152 DIVISION 0J<' WATER RESOURCES 



area between Hamner Avenue and the railway bridge as surface flow 

 in July, August, and September, 1932. This outflow was computed by 

 subtracting the discharge measured at the Hamner Avenue gaging 

 station from the discharge measured at the railway bridge station. If 

 there had been no losses by evaporation and transpiration in this 

 stretch, this water would have represented the ground water inflow to 

 the area. 



During this period weekly observations were made at Well B-3, 

 just outside the zone of natural losses. These observations show that 

 the water t<ible gradually declined from the middle of May, 1932 (when 

 the observations were laegun) to September 8. The weekly decline 

 ranged from 0.05 to 0.10 foot. After September 8 the water table 

 showed a gradual rise until December 1, when observations were dis- 

 continued. If the stage of the water table is an indication of the rate 

 of inflow, then the rate of inflow gradually decreased from the middle 

 of May until September 8. Therefore, it would seem that the fluctua- 

 tions in the outflow, as shown on graph D, must have been developed 

 by the evaporation and transpiration in the area of natural losses, 

 between the points marked ^ on Plate II. 



In computing the daily outflow numerous errors arise because of 

 the time elements and inaccuracies in the data. The effect on the water 

 table of either a day of very heavy natural losses or a day of light 

 losses might not be completely transmitted to the discharge into the 

 river for several hours. For these reasons it was decided to compute 

 all the daily data of discharge into means for overlapping three-day 

 periods. The records for temperature, evaporation, and transpiration 

 were converted into corresponding three-day means. 



During the summer all the flow in the Santa Ana River below 

 Riverside comes from underground sources except during periods of 

 direct run-off due to rainfall. Records for 3 years at the summer 

 stations seem to indicate that the water surface of the river fluctuates 

 practically in unison at all the stations, unless affected by other than 

 natural conditions. A 10-day period of these records has been plotted 

 on Plate IV, which shows how closely each record follows the others. 

 The numerous minor fluctuations exhibited in these gage-height records 

 are caused mainly by the movement of sand waves past the stations. 

 To some extent the scouring and building up of the do^^^lstream chan- 

 nel will likewise cause such fluctuations. The river is seldom more 

 than 2 feet deep and usually less than 50 feet wide at each of these 

 stations. Plate IV shows that the daily cycle is fairly uniform at all 

 points. At each station the maximum stage occurs a few hours before 

 noon and the minimum stage between 3 and 6 o'clock in the afternoon. 

 The river can be compared to a long reservoir, the water surface of 

 which passes through a daily cycle. Not only do the daily fluctuations 

 occur in unison throughout this stretch of the river, but the longer 

 cycles, such as that indicated by the record for August 5 to 25, show 

 almost uniform change in the water surface of the river at the several 

 gaging stations. 



The E series of wells were dug and water-stage recorders installed 

 on them during the spring of 1932, through aid furnished by the 

 Orange County Flood Control District. Well E-1 was dug at the toe 

 of a small bench parallel to the river channel, 1000 feet from the river. 



