Study on wind-driven flow under the influence of water freezing in winter in a northern shallow lake

Six empirical formulae of the wind drag coefficient were considered in a MIKE21 hydrodynamic model to study properties of wind-driven flow in a shallow lake in the northern city (Dongchang Lake in Liaocheng, Shangdong, China) under a real wind condition. Moreover, the influence of ice cover area on simulated result was also analysed. The results showed that the accuracy was improved about 20% when the wind drag coefficient was varied with real wind field than when it was constant. That is, the model with real wind could accurately describe the wind-driven flow process of the Dongchang Lake. Among the six formulae of the wind drag coefficient, the one proposed under breeze condition was best. Freezing water has significant effected on numerical simulation of wind-driven flow, especially in the zone of ice cover. The influence of wind stress on water flow has been weakened or counteracted under water freezing. Compared with the traditional wind-driven flow simulation, it was necessary to consider ice condition or to adjust the wind drag coefficient in MIKE21 in a northern shallow lake. The results might give a reference for the water resources management in a northern shallow lake.