Lake Allos, French Alps 1360 Year Flood Deposit Data Wilhelm, B.; Arnaud, F.; Sabatier, P.; Crouzet, C.; Brisset, E.; Chaumillon, E.; Disnar, J.R.; Guiter, F.; Malet, E.; Reyss, J.-L.; Tachikawa, K.; Bard, E.; Delannoy, J.-J. Wilhelm, B. Arnaud, F. Sabatier, P. Crouzet, C. Brisset, E. Chaumillon, E. Disnar, J.R. Guiter, F. Malet, E. Reyss, J.-L. Tachikawa, K. Bard, E. Delannoy, J.-J. Little Ice Age (LIA) Medieval Warm Period North Atlantic Oscillation Other Hydroclimate Reconstruction earth science/paleoclimate/paleolimnology (event layer,sediment,null,count,null,paleolimnology,null,null,N,flood events) earth science/paleoclimate/paleolimnology (age,null,null,year Common Era,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (event layer,sediment,null,millimeter,null,paleolimnology,null,null,N,flood events) earth science/paleoclimate/paleolimnology (Lake Allos>LATITUDE 44.236>LONGITUDE 6.7092) Investigation of Lake Allos sediments revealed ~160 graded layers, interpreted as flood deposits, over the last 1400 yr. Comparisons with records of historic floods support the interpretation of flood deposits and suggest that most recorded flood events are the result of intense meso-scale precipitation events. As there is no evidence for any major changes in erosion processes in the catchment since the Medieval Warm Period (MWP), we interpret the Allos record in terms of repeated intense precipitation events over the last millennium, with a low flood frequency during the MWP and more frequent and more intense events during the Little Ice Age. This interpretation is consistent with the pattern of increasingly humid conditions in the northwestern Mediterranean region. This long-term trend is superimposed on high frequency oscillations that correlate with solar activity and autumnal North Atlantic Oscillation (NAO). Finally, a comparison of flood records across the northwestern Mediterranean region showed that intense precipitation events in Allos (east of the Rhône Valley) were out of phase with events in the Cévennes (west of the Rhône) but in phase with events in eastern Spain. Supported by meteorological analyses, this suggests an oscillation in atmospheric circulation patterns over the northwestern Mediterranean. STUDY NOTES: Annual flood deposit thickness data from Lake Allos, Mediterranean French Alps, for the past 1360 years. The Lake Allos sediment sequence consists of 160 normally graded beds containing markers indicating an allochtonous origin for the sediment (terrestrial macro-remains and Ca-enrichment). These beds are interpreted as flood deposits, associated with extreme precipitation events in the northwest Mediterranean region. Grain size analysis (Malvern Mastersizer S) was conducted on core ALO09P13, retrieved from the northern basin of the lake. Sampling was at a continuous interval of 5 mm. Lake Allos, Mediterranean French Alps: 44°14.16'N, 6°42.55'E, 2230m elevation, 20m water depth. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Wilhelm, B. Investigator : Arnaud, F. Investigator : Sabatier, P. Investigator : Crouzet, C. Investigator : Brisset, E. Investigator : Chaumillon, E. Investigator : Disnar, J.R. Investigator : Guiter, F. Investigator : Malet, E. Investigator : Reyss, J.-L. Investigator : Tachikawa, K. Investigator : Bard, E. Investigator : Delannoy, J.-J. 2012-06-27 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13057 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/france/allos2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/france/allos2012.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/france/allos2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/france/allos2012.xls English https://www.ncdc.noaa.gov/paleo/study/13057 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/france/allos2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/france/allos2012.xls Wilhelm, B., F. Arnaud, P. Sabatier, C. Crouzet, E. Brisset, E. Chaumillon, J.-R. Disnar, F. Guiter, E. Malet, J.-L. Reyss, K. Tachikawa, E. Bard, and J.-J. Delannoy. 2012. 1400 years of extreme precipitation patterns over the Mediterranean French Alps and possible forcing mechanisms. Quaternary Research, Vol. 78, Issue 1, July 2012, pp. 1-12. DOI: 10.1016/j.yqres.2012.03.003 START YEAR: 650 AD * END YEAR: 2009 AD 6.7092 44.236 6.7092 44.236