civil engineering -- manning's equation through channel

    1. The problem statement, all variables and given/known data

    I'm given the slope S, the flow Q, the n value, and the diameter of the pipe. I am asked if the channel can handle a certain depth D of water.

    2. Relevant equations

    V = (1/n)*R^(2/3) x S^(1/2)

    3. The attempt at a solution

    I don't understand what I need to do. R is the hydraulic depth which is defined as the cross sectional flow divided by the wetted perimeter. Do I use the depth in question, D, and convert this into a hydraulic radius? How? I don't know how to calculate the area of a circle filled to just above half of its radius....
  2. jcsd
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