Resolving the influence of climatic forcing on rock glacier dynamics: a numerical modelling approach

In the past decades, seasonal and inter-annual variability in rock glacier flow has been observed (e.g. Haeberli, 1985; Arenson, 2002). Temperature forcing and liquid water have been proposed as key processes to explain these variations in kinematics (among others: Ikeda, 2008; Wirz et al., 2016). Numerical modelling studies exist to investigate rock glacier flow (e.g. Kääb et al., 2007; Müller et al., 2016; Monnier and Kinnard, 2016). However, the relative influence of the identified climatic forcing on rock glacier dynamics has not yet been quantitatively assessed against real-world data.

We investigate rock glacier flow variability by designing 1-dimensional numerical models that couple climatic forcing to different creep relations, including heat conduction and subglacial hydrology. We compare the modelling with borehole temperatures and surface velocity measurements from several sites of the PERMOS and PermaSense monitoring networks. We find that velocity variations cannot be explained from the influence of temperature on rock glacier rheology alone. Coupling variations in water input to a water pressure dependent creep relation, we are able to reproduce the observed velocity variations both in magnitude and temporal pattern over time scales from several months to several years.