Abstract. The quantification of volumetric ice and water content in active rock
glaciers is necessary to estimate their role as water stores and
contributors to runoff in dry mountain catchments. In the semi-arid to arid
Andes of Argentina, active rock glaciers potentially constitute important
water reservoirs due to their widespread distribution. Here however, water
storage capacities and their interannual changes have so far escaped
quantification in detailed field studies. Volumetric ice and water content
was quantified using a petrophysical four-phase model (4PM) based on
complementary electrical resistivity tomography (ERT) and seismic refraction
tomography (SRT) in different positions of the Dos Lenguas rock glacier in the
upper Agua Negra basin, Argentina. We derived vertical and horizontal
surface changes of the Dos Lenguas rock glacier, for the periods 2016–2017
and 2017–2018 using drone-derived digital elevation models (DEMs). Interannual
water storage changes of −36 mm yr−1 and +27 mm yr−1
derived from volumetric surface changes for the periods 2016–2017 and
2017–2018, respectively, indicate that significant amounts of annual
precipitation can be stored in and released from the active rock glacier. Geophysical results show heterogeneous ice and water content with ice-rich
permafrost and supra-, intra- and sub-permafrost water pathways at the end
of the thaw period. Active layer and ice-rich permafrost control traps and
pathways of shallow groundwater and thus regulate interannual storage
changes and water releases from the active rock glaciers in the dry mountain
catchment. The ice content of 1.7–2.0 × 109 kg in the active
Dos Lenguas rock glacier represents an important long-term ice reservoir, as
do other ground ice deposits in the vicinity, if compared to surface ice
that covers less than 3 % of the high mountain catchment.
Excess topography measures for each grid cell in a digital elevation model (DEM) the rock-column height above an arbitrarily defined threshold slope surface. The threshold slope surface is an idealized
The quantification of rock glacier kinematics on a regional basis has gained increasing importance in recent years. Here, we applied an image tracking approach on high-resolution aerial imagery to infer surface kinematics of 129 mapped rock glaciers in the Kaunertal, Austrian Alps. We find significant surface movement for 30 features with mean velocities falling between 0.11 and 0.29 m yr−1 and a maximum of 1.7 m yr−1. Local analysis and comparison to earlier studies reveals significant increases in rock glacier velocities in the study area. From the rock glacier inventory and high-resolution digital topography, we computed a series of morphometric parameters to analyze potential controls on rock glacier creep and to predict rock glacier activity using random forests and logistic regression models. The results point towards a stronger dependence of velocities on parameters describing general inclination, potentially acting as proxies for internal rock glacier properties, while activity states seem to be regulated mainly by rock glacier dimensions and topoclimate. Using a parameter subset, we successfully separated active from inactive rock glaciers with accuracies of up to 77.5%, indicating a promising approach to predict rock glacier activity solely relying on parameters that can be derived from regionally available data sets.
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