Abstract Volume6th Swiss Geoscience MeetingLugano, 21st – 23rd November 2008

Apply!Geosciences

6th Swiss Geoscience Meeting 2008 - Lugano6th Swiss Geoscience Meeting 2008 - Lugano

Institute of Earth Sciences

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gy 6. Apply! Snow, ice and Permafrost Science +

Geomorphology (Open Session)M. Hoelzle, A. Bauder, B. Krummenacher, C. Lambiel, M. Lüthi, M. Phillips, J. Schweizer, M. Schwikowski + M. Bollschweiler, G. R. Bezzola, R. Delaloye, C. Graf., N. Kuhn, E. Reynard

Swiss Snow, Ice and Permafrost Society + Swiss Geomorphological Society

6.1 BauderA.&HussM.:Longtermpointobservationsofseasonalmassbalance:akeytounderstanding20thcenturyclimatechange

6.2 BodinX.,SchoeneichP.,LhotellierR.,GruberS.,DelineP.,RavanelL.,MonnierS.:AfirstassessmentofthepermafrostdistributionintheFrenchAlps

6.3 CaprezJ.,MaischM.,vonPoschingerA.:TheFlimsRockslide-3DterrainmodellingandvolumecalculationswithGISapplication

6.4 ChampagnacJ.-D.,SchluneggerF.,NortonK.,vonBlanckenburgF.,AbbühlL.,SchwabM.:Erosion-drivenupliftofthemodernCentralAlps

6.5 DarmsG. &HoelzleM. : First results of firn temperaturemeasurements in 2008 on Colle Gnifetti,Monte Rosa,Switzerland

6.6 FierzC.&LehningM.:Snowtemperatures:measurementandmodelling

6.7 FischerL.,EisenbeissH.,KääbA.,HuggelC.,HaeberliW.:CombinedLiDARandphotogrammetryforstability-relatedchangedetectioninglacierisedandfrozenrockwalls-AcasestudyintheMonteRosaeastface

6.8 FontanaG.,ScapozzaC.,ReynardE.:LateglacialglacierevolutionoftheGreinaregion(CentralSwissAlps)

6.9 FontanaG.,ScapozzaC.,ReynardE.:GeomorphologicalmapoftheGreinaregion(CentralSwissAlps)

6.10 FoppaN.,SeizG.,WalterspielJ.:ObservationoftheCryosphere–Switzerland’scontributiontotheGlobalClimateObservingSystemGCOS

6.11 FreiE.,HeggliM.,SchneebeliM.:Replicamethodforthree-dimensionalX-raymicrotomographicimagingofsnow

6.12 FreyH.,BusarelloC.,FrauenfelderR.,HaeberliW.,HoelzleM.,MayB.,RauS.,WagenbachD.,WagnerS.:TheiceridgeatMurtèl/Corvatsch:Studyinga(c)oldarchive

6.13 HauckC.&HilbichC.:Applicationofoperationalgeophysicalmonitoringsystemsonalpinepermafrost

6.14 HeggliM.,KöchleB.,PinzerB.,SchneebeliM.: Thermalconductivityofsnow:Howtofindabetterparameterisati-on?

6.15 LambielC.,ScapozzaC.,PieracciK.,BaronL.,MarescotL.: Thermalandelectricalpropertiesofaperiglacial talusslope

6.16 LinsbauerA.,PaulF.,HoelzleM.,HaeberliW.:ModellingofglacierbedtopographyfromglacieroutlinesandDEMdatainaGIS

6.17 LüthiM.:Transientresponseofidealizedglacierstoclimatevariations

6.18 MorardS.&DelaloyeR.:Airflowvelocitymeasurementsinventilatedporousdebrisaccumulations

6.19 PaganoL.:InventoryofgeomorphositesofBavonaandRovanavalleys(Ticino)

6.20 ParisodJ.,SennC.,PfeiferH.-R.,VennemannT.:Evaluationdeseffetsdel’enneigementartificielsurlachimiedusolpar comparaison de l’effet de la neige naturelle, artificielle, avec et sans additif: Cas de Cran-Montana-Aminona,Valais,Suisse.

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6.21 PaulF.&HaeberliW.: Spatialvariabilityofglacierelevationchanges in theAlpsobtained fromdifferencing twoDEMs

6.22 PaulF.,KääbA.,RottH.,ShepherdA.,StrozziT.: GlobGlacier:AnewESAprojecttomaptheworld’sglaciersfromspace

6.23 PhillipsM.,ZenklusenMutterE.,Kern-LuetschgM.:Rapidpermafrostdegradationinducedbynon-conductiveheattransferwithinatalusslopeatFlüelaPass,SwissAlps.

