26 Quantity of Water Consumed in Irrigation. 



obtained in one locality, the same duty may be estimated for 

 elsewhere, notwithstanding differences of climate, of soil, in 

 the quantity of water available, in the length of canal the 

 water has to traverse before reaching the fields, in the mode 

 of using the water, in the crops grown, in the number of 

 waterings they require, and in several other respects. The 

 number of acres irrigated per cubic foot per second of 

 discharge may be sufficient information to base calculations 

 on when one country only is concerned, and there are 

 certain points of resemblance in the schemes, though not 

 always even then ; but when the information is required 

 for application in another country, and under wholly 

 different conditions, it is too vague to be of much use. 

 The following instances of the actual duty obtained 

 on certain canals in various countries may be taken in 

 illustration of this : — 



Countries and Canals. 



Acres irrigated per 



cubic foot per 



second of supply. 



Authorities. 





Extremes. 



Aver- 

 age. 





T ■,. { Eastern Jumna Canal. . 

 lnaia \ Ganges Canal 



Spain — Canals from River Turia 



T , , j Canals in Lombardy . . 

 Italy | ^ Piedmont . . 



184 to 291 

 154 to 239 



38 to 114 



62 to 104 

 43 to 106 



216) 

 190 ( 



78 



70) 



55 j 



Official Report* — Re- 

 sults of ten years, 1866 

 to 1876. 



Major Scott Moncrieff, 

 R.E.f 



Col. Baird Smith, R.E.+ 



Even in one canal there are differences; thus in one 

 division of the Ganges Canal a duty of 97 acres only was 

 obtained in 1875-76, while in another the duty was 290 

 acres ; in the cold season only, one division gave 41 acres 

 and another 204 acres (see par. 6). 



4. The volume of any stream, which is to be turned 

 wholly into a canal for irrigation, will be consumed as 

 follows : — 



(1) By loss at the head itself. 



(2) By loss from escapes provided at convenient places to 

 insure the safety of the works. 



* Irrigation Revenue Report of the North-western Provinces (India) for the 

 year 1875-76, page 13, par. 23. 



f Irrigation in Southern Europe (1868), page 168. 



I., pages 116 to 298. 



\ Italian Irrigation (1855), Vol. 



