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| Titel |
Unit stream power as a base for regional river typology |
| VerfasserIn |
Eric Hallot, Geoffrey Houbrechts, Yannick Levecq, François Petit |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040739
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| Zusammenfassung |
| In order to assess the hydromorphological quality of surface waters, stakeholders need river
typologies accurate and functional enough to be a really efficient management tool. From a
typological study based a broad set of hydromorphological field data, we have shown that
some variables, like the unit stream power (Ï), are particularly appropriate to describe the
dynamics of a river. Initial results of repeated measurement in more than 80 sites
revealed a regional differentiation based on critical values of stream power at bankfull
discharge.
The aim of this study is to present a unit stream power mapping for the whole network
based on general equation Ï = Ï.g.Q.S-w, with Ï the density of water, g the acceleration due
to gravity, Q the discharge, S the slope and w the channel width). Slope is extracted from
DEM. Bankfull discharge and width estimations are furnished by allometric equations using
the watershed area. Different coefficients are used according to regional differentiations
based on bedload size and watershed permeability. The statistical significance of all
equations was tested by covariance analysis. A correction taking into account the used
log-log scale, was also applied to the obtained allometric equations (Fergusson,
1988).
Using a 30 x 30 meters DEM, GIS routines were developed. A first one automatically
sectorizes the network and a second evaluates the unit streamspower in each location. We
propose a 7-level classification in accordance with the associated morphological processes
describe in the literature (from fixed meanders to step-pools system). The mapping unit starts
at the Strahler second order.
Our results not only support a regional typology, but moreover allow us to describe
natural regions in function of river dynamics and to estimate the resistance of restoration
works like vegetal techniques. It can also provide estimates of the excess stream power (the
fraction of the actual stream power exceeding the power at which bedload particles start to
move)
(Fergusson, R.,I., 1988. River loads underestimated by rating curves, Water Resour. Res.,
24(7), 1217–1219.) |
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