Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Toward a universal model of hyporheic exchange and nutrient cycling in streams
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 ≈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.
Toward a universal model of hyporheic exchange and nutrient cycling in streams
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 ≈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.
Toward a universal model of hyporheic exchange and nutrient cycling in streams
Ahmed Monofy (Autor:in) / Stanley B. Grant (Autor:in) / Fulvio Boano (Autor:in) / Megan A. Rippy (Autor:in) / Jesus D. Gomez‐Velez (Autor:in) / Sujay S. Kaushal (Autor:in) / Erin R. Hotchkiss (Autor:in) / Sydney Shelton (Autor:in) / Monofy, Ahmed / Grant, Stanley B.
01.01.2024
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
C03-4 EFFECT OF SINUOSITY ON HYPORHEIC EXCHANGE IN NATURAL STREAMS AND RIVERS
| British Library Conference Proceedings | 2005
Impact of watershed topography on hyporheic exchange
| British Library Online Contents | 2016
Residence time of bedform-driven hyporheic exchange
| British Library Online Contents | 2008
Bedform-induced hyporheic exchange with unsteady flows
| British Library Online Contents | 2007