Biomorphological scaling laws from convectively accelerated streams

Worldwide convectively accelerated streams flowing in downstream-narrowing riversections show that riverbed vegetation growing on alluvial sediment bars gradually disap-pears forming a front beyond which vegetation is absent. We revise a recently proposedanalytical model able to predict the expected longitudinal position of the vegetation front.The model was developed considering the steady state approximation of 1-D ecomorpho-dynamics equations. While the model was tested against flume experiments, its extensionand application to the field is not trivial as it requires the definition of proper scalinglaws governing the observed phenomenon. In this work, we present a procedure to cal-culate vegetation parameters and flow magnitude governing the equilibrium at the reachscale between hydro-morphological and biological components in rivers with converg-ing boundaries. We collected from worldwide rivers data of section topography, hydro-geomorphological and riparian vegetation characteristics to perform a statistical analy-sis aimed to validate the proposed procedure. Results are presented in the form of scal-ing laws correlating biological parameters of growth and decay from different vegetationspecies to flood return period and duration, respectively. Such relationships demonstratethe existence of underlying selective processes determining the riparian vegetation both interms of species and cover. We interpret the selection of vegetation species from ecomor-phodynamic processes occurring in convectively accelerated streams as the orchestrateddynamic action of flow, sediment and vegetation characteristics.