Journal article
Hyporheic-Zone Processes and Stream Oxygen Dynamics: Insights From a Multiscale Reactive Transport Model
Water resources research, Vol.62(1), e2025WR040208
01/01/2026
DOI: 10.1029/2025WR040208
Abstract
Aquatic ecosystem metabolism encapsulates the daily fixation (gross primary production, ) and mineralization (ecosystem respiration, ) of organic carbon. In fluvial systems, these are commonly estimated by inverse solutions to field observations using a model that describes oxygen concentrations varying in the water column in response to metabolic fluxes and air-water gas exchange controlled by a rate coefficient . The most common conceptual model is the single-station metabolism (SSM) model. The simplicity and flexibility of this conceptualization make it attractive; however, it implicitly assumes that all the processes that consume oxygen in fluvial systems can be lumped into a bulk estimate of respiration with poorly understood consequences for estimates of , , and . Here, we focus on the implications of using SSM conceptualization when estimating metabolic fluxes from oxygen dynamics in channels where hyporheic exchange occurs. We use a new multiscale numerical model for reactive transport in streams that represents hyporheic exchange and streambed heterotrophic respiration. Nondimensionalization of this model reveals dimensionless groups that collectively control oxygen dynamics. Numerical experiments offer a mechanistic understanding of the impacts of hyporheic exchange on diel oxygen dynamics revealing that potential biases arise from neglecting mass transfer limitations. Specifically, we found that hyporheic exchange significantly affects diel oxygen dynamics, even for nonreactive streambed sediments. Moreover, while the SSM performs well in many situations, we find conditions where significant bias is produced by hyporheic exchange, even when oxygen data are well-fitted. These situations pose a major challenge in the interpretation of metabolism assessment estimates.
Details
- Title: Subtitle
- Hyporheic-Zone Processes and Stream Oxygen Dynamics: Insights From a Multiscale Reactive Transport Model
- Creators
- J. D. Gomez-Velez - University of IowaS. S. Rathore - Oak Ridge National LaboratoryM. J. Cohen - University of FloridaS. L. Painter - Oak Ridge National Laboratory
- Resource Type
- Journal article
- Publication Details
- Water resources research, Vol.62(1), e2025WR040208
- DOI
- 10.1029/2025WR040208
- ISSN
- 0043-1397
- eISSN
- 1944-7973
- Publisher
- Amer Geophysical Union
- Number of pages
- 28
- Grant note
- DE-AC05-00OR22725 / Office of Science of the U.S. Department of Energy; United States Department of Energy (DOE) Watershed Dynamics and Evolution (WaDE) Science Focus Area; IDEAS Watersheds / U.S. Department of Energy; United States Department of Energy (DOE)
- Language
- English
- Date published
- 01/01/2026
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9985130217702771
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