Figure 1,— Location of study streams, Hollis area. 



laboratory study of the dependence of inter- 

 change upon stream gradient and profile and 

 gravel permeability is being carried on by 

 the writer as a thesis research program at 

 the University of Minnesota Department of 

 Chemical Engineering. 



The primary purpose of this paper is to 

 present a theory of interchange. Results of 



field experiments demonstrating interchange 

 are also described. 



THEORY OF INTERCHANGE AND 

 INTRAGRAVEL OXYGEN RESUPPLY 



The initial source of oxygen that is dis- 

 solved in intragravel water is the atmosphere. 

 The purpose of this discussion is to describe 



