148 



Bulletin 86 



quately against changes of temperature and against being damaged 

 \y farm machinery. 



The systems of outlets and gates used in California are of many 

 designs. One of the ingenious schemes, Fig. 32, is that used by 

 orange growers near Riverside, for small streams, where the slopes 

 are from one to four feet per hundred. The gate pits are made of 



DB.TAtL. OF OVE.B.FLOW 



A > 



1 



Fig. 32. — Method of construction of orcliard pipe lines in the citrus district around 

 Riverside, California. Each overflow stand holds back the water at a definite level 

 and permits irrieating: from the risers between it and the next overflow stand. 



8-inch and 16-inch pipe. Their frequency on the line depends upon 

 the fall. When the gate is closed, the water rises in one column 

 and overflows into the line again. The water level is held at the 

 desired height without the aid of valves. This system is modified 



^i!^ 



Fier. 33. — Map of a 540-acre field at Continental, showing- 



