AbstractIn this paper, the error source in assessing the bathymetry by a recently presented method, the dispersive surface classificator, is discussed. This method is based on the analysis of X-band radar image sequences of sea-surface waves to determine spatial maps of hydrographic parameters. To implement this objective, the radar-deduced bathymetry is validating by multibeam echosounder data. The accuracy of the method is high in homogeneous areas and reduced at the areas of bathymetric gradient and lower but comparable with multibeam echosounder data, under the assumption of the spatial resolution. The identification of systematic correlation of the absolute value of the error with the slope is significant and insignificant with the actual depth itself. The spatial correlation of the error illustrates that the direction of the wave field influences the neighboring grid cell in the same direction. The application of the method during crucial weather conditions is the main advantage and permits the accurate operational nearshore monitoring for several applications.