123 



classification. Typical vegetative grovrth along the Santa Ana 

 River is depicted in Plate IV-B. 



TABLE 37 

 CLASSIFICATION OF VEGETATIVE COVER, SANTA ANA RIVER, CALIF. 



Type of vegetation 



Heavy tree cover 



Grass 



Light brush cover 



Heavy brush cover 



Bare sand 



Swamp plants, sedges, etc, 



Water surface 



Cultivated 



Light tree cover 



Totals 



4040 



100.0 



Natural losses of the area, determined as a result of the 

 investigation, were computed on the basis of various tests and 

 studies rather than actual consumptive-use measurements. Evapora- 

 tion losses, stream flow at several gaging stations, temperature, 

 gro\ind-water fluctuations, and changes in gro\md-water storage 

 were recorded during the summers of 1931 and 1932. Consumptive 

 use of water was likewise estimated by means of ground-water fluc- 

 tuations beneath a group of willows. The method of analysis of 

 ground-water fluctuations has been previously discussed. 



Consumptive use during two summer seasons from July 1 to 

 September 30 averaged 66 per cent of the evaporation from a Weather 

 Bureau pan or approximately the amount of evaporation from a body 

 of water of extent equal to the area involved. The loss of ground 

 water due to transpiration and evaporation averaged nearly 20 per 

 cent of the annual inflow into the area in a 2-year period. 



The percentage of loss during the summer was even greater. 

 It was during these months, when water had the highest value for 

 irrigation, that the entire flow of the river was diverted into 

 canals for irrigation of citrus lands at points below the Prado 



