THE VENTURI FLUME 
By V. M. Cone, 
Irrigation Engineer , Office of Public Roads and Rural Engineering , United States 
Department of Agriculture 
INTRODUCTION 
Many devices have been developed for the measurement of water under 
field conditions—for example, in its delivery to irrigators. Nearly all 
of these devices employ the principles of either the weir or the orifice 
and, though each device is adapted to use iii certain localities, probably 
none works satisfactorily under a great variety of field conditions. The 
ideal measuring device would (i) be inexpensive to construct, (2) be simple 
to operate, (3) require little maintenance, (4) be free from working parts, 
(5) be accurate in its measurement, (6) be free from sand, silt, or floating- 
trash troubles, and (7) require but little loss of head in the ditch. Such 
a panacea for all measurement-of-water ills does not seem probable, but 
progress is undoubtedly being made toward that end. The type of flume 
tested in the experiments on which this report is based possesses many 
of the qualities enumerated and may prove to be a satisfactory measur¬ 
ing device under general field conditions. 
The purpose of this article is to present the fundamental plans and 
results of preliminary experiments on a new type of device, called the 
“Venturi flume/’ for measuring water in open channels, in order that 
those in practical need of such a device may know of its existence. 
Furthermore, it is hoped that the construction of larger sizes of Venturi 
flumes than were tested in the laboratory will be encouraged thereby 
and that they can be calibrated. It is not probable that the last word 
has been said on the design of the Venturi flume, for, although it has 
considerable promise, changes in details may prove to be necessary. 
The laboratory and field tests made thus far have failed to develop any 
serious inherent defects in the device. 
Experiments made in the hydraulic laboratory at Fort Collins, Colorado, 
on measuring devices led to the development of the so-called Venturi 
flume during the season of 1915. It consists essentially of a flume with 
a converging and a diverging section and short “throat” section between 
them. The floor, which is level, is placed at the elevation of the bottom 
of the channel in which it is set. After many experiments had been 
made with different forms and shapes, the designs shown in figures 1, 6, 
7, and 11 were adopted as most* nearly meeting practical requirements. 
Venturi flumes with rectangular and trapezoidal cross sections (fig. 1, 6) 
no doubt will be the most used, but the other types (fig. 7, 11) were 
designed to meet special conditions where small flows must be measured. 
(« 5 > 
Journal of Agricultural Research, 
Washington, D. C. 
hx 
Vol. IX, No. 4 
Apr. 23,1917 
Key No. D—xo 
