ABSTRACT
The generation of the computational grid is a crucial step for 2D hydrodynamic-based surface runoff models at basin scale, deeply influencing the results in terms of water depth, flow velocity, and discharge. This choice is often left to the modeler experience and it is rarely discussed. Its impact on the model results is seldom analyzed. A procedure to generate an a priori computational grid is here proposed. The result is a reliable mesh built in a time-saving process without any trial simulation. The 2D Fourier analysis is applied to a DEM to compute the power spectrum and to identify the significant characteristic scales (which can be related to the grid resolution) as well as their location in the catchment. The a priori grid reduces computational times of 87% if compared to a fine grid exploiting the available DEM resolution, with negligible errors on outflow hydrographs and flooded areas extent.
