Marcia Phillips

Mountain permafrost: development and challenges of a young research field

An overview is given of the relatively short history, important issues and primary challenges of research on permafrost in cold mountain regions. The systematic application of diverse approaches and technologies contributes to a rapidly growing knowledge base about the existence, characteristics and evolution in time of perennially frozen ground at high altitudes and on steep slopes. These approaches and technologies include (1) drilling, borehole measurement, geophysical sounding, photogrammetry, laser altimetry, GPS/SAR surveying, and miniature temperature data logging in remote areas that are often difficult to access, (2) laboratory investigations (e.g. rheology and stability of ice– rock mixtures), (3) analyses of digital terrain information, (4) numerical simulations (e.g. subsurface thermal conditions under complex topography) and (5) spatial models (e.g. distribution of permafrost where surface and microclimatic conditions are highly variable spatially). A sound knowledge base and improved understanding of governing processes are urgently needed to deal effectively with the consequences of climate change on the evolution of mountain landscapes and, especially, of steep mountain slope hazards as the stabilizing permafrost warms and degrades. Interactions between glaciers and permafrost in cold mountain regions have so far received comparatively little attention and need more systematic investigation.

First results of investigations on hydrothermal processes within the active layer above alpine permafrost in steep terrain

The aim of this study is to obtain a better understanding of the interactions of hydrological and thermal processes in the active layer of alpine permafrost in steep terrain with coarse-grained blocky surface material. Specially developed measuring equipment was installed in the active layer of a steep scree slope above Pontresina on Muot da Barba Peider, in the Upper Engadin, Switzerland, to determine ground temperatures, heat flux, water infiltration rate, soil water contents, surface level of the saturated zone, electrical water conductivity, vapour flux and downslope displacement. In addition, meteorological parameters such as air temperature and snow depth were measured. First results obtained during a thawing period showed that hydrological and thermal parameters in the ground, slope stability and meteorological parameters are closely correlated in time. An instantaneous increase in ground temperature is caused by the non-conductive heat transfer mechanisms of water convection and release of latent heat due to phase change of infiltrated snow meltwater. Downslope displacement also begins simultaneously, during meltwater infiltration, and can be ascribed to the presence of excess water in the ground. These are the first hydrothermal investigations that have been effected in a steep, coarse-grained active layer above alpine permafrost.

THERMAL REGIME OF ROCK AND ITS RELATION TO SNOW COVER IN STEEP ALPINE ROCK WALLS: GEMSSTOCK, CENTRAL SWISS ALPS

Abstract Snow cover influences the thermal regime and stability of frozen rock walls. In this study, we investigate and model the impact of the spatially variable snow cover on the thermal regime of steep permafrost rock walls. This is necessary for a more detailed understanding of the thermal and mechanical processes causing changes in rock temperature and in the ice and water contents of frozen rock, which possibly lead to rock wall instability. To assess the temporal and spatial evolution and influence of the snow, detailed measurements have been carried out at two selected points in steep north‐ and south‐facing rock walls since 2012. In parallel, the one‐dimensional energy balance model SNOWPACK is used to simulate the effects of snow cover on the thermal regime of the rock walls. For this, a multi‐method approach with high temporal resolution is applied, combining meteorological, borehole rock temperature and terrain parameter measurements. To validate the results obtained for the ground thermal regime and the seasonally varying snowpack, the model output is compared with near‐surface rock temperature measurements and remote snow cover observations. No decrease of snow depth at slope angles up to 70° was observed in rough terrain due to micro‐topographic structures. Strong contrasts in rock temperatures between north‐ and south‐facing slopes are due to differences in solar radiation, slope angle and the timing and depth of the snow cover. SNOWPACK proved to be useful for modelling snow cover–rock interactions in smooth, homogenous rock slopes.

Rock slope failure in a recently deglaciated permafrost rock wall at Piz Kesch (Eastern Swiss Alps), February 2014

In February 2014, a rock pillar with a volume of around 150 000 m collapsed at Piz Kesch in the Eastern Swiss Alps. A reconstruction of the conditions prior to the event and of the event itself is presented on the basis of different sources of data. The methods applied include photogrammetry, terrestrial laser scanning, structural geological analysis, examination of meteorological data, carbon-14 (C) dating of organic material in permafrost ice from a tension crack and numerical modelling of likely modes of failure. Despite a complete lack of in situ measurements in the rock wall prior to the event and of direct observations during the event, the available data allow the determination of the approximate timing of the event as well as the structural predisposition, the probable mode of failure and the timescale of several millennia involved in the triggering of the failure of the rock pillar. The interdisciplinary analysis of this event contributes towards understanding the complex interaction of processes involved in large rock slope failures currently occurring in warming mountain permafrost regions. Copyright

Remote and Terrestrial Ground Monitoring Techniques Integration for Hazard Assessment and Prediction in Densely Populated Mountain Areas

The uncertainty related to disasters generated by climate change and anthropogenic modifications of the environment adds yet another challenge for the decision makers, in terms of strategies, regulations and technologies adopted for protecting the communities without limiting their development and increasing their resilience to natural hazards. In mountain regions the choice of appropriate sites for infrastructure such as roads, railways, cable cars or hydropower dams is often very limited. In parallel, the increasing demand for supply infrastructure induces a continuous transformation of the territory. The new role played by the precautionary monitoring in the risk governance becomes fundamental and may overcome the modeling of future events, which represented so far the predominant approach to these sort of issues. The monitoring carried out by radar satellite systems represents, for practicability, resolution and cover, a good solution for keeping under observation extensive areas affected by hydrogeological instability. On the other hand, satellite remote sensing needs to be corroborated by terrestrial measurements particularly in the case they are used to evaluate an increasing of the deformation trend for community protection. Basing on the experience of European Projects as SAFER (http://www.ecmwf.int/research/EU_projects/SAFER) and SAFELAND (http://www.safeland-fp7.eu), the Interreg funded project SloMove aims to structure and consolidate methodologies in order to integrate differential interferometry technique with most common terrestrial technologies as D-GPS and Terrestrial Laser Scanning for monitoring slow mass movements. Within the project, the partnership has identified two test sites located between 2,500 and 3,000 m of altitude, in South Tyrol, Italy, and Grisons Canton, Switzerland.