COASTAL EROSION REVEALS PERMAFROST AT KAKTOVIK ALASKA.

KAKTOVIK

KAKTOVIK ALASKA• Located on the northern coast of Alaska in

the Arctic National Wildlife Reserve.• Populated by 293 people (2000) where

the main employment is in services with scientific research and tourism providing additional income to the community.

• Subsistence hunting of marine and land animals is an important source of food to the people of Kaktovik.

• The decline in shore fast ice has allowed the increased erosion of the coast.

• Coastal erosion threatens the viability of the airport which is the main link with the rest of Alaska. A 2006 report by the U.S. Army Corp of Engineers' suggests that it would cost $40 million to relocate the airport to a more secure site. © c. D’Agorne

Exposed cliff showing permafrost features.

Active layer

Ice wedge

Permafrost layer© C.D’Agorne

PERMAFROST TERMSActive layer. This layer freezes during the winter allowing water to trickle down when the soil thaws during the short summer season. Ice wedge. The trickling water freezes in the spaces created. Successive freeze thaw action enlarges these spaces in the soil allowing the eventual creation of permafrost features such as pingos and sinking ground.Permafrost. Defined as a situation where the soil, gravel or rock temperature of the ground does not rise above 0⁰c for more than two years.

Can you identify the permafrost features revealed by the picture of an eroded cliff at Kaktovik Alaska?

© C. D’Agorne

DEALING WITH PERMAFROST.

Permafrost is a constant issue for any structures that are built in Arctic locations such as the school in Kaktovik Alaska or a new office in Anadyr Chukotka. This leads to damage and extra infrastructure costs. Suggest what measures an engineer might have to consider when building the following.a. Housingb. Roadsc. Oil or gas pipelinesd. Schoolse. Airports

©R. Casey

© C. D’Agorne