120 THE ANDES OF SOUTHERN PERU 



may be added not only by a better use of the water but also by the 

 diversion of streams and lakes from the Atlantic to the Pacific. 

 Figs. 67 and 68 represent such a project, in which it is proposed to 

 carry the water of Lake Choclococha through a canal and tunnel 

 under the continental divide and so to the head of the lea Valley. 

 A little irrigation can be and is carried on by the use of well water, 

 but this will never be an important source because of the great 

 depth to the ground water, and the fact that it, too, depends ulti- 

 mately upon the limited rains. 



The inequality of opportunity in the various valleys of the 

 coastal region depends in large part also upon inequality of 

 river discharge. This is dependent chiefly upon the sources of the 

 streams, whether in snowy peaks of the main Cordillera with 

 fairly constant run-off, or in the western spurs where summer 

 rains bring periodic high water. A third type has high water dur- 

 ing the time of greatest snow melting, combined with summer 

 rains, and to this class belongs the Majes Valley with its sources 

 in the snow-cap of Coropuna. The other two types are illustrated 

 by the accompanying diagrams for Puira and Chira, the former 

 intermittent in flow, the latter fairly constant/' 



' The Boletin de Minas del Peru, No. 34, 1905, contains a graphic representation 

 of the regime of the Rio Chili at Arequipa for the years 1901-1905. 



