GATE STRUCTURES FOR IRRIGATION CANALS. 



41 



figure 2, shows one of these gates before the canal bank has been 

 completed. The roofing over the box will serve as a bridge. The 

 wings of these gates extend at right angles to the flume a distance 

 equal to the height of the flume. The upper wings and the cut-off 

 wall under the upper end of the floor extend 2 feet below the floor, 

 as a rule, but this dimension is adjusted to suit local conditions. The 

 flume is 12 feet long, 4 feet or more high, and between 4 and 10 feet 

 wide. The radial gate face is made of a double thickness of 1-inch 

 redwood, the wooden radial arms carrying the thrust of the water 

 from near the center of pressure on the gate when the canal is full 

 to the 4-inch galvanized iron pipe axle extending across the flume 



Drawn t>y 5c obey: 



Fig. 10. — Reinforced concrete delivery gate from main canal, California Development Co., 



California. 



about 2 feet in front of the rear end of the flume. This gate is more 

 easily lifted when the water is in the canal than when there is no 

 water, as the hydraulic pressure thrusts the gate against the axle 

 and tends to float the gate. An iron bar with a handle at the free end 

 is attached to the gate so that the latter may be lifted easily and 

 locked in position by locking the bar over a hasp loop. 



This type of construction might be readily adapted to lateral and 

 even branch canal gates, as the forms are extremely simple, yet the 

 structure is remarkably efficient. 



