Morphodynamic effects of riparian vegetation growth after stream restoration

Abstract

The prediction of the morphological evolution of renaturalized streams is important for the success of restoration projects. Riparian vegetation is a key component of the riverine landscape and is therefore essential for the natural rehabilitation of rivers. This complicates the design of morphological interventions, since riparian vegetation is influenced by and influences the river dynamics. Morphodynamic models, useful tools for project planning, should therefore include the interaction between vegetation, water flow and sediment processes. Most restoration projects are carried out in USA and Europe, where rivers are highly intervened and where the climate is temperate and vegetation shows a clear seasonal cycle. Taking into account seasonal variations might therefore be relevant for the prediction of the river morphological adaptation. This study investigates the morphodynamic effects of riparian vegetation on a re‐meandered lowland stream in the Netherlands, the Lunterse Beek. The work includes the analysis of field data covering 5 years and numerical modelling. The results allow assessment of the performance of a modelling tool in predicting the morphological evolution of the stream and the relevance of including the seasonal variations of vegetation in the computations. After the establishment of herbaceous plants on its banks, the Lunterse Beek did not show any further changes in channel alignment. This is here attributed to the stabilizing effects of plant roots together with the small size of the stream. It is expected that the morphological restoration of similarly small streams may result in important initial morphological adaptation followed by negligible changes after full vegetation establishment. Copyright © 2018 John Wiley & Sons, Ltd.

Morphological Adaptation of River Channels to Vegetation Establishment: A Laboratory Study

“…This vegetation configuration exhibits significant resistance for the flow intensity of our experimental stream. Similar characteristics were observed in the Lunterse beek in the Netherlands (e.g., Vargas‐Luna et al, ).…”

“…The experiments describe systems in which plants are not easily eradicated and are inspired by the Lunterse beek, a well‐monitored, small stream located in the Netherlands in which the conditions considered here were observed (see Vargas‐Luna et al, , for a complete description). However, the results of our experiments are not intended to be scaled with this or any other specific river.…”

Connecting Fluvial Levee Deposition to Flood‐Basin Hydrology

“…Similarly, during flood, more deposition tends to occur on shorter levees, but there is no clear control on the magnitude of deposition (Smith et al, ). There is some field evidence that vegetation influences levee occurrence (Vargas‐Luna et al, ) and shape (Pierik et al, ), but in these cases it is hard to isolate the cause and effect. Levee shape should also be related to the dominant grain size, because all else being equal, channels with fine‐grained sediment should produce wide levees, but the relationship is often ambiguous (Adams et al, ).…”

Revisiting Waal River Training by Historical Reconstruction

“…The long-term morphological responses are reproduced with a two-dimensional depth-averaged (2DH) model based on the open-source Delft3D code. The numerical approach adopted in this study is supported by Le et al (2018b), who successfully reproduced the long-term morphological developments observed in an experimental channel separated by a longitudinal training wall; by McCoy et al (2008), who modeled a channel with a series of groynes; by Arboleda et al (2010), who simulated floodplain sedimentation in the historical Waal River; and by Vargas-Luna et al (2018), who successfully applied Baptist et al's (2003) formulation, implemented in Delft3D, for the assessment of the effects of floodplain vegetation on water levels.…”