Simulation of water temperature and dissolved oxygen distribution in Lake Vegoritis, Greece

Changes in lake water temperature and temperature stratification dynamics can have a profound effect on lake biological and chemical processes. A one-dimensional temperature stratification and oxygen prediction model was developed to simulate the seasonal temperature cycle and oxygen distribution for Lake Vegoritis in Northern Greece. The submodel of heat transport is based on the non-linear heat transfer equation using daily weather parameters as input data. The dissolved oxygen (D.O.) submodel is based on the unsteady diffusion equation with the oxygen fluxes through the free surface and bottom of lake as boundary conditions, and photosynthetic oxygen production, biochemical oxygen demand and plant respiration as internal sources and sinks. The solution of these equations uses the finite element method. The model was calibrated and verified by using data from Lake Vegoritis from two different years (1981 and 1993). The model results showed that there was good agreement between the simulated and the measured values of water temperature and D.O. at different depths in the lake and on different days of the year.