Hydrometeorological and Topographic Controls on Rock Glacier Kinematics: A Case Study From Southeastern Alaska

Abstract

Rock glacier kinematics are indicators of alpine climate change, yet the relative influence of thermal and hydrological processes on their motion remains poorly constrained. This uncertainty limits our ability to predict how these permafrost landforms will respond to ongoing climate change. Here, we present a mechanistic case study of seven active rock glaciers in Wrangell–St. Elias National Park, Alaska (USA) was selected to span contrasting aspects, snow insulation, and kinematic behavior. Using multi-temporal Sentinel-1 interferometric synthetic aperture radar (InSAR) data from 2018 to 2022, we derived high-resolution (∼30 m) velocity maps and deformation time series by combining ascending and descending observations and assuming predominantly downslope motion. Independent Component Analysis (ICA) was applied to separate long-term trends from seasonal signals, enabling the characterization of deformation components associated with environmental forcing. We then quantified the water infiltration effects by estimating hydraulic conductivity from the observed lag times between snowmelt and seasonal deformation peaks. Subsurface thermal regimes were simulated using the CryoGrid land surface and permafrost model. Results reveal that rock glaciers with greater solar radiation and warmer subsurface conditions exhibit enhanced meltwater infiltration and stronger seasonal deformation, while colder, shaded sites remain relatively stable. This combined InSAR, ICA, hydraulic, and thermal analysis highlights how hydrological and thermal controls govern spatial variability in rock glacier kinematics, offering insights into the sensitivity of permafrost landforms to ongoing climate change.