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Ecological functioning of the marne reservoir (upper seine basin, France)

par Garnier, Josette;Billen, Gilles ;Sanchez, Nathalie;Leporcq, Bruno
Référence River research and applications, 16, 1, page (51-71)
Publication Publié, 2000-01

Article révisé par les pairs

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Résumé :

The Marne reservoir (Der and Champaubert Lakes, 48 km2, 8 m mean depth) is one of the three major reservoirs constructed on the upper reaches of the Seine river to regulate its flow. The major features of the ecological functioning of the reservoir were analysed on the basis of results obtained in a 3-year routine sampling programme where the main variables of water quality were determined upstream, downstream and within the reservoir. Planktonic and benthic processes were also investigated in 1 year. A model of the reservoir was developed by coupling the RIVE model (which describes the major microbiological processes involved in the ecological functioning of aquatic systems), with a description of the morphology and hydrology of the reservoir. The model was used to simulate the seasonal and year-to-year variations of nutrients (N, P, Si) and phytoplankton biomass, and to compare them with the observed data. The model was then used to explore the effect of different control factors on denitrification, namely residence times and phosphorus loading. The results showed little influence on the absolute amount of nitrate denitrified within a realistic range of residence times and phosphorus loading. The Marne reservoir appears however to be a significant sink for nitrate (40% of the influx is eliminated), but this reduction represents only 10% of the nitrate flux at the outlet of the Marne sub-basin. Copyright © 2000 John Wiley & Sons, Ltd.