WATER T,OSSES FRO:\r WET AREAS 



67 



Adjustment Factors 



Previous tables have shown weekly' or monthl_y use of water by 

 each oTowtli at tlie several stations, but Table 22 contains the observed 

 average yeai'ly eonsumplive use and also an estimated factor for adjust- 

 ment of such use to consumptive use over large areas. This factor for 

 tules and cat-tails is based upon experiments carried on at Victorville 

 and reported in Chapter III. No experiments have been made to deter- 

 mine a factor for grasses, but conditions of tank growth are so nearly 

 those of the tield, that factors for these crops have been taken as 100 

 per cent. A tentative factor of 85 per cent has been adoi)ted for 

 willow as previously stated. 



TABLE 22 



SUMMARY OF TANK INVESTIGATIONS SHOWING ESTIMATED ANNUAL 

 CONSUMPTIVE USE OF WATER IN MOIST AREAS 



1 Evaporation from surface of bare soil. 



2 Tules grown in tank 251^ inches in diameter. 

 ' Tules grown in tank 6 feet in diameter. 

 'See Table 21. 



No data are available for estimating an adjustment factor for wire 

 rusli. While the tank in which it grew was not set in a field of similar 

 groAAih, it Avas surrounded by grass and weeds. It is possible, since it 

 did not grow in its natural habitat as did the salt grass, that change of 

 environment was responsible for an increased consumptive use as is the 

 ease with tules in isolated tanks. 



In Table 22 there are also presented estimates, based upon experi- 

 ments, of the annual drafts upon the ground water by noneconomic 

 native growths found in moist areas in the Santa Ana basin. These 

 estimates are only for those depths to ground water at which the 



