WATER LOSSE.S FRO:\r WET AREAS 157 



that the inflow decreased during the period. For this reason, curves 

 were drawn through small groups of consecutive observations, as the 

 change in inflow would be little for short periods. 



The average slope of these curves indicates that a change in stage 

 of the water table amounting to 0.001 foot represents the equivalent of 

 a change in outflow of 0.11 second-foot. If the changes in stage at 

 well D represent the average for the area, then the average specific 

 yield for the section of the gravel unwatered during the season is 

 about 12 per cent. Using the factor of 0.11 second-foot per 0.001 foot 

 of change in water level, the change in storage for the entire record 

 was converted into second-feet. The daily measured outflow was then 

 corrected for changes in storage. • The term "corrected outflow" as 

 used throughout the remainder of this report represents the measured 

 outflow plus or minus the change in storage. 



Computations of natural losses and inflow between Hamner Avenue 



and The Atchison, Topeka and Santa Fe Railway Bridge stations. 



In discussing the basic formula for the inflow, it was stated that 

 if the inflow remains constant, the outflow plus or minus changes in 

 storage will vary inversely with the natural losses. On Plate VIII are 

 plotted the relations between the daily corrected outflow and the daily 

 evaporation and temperature for July, August, and September, 1932. 

 The figure opposite each point represents the day of the month. The 

 fact that the observations as i3lotted shifted to the right is apparently 

 due to gradual decrease in rate of inflow as the season progressed. The 

 trend of consecutive observations had more to do in the development 

 of the slope of the monthly curves than the mere averaging of the 

 points, because during short periods the inflow would change little, 

 leading only two principal variables — namely, corrected outflow and 

 natural losses. Thus the third variable is practically eliminated, leav- 

 ing a close relation between corrected outflow and temperature or 

 evaporation, as represented by the slope of the curve. Curves similar 

 to those on Plate VIII were also drawn for 1931. 



The temperature record was obtained from the thermograph record 

 at the Prado evaporation station. A stud}' of the ground water fluctua- 

 tions showed that practically all the transpiration occurred between the 

 hours of 8 a.m. and 4 p.m. each day. For this reason the daily tempera- 

 ture figures here used represent the average temperature for the period 

 of 8 a.m. to 4 p.m. The data seem to indicate that little or no trans- 

 piration occurs in this area when the average daily temperature is 

 below 60°. If the natui'al losses in this area varied in direct pro- 

 portion with the temperature above 60°, then for each 10° more than 

 60° the loss would have amounted to 7.7 second-feet in 1931 and 8.0 

 second-feet in 1932. 



For the period in 1931 the records from the evaporation pan at 

 Prado were used in plotting the relation of evaporation to corrected 

 outflow. In 1932, however, 0T\dng to imperfect operation of the 

 apparatus, the daily evaporation record at Prado was not entirely 

 satisfactory. For this reason, the record from the evaporimeter at 

 Pomona, operated by C. A. Taylor, of the Bureau of Agricultural 

 Engineering, was used for 1932. This evaporimeter is less than 15 

 miles from the Santa Ana River area, and the evaporation there should 



