Hydraulic mangement of filamentous algae in open-channel networks : case study in Southern France

Ophélie Fovet (1) , Gilles Belaud (2) , L. Lancar (3) , X. Litrico (1) , J.-P. Baume (1) , Pierre-Olivier Malaterre (1) , O. Genthon (3)

1 UMR G-EAU - Gestion de l'Eau, Acteurs, Usages
2 UMR ITAP - Information – Technologies – Analyse Environnementale – Procédés Agricoles
3 SCP - Société du Canal de Provence et d'Aménagement de la Région Provençale

Periphyton constitutes the benthic compartment of aquatic environments such as artificial channels which are specific eco-systems for many reasons. Firstly, they have to fulfill hydraulic performance and water quality objectives. These objectives may be affected by filling problems due to algal developments and sanitary risks linked to toxins secreted by Cyanobacteria. Second, compared to natural streams, artificial channels have a relatively simple geometry and their hydraulic variables are easier to monitor. Also, cross regulators allow the managers to control discharges and water elevations. Periphyton dynamics depend on several factors and hydrodynamic is one of the most crucial one. In this article we analyze an original strategy for algal control currently used in a branch of the Canal de Provence (South of France). The management strategy consists of regular flushes causing increases of the bed shear stress from upstream to downstream and consequently algal filament cutting. This is achieved by increasing the discharge at the upstream end of the branch. We first show that turbidity can be used as an indicator for algal detachment. Then, a detachment model is proposed and coupled with the hydrodynamic simulation of the system. It can be fitted very satisfactorily on the turbidity measurements and can be used to improve the management strategy, such as reducing the discharge released.

Mots clés: HYDRODYNAMIQUE; CANAL D'IRRIGATION; ALGUE; FILAMENTOUS PERIPHYTON; IRRIGATION CANAL; HYDRODYNAMICS; SHEAR STRESS; ECO-HYDRAULICS; OPEN-CHANNEL FLOW

Domaines: Sciences de l'environnement

Ophélie Fovet, Gilles Belaud, L. Lancar, X. Litrico, J.-P. Baume, et al.. Hydraulic mangement of filamentous algae in open-channel networks : case study in Southern France. International Conference of Science and 7th 7th ISE & 8th HIC Conference,, Information Technologies for Sustainable Management of Aquatic Ecosystems, a joint meeting of the 7th Symposium on Ecohydraulics and 8th Conference on Hydroinformatics, Jan 2009, Concepcion, Chile. 10 p. ⟨hal-00468858⟩