Quantity of Water Consumed in Irrigation. 27 



(3) By loss from evaporation and percolation — 

 (a) In the canal itself. 



(h) In the distributaries, called in Northern India 

 rdjbahas. 



(c) In the village watercourses, called guls. 



(d) In the small field channels, for the supply of one field 



only at a time. 

 (N.B. — c and d might be noticed under one head, but a 

 division is convenient for the purpose of this 

 paper.) 



(4) Lost by accidental breaches of banks and by carelessness 

 of cultivators. 



(5) Utilised in irrigating the fields. 



5. The consumption under these several heads may be 

 more fully explained as follows : — Head (1) represents the 

 difference between the volume of water flowing down the 

 stream and that entering the canal. Head (2) explains the 

 difference between the supply entering the canal and that 

 available for irrigation. The consumption under these two 

 heads may be neglected in this paper, since the results 

 adopted are based on the net supply of water available. 

 The loss under (3) is an item of the greatest uncertainty ; it 

 is affected by the lengths of the several portions of the 

 works along which the water has to travel, and by the 

 nature of the soil. A village watercourse is here supposed 

 to be one for the supply of a whole village or a large portion 

 of a village, situated at a distance from a distributary ; on 

 the average such may be a mile in length, or, perhaps, a little 

 more. The field channels — for the supply of one field only 

 at a time — may be on the average, perhaps, 200 yards in 

 length. Head (4) is an uncertain quantity ; the best 

 way of providing for the loss of water by breaching of banks 

 is, perhaps, to consider it as part of the loss (under 36, 3c) 

 from the distributaries, &c, breached, and for the rest (waste 

 by cultivators) to increase the allowance per acre irrigated. 

 By this arrangement this item of loss need not be further 

 considered separately. Head (5) represents the useful 

 employment of the water ; every effort should evidently 

 be made to increase the proportion of water under this head 

 by reducing that under the other heads. For practical pur- 

 poses, the quantity of water consumed may be divided into 

 two parts — (1) that usefully employed in the field, and (2) 

 that lost in the canal and watercourses, large and small. 



d2 



