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| Titel |
Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions |
| VerfasserIn |
I. Jalón-Rojas, S. Schmidt, A. Sottolichio |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 6 ; Nr. 19, no. 6 (2015-06-18), S.2805-2819 |
| Datensatznummer |
250120744
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| Publikation (Nr.) |
 copernicus.org/hess-19-2805-2015.pdf |
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| Zusammenfassung |
| Climate change and human activities impact the volume and timing of
freshwater input to estuaries. These modifications in fluvial discharges are
expected to influence estuarine suspended sediment dynamics, and in
particular the turbidity maximum zone (TMZ). Located in southwest
France, the Gironde fluvial-estuarine system has an ideal context to
address this issue. It is characterized by a very pronounced TMZ, a decrease
in mean annual runoff in the last decade, and it is quite unique in having a
long-term and high-frequency monitoring of turbidity. The effect of tide and
river flow on turbidity in the fluvial estuary is detailed, focusing on
dynamics related to changes in hydrological conditions (river floods,
periods of low discharge, interannual changes). Turbidity shows hysteresis
loops at different timescales: during river floods and over the
transitional period between the installation and expulsion of the TMZ. These
hysteresis patterns, that reveal the origin of sediment, locally resuspended
or transported from the watershed, may be a tool to evaluate the presence of
remained mud. Statistics on turbidity data bound the range of river flow
that promotes the upstream migration of TMZ in the fluvial stations. Whereas
the duration of the low discharge period mainly determines the TMZ
persistence, the freshwater volume during high discharge periods explains
the TMZ concentration at the following dry period. The evolution of these
two hydrological indicators of TMZ persistence and turbidity level since
1960 confirms the effect of discharge decrease on the intensification of the
TMZ in tidal rivers; both provide a tool to evaluate future scenarios. |
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