Thanks to the many who replied on the back channel to my puzzlement
over a disagreement I had with a student in my fish biology class.
The ruling is virtually unanimous: I'm all wet. Flow velocity is not
solely, or even predominantly, a function of gradient.
Well-established formulae (especially Manning's formula) express
velocity as a function of gradient, hydraulic radius (dependent on
channel depth and width) and bottom roughness. While low order
streams have high gradient the other two terms tend to retard flows.
I especially appreciated the gentility of the responses. What seemed
puzzling yesterday is now just about intuitive, yet the respondents
did not write as if this were a trivial matter and I a loutish dolt.
Thanks to the netter who pointed out my careless mis-statement about
the quantification of discharge.
I would be happy to send the responses I got to any who request it.
I have saved
) ` \\
fish class home page:
Department of Ecology and Evolutionary Biology
75 N. Eagleville Rd.
University of Connecticut
Storrs CT 06269-3042
Phone (860) 486-4692
Fax (860) 486-4320