Experimental study of the solute transport in the interfacial exchange zone (IEZ) of a gravel stream bed

Qin Qian, Jeffrey J. Clark, Vaughan R Voller, Heinz G. Stefan

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

Solute exchange between overlying water and the sediment bed of a stream have important effects on the chemical mass balance and biological activities in both the water column and the sediment. Previous studies did not consider the coupled and cumulative contributions of turbulence in the overlying water, water surface waves, and underflow to the solute transport in the Interfacial Exchange Zone (IEZ), although these processes have been studied individually. To investigate the interaction, eight carefully designed experiments of solute exchange in the pore system of a stream gravel bed were conducted. The data analysis showed that the turbulent flow over the bed, the underflow, and the wave-induced advection enhanced the solute exchange and penetration of a conservative solute into a stream gravel bed. The maximum penetration depth under the turbulent current was 15 cm in 3000s; however, the penetration depth reached 20 cm in less than 1000s when surface waves were present. A coupled hydrodynamic and solute transport model was developed to estimate vertical dispersion coefficients for solutes in a porous and permeable streambed. The enhanced dispersion coefficient that combines all three processes is a function of the near-bed coherent motion due to the turbulent current, relative dispersivity (longitudinal dispersivity/wave length), wave steepness, sediment hydraulic conductivity, and sediment porosity, and decreases exponentially with depth; however, the turbulence-enhanced dispersion without the wave effects is smaller and diminishes faster with depth compared with the wave-enhanced dispersion.

Original languageEnglish (US)
Title of host publicationWorld Environmental and Water Resources Congress 2013
Subtitle of host publicationShowcasing the Future - Proceedings of the 2013 Congress
Pages550-559
Number of pages10
StatePublished - Nov 18 2013
EventWorld Environmental and Water Resources Congress 2013: Showcasing the Future - Cincinnati, OH, United States
Duration: May 19 2013May 23 2013

Publication series

NameWorld Environmental and Water Resources Congress 2013: Showcasing the Future - Proceedings of the 2013 Congress

Other

OtherWorld Environmental and Water Resources Congress 2013: Showcasing the Future
CountryUnited States
CityCincinnati, OH
Period5/19/135/23/13

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    Qian, Q., Clark, J. J., Voller, V. R., & Stefan, H. G. (2013). Experimental study of the solute transport in the interfacial exchange zone (IEZ) of a gravel stream bed. In World Environmental and Water Resources Congress 2013: Showcasing the Future - Proceedings of the 2013 Congress (pp. 550-559). (World Environmental and Water Resources Congress 2013: Showcasing the Future - Proceedings of the 2013 Congress).