Abstract
Climate change is driving disturbance in hydrology and geomorphology in
terrestrial polar landscapes underlain by permafrost, yet measurements
of, and theories to understand, these changes are limited. Water flowing
from permafrost hillslopes to channels is often modulated by water
tracks, zones of enhanced soil moisture in unchannelized but curvilinear
depressions that concentrate water flow downslope. Water tracks, which
dominate hillslope hydrology in some permafrost landscapes, lack a
consistent definition and identification method, and their global
occurrence, morphology, climate relationships, and geomorphic roles
remain understudied. We combine a literature review with a synthesis of
prior work to identify uniting and distinguishing characteristics
between water tracks from disparate polar sites with a toolkit for
future field and remotely sensed identification of water tracks. Then,
we place previous studies within a quantitative framework of
“top-down” climate and “bottom-up” geology controls on track
morphology and hydrogeomorphic function. We find that the term “water
track” is applied to a broad category of concentrated suprapermafrost
flowpaths that exhibit varying morphology, degrees of self-organization,
hydraulic characteristics, subsurface composition, vegetation,
relationships to thaw tables, and stream order/hillslope position. We
propose that the widespread occurrence of water tracks on both poles
across varying geologic, ecologic, and climatic factors implies that
water tracks are in dynamic equilibrium with the permafrost environment
but that they may transition as the climate continues to warm. Current
knowledge gaps include these features’ trajectories in the face of
ongoing climate change and their role as an analog landform for an
active Martian hydrosphere.