A transient two-dimensional model with idealized topography (i.e., cross section of a rectangular lake) is examined using numerical models. The primary results define the behavior of the circulation and temperature distribution under a variety of circumstances. It is demonstrated that multiple circulation cells are likely to form in a basin with a broad and diffusive metalimnion, a strong and stable density stratification, and a modest wind stress. The present model is able to predict the formation, maintenance, and erosion of thermocline. The wind-driven current is observed to play a striking role in the development of thermocline. The current accelerates the establishment and contributes to the erosion of thermocline, which is in contrast to the one-dimensional pure diffusion model in which the circulation plays no role.