Depth-averaged flow simulation systems and methods provided herein employ parameterized templates for dynamical depth profiling for at least one step of a simulation. In one illustrative computer-based embodiment, the simulation method includes, for each map point at one given time step: determining a flow template and a sediment concentration template based on depth-averaged flow velocity and depth-averaged sediment concentrations of different classes of grain size for that map point; employing the templates to construct a vertically-distributed flow velocity profile and vertically-distributed sediment concentration profiles for associated classes of grain size for that map point, thereby obtaining 3D flow velocity and 3D sediment concentration fields; using the 3D fields to calculate fluid and sediment fluxes; updating the flow velocity and sediment concentration profiles based on the divergence of the fluxes; integrating the profiles to compute updated depth-averaged flow velocity and sediment concentrations and center of gravity; and solving the depth-averaged flow equations for the next time step.