The Salton Sea and Rainfall 



245 



nia. The excess in Arizona and New 

 Mexico was not strikingly large. 



Considering these facts in proper se- 

 quence, it will be observed, first, that 

 Salton Sea was not formed until after the 

 heavy rains of January, February, and 

 March, 1905, so that to ascribe the in- 

 creased rainfall to Salton Sea would be 

 to place the effect before the cause. 



Admitting, for the sake of argument, 

 that a body of water of the dimensions of 

 the present Salton Sea existed before 

 January, 1905, let us examine its probable 

 effect on the rainfall of the Southwest. 

 Its present dimensions are approximately 

 60 miles long, 8 miles broad, and say 25 

 feet deep on the average. These are 

 rough estimates, but they will serve the 

 purpose. The cubic contents would 

 therefore be 60 X 8 X 0.0047 = 2.2 cubic 

 miles of water. 



The normal annual rainfall of Arizona 

 as determined by Section Director Jesun- 

 ofsky is 11.75 inches. The rainfall for 

 several years previous to 1905 was as fol- 

 lows: 



1899 S 4 inches. 



1900 S.3 inches. 



1901 10.6 inches. 



1902 10. ,•? inches. 



I9"3 9.9 inches. 



1904 9.8 inches. 



1905 26.6 inches. 



From this statement it will be seen that 

 the excess for 1905 was 14.85 inches, an 

 amount more than equal to the normal 

 annual rainfall. An inch of rainfall per 

 square mile is equal to 72,516 short tons. 

 As the area of the territory is 113,956 

 square miles, the excess in tons for 1905 

 would be in roimd numbers 72,516 X 

 14.85 X 113,956= 122,717,500,000 short 

 tons. Converting this amount into cubic 

 miles of water for a comparison of its 

 volume with that of Salton Sea, we have, 

 as before, i inch of rainfall on a square 

 mile weighs 72,516 tons. A cubic mile 

 would be this weight X 5280 X 12 = 

 4.594,613,760 tons, or, assuming that the 

 temjierature was somewhat above 39° F., 

 say in round numbers 4,500,000,000 tons. 



The number of cubic miles of rain that 



fell in Arizona in excess of the average 



122,717 ^,. 



= 27. This quan- 



4500 



was, therefore, 



tity, as may be readily seen, is twelve 

 times greater than the total volume 

 of the Salton Sea. In other words, 

 the total volume of the latter would 

 barely suffice to produce one-twelfth of 

 the surplus rain that fell in Arizona, to 

 say nodiing of the rainfall in ad- 

 joining regions. The total amount of 

 water now in Salton Sea, if uniformly 

 distributed in Arizona, would cover the 

 Territory to the depth of about an inch 

 and a quarter, or the equivalent of one 

 good soaking rain. How then could the 

 evaporation from Salton Sea, even if it 

 amounted to 8 feet per annum, granting 

 that it was all condensed and precipitated 

 to earth, produce the enormous quantity 

 of water that fell in Arizona in 1905? 



As pointed out by Mr Arthur P. Davis 

 in the National Geographic jMagazine, 

 January, 1907, the advocates of the idea 

 that Salton Sea has caused an increase in 

 the rainfall of the Southwest seem to 

 have ignored the presence of the Gulf of 

 California, a body of water hundreds of 

 times larger than Salton Sea, and distant 

 from Arizona about the same number of 

 miles. This body of water washes the 

 shores of a region probably as arid as 

 can be found on this continent. It has 

 done so for centuries, yet no progressive 

 changes from arid to humid conditions 

 have been observed. 



Mr Davis has also pointed out that the 

 disaster which caused the formation of 

 Salton Sea has prevented the normal 

 overflow of the lands in the Colorado 

 Valley below Yuma. The areas of land 

 in that region which would have been 

 overflowed under normal conditions are 

 nearer to Arizona and New Mexico, and 

 of greater extent than Salton Sea, so that 

 if evaporation alone causes rainfall, the 

 tendency of the formation of Salton Sea 

 would have been to reduce rather than 

 increase the rainfall of Arizona and New 

 Mexico. 



