45-year cycles of water level oscillations in the KaraBogazGol - Caspian Sea system.
by
Santiago Giralt
Institute of Earth Sciences 'Jaume Almera' (CSIC). Lluis Sole i Sabaris s/n, E-08028 Barcelona (Spain)
Coauthors: Ramon Julià (Institute of Earth Sciences 'Jaume Almera' (CSIC). Lluis Sole i Sabaris s/n, E-08028 Barcelona, Spain), Suzanne Leroy (Department of Geography and Earth Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH, West London, UK), Francoise Gasse (CNRS - CEREGE, Europôle Méditerranéen l'Arbois - BP 80. 13545 Aix-en-Provence Cedex 04, France)

The water level instrumental record of the Caspian Sea (CS) and its terminal system the KaraBogaz Gol (KBG) show that during the last 100 years that lacustrine system has suffered water level oscillations of about 3.5 m of amplitude. These water level oscillations have strongly influenced the economy development of the surrounding countries (e.g. fishery, with especially emphasis with the sturgeon industry, and coastal infrastructures, such as harbours and nuclear power plants located in the Volga delta plain). Up to now, such water level oscillations have been qualified as 'erratic'.

The first meter of the KBG sedimentary infill has been studied in order to detect such water level oscillations and to understand the possible mechanisms that have triggered them. The petrological study of the sediments allowed to determine the main sedimentary processes of the KBG. The temporal framework was established by the 210Pb method. The water oscillations of the KBG for the last 200 years were reconstructed using the mineral composition of the sediments, and applying an statistical approach.

This reconstruction exhibit a water level regular oscillating pattern of about 45 years. Also it was compared with the instrumental record with a high degree of similitude for the period 1900 - 1940, whereas for the 1941 - 1976 such correlation is less conspicuous.

The first results suggest that the water level oscillations of the Caspian Sea - KaraBogaz Gol lacustrine system are mainly controlled by climate oscillations. From 1941, the anthropogenic management (with the first large scale irrigation plans in the Central Asia region and the regulation of the Volga river) would modify the natural trend.

Date received: July 26, 2002

Copyright © 2002 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caji-48.