42 



DIVISION OF WATER RESOURCES 



level and variety and age of crop being identical in each. Twelve tanks 

 were filled with undisturbed soil and three with loose soil settled in 

 svater. Complete installation data on tanks in ^^se at the Santa Ana 

 station, giving the diameter, the use made, period covered by test, 

 content, and depth to water table are shown for each tank in Table 6. 



TABLE 6 

 INSTALLATION DATA ON TANKS USED AT SANTA ANA STATION 



Tank 

 number' 



1-2-3 



1-2-3 



1-2-3 



4-5-6 



4-5-6 



7-8-9 



7-8-9.---- 

 10-11-12.. 

 10-11-12-- 

 13-14-15.. 

 13-14-15.- 



16 



17» 



18" 



19 



20 



21 



22 



23 



24 



25 



26 



Purpose 

 of tank 



Evaporation . 

 Evaporation . 

 Use of water - 

 Evaporation _ 

 Use of water - 

 Use of water - 

 Use of water. 

 Use of water - 

 Use of water - 

 Evaporation - 

 Use of water - 

 Evaporation - 

 Evaporation . 

 Evaporation - 

 Use of water. 

 Evaporation - 

 Use of water - 

 Use of water - 

 Use of water - 

 Use of water . 

 Use of water. 

 Evaporation . 



Period of test 



Beginning 



May, 1929 

 Oct., 1929 

 Oct., 1930 

 May, 1929 

 Oct., 1930 

 May, 1929 

 Oct., 1930 

 May, 1929 

 Oct., 1930 

 July, 1929 

 Oct., 1930 

 May, 1929 

 .A.ug., 1929 

 \ug., 1929 

 Aug., 1929 

 Mav, 1929 

 Mav, 1930 

 May, 1930 

 May, 1930 

 Mav, 1930 

 Aug., 1930 

 May, 1931 



Ending 



Oct., 1929 

 Oct., 1930 

 April, 1932 

 Oct., 1930 

 .\pril, 1932 

 Oct., 1930 

 April, 1932 

 Oct., 1930 

 April, 1932 

 Oct.. 1930 

 April. 1932 

 April, 1932 

 Mav, 1930 

 May, 1930 

 April, 1932 

 April, 1932 

 .April, 1932 

 .April, 1932 

 April, 1932 

 April, 1932 

 April, 1932 

 April, 1932 



Content of tank 



Bare soil 



Bare soil 



Salt grass 



Bare soil 



Salt grass 



Salt grass 



Salt grass -- 



Salt grass 



Salt grass 



Bare soil 



Salt grass 



Free water surface 



Water covered with oil film 



Water covered with oil film 



Round stem tules in water 



Free water surface 



Triangular stem tules in water 



Cat-tails in water 



Round stem tules in water 



Willow 



Wire rush 



Five per cent sodium chloride solution. 



Depth to 



water 



table in 



feet 



' Undisturbed soil was used in Tanks Nos. 1 to 12, inclusive; disturbed soil in Tanks Nos. 13, 14, and 15. 



2 Results of these experiments are published in State of California. Department of Public Works Bulletin No. 33. 



When the station was first installed, in 1929, four tanks had an 

 original growth of salt grass growing on the column of soil enclosed in 

 them, two others had salt grass transplanted in them, and the rest had 

 bare surfaces. Use of water by salt grass and evaporation from bare, 

 uncultivated soil was measured from these tanks from May, 1929, to 

 October, 1930, when several changes in water levels were made and all 

 bare-soil tanks had salt grass transplanted in them. The new grass did 

 not make good growth at first, and until gro^\•th began in the following 

 spring the recorded use of water was largely due to soil evaporation 

 rather than to consumptive use by the transplanted gi'ass. No further 

 changes were made in the crop grown or in the depth to water table 

 in any soil tank after the changes noted in October, 1930. 



For reasons which will be given later, measurements of evaporation 

 from bare, uncultivated soil surfaces in Tanks Nos. 1, 2, and 3 were 

 begun with an initial water table depth of 4 feet and were continued 

 thus throughout the summer of 1929. It soon became evident that this 

 water-table depth was greater than the limit of capillary rise of the 

 soil moisture. This was evidenced in part by the lack of soil moisture 

 in surface soil and proved beyond doubt by the fact that there was no 

 withdrawal of water from the Mariotte supply tanks during a five- 

 month period which included tlie warmest months of the year. 



In October following the period during which no evaporation 

 occurred the water-table levels were raised from 4 to 3 feet from the 



