Transition Zone Morphology Dynamics of Dissolved Oxygen (DO) in a Salinity‐Impacted Hyporheic Zone

Abstract Freshwater salinization is a common yet underappreciated environmental problem in rivers, how this process impacts the transport of dissolved oxygen (DO) hyporheic zone remains unknown. Using flume experiments and numerical simulations, we have demonstrated that morphological dynamics DO transition are controlled by dimensionless number Da·Ra −2 , measure rate aerobic respiration to free convection. At low oxic front breaks up into fingers which subsequently grow, leads accelerating shrinking anaerobic underlying sediment. As increases, growth instability decreases, plume suppressed delayed compared with saltwater‐freshwater interface, mixing area between saltwater freshwater. These results indicate freshwater syndrome can significant on functioning aquifer ecosystems unless regulated managed effectively.