Unravelling spatial heterogeneity of inundation pattern domains for 2D analysis of fluvial landscapes and drainage networks

• Published in: Journal of hydrology (Amsterdam) 2024-03, Vol.632, p.130728, Article 130728
• Main Authors: Costabile, Pierfranco, Costanzo, Carmelina, Lombardo, Margherita, Shavers, Ethan, Stanislawski, Lawrence V.
• Format: Article
• Language: English
• Subjects: 2D shallow water equations; Direct rainfall method; Drainage density; Hydrogeomorphic domains transition; Scaling laws; Stream network
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2024.130728

•Fluvial landscape analysis is performed using a hydrodynamic hierarchical framework.•Direct rainfall modelling as a novel tool to analyse the 2D features of river hydrography.•Link between inundation patterns domains (IPDs) and hydrogeomorphic process domains.•Comparison between hydrodynamic approaches for fluvial landscape analysis.•Susceptibility of the drainage network to expand as a function of IPDs heterogeneity. Fluvial landscape analysis is an essential part of geomorphology, hydrology, ecology, and cartography. It is traditionally focused on the transition between hillslopes and channel domain, in which the network drainage is represented by static flow lines. However, the natural fluctuations of the processes occurring in the watershed induce lateral and longitudinal expansions and contractions in the drainage patterns and variations of stream surface area. These dynamics can be better understood by introducing a two-dimensional (2D) view of catchment hydrography, in which river width and floodplain are included in the analysis. The novelty introduced in this work is the development of a hydrodynamic hierarchical framework (HHF) to analyse the transitions among geomorphic and hydrographic features of the fluvial landscape, distinguishing hillslope, unchanneled valleys, floodplains, and single/multithreads channels. HHF is based on the estimation of nested inundation pattern domains (IPDs) from digital elevation models and 2D hydrodynamic modeling. IPDs are defined by scaling laws that characterize log–log relations between watershed drainage density and unit discharge thresholds extracted from a 2D direct rainfall method (DRM) under steady state solutions. The physical significance of the IPDs is analysed within the context of both the physiographic features of the fluvial landscape and the rainfall rates employed as input for the modeling approach. Initially, the spatial heterogeneity of the IPDs is used to derive stream width metrics as a function of the rainfall rate. Then, a spatial index, representative of the IPDs' heterogeneity, is introduced as a measure of the susceptibility of the drainage network surface area to expansion and contraction. Finally, the consistency of the results is assessed in comparison to another hydrodynamic-based method for fluvial landscape analysis recently proposed in the literature. The proposed approach is analysed using challenging mountain and low-relief environments, characterized by multithread channels, me