Study of the thermal dynamics of two dammed lakes (Pareloup and Rochebut, France), using the EOLE model

EOLE is a hydrodynamic thermal model (one-dimensional vertical model) which simulates the evolution of the seasonal thermal stratification of a reservoir. It is a model based on representation of individual physical mechanisms, which takes into account the bathymetry of the reservoir, surface energy exchanges, and throughflow in the reservoir (rivers, pumping, turbining, residual stream flow, etc.). EOLE was applied to two reservoirs with extremely different characteristics: Pareloup Lake, a hydroelectric reservoir with a long residence time (1 year), and Rochebut, a reservoir with a short residence time (1 month). The good agreement between the calculated and measured thermal profiles in both cases indicates that the model enables very good reproduction of the thermal stratification in each reservoir, the vertical dynamics of water masses, the thermal regime of water restituted downstream, and year-to-year fluctuations over extended periods (12 consecutive 1 year cycles for Pareloup). The model was applied using the same set of coefficients in both studies, demonstrating that the predominant hydrodynamic phenomena in both reservoirs are well taken into account, providing the input data are sufficiently representative of the site under study. The precision of the results obtained and the relative simplicity of the EOLE representation have enabled us to use the model as a basic structure for modeling of an ecosystem.