Modelisation de la qualite des eaux des lacs profounds. Modele thermique et biogeochimique du lac du Bourget

In 1981, important works including diversion of the main sewers emptying into lake Bourget (one of the largest French Alpine lakes) have been implemented. In order to quantify the restoration of the water quality standards, a project including a detailed water quality survey (1988-89) and the thermal and biogeochemical modelling of the lake was undertaken. The model (Temperature, Phosphorus and Oxygen is one-dimensional vertical. It is based on the advection-diffusion equation. Results of the thermal model agree with the observed seasonal and long-term evolution of temperature in lake Bourget. The results of the biogeochemical sub-model for the calibration phase are presented.