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| Titel |
New geomorphic constraints on landscape sensitivity to climate in tectonically active areas |
| VerfasserIn |
Mitch D'Arcy, Alex Whittaker |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091594
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| Publikation (Nr.) |
 EGU/EGU2014-5896.pdf |
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| Zusammenfassung |
| It is widely accepted that channel longitudinal profiles are sensitive to tectonics, and can
record detailed information about the location, magnitude, and timing of fault uplift. However
fluvial landscapes are also shaped by climate, which controls river incision rates and channel
form via surface run-off and discharge controls. While these effects are widely studied in
modern rivers, understanding how long-term rainfall differences determine fluvial
landscape form remains an outstanding research challenge. Numerical models have
hypothesized a relationship between precipitation rate and channel geometry, but
to-date few empirical constraints exist. Here, we measure the normalised channel
steepness index (ksn) of over 800 channels in 6 study areas, each in a different
climatic setting. These regions exhibit a tenfold variation in modern precipitation
rate between them (~100-1000 mm yr-1), with well documented palaeo-climate
constraints, but they have similar uplift rates, allowing the tectonic variable to be
controlled. Our analysis accounts for glacial-interglacial climate variability, and by
considering the orographic coupling of rainfall with uplifted topography, we find
that channel steepness is significantly suppressed by higher precipitation rates, as
stream power erosion theory predicts. These findings help to resolve why highly
variable measurements of channel steepness are reported from different locations,
even when tectonic rates are comparable, and our results provide important new
constraints on the sensitivity of landscape to climate in tectonically-active landscapes. |
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