HYVARMED aims to analyze the spatial variability of hydrological changes and extreme events (droughts and floods) occurred in the Mediterranean Basin during the last millennium, based on the correlation of selected, multi-high resolution terrestrial records. Our goal is to test the hypothesis of a potential East-West climate see-saw mechanism operating in the region during this period, as evidenced by opposite hydrological patterns recorded in available terrestrial sequences both in western (Montcortès Lake, Iberian Peninsula) and eastern (Nar Lake, Turkey) areas. 

To achieve this goal we will obtain an annually resolved record of hydrological changes in the Central Mediterranean area based on the laminated sediments of Lake Butrint (Albania). This is a key region located between the two extremes of the basin, where high-resolution humidity records are absent. Cores are already available as a result of previous international cooperation with Swiss and Albanian teams. The expected chronological robustness of the age model obtained by the use of varve (annual) counting, combined with the presence of thick autighenic calcite laminae will provide a temporally highly-resolved record able to capture high-frequency variability and abrupt climate transitions. We will use stable isotopes in autighenic calcite (d18O, d13C) to accurately reconstruct changes in the water balances occurred in the region. We will investigate the annual deposition of sediments and the formation of varves in this lake, including their seasonal variations in relation to lake water physical-chemical conditions and how the isotopic signature is affected by low–frequency hydrological changes, in order to understand how the different hydrological signals are transferred to the sediments. Comparison of the isotope and geochemical evolution of available eastern and western records will test the main differences in timing and intensity of hydrological fluctuations across a W to E gradient and their variable impact in water resources and human activities in these regions. We will also investigate how reconstructed periodicities from these lake records relate to potential forcing mechanisms of climate variability during the last millennium, like the North Atlantic Oscillation (NAO), the Scandinavian Pattern (SCAND) and solar variability. The project represents a unique research opportunity because: i) cores are available and consequently, cost are greatly reduced; ii) preliminary analyses indicate the annual nature of the lamination, iii) the isotope-hydrology connections are relatively well-understood, iv) collaboration with other research teams ensure that other terrestrial records will be available for comparison and ensures the successful achievement of the main objectives of this project. 

The scarcity of high-resolution records to facilitate detailed correlations of continental sequences makes this study of special scientific interest. Understanding of the nature, timing, spatial variability and consequences of hydrological changes occurred in the Mediterranean basin during the last millennium will be of considerable relevance for the prediction of future climate change, identification of most vulnerable areas to hydrological extremes and thus, adoption of specific adaptation and mitigation policies for each region within the Mediterranean Basin.

Key Words: Mediterranean, hydrological variability, extreme events, floods, droughts, last millennium,E-W climate see-saw, high-resolution, varves, stable isotopes, terrestrial records