Difference between revisions of "Effect of vegetation on hydromorphodynamics"
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non-vegetated flows. In this way, vegetation potentially has a relevant effect on flow resistance, sediment transport and bank dynamics (see Table 1). | non-vegetated flows. In this way, vegetation potentially has a relevant effect on flow resistance, sediment transport and bank dynamics (see Table 1). | ||
| − | [[File:VegHymoInteractions_Hydromorphodynamics.png|center|thumb| | + | [[File:VegHymoInteractions_Hydromorphodynamics.png|center|thumb|600px| Table 1. Models for the effects of vegetation on hydromorphodynamics.]] |
===Vegetation and flow resistance=== | ===Vegetation and flow resistance=== | ||
Revision as of 18:20, 30 June 2015
Vegetation can influence river hydrodynamics by changing the turbulent flow field and the averaged velocity profiles in comparison with those that can be commonly found in
non-vegetated flows. In this way, vegetation potentially has a relevant effect on flow resistance, sediment transport and bank dynamics (see Table 1).
Vegetation and flow resistance
Future research is needed on the following topics:
- effect of different types and growth stages of vegetation (rigid or flexible) and different vegetation densities on flow turbulence structure and secondary currents of a stream;
- effect of plant reconfiguration with increasing flow velocity on drag;
- effect of the spatial distribution of vegetation at a reach scale on flow resistance;
- uprooting, breakage of plants during high-flow conditions may give rise to significant changes in flow resistance between the rising and falling limbs of the hydrograph;
- develop suitable parameterization to characterize different species.
Vegetation and bank dynamics
Tables 3 and 4 summarise the suitability of models with bank stability and accretion, respectively, for the analysis of hydromorphological pressures or the design of restoration measures.
Future research and modelling challenges:
- More work is needed to better understand the hydrological effects of riparian vegetation and to incorporate them into models of bank erosion and failures.
- Another area of knowledge gaps concerns modelling interactions of the various erosion processes and mass failures, and the relative role of vegetation on near-bank hydrodynamic flow conditions, erodibility parameters, and shear strength. In order to extend results from a bank profile to a reach and account for variability of hydrodynamic, geotechnical, and vegetational conditions, vegetation should be included into 3-D morphodynamic models.
- Concerning bank accretion modelling is still in its infancy. Recommendations relate to three main aspects: the inclusion of vegetation dynamics, the influence of the high variability of flows, and the up-scaling of the effects acting at different scales.
