5-6 Linking rock glacier motion to water output using InSAR and field hydrology

Session: Advances in Mountain Hydrology: Connecting Cryosphere, Surface, and Subsurface Processes

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Abstract:

Rock glaciers serve as important ice reservoirs in semi-arid mountainous regions, modulating outlet stream discharge and temperature. East-central Idaho hosts dozens of rocks glaciers that yield persistent discharge through the warm and dry summer-fall seasons. This project builds upon a continuing stream monitoring program to explore potential correlations between rock glacier velocity and hydrologic output by combining InSAR-derives rock glacier velocities with stream monitoring data. Dickey Peak stream has been continuously monitored since June 2023 for discharge, temperature, and specific electrical conductivity, and 6 other rock-glacier streams have been monitored for either one or two summer seasons. We predict a faster flowing rock glacier must contain sufficient ice content to produce a colder, more consistent stream throughout the summer-fall season. 

Seven rock glaciers in the Pioneer and Lost River Ranges have been analyzed with InSAR data spanning 2015-2025 and have been monitored hydrologically since June 2025 -- in some cases building on previous years’ monitoring. Rock glaciers with persistent stream discharge and temperature, coupled with robust ice-flow landforms, generally exhibit faster InSAR velocities. Initial analysis suggests slow to no motion in the winter, with the majority occurring in the summer months. Faster-moving rock glaciers (>4cm/yr), such as those at Dickey Peak, Mt. Howard, and Cobb Peak sustain cold, persistent streams throughout the summer. Moose Lake and Burnt Creek rock glaciers show very little motion (<1cm/yr), and their streams display waning discharge and warming temperature through the dry season. 

The Dickey Peak rock glacier stream flows through the dry season and remains very cold without only minor fluctuation (<3°C). In 2023 the stream stabilized at 230 L/s in mid-June and remained relatively constant through mid-September. Cedar Creek (3.6x basin area), a nearby non-rock glacier stream, declined from 550 to 300 L/s in the same period. Dickey Peak rock glacier stream had an average increase of 1.4°C while Cedar Creek warmed an average of 6.5°C. Because of these characteristics, we predict that this rock glacier contains internal ice that controls discharge and temperature of the stream while deforming and flowing downhill. Similar hydrologic patterns have been observed at six nearby rock glaciers streams, indicating the presence of stored ice. These initial findings suggest that InSAR may be useful in predicting the hydrology of rock glacier streams.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10861

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