24 
The Colorado Experiment Station 
Table 8 giving the results of the experiments on earth canals, 
was computed from the mean of all the wetted areas and perimeters 
in each of the sections. 
CANALS OF THE RIO GRANDE SYSTEM, DEL 
NORTE. The main canal of this project diverts water from the 
Rio Grande river where it enters the San Luis Valley, west of 
Del Norte. About a mile and a half below the diversion dam is 
the first bifurcation which is at the head of Lateral No. i. About 
two miles east of this point Lateral No. i-c takes out of Lateral 
No. i. 
The slope of the land of the San Luis Valley is exceptionally 
uniform for miles, consequently the canals are built on tangents for 
great distances. Under these conditions an excellent opportunity 
was presented for making hydraulic experiments of this nature. 
The material composing the bed of the canals varies from fine 
gravel to smooth, rounded, water-worn rocks six inches or more in 
thickness. Near the foot-hills, in the main canal, the waterway is 
very rough, being formed by the larger sized stones, while out 
farther in the valley, as in Lateral No. i-c, the rocks are smaller and 
fewer in number, and there is more gravel, which offers less resist¬ 
ance to the flow of the water. 
The section selected on the main canal was just above the first 
bifurcation and had a length of 2,000 feet with a fall of six feet. 
Fig. 6. Main Canal, Rio Grande System, Del Norte. 
(Fig. 6.) Benches were established at the outer edge of the 
bank every 500 feet opposite the places at which measurements 
were to be made in determining the hydraulic elements. On July 
20, 1912, elevations of the water surface were taken opposite these 
points, but owing to the large head of water and the swiftness of 
the current in the channel, wading was impossible at the time. 
Just below the bifurcation are two concrete rating stations with 
swing bridges, one in connection with the Main canal and the other 
in Lateral No. 1, from which the current meter measurements were 
made. The sum of the two discharges, 707 second feet, was taken 
as the discharge of the Main canal in the 2,ooo-foot length. 
The upper end of the experimental section on Lateral No. 1 
was about a mile below the first bifurcation. This was an even 
mile in length and presented ideal conditions for experimental 
