l8 VREDENBURG : RECENT ARTESIAN EXPERIMENTS IN INDIA. 



tide over years of deficient rainfall, the question has been asked 

 whether the water needed is' not already stored in natural artesian 

 reservoirs. It has already been pointed out how small is the area 

 irrigable from artesian sources in the deserts of Algeria and Baluchis- 

 tan, and it has been further argued that the water available from 

 that source could only increase at a rate comparable with an in- 

 crease of rainfall, and not comparable with the concomitant increase 

 of culturable ground. Therefore if there occurs any failure of the 

 rainfall in a country where rainfall is depended upon for cultivation, 

 the portion where this deficiency could be remedied by means of 

 artesian water would be insignificant. Another argument may yet 

 present itself: where artesian water is regularly put to contribution 

 for irrigation purposes, the amount which is used annually must be 

 kept within the limits of the average annual supply to the artesian 

 reservoir. If, on the other hand, the supply is to be drawn upon 

 only at intervals of several years, it might be asked whether it is not 

 possible that an artesian reservoir could exist whose structure is such 

 that it holds in store the supply of a number of years. This might 

 be drawn upon only in times of need, allowing the reservoir to be 

 replenished during intervening years favoured with a better rainfall. 

 In answer to this argument, it may first be pointed out that although 

 such natural conditions for the reservoir are possible, and in fact 

 do exist to a certain degree in some rare instances, 1 they are not 

 common, for they require the coincidence of quite a number of 

 favourable circumstances, such as an unusually large intake area, 

 a stratum unusually porous and unusually thick, and also an 



1 Major Powell attributes partly to this cause the diminution of flow which has been ob- 

 served in some of the American wells since the time when they were first sunk ; " it may 



happen that the stratum has capacity for the transmission of more water than is delivered to it. 

 If the latter relations exist in the case of a perfect or nearly perfect reservoir, and that 

 reservoir is tapped by numerous artesian wells, the initial discharge of water from the wells 

 is greater than the permanent discharge. The wells in such a case draw upon a body of water 

 which may have required years for its accumulation, and their conditions of permanent flow 

 are not reached until this accumulation has been exhausted." Eleventh Annual Report of the 

 Director of the United States Geological Survey, Part II, p. 262. 



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