322 



Irrigation and Drainage 



the gate by simply pulling upon it. This is very simple and 

 easily operated. In placing the sluice in the wall of the reser- 

 voir, great care is needed to get the dirt thoroughly tamped and 

 puddled about it, so that water shall not follow its sides and 

 develop a leak. 



To prevent injury from waves, the walls of the reservoir 

 should be sloping and not steeper inside than a rise of 1 in 2. 



Fig. 75. Sluice and gate for reservoir. (Kansas Asrr. Exp. Station.) 



At the outlet ditch there should be provided an overflow weir 

 sufficiently below the top of the wall to prevent wave action 

 from starting a cut in the top by breaking over. A reservoir, 

 completed and filled with water, is represented in Fig. 76, 

 but where these are made circular in form there must be less 

 seepage through the banks in proportion to the amount of water 

 stored, because less wall is required to enclose a given area 

 when this is circular. 



