Sediment deposition and bank accretion are promoted by the establishment and growth of pioneer plant species, a direct consequence of plant survival during flood events. Similarly, the uprooting of riparian vegetation on river bars during floods can subsequently alter hydraulics, sediment dynamics, and bar evolution. In this work, we focus on the removal of flexible seedlings due to both hydraulic forces and bed erosion, specifically examining failure mechanisms associated with root pull‐out. We provide a conceptual model and a new physical equation for predicting the flow and bed erosion conditions that promote the uprooting of plants. The model was validated by means of flume experiments employing two species of vegetation (i.e., common oats and a willow native to Europe). Furthermore, the Ombrone Pistoiese River (Tuscany, IT) was used as a case study to validate the physical model with respect to observed vegetation removal during a flood event. The results illustrate the capability of our model to predict conditions for vegetation removal and suggest that sediment transport is a necessary ingredient even for very young seedlings.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  We explore the correspondence between real plants and their rigid-cylinder description  Experiments, numerical models and real rivers are combined in the analyses  The cylinders diameter is relevant in representing the effects of the tested plants  Numerical models can represent the effects of high-density vegetation

Worldwide convectively accelerated streams flowing in downstream‐narrowing river sections show that riverbed vegetation growing on alluvial sediment bars gradually disappears, forming a front beyond which vegetation is absent. We revise a recently proposed analytical model able to predict the expected longitudinal position of the vegetation front. The model was developed considering the steady state approximation of 1‐D ecomorphodynamics equations. While the model was tested against flume experiments, its extension and application to the field is not trivial as it requires the definition of proper scaling laws governing the observed phenomenon. In this work, we present a procedure to calculate vegetation parameters and flow magnitude governing the equilibrium at the reach scale between hydromorphological and biological components in rivers with converging boundaries. We collected from worldwide rivers data of section topography, hydrogeomorphological and riparian vegetation characteristics to perform a statistical analysis aimed to validate the proposed procedure. Results are presented in the form of scaling laws correlating biological parameters of growth and decay from different vegetation species to flood return period and duration, respectively. Such relationships demonstrate the existence of underlying selective processes determining the riparian vegetation both in terms of species and cover. We interpret the selection of vegetation species from ecomorphodynamic processes occurring in convectively accelerated streams as the orchestrated dynamic action of flow, sediment and vegetation characteristics. © 2019 John Wiley & Sons, Ltd.