IN HUMID CLIMATES 



133 



Before such projects can be safely undertaken it is always 

 necessary to determine the annual stream flow through a series of 

 years. The supply of water for the project can thus be accurately 

 determined and the investment of money in the project is well 

 founded. For many years the United States Government has 

 gauged the stream flow in many parts of the country for the 

 purpose of determining the water supply. The information thus 

 recorded may be useful at any time that a project is contemplated. 



Canals are built to conduct the water from storage reservoirs 

 to the upper side of the area to be irrigated. Smaller canals or 



FIG. 89. A dredge digging a ditch for irrigating an extensive area. (U. S. D. A.) 



divisions are used to carry the water to different parts, and canal 

 systems may ramify the whole area (Fig. 89). 



Water from Dry Streams. Another plan of supplying water 

 for irrigation is to pump water from large wells in the beds of 

 submerged streams. The water from such wells is supplied to 

 the canals, by which it is conducted to the areas within reach. 

 A noted project using this system is near Garden City, Kansas, 

 where water is pumped from the apparently dry bed of the Ar- 

 kansas River. 



In humid climates water may be obtained from streams, wells 

 and springs. It may be pumped to small storage reservoirs or 



