Determining the terrain characteristics related to the surface expression of subsurface water pressurization in permafrost landscapes using susceptibility modelling
Warming of the Arctic in recent years has led to changes in the active layer and uppermost permafrost. In particular, thick active layer formation results in more frequent thaw of the ice-rich transient layer. This addition of moisture, as well as infiltration from late season precipitation, res...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-06-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/11/1403/2017/tc-11-1403-2017.pdf |
| Summary: | Warming of the Arctic in recent years has led to changes in the
active layer and uppermost permafrost. In particular, thick active layer
formation results in more frequent thaw of the ice-rich transient layer. This
addition of moisture, as well as infiltration from late season precipitation,
results in high pore-water pressures (PWPs) at the base of the active layer
and can potentially result in landscape degradation. To predict areas that
have the potential for subsurface pressurization, we use susceptibility maps
generated using a generalized additive model (GAM). As model response
variables, we used active layer detachments (ALDs) and mud ejections (MEs),
both formed by high PWP conditions at the Cape Bounty Arctic Watershed
Observatory, Melville Island, Canada. As explanatory variables, we used the
terrain characteristics elevation, slope, distance to water, topographic
position index (TPI), potential incoming solar radiation (PISR), distance to
water, normalized difference vegetation index (NDVI; ME model only), geology,
and topographic wetness index (TWI). ALDs and MEs were accurately modelled in
terms of susceptibility to disturbance across the study area. The
susceptibility models demonstrate that ALDs are most probable on hill slopes
with gradual to steep slopes and relatively low PISR, whereas MEs are
associated with higher elevation areas, lower slope angles, and areas
relatively far from water. Based on these results, this method identifies
areas that may be sensitive to high PWPs and helps improve our understanding
of geomorphic sensitivity to permafrost degradation. |
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| ISSN: | 1994-0416 1994-0424 |