90 Irrigation and Drainage 



territory of considerable rainfall, in order to fill the soil 

 and give rise to springs, streams, and wells, or there 

 could be no water for irrigation. It is only the accident 

 of a great stream like the Nile, gathering its waters in a 

 region of large rainfall, that makes any irrigation at all 

 possible in a rainless, desert country like Upper and 

 Lower Egypt. 



The distribution of the rainfall with reference to the 

 growing season, more than the quantity of it, is the 

 chief factor in determining whether irrigation will be 

 profitable or not. In the irrigated districts of Italy, 

 Spain, France, Austria -Hungary, Algiers, Cape Colony, 

 Asia Minor, Armenia, Victoria, South Australia, and 

 the westernmost part of the United States, there is a 

 tendency to a dry time in early or late summer, at the 

 time when crops need water most, or in some of these 

 countries it may be dry the whole season through, the 

 rainy season being in fall or winter. In China, south- 

 ern Japan, Siam and Ceylon the summer is rainy, but 

 there is a tendency to develop a short dry season in 

 midsummer. In Switzerland, Belgium, Denmark, Eng- 

 land, Bavaria, Madagascar, North Japan, Queensland, 

 and Mexico there is usually a uniform distribution of 

 rain throughout the whole of the growing season. In 

 these latter countries, however, while irrigation is prac- 

 ticed in them, it must be said that it is supplementary 

 rather than a necessity. 



