40 Quantity of Water Consumed in Irrigation. 



Sq. feet. 



Total. 



Distributary ... 2 X 5280 X 7 = 73,920 ),„, 9ft f . 

 Village channels 10 x 2640 x 3 = 79,200 f 10 ^ iZUS( l- "• 



Then, taking for one trial a depth of 4 inches for a watering, 

 and in another 4J inches (supposing half the land to be 

 excessively sandy, as much of it was), the depth lost in 

 channels would be 11 inches in the first case and 8 J inches 

 in the second, thus : — 





First Supposition. 



Second Supposition. 





Depth. 



Quantity. 



Depth. 



Quantity. 



Utilised in 20 acres 

 Lost over 153,000 sq. ft. 



inches. 



4 



11 



cubic feet. 



290,400 



141,600 



inches. 



a* 



cubic feet. 



326,700 



105,300 



Total consumption 



— 



432,000 



— 



432,000 



28. For the application of the foregoing results to 

 Australia or to other countries than India, certain local in- 

 formation is necessary. First, in order to estimate the 

 quantity of water required for actual irrigation (excluding 

 loss by percolation) it is necessary to ascertain, besides the 

 nature of the soil, what crops are to be irrigated, the number 

 of waterings to be given to each, the intervals between the 

 waterings and at what season water will be required. The 

 author would then allow for each watering a depth of from 3 to 

 5 inches, according to the soil, as shown in Appendix A. If 

 excess of water is to be used to save labour without any 

 compensation in other ways, a larger supply would have to 

 be allowed, according to the extra time the water would be 

 flowing on any plot of ground (see column 7 of Appendix 

 A). The result arrived at by multiplying the quantity con- 

 sumed per acre each time by the number of waterings and 

 by the area, will give the total quantity of water required 

 for irrigation, including only loss in the field-channels up to 

 a length, say, of 150 yards. More water might be used for 

 the first watering of a crop (called in N. India paleo), but less 

 would generally suffice afterwards, unless the ground were 

 continually stirred up, or the upper crust repeatedly broken 

 by hoeing. For the first few years the consumption of 

 water might, and probably would, be in excess of this 

 estimate, but good management should bring it down. 



29. To estimate the loss by percolation from a canal 

 and distributaries, the nature of the soil passed through 



