In the last decades, there has been a notable increase in the intensity of extreme flood events. Unfortunately, current predictions confirm that this trend will worsen, especially critical in mountainous regions where rivers and torrents react immediately with high peak discharge, leaving society with a lack of capacity to respond effectively. This emphasizes the urgent need to develop predictive tools to mitigate future economic and social damages resulting from such natural disasters. To simulate realistic high torrential turbulent flows, a three-dimensional approach is required, with a geometry based on actual terrain information data. In this study, we present a two-fluid fixed-mesh Eulerian approach based on a standard Galerkin Finite Element (FE) formulation. Level set is used to track the evolution of the interface between water and air. The weak pressure discontinuity at the interface between the two fluids is captured by an enrichment of the shape function space. A local condensation problem is solved inside each element to keep the same degrees of freedom of the global system.. This work has been implemented within the Kratos Multiphysics framework and takes advantage of automatic terrain reconstruction procedures, facilitating the automatic generation of 3D models from realistic Digital Elevation Models (DEM).