The role of models in assessing the impact of sewage overflows on feacal water contamination

Type Article
Date 2008
Language English
Author(s) Riou Philippe1, Le Saux Jean-Claude1, Dumas Franck1, Le Guyader Soizick1, Le Goff R.1, Maheux Frank1, Lamort Laure1, Pommepuy Monique1
Affiliation(s) 1 : IFREMER, france
Meeting Proceedings of the sixth international conference on molluscan shellfish safety, Blenheim, New Zealand, March 18th - 23rd 2007
Source Journal of Shellfish Research (National Shellfisheries Association), 2008
Keyword(s) Modeling, seawater fecal contamination, E. coli, virus, shellfish, climate change
Abstract Climate change contributes to local weather modifications such as storm events and heavy rainfall, and in particular, changes in the frequency and intensity of extreme storm and rainfall events. Observations have indicated that rainfall-runoff processes, like sewage overflow may induce fecal contamination in coastal water. Pathogens present in runoff water could therefore contaminate shellfish and be responsible for food-borne disease outbreaks.
Mathematical models for this were used to predict the effect of climate modifications on shellfish quality. Using a hydrodynamic model, simulations of water quality conditions under a variety of storm event scenarios were run and are presented here for a harvesting area in France. Major storm events occurring in the watersheds were selected to estimate the critical fecal loads which could be due to overflow. Escherichia coli fluxes were calculated for these scenarios. Norovirus fluxes were estimated from data in the literature. The hydrodynamic model was then used to calculate the impact of hydraulic load and wastewater inputs on seawater quality. Our results indicated that major rainfall events generated relatively high runoff volumes and high pathogen loadings to the sea which led to shellfish contamination. After an extreme contamination event, the time needed to recover good water quality as calculated using the model, depended on the sectors in question.
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Riou Philippe, Le Saux Jean-Claude, Dumas Franck, Le Guyader Soizick, Le Goff R., Maheux Frank, Lamort Laure, Pommepuy Monique (2008). The role of models in assessing the impact of sewage overflows on feacal water contamination. Journal of Shellfish Research Open Access version :