Ninth International Conference on Permafrost ... - IARC Research

Permafrost Characteristics and Climate Change Consequencesat Stockhorn and Gornergrat (Swiss Alps)IntroductionClemens Constantin Maag, Oliver Wild, Lorenz KingJustus-Liebig-University Giessen, GermanyMartin Baum, Sebastian Klein, Christin HilbichFriedrich-Schiller-University Jena, GermanyThe Stockhorn-Gornergrat tourist area is of high interestfor the study of mountain permafrost and aspects of climatechange. Within the EU-project PACE, a 100 m deep drillinglocated at 3405 m a.s.l. points to a permafrost thickness ofabout 170 m at the Stockhorn Plateau. Since then, longtermmonitoring of the bedrock and permafrost conditionsstarted. A reorganization of the ski region due to changedtourist expectations led to both new ski slopes and cablecar connections. The necessary construction work providesthe opportunity for new findings of the existing permafrostconditions. Stockhorn qualifies as a salient research area, asit is only marginally affected by the tourist industry yet iswithin the well-examined Zermatt research area, and only10 km by airline from Kleinmatterhorn (3883 m a.s.l.) (Kinget al. 2008). These conditions allow observation of climaticdevelopments due to climate change and constructionmeasures.Alpine Natural Hazards at GornergratClimate change and accompanying effects like risingtemperatures have created new alpine phenomena anddangers. Avalanches, rockfalls and water inclusionsmay appear more often due to the steady warming of theatmosphere. In 2003, the rise of temperatures resulted inpermafrost thaw and exceptional rockfalls (Gruber et al2004b). As further research projects showed, characteristicsof rock walls and their temperature depend not only on thequality of solar radiation and air temperature, but also ontheir topographic distribution (Gruber et al. 2004).As the Stockhorn and Gornergrat are highly frequented bylarge numbers of tourists and skiers, the characteristics ofthis area must be constantly monitored.Ground Ice at KelleThe area Kelle at the northern slopes of the east–westrunning Gornergrat crest (3135 m) and Hohtälli (3286m a.s.l.) is well known for its permafrost occurrences.Visible indicators are rock glaciers and perennial snowpatches. Scientific studies consisted of measurements ofground temperatures and BTS values (Philippi 2003) andthe development of permafrost models (Gruber 2000).In summer 2007, excavation work for a new ski run anda culvert system for artificial snow was carried out, andground ice was exposed at various sites. The new ski runhas a length of 2.5 km and 300 m altitudinal difference, andFigure 1. Ground ice of the rock glacier with water conduit forartificial snow production (lower right).crosses rock glaciers and rock glacier-like features. Nearsurfacetop layers were removed down to a depth of 8 to 10m at some places. This offered the rare opportunity to have alook inside these features. The excavation was accompaniedthroughout 2007 by researchers of different universities.Geophysical measurements were carried out (Hilbich et al.2007), ice samples taken, and the course of the ski tracksurveyed (Giessen, Zurich). Melting of the ground ice wasalready observed during the construction period.Geophysical AnalysesIn order to observe climate-related permafrost degradation,a fix ERT monitoring system was installed at the Stockhornplateau in summer 2005 (Hilbich et al. 2008) in close cooperationwith the PERMOS network (Permafrost MonitoringSwitzerland). It enables regular (preferably seasonal) semiautomaticmeasurements of the apparent electrical resistivityof the ground. The ERT section consists of 55 electrodeswith a spacing of 2 m, resulting in a length of 108 m in total.The vertical penetration depth is about 20 m.Figure 2 shows the computed results of an ERTmeasurement made in September 2007. The position ofthe PACE boreholes are marked; however they may have alateral offset of about 10 m to the ERT line.In addition, the electrode array was complemented by acoinciding fix transect for refraction seismic monitoring insummer 2007. For the refraction seismic monitoring, oneshort (2 m spacing) and one long (4 m spacing) section with24 geophones each were installed to account for both highspatial resolution (at a length of 46 m) and extension acrossthe whole ERT line (96 m).195