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Effect of near‐bed turbulence on chronic detachment of epilithic biofilm: Experimental and modeling approaches

Graba, Myriam and Moulin, Frédéric and Boulêtreau, Stéphanie and Garabétian, Frédéric and Kettab, Ahmed and Eiff, Olivier and Sanchez-Pérez, José-Miguel and Sauvage, Sabine Effect of near‐bed turbulence on chronic detachment of epilithic biofilm: Experimental and modeling approaches. (2010) Water Resources Research, vol. 46 (n°11). pp. 1-15. ISSN 0043-1397

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Official URL: http://dx.doi.org/10.1029/2009WR008679

Abstract

The biomass dynamics of epilithic biofilm, a collective term for a complex microorganism community that grows on gravel bed rivers, was investigated by coupling experimental and numerical approaches focusing on epilithic biofilm‐flow interactions. The experiment was conducted during 65 days in an artificial rough open‐channel flow, where filtered river water circulated at a constant discharge. To characterize the effect of near‐bed turbulence on the chronic detachment process in the dynamics of epilithic biofilm, local hydrodynamic conditions were measured by laser Doppler anemometry and turbulent boundary layer parameters inferred from double‐averaged quantities. Numerical simulations of the EB biomass dynamics were performed using three different models of chronic detachment based upon three different descriptors for the flow conditions: Discharge Q, friction velocity u*, and roughness Reynolds number k+. Comparisons of numerical simulation results with experimental data revealed chronic detachment to be better simulated by taking the roughness Reynolds number as the external physical variable forcing chronic detachment. Indeed, the loss of epilithic matter through the chronic detachment process is related not only to hydrodynamic conditions, but also to change in bottom roughness. This suggests that changes in the behavior and dimensions of river bed roughness must be considered when checking the dynamics of epilithic biofilm in running waters.

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Other partners > Ecole Nationale Polytechnique d'Alger - ENP (ALGERIA)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > Université de Bordeaux 1 (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Laboratory name:
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Deposited By:Nadia Kelmouss

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