Bed form-induced hyporheic exchange and geochemical hotspots

Journal Article · 03 September 2021 · Advances in Water Resources

DOI: https://doi.org/10.1016/j.advwatres.2021.104025 · OSTI ID:1976800

Behzadi, Faranak ^[1]; Wallace, Corey D. ^[2]; Ward, Dylan ^[2]; Zhou, Haiyan ^[3]; Versteeg, Roelof ^[3]; Soltanian, Mohamad Reza ^[2]

---

1. University of Cincinnati, OH (United States); OSTI
2. University of Cincinnati, OH (United States)
3. Subsurface Insights, LLC, Hanover, NH (United States)

Small-scale bed form topographies control hyporheic exchange and biogeochemical processes within aquatic sediments, which ultimately affect water quality and nutrient cycling at the watershed scale. The impact of three-dimensional and small-scale bed form topographies on hyporheic exchange and solute mixing is investigated in the present work. The effect of bed form morphologies on the development of zones of enhanced reaction rates (i.e., hotspots) is also studied. A computational fluid dynamics model to simulate river flow over bed forms is combined with a subsurface flow and multicomponent reactive solute transport model. A wide variety of bed form topographies are generated using geometric models by varying parameters controlling curvature as well as bed form wavelength and amplitude. The results in this research suggest that out-of-phase bed forms generate more complex hyporheic flow patterns which reduce the efficiency of solute transformations. Higher phase shifts in bed form shapes result in overall higher average velocity, larger zones of enhanced pressure and reaction rates, and higher amounts of solute exchange. Moreover, the bed form shapes control the reaction process for a wide range of sediment conductivities. Here this study advances the understanding of the effects of complex and small scale morphological features on hyporheic exchange processes including the rate and spatio-temporal distribution of reaction hotspots.

• Research Organization: Subsurface Insights, LLC, Hanover, NH (United States); University of Cincinnati, OH (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE; USDOE Office of Science (SC); University of Cincinnati
• Grant/Contract Number: SC0019621
• OSTI ID: 1976800
• Journal Information: Advances in Water Resources, Journal Name: Advances in Water Resources Journal Issue: C Vol. 156; ISSN 0309-1708
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English