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| Titel |
Resistance to uprooting of Alfalfa and Avena Sativa and related importance for flume experiments |
| VerfasserIn |
K. Edmaier, B. Crouzy, P. Burlando, P. Perona |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067125
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| Zusammenfassung |
| Vegetation influences sediment dynamics by stabilizing the alluvial sediment with its root
system. Thus, vegetation engineers the riparian ecosystem by contributing to the formation
and stabilization of river bars and islands. The resistance to uprooting of young plants in
non-cohesive sediment depends on the competition between flow induced drag and root
growth timescales. The investigation of flow-sediment-plant interactions in situ is difficult
since variables cannot be controlled and material hardly be collected. In order to investigate
ecomorphological processes, laboratory experiments are essential and have gained
importance in the last decade.
To achieve a better understanding of the dependence of resistance to uprooting on the root
system (length and structure) we conducted vertical uprooting experiments with Alfalfa and
Avena Sativa which are both species that have been used in flume experiments on
vegetation-flow interactions (e.g. Tal and Paola, 2010; Perona et al., in press). Seeds were
seeded on quartz sand and vertically uprooted with constant velocity whereat the weight force
required to uproot a seedling was measured. After uprooting, roots were scanned
and analyzed and the correlation of root parameters with the uprooting work was
studied.
Total root length was found to be the best explanatory variable, in particular the
uprooting work increases following a power law with increasing root length. The
impact of other root parameters (main root length, root number, tortuosity) on the
uprooting work was as well analyzed. Still, not all influencing root parameters could
be captured, like the angle between roots or root hair distribution. Environmental
conditions like grain size and saturation were also found to have an effect on the
uprooting resistance of roots. So, lower saturated sediment results in a higher uprooting
work.
This work is a first step to better understand the energy regime for vegetation uprooting and
its dependence on various biological and hydraulic variables. Future experiments using the
same sediment and vegetation species will apply this knowledge to further investigate
flow-vegetation-sediment interactions.
References:
Perona, P.; Molnar, P.; Crouzy, B.; Perucca, E; Jiang, Z; McLelland, S; Wüthrich, D;
Edmaier, K; Francis, R.; Camporeale, C.; Gurnell, A.: Biomass selection by floods and
related timescales: Part 1. Experimental observations, Advances in Water Resources, in
press
Tal, M. and Paola, C.: Effects of vegetation on channel morphodynamics: results and insights
from laboratory experiments, Earth Surface Processes and Landforms, 35, 1014–1028 (2010) |
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