Determination of lake level changes by grain size distribution of sublacustrine channel deposits (Karasu-Lake Van-Türkiye)

This study aims to determine the grain size distribution of a sediment core taken from sublacustrine channels located on the eastern shelf of Lake Van, extending from the Karasu River, and use this distribution to identify changes in lake water levels. The dating of the core was carried out using the varve counting method. According to the results obtained from the research, the 2-meter-long core sediment sequence represents 2400 years of history. The sediment sequences clay content ranges from 7.06% to 85.1%, silt content from 12.8%-90.7%, and sand content from 0% to 11.2%. the mean grain size ranges between 5.4-9.4 Ø, with sorting degrees between 1.35-4.97 Ø and skewness values between -0.77 to +0.58 Ø. It was determined that during the warm and humid periods, the average grain size decreased, and the lake level rose, whereas during cold and dry periods, the average grain size increased, and the lake level decreased. As a result, over the 2400 year BP, six climatic phases were identified, consisting of three cold and dry and three warm and humid periods. These periods parallel the North Hemisphere's climatic phases, which are named, in chronological order from oldest to youngest, the Near East Aridification Phase, Roman Warm Period, Dark Ages Cold Period, Medieval Warm Period, Little Ice Age, and Modern Warm Period.