THE CONTRIBUTION OF SHORE THERMOABRASION TO THE LAPTEV SEA SEDIMENT BALANCE F.E. Are Petersburg State University of Means of Communications, Moskovsky av. 9, St.-Petersburg, 190031, Russia e-mail:
[email protected] Abstract A schematic map of Laptev Sea shore dynamics is compiled for the first time, using available published data. It shows the distribution of thermoabrasion shores, mean long-term shore retreat rates, and areas of seabed ero- sion and accretion. The amount of sediment released to the sea from the 85 km Anabar-Olenyok section of the coast is calculated, as an example, at 3.4 Mt/year. These results are compared with published data on sediment transport of rivers running into the Laptev Sea. Estimates of the Lena River discharge range from 12 to 21 Mt/year, of which only 2.1 to 3.5 Mt may reach the sea. The analysis shows that the input of thermoabrasion at mean shoreline retreat rates of 0.7 to 0.9 m/year is at least of the same order as the river input and may great- ly exceed it. Introduction ble to determine the input from shore thermoabrasion offshore more accurately. Thousands of kilometres of Arctic sea coast retreat at rates 2-6 m/year under the action of thermoabrasion1 Maps of shore dynamics are needed to solve this (Are, 1985; Barnes et al., 1991). Tens of square kilome- problem and others related to climate change impacts. tres of Arctic land therefore are consumed by the sea Such maps have been compiled for about 650 km of every year.