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| Titel |
Regional assessment of the multi-decadal changes in braided riverscapes following large floods (Example of 12 reaches in South East of France) |
| VerfasserIn |
B. Belletti, S. Dufour, H. Piegay |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: Sediment Transport and Landscape Dynamics (SALADYN) Workshop 2012 ; Nr. 37 (2014-04-22), S.57-71 |
| Datensatznummer |
250121290
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| Publikation (Nr.) |
 copernicus.org/adgeo-37-57-2014.pdf |
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| Zusammenfassung |
| The district of the France Rhône basin is characterised by several
braided reaches, preserved from the widespread disappearing occurred in the
20th century. Even if the overall pattern is evolving through a general
river narrowing, some reaches have shown to be still active and have
widened. The preliminary results suggest that differences in width pattern
could be related to several factors, such as high magnitude and low
frequency floods, and geographical position in the catchment which
influences bedload delivery conditions and vegetation recruitment related to
climate. From an initial set of 53 braided reaches, we selected 12 sites,
distributed into four main hydro-geographical regions. Reaches were selected
to be representative of the overall study area. We analysed the braiding
width pattern and the vegetation pattern dynamic among five observation
periods dating from the 1950s to the 2000s. We hypothesised that a
comparative analysis of a detailed temporal trajectory (i.e. five dates) of
a set of rivers within several hydro-geographical contexts would allow us to
better distinguish the relative role of floods (in terms of magnitude and
duration) and other controlling factors acting at the regional scale. We
showed that active channel width is controlled mainly by Q10 flood and
secondarily by bedload availability whereas island pattern is in large part
independent of flood series characters. Moreover a clear regional
differentiation, constant over time, in terms of riverscape response is
observed, mainly opposing south-western and south-eastern reaches. This
opposition depends on several concurring factors, i.e. the flood characters,
the river activity, the human influence and the climate. Finally, these
findings allowed us to highlight those sectors in which the braided pattern
could disappear, and those sectors in which the braided pattern is still
active, because critical processes responsible of channel dynamic are still
present. |
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