Simulation of a mesotrophic reservoir (Lake Pareloup) over a long period (1983–1998) using ASTER2000 biological model

Lake Pareloup is studied since 1983. The model ASTER that simulated the ecosystem of the lake during the first phase of the study (1983–1987) has been modified. The new model, called ASTER2000 aims to improve the estimation of the trophic level and the water quality of different reservoirs. To this purpose, NH4, NO3 and O2 were added as state variables. Affluents and pumping inflow have also been considered in order to consider the evolution of the watershed inflow and the variation from year to year in rainfall and pumping inflow. We have a long data series (1983–1998) that allows testing the model under different hydro-climatic conditions. The model simulates the state variables for this period in a satisfactory way. The evolution of nutrient concentrations differences bound to year-to-year entries are well represented, which would have been impossible with the original model. The addition of variables permits to rely on a larger range of the water quality criteria. In combination with the thermal forcing (temperature and stratification) provided by the EOLE model, ASTER2000, represents a strong and easy tool which could be used on many other reservoirs. The main modification necessitated in such applications concerns the type of diatoms dominating: consumed or not by the zooplankton. It is also indispensable to have input data in line with the structure of the model.