Description of an indirect method (IDPR) to determine spatial distribution of infiltration and runoff and its hydrogeological applications to the French territory

Abstract It is commonly accepted in geospatial analysis that automated calculation of thalweg networks from a digital elevation model produces a theoretical flow system that overall represents the branching of in-place hydrographic networks. However, in detail this theoretical network is too different from the natural river network to substitute for the systematic digitization of rivers. Numerous papers seek to optimize numeric calculations to reduce this discrepancy but none has proposed to use this difference as data specific to the context under study. Toward this end, the principal idea behind the IDPR (Network Development and Persistence Index) is to apply a particular metric to disparity measurements between the theoretical drainage system produced by the raw automatic analysis of a digital model and the field reality represented by branching rivers. By measuring the difference between a simplified modeling of water pathways based on a hypothesis of homogeneous and isotropic terrain and the complexity of a natural network subject to the properties of the land surface it crosses, this metric makes it possible to determine spatial distribution of infiltration and runoff.