Permafrost Terrain Stability and Thermokarst Monitoring: - Arctic LCC

90. Lin, Z., Niu, F., Xu, Z., Xu, J., and Wang, P., 2010, Thermal regime of a thermokarst
lake and its influence on permafrost, Beiluhe Basin, Qinghai-Tibet Plateau. Permafrost
and Periglacial Processes, p. 21, no. 4, p. 315–324.
This paper examined the spatial distribution of permafrost under and around a thermokarst
lake, and monitored lakeshore retrogression. Eighty percent of the shoreline collapsed each
year, with most of the collapse occurring in the late summer. Thaw depths were greater on
the lakeshore relative to the surrounding terrain, and there appeared to be a through-going
talik in the lake bottom. The lake bottom temperature ranged from 2 to 10°C, and the warm
lake created a large thaw bulb and thermal signature that could be detected in the subpermafrost
ground many tens of meters from the lake edge.
91. Ling, F., and Zhang, T., 2004, Modeling study of talik freeze-up and permafrost
response under drained thaw lakes on the Alaskan Arctic Coastal Plain: Journal of
Geophysical Research, v. 109, no. D1, D01111.
This paper presents a heat transport model to calculate the time needed for the talik beneath
a lake to refreeze following lake drainage. Three initial ground temperature conditions were
considered, and taliks of 28, 43, and 53 m thickness were determined to refreeze in 40, 106,
and 157 years, respectively. Refreezing is slowed significantly by the latent heat of fusion
needed to change water from a liquid to solid form. The authors recognized that a model
also capable of handling advective heat transport owing to the flow of water in the talik
would result in a more accurate result.
92. Ling, F., Wu, Q., Zhang, T., and Niu, F., 2012, Modelling open talik formation and
permafrost lateral thaw under a thermokarst lake, Beiluhe Basin, Qinghai Tibet
Plateau: Permafrost and Periglacial Processes, v. 23, no. 4, p. 312–321.
This paper uses a two-dimensional unsteady finite-element model with heat transfer and
phase change to model talik formation in a study lake. Thermokarst lakes constitute a major
heat source capable of raising ground temperatures in the surrounding terrain, and the
greatest mean thaw rate (24.8 cm/y) occurred within the first 50 years after lake formation,
93. Little, J.D., Sandall, H., Walegur, M.T., and Nelson, F.E., 2003, Application of
differential global positioning systems to monitor frost heave and thaw settlement in
tundra environments: Permafrost and Periglacial Processes, v. 14, no. 4, p. 349–357.
This paper describes the use of differential Global Positioning Systems (DGPS) for
monitoring seasonal and annual frost heave and thaw settlement on the Arctic Coastal Plain
of northern Alaska. The authors developed acrylite (durable lightweight plastic), tubeshaped
platform targets with a prong-like bottom. The targets were about 20 cm long and 2.5
cm in diameter. The targets were installed towards the end of the thaw season. The time
required to make measurements at the targets varied from less than 1minute for stop-and-go
kinematic to more than 10 minutes for rapid static DGPS survey mode. Using the rapid
static configuration, the authors surveyed a field site composed of 30 targets using the rapid
static survey method in 5–8 hours with a vertical error of about 1.5 cm. When these surveys
were repeated within and among years, the authors measured about 1–2 cm of heave
associated with the freeze-up period and 4–5 cm of subsidence at the time of maximum
summer thaw. The advantages of DGPS include great accuracy and automatic placement of
surveys within well-established geodetic coordinate systems. Drawbacks involve high costs,
target reinsertion difficulties, and physical demands. DGPS entails significant time
requirements compared to traditional leveling techniques when surveying small areas.
However, DGPS has the potential to measure large regions much more rapidly than classical
methods.
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