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| Titel |
Characterising the roughness properties of alluvial river banks using terrestrial laser scanning. |
| VerfasserIn |
D. M. Powell, D. Ackerley |
| 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 |
250060521
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| Zusammenfassung |
| Form roughness generated by the irregular topography of alluvial river banks can be a
major component of the total flow resistance and bank shear stress with important
consequences for modelling stage-discharge relationships and bank erosion. Current
models of form roughness assume that the topographic features of a bank can be
approximated by a series of Gaussian-shaped roughness elements parameterised
in terms of a protrusion height H, a streamwise length scale Ïă (equivalent to the
standard deviation of a Gaussian probability distribution) and a spacing λ between
crests. It is further assumed that bank roughness parameters do not vary over time
as the bank erodes. Empirical data supporting these assumptions are, however,
limited and further work is needed to fully assess the roughness properties of alluvial
banks and the sensitivity of bank roughness parameters to changes in bank geometry
generated by bank erosion and retreat. In this study, the technique of terrestrial laser
scanning is used to conduct high resolution surveys of actively eroding alluvial river
banks on two rivers in the English Midlands. The data are used to derive digital
elevation models of river bank microtopography which are subjected to a suite of
visualisation and analytical techniques to determine the roughness properties of the
banks at different scales and how these properties vary over time as bank erosion
modifies the local topography. The findings are discussed in relation to modelling
strategies for predicting flow resistance and bank shear stresses in alluvial rivers. |
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