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. 



Introduction , 



Nomenclature 



Historical 



Necessary field data for values of n. 

 Scope of experiments . 



Equipment and methods employed for col- 

 lecting field data 



Correction for velocity heads 



Elements of field tests to determine retarda- 

 tion factors in Kutter and Chezy formulas. 16 



Description of channels 



The use of values of « 



Recommendations for values of n for diflerent 



kinds of channels 



Estimation charts 



Variations of « in the same channel 



Conclusions 



15 Acknowledgements. 



Appendix . 



Page. 

 28 



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 bo 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.— Thte bulletin treats of the subject of flowing water in irrigation channels. It is based on field 

 t«itfl ma^le for the purywse of dot^Tmining the retardation factor in Kiiltcr's formula under the various 

 conditlorui found in practice. The data secured are intended to aid in the design and con.struction of irri- 

 gation and similar channels. Thi.H publication i.s offered for u.so 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 oi)cn channeln. 

 79256'— Bull. 194—15 1 



