FLOW OF WATER IN IRRIGATION DITCHES 



24I 



Group No. 7 



71=0.0377 to 0.0424 



Channels rough and rocky. 



Character of Channel 



Dis- 

 charge 



Area 

 Water 

 Section 



Mean 

 Vel. 



Slope 



Rough; coarse gravel and cobbles 



Rocky; overgrown with alfalfa 



Rough; coarse gravel 



Loose gravel; long waving water plants 



i-5 

 2-5 

 1 .2 



3ii 



1 .1 

 5-6 

 1 .1 



20.4 



i-33 

 0.44 

 1 .10 

 i-52 



.0171 

 .0029 

 .0170 

 .0012 



•0377 

 •0393 

 .0423 

 .0424 



Group No. 8 



n =0.0469 to 0.0529 



The characteristic of this group was the heavy vegetation in the channels. 



In 1908 some observations were made on irrigation ditches in the 

 northern part of Colorado with a view of obtaining further data on the 

 value of n. Thisw as chiefly done by Mr. Arthur C. Preston as 

 thesis work in the Department of Civil Engineering. The readings 

 were taken with a Price current meter generally, the six-tenths method 

 being used, that is, the velocity at o . 6 the depth was taken as the mean 

 velocity for each division of the cross-section. The results of these 

 observations will now be summarized. The photographs were mainly 

 taken at other times than when the readings were made, usually when 

 the water was very low or else was not flowing at all, in order to show the 

 character of the channel to better advantage. The results are tabulated 

 at the end. 



Observation No. 1. Empire Intake Canal 

 This canal is the largest and in the best condition of those tested. 

 The alignment throughout the 400 feet is perfectly straight, the banks 



