BULLETIN OF THE 
No. 194 
Contribution from Office of Experiment Stations, A. C. True, Director 
May 10, 1915. 
(PROFESSIONAL PAPER.) 
THE FLOW OF WATER IN IRRIGATION CHANNELS. 
By Fred. C. Scobey, Irrigation Engineer. 
CONTENTS. 
Page. 
Introduction 1 
Nomenclature 2 
Historical 2 
Necessary field data for values of n 4 
Scope of experiments 7 
Equipment and methods employed for col- 
lecting field data 7 
Correction for velocity heads 15 
Elements of field tests to determine retarda- 
tion factors in Kutter and Chezy formulas. 16 
Page. 
Description of channels 28 
The use of values of to 45 
Recommendations for values of n for different 
kinds of channels 47 
Estimation charts 52 
Variations of n in the same channel 58 
Conclusions 60 
Acknowledgements 61 
Appendix 62 
INTRODUCTION. 
Irrigation systems are designed with the object in view of supply- 
ing certain quantities of water to the soil. These predetermined 
quantities of water must be carried in certain definite channels — of 
earth, wood, concrete, steel, or other material. Very often the same 
canal will include channels of all the above materials. Obviously 
channels in the smoother materials will convey water with less retar- 
dation than those in rougher ones. In order to proportion correctly 
the size of the channel in any given material, the extent to which the 
flow of water will be retarded by the character of the channel and 
other conditions must be known. Since this knowledge can come 
only through actually measuring the flow in channels under known 
conditions, it follows that the greater number of tests there are 
available the more definite is the information at the service of the 
engineer designing canals. 
Note.— This bulletin treats of the subject of flowing water in irrigation channels. It is based on field 
tests made for the purpose of determining the retardation factor in Kutter's formula under the various 
conditions foimd in practice. The data secured are intended to aid in the design and construction of irri- 
gation and similar channels. This publication is offered for use of engineers designing and measuring irri- 
gation, drainage, and power channels, and for courts and attorneys at law Interested in cases involving 
the carrying capacities of open channels. 
79256°— Bull. 194—15 1 
