Author(s): Runye Zhu; Ryota Tsubaki

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Keywords: Flexible vegetation; River morphology; Numerical simulation

Abstract: The interaction between riparian vegetation and river morphology development has attracted the attention of researchers for many years and significant progress has been made in numerical simulations. In previous 2D numerical simulations of river morphology development, according to a thorough literature search, the effects of vegetation flexibility has not yet been studied. The objectives of this study were to specify how and how much vegetation flexibility can influence river morphological development. We combined the Delft3D morpho­ dynamic model with a model predicting vegetation dynamics and reconfiguration under the influence of shallow water flow. In the model, vegetation can colonize dry places during low discharge and can be destroyed by scour­ ing and burial during floods. To clarify the effect of flexibility, rigid and flexible vegetation were compared. We determined that: 1) flexibility impacts averaged water depth and active river width, and, thus, influences river morphology over the long term; 2) flexible vegetation can elevate the river bed faster than rigid vegetation, and rivers with flexible vegetation yield a larger area with higher elevation; and 3) flexible vegetation is more easily destroyed by flooding than rigid vegetation, and can affect habitat areas in simulations. Since vegetation flexi­ bility can generate non­negligible effects on river morphology development over long term, our results indicate that vegetation flexibility should be taken into consideration in river morphology simulations.

DOI:

Year: 2020