Numerical Modeling of Plant Root Controls on Gravel Bed River Morphodynamics

Abstract

The role of vegetation in shaping the geomorphology of rivers and deltas, along with tidal and estuarine environments, is widely recognized. While mutual interactions between flow, plant canopy, and morphodynamics have been extensively investigated, similar studies considering plant roots are limited. Here we present results from a numerical model that quantify the feedbacks of both the aboveground and belowground vegetation on gravel bed river morphodynamics. Plant root biogeomorphic feedbacks, that is, uprooting and root-enhanced riverbed cohesion, are quantified through the description of the vertical root distribution. By investigating the evolution of the riverbed of a straight gravel channel with a vegetated patch, we show that uprooting is the primary plant root biogeomorphic feedback determining the evolution of the riverbed and the competing influence of the potential flow erosion versus uprooting depth mediates the plant root controls on morphodynamics. These findings broaden our understanding on the role played by plant roots on gravel bed river morphodynamics.