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# Critical Depth of Open-Channel Flow

Posted in Hydraulics |  Email This Post |

For a given value of specific energy, the critical depth gives the greatest discharge, or conversely, for a given discharge, the specific energy is a minimum for the critical depth.

For rectangular channels, the critical depth, dc ft (m), is given by

dc =[Q2/b2g]1/3

where
dc =critical depth, ft (m)

Q= quantity of flow or discharge, ft3/s (m3/s)

B= width of channel, ft (m)

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• Ravi January 6, 2009 at 11:41 am

Hi,
It is good………

• Peppernspice March 20, 2009 at 7:27 pm

this is what i’ve been looking for..
simple and straightforward!
thanks

• mazetas October 5, 2010 at 11:57 am

that was short and sharp

• Flash January 6, 2011 at 7:54 am

What does q equal if its a wide channel ?

• Conor March 23, 2011 at 3:00 pm

q = Q/b ; (m³s-1/m)
b = the channel width ; (m)
Q = flow rate ; (m3/s)

• Tamrat February 10, 2012 at 10:53 am

The concept of critical depth for engineer is like you wrote here. That is great way. But the meaning critical depth is that water molucule upstream and downstream of the critical depth wont comunicate. It is a point of discontinity.

• Eng. Sayed Rasekh December 21, 2012 at 10:42 am

if we introduce more formula for tripoziod channel it would be useful

• Komal SHARMA April 10, 2017 at 10:01 am

The specific energy of triangle channel for critical depth