Toward a Universal Model of Hyporheic Exchange and Nutrient Cycling in Streams

Ahmed Monofy; Stanley B. Grant; Fulvio Boano; Megan A. Rippy; Jesus D. Gomez-Velez; Sujay S. Kaushal; Erin R. Hotchkiss; Sydney Shelton

doi:10.1029/2024AV001373

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Toward a Universal Model of Hyporheic Exchange and Nutrient Cycling in Streams

Journal article

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Toward a Universal Model of Hyporheic Exchange and Nutrient Cycling in Streams

Ahmed Monofy, Stanley B. Grant, Fulvio Boano, Megan A. Rippy, Jesus D. Gomez-Velez, Sujay S. Kaushal, Erin R. Hotchkiss and Sydney Shelton

AGU advances, Vol.5(6), p.n/a

12/2024

DOI: 10.1029/2024AV001373

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Abstract

In this paper we demonstrate that several ubiquitous hyporheic exchange mechanisms can be represented simply as a one-dimensional diffusion process, where the diffusivity decays exponentially with depth into the streambed. Based on a meta-analysis of 106 previously published laboratory measurements of hyporheic exchange (capturing a range of bed morphologies, hydraulic conditions, streambed properties, and experimental approaches) we find that the reference diffusivity and mixing length-scale are functions of the permeability Reynolds Number and Schmidt Number. These dimensionless numbers, in turn, can be estimated for a particular stream from the median grain size of the streambed and the stream's depth, slope, and temperature. Application of these results to a seminal study of nitrate removal in 72 headwater streams across the United States, reveals: (a) streams draining urban and agricultural landscapes have a diminished capacity for in-stream and in-bed mixing along with smaller subsurface storage zones compared to streams draining reference landscapes; (b) under steady-state conditions nitrate uptake in the streambed is primarily biologically controlled; and (c) median reaction timescales for nitrate removal in the hyporheic zone are approximate to ${\approx} $0.5 and 20 hr for uptake by assimilation and denitrification, respectively. While further research is needed, the simplicity and extensibility of the framework described here should facilitate cross-disciplinary discussions and inform reach-scale studies of pollutant fate and transport and their scale-up to watersheds and beyond.

Geology

Physical Sciences

Geosciences, Multidisciplinary

Science & Technology

Details

Title: Subtitle: Toward a Universal Model of Hyporheic Exchange and Nutrient Cycling in Streams
Creators: Ahmed Monofy - Waters (United States)
Stanley B. Grant - Waters (United States)
Fulvio Boano - Politecnico di Torino
Megan A. Rippy - Virginia Tech
Jesus D. Gomez-Velez - Virginia Tech
Sujay S. Kaushal - Earth System Science Interdisciplinary Center
Erin R. Hotchkiss - Virginia Tech
Sydney Shelton - Earth System Science Interdisciplinary Center
Resource Type: Journal article
Publication Details: AGU advances, Vol.5(6), p.n/a
DOI: 10.1029/2024AV001373
ISSN: 2576-604X
eISSN: 2576-604X
Publisher: Amer Geophysical Union
Number of pages: 25
Grant note: 2021015; 2020814; 2020820; 2312326 / National Science Foundation; National Science Foundation (NSF) 21-001 / U.S. National Science Foundation Growing Convergence Research Program U.S. Department of Energy as part of the Watershed Dynamics and Evolution (WaDE) Science Focus Area at Oak Ridge National Laboratory Metropolitan Washington Council of Government IDEAS watersheds project Virginia Tech College of Engineering Research Task Force project H2OStorm, Compagnia di San Paolo through the Joint Research Projects Initiative
Language: English
Date published: 12/2024
Academic Unit: Civil and Environmental Engineering
Record Identifier: 9984962531302771

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