The commonly used linear k-e turbulence model is shown to be incapable of accurate prediction of turbulent flows, where non-isotropy is dominant. Two examples of non-isotropic flows, which have a wide range of applications in marine waters, are saline water flow and the stratified flows due to temperature gradients. These relate to stratification and consequently, variation of density through vertical layers. In this paper, a nonlinear k-e turbulence model, firstly presented by Speziale (1987) and was implemented in the existing hydrodynamic model. The energy equation has been also added and solved in the hydrodynamic model. The hydrodynamic model solves the fully nonlinear Navier-Stokes equations based on an ALE (Arbitrary Lagrangian Eulerian) description. The model is an extension to WISE (Width Integrated Stratified Environments) 2DV numerical model, originally developed by Hejazi (2002). The simulated values have been compared with the experimental data and have shown acceptable agreements. The predictions are also compared with the results of the original model employing a standard buoyant k-e turbulence model, which showed the advantage of the new turbulence model in prediction of non-isotropic flows.