Frictional Resistance in Artificial Waterways 7 
by the sheet metal under the weight of the water. Wetted areas 
were obtained from the diagram by use of the planimeter. 
Figures 1 and 2 show cross-sections of flumes on the King 
Lateral Extension on the Uncompahgre Project, near Montrose. 
The dashed lines represent the semi-circular shape of the flume 
when empty, and the parabolic form of curve assumed by the sheet 
metal under the weight of the water is represented by the solid 
lines. The bottoms of these flumes were depressed 0.2 feet when 
about one-third full of water. 
Figure 3 shows a cross-section of a flume on the Garland 
Canal, Blanca. A depression of o. 11 ft. on the bottom takes place 
when this flume is one-eighth full. Sufficient measurements 
could not be made to determine the distorting effects of other heads 
because of the difficulty of having the quantity of water varied. 
However, these serve to illustrate the fact that allowance should 
& f 
be made for this sag if the proper grade and elevation of the flume 
in relation to the channels of approach and recession be maintained 
when water is passing through. The change in the amount of 
cross-sectional area due to this distortion, is inappreciable and 
would not affect the carrying capacity of the flume. 
The corrugated flumes experimented upon showed no change 
under weight of water from the semi-circular form. 
GROUP NO. 1. SHORT FLUMES WITH WASTE- 
WAYS. On the Willcox canal, of the Grand Valley Irrigation 
District, near Grand Valley, are a number of rather short flumes 
which span the arroyos leading from the mesas and serve as waste- 
