Past variations of Lake Sevan (Armenia, lesser Caucasus): documenting climate triggers for the Near East and delivering insights for a sustainable management
Résumé
<p>To understand the long-term patterns of atmospheric circulation in Eurasia, current paleoclimatic reconstruction syntheses lack accurate data for the Near East. In this semi-arid zone, precipitation is the key factor to be studied that strongly controls ecosystems and human societies. Few data are available from Lake Sevan (1900.52 m above sea level, 1,279 km², 38.2 km<sup>3</sup> as of January 1, 2021), the largest fresh-water lake in the Near East, whose past level variations may document seasonal to millennial precipitation changes.</p><p>We present here the preliminary results of the interdisciplinary Sevan-up Project. Its ambition is to develop a high resolution lake level reconstruction (which is expected to be preserved from the influences of long ecological processes and from human activities) and other climatic proxies (from pollen and molecular biomarker) in view to quantify precipitation changes during the Holocene.</p><p>The Early Holocene climate characteristics (strong seasonality) and environment (prevalence of steppe ecosystems) may raise an analogous model of future conditions in the Near East which will be affected by enhanced continentalism. The study of littoral and deep sedimentary deposits will potentially reveal the consequences of past variations in lake levels on its hydrodynamic functioning and trophic status. These results will give crucial information on how to improve the lake's water management with the goal to reach a sustainable use and a better ecological state. Indeed, seasonal stratification onsets and trophic status dramatically changed since the man-made water-level fall during the Soviet times (40% of its volume).</p>