156 DIVISION OF WATER RESOURCES 



White,'' in his work on daily fluctuations of the water table in 

 the Escalante Valley, Utah, developed the formula q = y (24r ± s) in 

 which q is the depth of water used by the plants, y is the specific yield 

 of the water-bearing material, r is the hourly rate of rise of the water 

 table from midnight to 4 a.m., and s is the net fall or rise of the water 

 table during- the 24-hour period. The hours of midnight to 4 a.m. 

 were selected in determining the rate r, because during these hours the 

 transpiration and evaporation losses would be at a minimum. 



As shoT^Ti at the left on Plate VII, the measured daily outflow 

 between Hamner Avenue and The Atchison, Topeka and Santa Fe Rail- 

 way Bridge was plotted against the daily tran.spiration ( 24r ± s) as 

 computed from the record of well D. The (24r ± s) expressed in feet 

 of ground water represents the amount the water table would have 

 dropped if there was no recharge. The figure opposite each observa- 

 tion represents the day of the month. The observations were next 

 classified as to rising or falling water table, representing increase or 

 decrease in storage. A curve was drawn such that it represents the 

 average slope of a series of shorter lines drawn through consecutive 

 points, having much the same change in storage. As a rule most of 

 the observations to the left of the curve showed a drop in storage, 

 while those to the right showed a gain. 



As stated before, outflow ± change in storage should vary 

 inversely with natural losses, provided the inflow does not change. It 

 was next assumed that the difference between the quantity computed 

 from this curve and the actual outflow represented the change in stor- 

 age. For example, on September 30 the outflow was 35.7 second-feet. 

 The curve shows that the outflow should have been about 37.2 second- 

 feet if there had not been any change in storage. On this day the 

 water table at well D came up 0.020 foot. The assumption was made 

 that the building up of this storage by 0.020 foot required the 1.5 

 second-feet that failed to appear in the river. Likewise on August 19 

 the water table dropped 0.040 foot. The outflow for this day was 27.7 

 second-feet. The curve indicates that the discharge should have been 

 23.8 second-feet if there had been no change in storage. It was there- 

 fore assumed that on this day the outflow was 3.9 second-feet greater 

 than that shown by the curve, because its equivalent was drawn from 

 storage to satisfy the demands represented by the natural losses. 



The records of ground water fluctuations obtained on a few other 

 wells in this area indicate that as a rule the daily change in storage 

 was about in direct proportion to the change in storage at well D. 

 It was therefore assumed that the changes shown by the record obtained 

 at well D were in direct proportion to the mean changes in storage in 

 the entire area between the Hamner Avenue and The Atchison. Topeka 

 and Santa Fe Railway Bridge gaging stations. The daily changes in 

 storage at Avell D were then plotted against the excess or deficiency in 

 the outflow. If the inflow to the area had remained constant and the 

 changes in storage at well D had been representative of the area, these 

 points .should have plotted a well-defined curve. The movement of 

 certain plotted points from the left of the curve to the right indicates 



a White, W. N., A method of estimating ground water supplies based on di.s- 

 charge by plants and evaporation from soil : U. S. Geol. Surv-ey "Water-Supply Paper 

 6.'>9, pp. i-105, 1932. MTiite states that the principle underlying this formula was in 

 part suggested by G. E. P. Smith in his earlier work (p. 8). 



