DATE2016-05-27 14:29:53
IDABSTRACT20160527142953-0981
CONTACTtimvanderschriek@gmail.com
PRESENTATIONORAL-PARALLEL
INVITED0
IDSESSION3
TITLEQUANTITATIVE WATER LEVEL VARIABILITY OF LAKE PRESPA (SW BALKANS) DURING THE LATE HOLOCENE RECONSTRUCTED FROM BEACH RIDGE SEDIMENTS: IMPLICATIONS FOR MEDITERRANEAN HYDRO-CLIMATIC CHANGES FROM THE MEDIEVAL CLIMATE ANOMALY TO THE PRESENT
AUTHORSTim Van Der Schriek (1), Christos Giannakopoulos (1)
AFFILIATIONS
  1. National Observatory Of Athens Athens (Greece)
ABSTRACTWe present new quantified hydro-climatic data from the past 1000yrs, based on the Prespa Lake level record (SW Balkans). Numerical reconstructions of precipitation-driven inflow changes focus on the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA), and are placed in a Holocene perspective. Mediterranean lake-proxy reconstructions show a distinct W-E pattern over the past millennium, linked to the North Atlantic Oscillation (NAO). The West experienced dry conditions during the MCA (NAO: predominantly positive); wetter conditions / negative NAO phases dominated the LIA. The East experienced roughly opposite conditions. The Balkans is located at the juncture of these contrasting hydro-climatic domains. However, regional high-resolution lake-proxy records from this period are sparse and the pattern of hydro-climatic change is not clear. Absolute lake-stage index-points are of great value to interpret different lake-proxies and to produce regionally robust hydro-climate histories. The Prespa isthmus beach ridge complex offers a unique opportunity to create an absolute stage record. Beach ridge sediments accurately register annual lake fluctuations which are driven by wet season precipitation. Absolute stage index points were dated by OSL & 14-C age-estimation methods. Lake surface areas at dated index points were reconstructed using geomorphic / chronostratigraphic methods. All major low/high lake phases over the past ~1000 years were identified and dated in the sediment record. Low lake levels (842-846m) during the MCA (~900-1420AD) suggest drier wet seasons, except for several decades after 1230AD (lake: 847-848m). Lake levels were high (>847m) ~1450-1987AD, except for a multi-decadal fall to ~845m around 1640AD suggesting a dry spell. Low levels after 1987AD (842-845m) were mainly caused by water abstraction. These hydro-climatic changes are similar to those in the west-central Mediterranean. However, lake-proxy records to the east of Prespa suggest an opposite pattern; the boundary between these two domains likely runs along the spine of the Balkans. MCA-LIA lake variability is superimposed on a long-term drying trend starting ~5000yrs ago, fitting the broad-scale E Mediterranean pattern. Over this time, max (min) inflow during wet (dry) periods successively decreased. Inflow variability related to wet/dry periods was in the order of 5-10%. This limited variation had, however, large consequences for lake level which fluctuated between 842-852.5m.
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