WATER LOSSES P^ROM WET AREAS 23 



specific retention are apparent rather than real, as they apply only to 

 conditions of hi^-h water table. True values can be obtained only 

 when measured from a high colunui of soil, disregarding the fringe 

 of capillary moisture. 



9. Alkali deposits occurred on the surface of several soil moisture 

 tanks at the Santa Ana station, depending in amount on the depth 

 to water table in the tank, ^luch of this alkali was originally present 

 in the soil, but it was increased by the small amounts in solution in 

 the water consumed. During the first two seasons, when the soil tanks 

 were covered during rain storms. th(> concentration of alkali on the 

 surface increased month by month. During the third season, much 

 of the surface deposit was carried back into the soil by rainfall pene- 

 tration, causing a redistribution. Chemical analyses of soils taken from 

 the tanks at the end of the investigation show a high pH value and 

 where the water table was close to the tank surface a very high con- 

 centration of salts in the top inch of soil. As salt grass is alkali 

 resistar:iC it is doubtful if the rate of transpiration was affected. 



Alkali was very much less in amount at the San Bernardino station, 

 and no deposits occurred on the tank surfaces. Water used in the 

 tests was from an artesian well and was relatively pure. The distribu- 

 tion of salts was greater in the top soil, decreasing in amounts toward 

 the water tables. The same was true of the pH values. 



Victorville Station . 



In November, 1930, an experiment station was established near 

 Victorville for the purpose of measuring evaporation and transpiration 

 losses from moist areas along the Mojave River and for recording 

 meteorological data. The work was correlated with the stream flow 

 measurements being made by the U. S. Geological Survey to determine 

 the consumptive use of water between gaging stations at several loca- 

 tions on the river. 



The experiment station was located in and on the bank of a small 

 cienaga on the east side of the IMojave River. The equipment consisted 

 of three tule tanks, a standard Weather Bureau evaporation pan, an 

 anemometer, a set of standard maximum and minimum thermometers 

 and a thermograph housed in a standard shelter, a rain gage and a 

 ground well. Previous investigations regarding consumptive use of 

 water by native A^egetation along stream channels* indicate that if 

 data from tanks are to be used in estimating losses from larger areas 

 under field conditions, the tanks should be set in a field of natural 

 growth similar to that in the tanks. Two tule tanks were therefore 

 placed in the swamp, one 2 feet in diameter and the other 6 feet in 

 diameter. A third tule tank, similar to those used at the Santa Ana, 

 Prado, and San Bernardino stations, was set in the ground on the 

 bank for the purpose of demonstrating the effect of exposure on the 

 use of water by plants grown in tanks. The standard Weather Bureau 

 evaporation pan was also placed on the bank with similar exposure. 



Observations were made on evaporation, consumptive use of water 

 from tules, "u-ind movement, rainfall, and temperatures from Febru- 

 ary 1, 1931, to February 28. 1933. The results indicate the following 

 conclusions : 



* California State Department of Public Works Bulletin No. 33, Rainfall Pene- 

 tration and Consumptive Use of Water in the Santa Ana River Valley and Coastal 

 i'lain, by Harry F. Blaney, C. A. Taylor, and A. A. Young. Chapter 4. 



