A statistical analysis of topography is performed on a square domain using different sizes of window applied to a Digital Elevation Model covering Southern France. For a given window, a two-dimensional linear drift is defined by fitting a plane through the topography, the direction and magnitude of its slope and the explained variance is then computed. After removing the previously defined linear drift, two-dimensional statistics of the residual topography is used to define the direction of lengthening of the topography called the direction of polarization. The data are evenlydistributed on a space grid of one kilometre. We detect correlations between the mean plane and statistics orientations and the mean drainage pattern. According to this approach, two scale thresholds are detected around 6km and 2 km.