Ice gouging topography on the Caspian and Aral seas bottom

Abstract

Ice gouging is a destructive mechanical impact of ice on the underlying ground surface associated with ice cover dynamics, ice hummocking (ridging) and formation of grounded hummocks (stamukhas) under hydrometeorological factors and coastal topography. Ice scours in the Northern Caspian Sea were discovered in 1950s, but ice gouging processes were taken into consideration only in 2012, when the accident on Kashagan gas field (Kazakhstan) occurred. Recently we found ice scours on the dried bottom of the Aral Sea. Ice gouging microrelief on the Caspian seabed was researched using specialized geophysical equipment — side-scan sonar and multibeam sounding. We have a unique opportunity to study ice scours on the Aral Sea dried bottom by direct methods, but now they are observed only by remote sensing technologies. When sea level is not stable the most intensive gouging takes place on the depths from 2 to 5 m. Ice scours are widespread on the Caspian and Aral seabed because their level was significantly changing during XX century. Climatic changes and anthropogenic influence can cause changes in conditions of ice scour formation. Studying of the ice scours parameters on the Aral Sea dried bottom has a great economic and fundamental importance for comprehension of ice gouging conditions and intensity in shallow freezing seas and big lakes.