Abstract
During higher discharges, riparian vegetation becomes partially or fully
submerged and interacts with the flow and sediment transport by acting
as a roughness element to the flow. The geometry of flexible vegetation
such as willows adjusts to the drag forces exerted by the flow,
resulting in a strong variation of the flow resistance depending on the
flow characteristics. So far, the deformation of submerged shrubby
plants through bending and streamlining was considered in friction
factors based on empirical data on plant deformation. We attempt to
develop a mechanically based streamlining model for shrubby vegetation
by considering the bending of stem and branches as well as the torsion
acting onto the bases of the branches as a consequence of drag forces of
the flow. For that purpose, we investigated several plants of Salix
viminalis, which were coppiced to obtain multiple branches for a more
natural, shrubby growth, to be further used in a research channel which
offers free flowing discharges up to 10 m3 s-1. We determined the
three-dimensional geometries of several plants by performing a
photogrammetric analysis, and systematically measured branch and stem
thicknesses at several locations. The obtained geometries and data on
elastic modulus and shear modulus served for the development of a
generic representation of the plant geometry and properties, which is
used for the development of the mechanically based model of plant
deformation. Preliminary results showed a significant contribution of
torsion to plant deformation, emphasising the need of its consideration
in physically based deformation models.
| Original language | English |
|---|---|
| Pages (from-to) | 18876 |
| Journal | Geophysical Research Abstracts |
| Volume | 19 |
| Publication status | Published - 1 Apr 2017 |
| Externally published | Yes |
| Event | 19th European Geosciences Union General Assembly 2017 - Wien, Austria Duration: 23 Apr 2017 → 28 Apr 2017 |
Austrian Fields of Science 2012
- 207114 Water management