IRRIGATION AND WATER STORAGE. 



139 



sufficiently high level 7 feet or higher to be run upon 

 the cultivation by gravitation. The soil is very porous, 

 originally it was barren sand, and the water sinks into it 

 rapidly, feeding the roots in its passage when the water 

 is suitable. At Mildura, and other settlements on the 

 Darling, soakage is the system followed. 



Irrigation for Grass. Where water can be brought 

 upon pasture land at a sufficient elevation, it may be 

 allowed to trickle over the surface and sink into the land. 

 Comparatively steep land may be treated in this way. 



Crop Irrigation. Where water is run upon cul- 

 tivated land, whether under field crops, orchard, or 

 vegetables, we have to be careful that the soil is not 

 washed away. In laying out the land, the channels 

 through which the water is to pass, opened by plough or 

 hoe, as A B in illustration, should not be steeper than 1 foot 



DITCH <- 



Furrows for Irrigating Field or Orchard. 



in 10 ; 1 in 100 is better. Water runs effectively with a 

 fall of 6 feet per mile ; in all steeper gradients there are 

 risks of washing away the soil. 



Irrigation Land with Gradual Fall. In the plan shown, 



at upper end is the ditch, 

 flume, pipe, or other 

 source of water supply. 

 The arrow shows the 

 course of the water-flow. 

 Near the butt of the ar- 

 row, in the water course, 

 by a gate or other means, 

 the water is stopped and 

 tin- How directed into the 

 feeder, from which it is 

 led upon the ground in 

 furrows (A A A). At the 

 lower end of these fur- 

 rows it may be turned 

 (B B B) into the channels 



A Model Irrigation Paddock. 



