Horizontal Mixing in the Shallow Palic Lake Caused by Steady and Unsteady Winds

Horizontal mixing in shallow lakes plays a significant role in sustaining sound life-supporting processes by facilitating homogenization of water in terms of suspended and dissolved matter. A simple method for the quantification of mixing has been outlined in order to establish a reliable basis of comparison; subsequently, it has been applied to the following studied cases. Mixing has been studied by numerical experiments through the case of the shallow Palic Lake. The mathematical formulation of the applied numerical model is described in detail. In the following, the significance of each current driving force influencing the flow patterns has been analyzed. Wind forcing has by far outweighed other forces. Because of this, focus has been put on the influence of wind action on mixing. The intensity of mixing, induced by characteristic steady winds, has been compared with that produced by unsteady winds. Results at the end of both 30- and 60-day wind forcing periods are presented. They suggest that large-scale circulations dominate the mixing processes. Consequently, a steady wind inducing favorable, far-reaching circulations may result in outstanding mixing in a short period of time. In the long run, however, unsteady winds produce more intensive mixing.