Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy
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 m...
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2013-05-01
|
| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/9/1193/2013/cp-9-1193-2013.pdf |
| _version_ | 1818139950589149184 |
|---|---|
| author | B. Vannière M. Magny S. Joannin A. Simonneau S. B. Wirth Y. Hamann E. Chapron A. Gilli M. Desmet F. S. Anselmetti |
| author_facet | B. Vannière M. Magny S. Joannin A. Simonneau S. B. Wirth Y. Hamann E. Chapron A. Gilli M. Desmet F. S. Anselmetti |
| author_sort | B. Vannière |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-11T10:36:14Z |
| format | Article |
| id | doaj.art-f069e4f9ddb742a2abce50f8762b9300 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-11T10:36:14Z |
| publishDate | 2013-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-f069e4f9ddb742a2abce50f8762b93002022-12-22T01:10:43ZengCopernicus PublicationsClimate of the Past1814-93241814-93322013-05-01931193120910.5194/cp-9-1193-2013Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern ItalyB. VannièreM. MagnyS. JoanninA. SimonneauS. B. WirthY. HamannE. ChapronA. GilliM. DesmetF. S. AnselmettiTwo 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.http://www.clim-past.net/9/1193/2013/cp-9-1193-2013.pdf |
| spellingShingle | B. Vannière M. Magny S. Joannin A. Simonneau S. B. Wirth Y. Hamann E. Chapron A. Gilli M. Desmet F. S. Anselmetti Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy Climate of the Past |
| title | Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy |
| title_full | Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy |
| title_fullStr | Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy |
| title_full_unstemmed | Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy |
| title_short | Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy |
| title_sort | orbital changes variation in solar activity and increased anthropogenic activities controls on the holocene flood frequency in the lake ledro area northern italy |
| url | http://www.clim-past.net/9/1193/2013/cp-9-1193-2013.pdf |
| work_keys_str_mv | AT bvanniere orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT mmagny orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT sjoannin orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT asimonneau orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT sbwirth orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT yhamann orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT echapron orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT agilli orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT mdesmet orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly AT fsanselmetti orbitalchangesvariationinsolaractivityandincreasedanthropogenicactivitiescontrolsontheholocenefloodfrequencyinthelakeledroareanorthernitaly |