This paper is focused on the contribution that the two‐dimensional Shallow Water Equations could provide in respect to the fields of research devoted to the river networks analysis. The novelty introduced in this work is represented, in particular, by the hydraulic characterization of the river drainage networks, starting from flow patterns simulated by the two‐dimensional Shallow Water Equations on high‐resolution digital elevation model (DEM) through the analysis of water depths flowing down the hillslopes, channelized in both the main river and in all the tributaries or stored in small depressions. The first finding of this research is the determination of scaling laws that describe the relations between the water depth threshold, used to identify the network cells, and a dimensionless area, related to the total area of the network cells themselves. The observed bimodal scaling behavior has been considered as representative of the flow patterns belonging to the channel networks (CN) and hillslope plus channel networks (HCN), the physical and geomorphological interpretation of which has been provided from a multifractal point of view. In particular, the analysis of the multifractal spectra highlights significant variations in the multifractal signatures, between the CN and the HCN structures, leading to the proposal of a novel criterion for channels heads detection that has provided encouraging predictions of field observations.

Topographic depressions in Digital Elevation Models (DEMs) have been traditionally seen as a feature to be removed as no outward flow direction is available to route and accumulate flows. Therefore, to simplify hydrologic analysis for practical purposes, the common approach treated all depressions in DEMs as artefacts and completely removed them in DEMs’ data preprocessing prior to modelling. However, the effects of depression filling on both the geomorphic structure of the river network and surface runoff is still not clear. The use of two-dimensional (2D) hydrodynamic modeling to track inundation patterns has the potential to provide novel point of views on this issue. Specifically, there is no need to remove topographic depression from DEM, as performed in the use of traditional methods for the automatic extraction of river networks, so that their effects can be directly taken into account in simulated drainage patterns and in the associated hydrologic response. The novelty introduced in this work is the evaluation of the effects of DEM depression filling on both the structure of the net-points characterizing the simulated networks and the hydrologic response of the watersheds to simplified rainfall scenarios. The results highlight how important these effects might be in practical applications, providing new insights in the field of watershed-scale modeling.