Experimental and Numerical Investigation on the Impact of Emergent Vegetation on the Hyporheic Exchange

Hyporheic exchange leads to the transfer of gases, solutes, and fine particles across the sediment‐water interface, playing a critical role in biogeochemical cycles and pollutant transport in aquatic environments. While in‐channel vegetation has been recognized to enhance hyporheic exchange, the mec...

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Vydáno v:Water resources research Ročník 61; číslo 10
Hlavní autoři: Huang, S. H., Nuli, R., Kang, P. K., Shen, L., Yang, J. Q.
Médium: Journal Article
Jazyk:angličtina
Vydáno: Washington John Wiley & Sons, Inc 01.10.2025
Wiley
Témata:
Aquatic ecosystems
Aquatic environment
Biogeochemical cycle
Biogeochemical cycles
Creeks & streams
Emergent aquatic plants
Emergent vegetation
Environmental management
Environmental restoration
Exchanging
Experiments
Flow velocity
flume experiments
Flumes
Hydrogels
hyporheic exchange
Laboratories
Nitrates
numerical simulation
Numerical simulations
Permeability
Pollution dispersion
Pollution transport
Pressure distribution
Project management
Refractive index
Refractivity
Sediment
Sediments
Simulation
Solutes
Surface flow
turbulence
Vegetation
Velocity
Water
ISSN:0043-1397, 1944-7973
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Shrnutí:Hyporheic exchange leads to the transfer of gases, solutes, and fine particles across the sediment‐water interface, playing a critical role in biogeochemical cycles and pollutant transport in aquatic environments. While in‐channel vegetation has been recognized to enhance hyporheic exchange, the mechanisms remain poorly understood. Here, we investigated how an emergent vegetation canopy impacts hyporheic exchange using refractive index‐matched flume experiments and coupled numerical simulations. Our results show that at the same mean surface flow velocity, vegetation increases the hyporheic exchange velocity by four times compared to the non‐vegetated channel. However, the hyporheic exchange velocity does not increase further with increasing vegetation density. In addition, our results show that the hyporheic exchange velocity scales with the square root of sediment permeability. Our findings provide a predictive framework for hyporheic exchange in vegetated channels with varying vegetation densities and sediment permeabilities and could guide the future design of environmental management and restoration projects using vegetation. Plain Language Summary Aquatic vegetation is known to increase hyporheic exchange, which facilitates the exchange of gases, solutes, and fine particles between surface water and pore fluids within the sediment beds. Due to its ability to regulate the fate of pollutants, vegetation has been used to remediate contamination in many riverine and coastal restoration projects. However, the mechanisms through which vegetation enhances hyporheic exchange remain poorly understood, making it challenging for engineers to design effective restoration projects. In this study, we investigated how an emergent vegetation canopy impacts hyporheic exchange using both laboratory experiments and numerical simulations. Our results showed that at the same mean surface flow velocity, hyporheic exchange was four times faster in the vegetated channel than in a channel without vegetation. However, further increases in vegetation density did not enhance hyporheic exchange. Moreover, our results show that the hyporheic exchange velocity scaled with the square root of the sediment permeability. These findings provide theoretical guidance for engineers to estimate the hyporheic exchange rate in a vegetated channel and design effective restoration projects using aquatic vegetation. Key Points Index‐match experiments and coupled numerical simulations reveal detailed vertical flow paths around vegetation stems Stem‐scale vertical flow and canopy‐scale subsurface flow govern hyporheic exchange, as confirmed by experimental and numerical analyses Hyporheic exchange rate increased four times in a vegetated channel compared to a bare channel but did not increase with vegetation density
Bibliografie:S. H. Huang and R. Nuli are co‐first authors.
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ISSN:0043-1397
1944-7973
DOI:10.1029/2025WR040217