WATER LOSSES FROM WET AREAS 155 



movements of sand waves and scour in the channel. The record seemed 

 to have little if any relationsliip to the records at well E-3 or to those 

 of the other river stations. This would seem to indicate that on very- 

 wide sections of river channel the effect of ground water fluctuations 

 on the stage of the water in the river is greatly reduced. In wells 

 located along the river, such as well E-4, the condition of the channel 

 do-vATistream from the station apparently controls, to a major degree, 

 the level of the water surface at the well. Plate I shows that in this 

 stretch of the river, sections as wide as that at well E-4 are few and 

 cover only short distances of river channel. 



Computations of changes in storage and corrected outflow. 



The following equation gives the entire disposal of all the Avater 

 entering any area along the river : 



inflow = Natural losses ± Change in ground water storage + Outflow. 



On Plate II the different members of this equation are illustrated. 

 The inflow is the quantity of ground water passing the points marked 

 ^; the natural losses are the quantity of water discharged through 

 transpiration and through evaporation of both ground water and river 

 water ; and the outflow is the measured gain in the flow of the river in 

 the area. 



It is possible for the natural losses to occur either from the ground 

 water storage or from the inflow. If the losses are drawn entirely 

 from storage, then the measured outflow will represent the inflow to the 

 area. On the other hand, if the losses are drawn entirely from the 

 inflow the storage will remain unchanged, and the outflow will be 

 equal to the inflow minus the natural losses. Practically' the entire 

 period of record falls between these two extremes. Possibly these rela- 

 tions can best be illustrated by inserting figures in the basic formula 

 as follows: 



Inflow = Natural losses ± Change in storage + Outflow. 



Second feet Second feet Second feet Second feet 



(a) 50 = 10 + 5 4- 35 



(ft) 50 = 10 + +40 



(c) 50 = 10 — 5 + 45 



In each of these computations the inflow and natural losses remain 

 constant, yet the measured outflow varies from 35 to 45 second-feet. 

 In ^, 5 second-feet of the inflow was placed in storage, leaving 35 

 second-feet as outflow. In **, the storage did not change ; consequently 

 the outflow represents inflow minus the natural losses. In °, 5 second- 

 feet of the 10 second-feet of natural losses was drawn from storage, 

 which would leave 45 second-feet of the inflow to appear as outflow. 

 From these computations it is evident that if the inflow remains con- 

 stant, then the outflow plus or minus the change in storage must vary 

 inversely with the natural losses. Also, on days when the changes in 

 storage are equal, then the outflow will vary inversely with the natural 

 losses. 



Tlie change in storage to be used in this equation was determined 

 by the following method : 



