not a result of direct runoff and without the effects of regulation, 

 diversion, or other works of man. Also called sustaining flow. 



flow, laminar — That type of flow in a stream of water in which each par- 

 ticle moves in a direction parallel to every other particle. 



flow, low — The lowest discharge recorded over a specified period of time. 



flow, low summer — The lowest flow during <: typical open-water season. 



flow, uniform — A flow in which the velocities are the same in both magni- 

 tude and direction from point to point. Uniform flow is possible only 

 in a channel of constant cross section. 



flow, varied — Flow occurring in streams having a variable cross section 

 or slope. When the discharge is constant, the velocity changes with 

 each change of cross section and slope. 



fork length — The length of a fish measured from the tip of the nose to the 

 fork i n the tail. 



freeze front — A surface that may be stationary, which has a temperature 

 of C and is warmer on one side of the surface and colder on the 

 other . 



frequency curve — A curve of the frequency of occurrence of specific 

 events. The event that occurs most frequently is termed the mode. 



gage — A device for indicating or registering magnitude or position in spe- 

 cific units, e.g., the elevation of a water surface or the velocity 

 of flowing water. A staff graduated to indicate the elevation of a 

 water surface. 



geomorphology — The study of the form and <levelopment of landscape fea- 

 tures. 



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