The Venturi Flume 
21 
diagram that a loss of head of 0.3 feet would occur. This amount, 
added to the downstream depth, will be approximately 2.8 feet, or 
the depth above the flume when discharging 50 second feet. 
V-NOTCH VENTURI FLUME 
For a number of years there has been a demand for a meas- 
uring device that would accommodate comparatively small flows 
with a minimum loss of head through the structure. To meet this 
need, a V-notch Venturi flume has been calibrated for flows from 
0.1 to 10 second feet. In this flume, the throat is formed by two 
plane surfaces, one foot wide and intersecting at the floor line at an 
angle of approximately 53°, or with a side slope of ^ to 1. The 
sides of the converging and diverging sections also have this same 
side slope, measured in the plane normal to the axis of the flume. 
Plate II shows a V-notch flume and automatic gage height recorder, 
installed in a small stream. The standard dimensions of this special 
type flume are given in Figure 10. 
FIGURE 10. — Standard Plans for V -Notch Venturi Flume with Side 
Slopes V 2 to 1. 
