Pathways of ice-wedge degradation in polygonal tundra under different hydrological conditions
<p>Ice-wedge polygons are common features of lowland tundra in the continuous permafrost zone and prone to rapid degradation through melting of ground ice. There are many interrelated processes involved in ice-wedge thermokarst and it is a major challenge to quantify their influence on the...
Main Authors: | , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2019-04-01
|
Series: | The Cryosphere |
Online Access: | https://www.the-cryosphere.net/13/1089/2019/tc-13-1089-2019.pdf |
Summary: | <p>Ice-wedge polygons are common features of lowland tundra in the continuous
permafrost zone and prone to rapid degradation through melting of ground ice.
There are many interrelated processes involved in ice-wedge thermokarst and
it is a major challenge to quantify their influence on the stability of the
permafrost underlying the landscape. In this study we used a numerical
modelling approach to investigate the degradation of ice wedges with a focus
on the influence of hydrological conditions. Our study area was Samoylov
Island in the Lena River delta of northern Siberia, for which we had in situ
measurements to evaluate the model. The tailored version of the CryoGrid 3
land surface model was capable of simulating the changing microtopography of
polygonal tundra and also regarded lateral fluxes of heat, water, and snow.
We demonstrated that the approach is capable of simulating ice-wedge
degradation and the associated transition from a low-centred to a
high-centred polygonal microtopography. The model simulations showed
ice-wedge degradation under recent climatic conditions of the study area,
irrespective of hydrological conditions. However, we found that wetter
conditions lead to an earlier onset of degradation and cause more rapid
ground subsidence. We set our findings in correspondence to observed types of
ice-wedge polygons in the study area and hypothesized on remaining
discrepancies between modelled and observed ice-wedge thermokarst activity.
Our quantitative approach provides a valuable complement to previous, more
qualitative and conceptual, descriptions of the possible pathways of
ice-wedge polygon evolution. We concluded that our study is a blueprint for
investigating thermokarst landforms and marks a step forward in understanding
the complex interrelationships between various processes shaping ice-rich
permafrost landscapes.</p> |
---|---|
ISSN: | 1994-0416 1994-0424 |