La Mer et les Rejets Urbains. Bendor, 13-15 juin 1990.
IFREMER. Actes de Colloques 11. pp 221 à 236
15
CARACTERISTIQUES ET MODELISATION D'UN REJET PAR
EMISSAIRE
B. THOUVENIN
IFREMER Centre de TOULON, DRO/EM, B.P. 330, 83507 LA SEYNE CEDEX
ABSTRACT - The fate of urban effluent discharged to the sea firstly dépends on the physical processes, more
particularly the mixing and the transport mechanisms induced by the currents. An urban sewage discharged from
an outfall structure is subject to two steps of dilution : it first cornes up to the surface where it is swept by the
horizontal currents, and then dispersed along the Coastal area. Several long-term measurements hâve been
completed in order to reach a better understanding of the marine environment in ternis of thermical stratification
and currents. The area studied expands one or two kilometers around the discharge point, and it assumed that both
the streams and the thermical stratification are on the whole unvarying. The behaviour of the effluent discharged
into the marine environment has been observed under various conditions, and several methods for the identification
of the sewage were used. Classical modélisation means were applied, then adapted as a fonction of the results
observed. Some of the hypothesis generally put forward to simplify the computations were tested. Finally, impact
zones of détergents and fecal bacteria were computed, with effect of sunlight on bacterial die-off.
INTRODUCTION
En Méditerranée, en l'absence de marée, la dilution d'un rejet émis directement en surface
est assez faible, à moins d'avoir des courants suffisamment forts. Pour augmenter cette
dilution dès l'injection de l'effluent dans le milieu marin, les aménageurs utilisent des
diffuseurs et des émissaires qui envoient les rejets loin de la côte et, tout au moins en région
Provence-Alpes-Côte d'Azur, par des profondeurs importantes.
221
IFREMER. Actes de Colloques 11. pp 221 à 236
15
CARACTERISTIQUES ET MODELISATION D'UN REJET PAR
EMISSAIRE
B. THOUVENIN
IFREMER Centre de TOULON, DRO/EM, B.P. 330, 83507 LA SEYNE CEDEX
ABSTRACT - The fate of urban effluent discharged to the sea firstly dépends on the physical processes, more
particularly the mixing and the transport mechanisms induced by the currents. An urban sewage discharged from
an outfall structure is subject to two steps of dilution : it first cornes up to the surface where it is swept by the
horizontal currents, and then dispersed along the Coastal area. Several long-term measurements hâve been
completed in order to reach a better understanding of the marine environment in ternis of thermical stratification
and currents. The area studied expands one or two kilometers around the discharge point, and it assumed that both
the streams and the thermical stratification are on the whole unvarying. The behaviour of the effluent discharged
into the marine environment has been observed under various conditions, and several methods for the identification
of the sewage were used. Classical modélisation means were applied, then adapted as a fonction of the results
observed. Some of the hypothesis generally put forward to simplify the computations were tested. Finally, impact
zones of détergents and fecal bacteria were computed, with effect of sunlight on bacterial die-off.
INTRODUCTION
En Méditerranée, en l'absence de marée, la dilution d'un rejet émis directement en surface
est assez faible, à moins d'avoir des courants suffisamment forts. Pour augmenter cette
dilution dès l'injection de l'effluent dans le milieu marin, les aménageurs utilisent des
diffuseurs et des émissaires qui envoient les rejets loin de la côte et, tout au moins en région
Provence-Alpes-Côte d'Azur, par des profondeurs importantes.
221