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| Titel |
Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy |
| VerfasserIn |
B. Vanniere, M. Magny, S. Joannin, A. Simonneau, S. B. Wirth, Y. Hamann, E. Chapron, A. Gilli, M. Desmet, F. S. Anselmetti |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 3 ; Nr. 9, no. 3 (2013-05-31), S.1193-1209 |
| Datensatznummer |
250018061
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| Publikation (Nr.) |
 copernicus.org/cp-9-1193-2013.pdf |
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| Zusammenfassung |
| Two lacustrine sediment cores from Lake Ledro in northern Italy were studied
to produce chronologies of flood events for the past 10 000 yr. For this
purpose, we have developed an automatic method that objectively identifies
the sedimentary imprint of river floods in the downstream lake basin. The
method was based on colour data extracted from processed core photographs,
and the count data were analysed to capture the flood signal. Flood
frequency and reconstructed sedimentary dynamics were compared with
lake-level changes and pollen inferred vegetation dynamics. The results
suggest a record marked by low flood frequency during the early and middle
Holocene (10 000–4500 cal BP). Only modest increases during short intervals
are recorded at ca. 8000, 7500, and 7100 cal BP. After 4500–4000 cal BP, the
record shows a shift toward increased flood frequency. With the exception of
two short intervals around 2900–2500 and 1800–1400 cal BP, which show a
slightly reduced number of floods, the trend of increasing flood frequency
prevailed until the 20th century, reaching a maximum between the
16th and the 19th centuries. Brief-flood frequency increases
recorded during the early and middle Holocene can be attributed to cold
climatic oscillations. On a centennial time scale, major changes in flood
frequency, such as those observed after ca. 4500/4000 and 500 cal BP, can be
attributed to large-scale climatic changes such as the Neo-glacial and
Little Ice Age, which are under orbital and possibly solar control. However,
in the Bronze Age and during the Middle Ages and modern times, forest
clearing and land use probably partially control the flood activity. |
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