Evaporation and energy budget in Lake Vegoritis, Greece

Abstract

Evaporation is one of the main components in both the energy and water budgets of lakes and a primary process of water loss for most of them. A one-dimensional, eddy diffusion model of lake’s water temperature distribution is used to evaluate daily evaporation values as a residual of the energy budget in Lake Vegoritis in Northern Greece and for the year of 1993. Lake Vegoritis has been under a continuous deficit in the water balance for up to three decades. The water temperature model, calibrated with measured values from two different years, is used reversely to evaluate the evaporation through the energy budget. The equilibrium temperature approach for the surface boundary condition is used in the model, as well as the simplification of Bowen ratio in the energy budget. Evaporation values estimated by the model are used for determining a mass transfer-based evaporation equation for Lake Vegoritis. Estimated evaporation rates show a characteristic annual cycle with low values at spring and the highest values at summer. The energy stored in the lake at spring and early summer is released to the environment later in the year as sensible and mainly as latent heat.