Modeling study of talik freeze‐up and permafrost response under drained thaw lakes on the Alaskan Arctic Coastal Plain

Abstract

Numerical simulations were conducted to investigate the long‐term impact of thaw lake drainage on the thermal regime of ground under and around drained thaw lakes on the Alaskan Arctic Coastal Plain. The numerical model used in this study is a two‐dimensional unsteady finite element model for heat transfer with phase change under a cylindrical coordinate system. The initial conditions are the simulated ground thermal regime and talik thickness data at year 3000 under a thaw lake with long‐term mean lake bottom temperatures of 1.0, 2.0, and 3.0°C near Barrow, Alaska. The simulated results indicate that lake drainage leads to a rapid freeze‐up of talik and a substantial decrease in permafrost temperatures under the former lake bottom. The initial ground temperature conditions have significant influence not only on the talik freeze‐up time, but also on the permafrost temperature decrease processes. After thaw lake drainage, taliks with thicknesses of 28, 43, and 53 m under the lake will freeze‐up completely by 40, 106, and 157 years, and the corresponding ratios of upward and downward freeze‐up depths for the three simulation cases are 1: 8.0, 1: 7.6, and 1: 6.1, respectively. After completion of talik freeze‐up, permafrost temperatures still decreased with time and gradually reached a relatively stable value, depending on the initial ground temperature and the distance to the former lake bottom.