On the description of the basin effective drainage structure

The relationships between the local properties of the morphological elements of a drainage basin and its drainage structure are analysed. Two theoretical approaches are used for which hydro-dynamics and basin morphology are respectively assumed to represent the lowest and the highest starting scale level. The results show a convergence toward the idea of slope scaling with contributing area in river networks. This concept is then used as an indicator of channel initiation and maintenance for the identification of the effective drainage structure of the basin on the basis of existing digital elevation models (DEMs). Integral properties of the single DEM pixel are finally introduced to reduce the noise owing to a possible DEM low accuracy, e.g. in the estimation of the local slope value from the elevation data set. The resulting network is characterized by a non-uniform drainage density, as expected for natural river networks.