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| Titel |
Rapid fluvial aggradation in response to climate change in northwestern Argentina |
| VerfasserIn |
Andrew Wickert, Taylor Schildgen, Manfred Strecker |
| 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 |
250108086
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| Publikation (Nr.) |
 EGU/EGU2015-7817.pdf |
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| Zusammenfassung |
| River channels near the edge of the northwestern Argentine Andes are rapidly aggrading at
present, with preliminary estimates suggesting rates of ~20 cm yr-1. This mirrors cycles of
extensive aggradation over the past 100,000 years that formed pronounced fill terraces
along regional valley networks and record periods in which in which climate-driven
sediment supply overcame uplift-driven river incision (Robinson et al, 2005). Here
we use the new SedFlow model (Heimann et al., 2014) to help us understand the
causes and spread of aggradation across these basins in the modern system, with the
additional eventual goal to better interpret the geologic record. We provide field-derived
grain-size distributions, field-measured and remotely-sensed channel widths and
valley slopes, and a variety of possible sediment source locations and amounts
as inputs to SedFlow, which routes sediment through the fluvial channel network
to produce time-evolving predictions of aggradation and incision. We compare
these predictions against changes in topography measured by IceSAT (Zwally et
al., 2014) and field surveys. We initially test the system response to a series of
isolated sediment inputs to observe interactions between tributary systems and the
mainstem river. Recent observations indicate that debris-flow induced landslides are
important contributors to aggradation in these rivers (Cencetti and Rivelli, 2011).
These and other sediment production and transport processes are likely driven by
variations in the El Niño Southern Oscillation (ENSO) (Bookhagen and Strecker, 2009).
Therefore, we then run SedFlow with sediment inputs distributed across the landscape
based on locations where ENSO influences may trigger enhanced landsliding. These
model experiments help us towards our end goal of providing a more quantitative
basis to interpret field observations of landscape response to changing patterns of
precipitation.
References:
Bookhagen, B. and Strecker, M.: Amazonia: Landscape and Species Evolution,
in Amazonia, Landscape and Species Evolution: A Look into the Past, edited by
C. Hoorn and F. P. Wesselingh, Wiley-Blackwell Publishing Ltd., Oxford, UK.,
2009.
Cencetti, C. and Rivelli, F. R.: Landslides Dams Induced by Debris Flows
in Quebrada Del Toro (Province of Salta, Argentina), in 5th International
Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and
Assessment, pp. 645–650, Casa Editrice Università La Sapienza, Padua, Italy.,
2011.
Heimann, F. U. M., Rickenmann, D., Turowski, J. M. and Kirchner, J. W.:
sedFlow – an efficient tool for simulating bedload transport, bed roughness, and
longitudinal profile evolution in mountain streams, Earth Surf. Dyn. Discuss.,
2(2), 733–772, doi:10.5194/esurfd-2-733-2014, 2014.
Robinson, R. a. J., Spencer, J. Q. G., Strecker, M. R., Richter, a. and
Alonso, R. N.: Luminescence dating of alluvial fans in intramontane basins
of NW Argentina, Geol. Soc. London, Spec. Publ., 251(1), 153–168,
doi:10.1144/GSL.SP.2005.251.01.11, 2005.
Zwally, H., R. Schutz, C. Bentley, J. Bufton, T. Herring, J. Minster, J. Spinhirne,
and R. Thomas. GLAS/ICESat L1B Global Elevation Data. Version 34. GLA06.
Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data
Center. http://dx.doi.org/10.5067/ICESAT/GLAS/DATA126. 2014. |
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