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| Titel |
Global scale analysis of the stream power law parameters based on worldwide 10Be denudation rates |
| VerfasserIn |
Marie-Alice Harel, Simon Mudd, Mikael Attal |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101996
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| Publikation (Nr.) |
 EGU/EGU2015-1271.pdf |
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| Zusammenfassung |
| The stream power law, expressed as E = KAmSn where E is erosion rate [LT-1], K is
erodibility [T-1L(1-2m)], A is drainage area [L2], S is channel gradient [L/L] and m and n
are constants, is the most widely used model for bedrock channel incision. Despite its
simplicity and limitations, the model has proved useful for a large number of applications
such as topographic evolution, knickpoint migration, palaeotopography reconstruction, and
the determination of uplift patterns and rates. However, the unknown parameters K, m and n
are often fixed arbitrarily or are based on assumptions about the physics of the erosion
processes that are not always valid, which considerably alters the use and interpretation of the
model.
In this study, we compile published 10Be basin-wide erosion rates (n = 1335) in order to
assess the m/n ratio (or concavity index), the slope exponent n and erodibility coefficient K
using the integral method of channel profile analysis. These three parameters are calculated
for 66 areas and allow for a global scale analysis in terms of climatic, tectonic and
environmental settings. Our results suggest that (i) many sites are too noisy or do not have
enough data to predict n and K with a satisfying level of confidence; (ii) the slope
exponent is predominantly greater than one, meaning that the relationship between
erosion rate and the channel gradient is non-linear, supporting the idea that incision is
a threshold controlled process. Furthermore, a multi-regression analysis and the
calculation of n and K using a reference concavity index m/n = 0.45 demonstrate
that (iii) many intuitive or previously demonstrated local-scale trends, such as
the correlation between erosion rate and climate, do not appear at a global scale. |
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