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On modeling chronic detachment of periphyton in artificial rough, open channel flow

Graba, Myriam and Kettab, Ahmed and Sauvage, Sabine and Sanchez-Pérez, José-Miguel On modeling chronic detachment of periphyton in artificial rough, open channel flow. (2012) Desalination and Water Treatment, vol. 41 . pp. 79-87. ISSN 1944-3994

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Official URL: http://dx.doi.org/10.1080/19443994.2012.664681

Abstract

Periphyton communities, which are native to river beds, serve as a functional indicator of river health but remain one of the least-studied communities despite the significant increase in the examination of aquatic microbial communities in recent years. In this study, we tested the relevance of three formulations of the chronic detachment term in a simple model for the biomass dynamics of periphyton. Numerical simulations of the periphyton biomass dynamics were performed by using three different descriptors for the flow conditions: the discharge Q, the friction velocity u⁄, and the roughness Reynolds number k+ = u⁄ks/m (where m is water kinetic viscosity and ks is the Nikuradse equivalent sand roughness). Comparisons of numerical simulation results with experimental data from literature revealed chronic detachment to be better simulated by taking the roughness Reynolds number as the external variable of detachment. These results support the idea that transport phenomena that occur in the nearbed layer, e.g. chronic detachment of periphyton matter or vertical transport of nutrients and pollutants in submerged aquatic canopies, are not related to a single turbulence descriptor such as the friction velocity u⁄. Its description requires at least two descriptors, here the friction velocity u⁄ and the Nikuradse equivalent sand roughness ks, which depend on the initial form and dimensions of the colonized substratum, and its changes owing to the thickness, resistance, and composition of the epilithic matter.

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
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
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Deposited By: Nadia Kelmouss
Deposited On:23 May 2012 09:13

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