LIST OF PLATES 



Plate Page 



I. A. Screw jack working against anchored cable, forcing 

 soil tank 6 feet into the ground to capture un- 

 disturbed soil 21+ 



B. Soil sampling equipment: compressor unit (on truck), 

 pneumatic driving hammer (in operator's hands), 

 ordinary soil tube hammer (on ground) and soil 

 tube jack 24 



II. A. Willows 6 to 7 feet high growing in 6-foot diameter 



tank at Santa Ana, Calif. 47 



B. Alders in Coldwater Canyon between middle and lower 



controls 47 



III. A. Flow recorder installation in Coldwater Canyon: 



above, 7-d.ay chart on clock-driven drum; below, 

 spiral cam which permits a direct record on the 



chart in units of discharge 78 



B. Site of experimental station at Isleta, N. Mex. , 



showing type of surroiinding vegetation. Consump- 

 tive use of water by sedge was determined in the 

 small area fenced at the extreme right 78 



IV. A. Cattails in tank surrounded by similar growth at 



Isleta, Middle Rio Grande Valley, N. Mex. 96 



B. Dense growth of water-loving shrubs and trees along 

 the Santa Ana River, near Prado, Calif. Studies 

 have shown this vegetation uses not less than 50 

 acre-inches per acre of water 96 



V. A. Dense growth of bank vegetfation using water from an 



irrigation canal in Imperial Valley, Calif. 139 



B. Wild sunflower plant in California. Sunflowers are 



remarkably thrifty for long periods in very dry 

 places 139 



C. Mesquite in the Coachella Valley, Calif., illustrat- 



ing size of bush. This is found in areas where 

 ground water is within reach of root systems. The 

 size is an indication of depth to water table; 

 high ground water results in tall, dense growth-- 139 



VI. A. Tall, dense Cottonwood and willow growth along dry 

 bed of San Luis Rey River, San Diego County, 

 Calif. Much of the surface flow sinks into the 

 gravels and is absorbed by vegetation 140 



B. Typical swamp area. Tules used large amoimts of 



t water 140 



C. Tules 6 to 8 feet high, growing in open water 140 



VII. A. Creosote bush and other vegetation in the desert 

 illustrating the habit of wide spacing between 

 plants owing to the scarcity of moisture in the 

 soil 141 



B. Eucalyptus grove on eroded bank, illustrating depth 

 of rainfall penetration at about 7 feet as indi- 

 cated by dark shadowy line below the light color- 

 ed gravel strata. Note tree roots extending 

 through the gravel into finer soil 141 



VIII. A. Chaparral, illustrating extensive root system ex- 

 posed by flood 142 



B. Johnson grass ( Sorghum halepense ) growing in young 

 orange grove, Calif., where soil was unusually 

 moist 142 



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