6.24 RoerI.,HoelzleM.,HaeberliW.,KääbA.:RockglacierdynamicsintheSwissAlps–comparingkinematicsandthermalregimesintheMurtèl-Corvatschregion

6.25 ScapozzaC.,GexP.,LambielC.,ReynardE.:Electromagneticprospectinginalpinepermafrost:examplesfromtheSouthernSwissAlps

6.26 ScapozzaC.,MariS.,ValentiG.,StrozziT.,GexP.,FontanaG.,MüllerG.,LambielC.,DelaloyeR.,ReynardE.:PermafrostmapoftheEasternTicinoAlps

6.27 ThelerD.,BardouE.,ReynardE.: Conceptualisingsedimentcascadestoenhancedynamicgeomorphologicalmap-ping

6.28 WorniR.,PulgarínB.,AgudeloA.,HuggelC.:Glaciervolcanointeractionsandrelatedhazardsduringthe2007erup-tivecrisisatNevadodelHuila,Colombia

6.29 WüthrichC.,BegertM.,ScherrerS.C.,Croci-MaspoliM.,AppenzellerC.,WeingartnerR.:Analysesofnewlydigitisedsnowseriesoverthelast100years+inSwitzerland

6.30 ZenklusenMutterE.,PhillipsM.,BlanchetJ.:EvidenceofwarmingindisturbedandundisturbedpermafrostterrainatSchafberg(Pontresina,EasternSwissAlps)

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gy 6.1

Long term point observations of seasonal mass balance: a key to understanding 20th century climate change

BauderAndreasandHussMatthias

Versuchsanstalt für Wasserbau, Hydrologie and Glaziologie (VAW), ETH Zürich, Gloriastrasse 37-39, CH-8092 Zürich (bauder@vaw.baug.ethz.ch)

Pointobservationsofglaciersurfacemassbalanceatfixedlocationsdirectlyreflectclimaticvariationsandarenotbiasedbyuncertainspatialinterpolationofmassbalanceorthechangeinglaciersurfacearea.Thus,theyareconsideredtobethebestindicatorforchangesintheclimaticforcingonglaciers(Vincentandothers,2004;Ohmuraandothers,2007).Fourlongterm time series of seasonalmass balance observations (Fig. 1) at fixed locations have been compiled for two stakes onClaridenfirnandonestakeonGrosserAletschgletscherandSilvrettagletscher,Switzerland,allstartingin1914(HussandBauder,inpress).Thesedatarepresentthelongestseriesofdirectmassbalancemeasurementsworldwide.

Usingamassbalancemodelbasedonthetemperature-indexapproach,thefieldobservationsarecorrectedforvaryingdates,inconsistency,systematicerrorsanddatagaps.Theresultinghomogenizedcontinuous93-yeartimeseriesfromthethreeglacierscovermostofthe20thcenturyandenabletoinvestigatetemporal,regionalandaltitudinalvariabilityofmassba-lanceandfluctuationsintheclimaticforcingonglaciers.

Longtermvariationsinmassbalancearemainlydrivenbychangesinsummerablation.Threestakes(Clariden,Silvretta)locatedneartheequilibriumlinedisplaysignificantlylowersummerbalancesinthemid1960stomid1980s,whereasthehighaltitudesite (Aletsch)showsoppositetrends. Twoperiodsofenhancedclimaticforcingaredetected,1943-1953and1987-2007.Atallstakestheenergyconsumedformeltwashigherinthe1940sinspiteoflowerairtemperaturesthanduri-ngthelasttwodecades.

Figure1.Seasonalobservationsofpointbasednetandwinterbalancesince1914fromfoursitesintheSwissAlps.

REFERENCESHuss,M.andBauder,A.(inpress).Twentiethcenturyclimatechangeinferredfromfourlong≈termpointobservationsof

seasonalmassbalance.AnnalsofGlaciology,50.Ohmura,A.,Bauder,A.,≈Müller,H.andKappenberger,G.(2007).Long-termchangeofmassbalanceandtheroleofradiation,

AnnalsofGlaciology,46,367--374.Vincent,C.,Kappenberger,G.,Valla,F.,Bauder,A.,Funk,M.andLeMeur,E. (2004). Influenceofclimatechangeoverthe

20thCenturyonfourFrenchglaciermassbalances.GeophysicalResearchLetters,109,D10104.(10.1029/2003JD003857.)

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Towards a first assessment of the permafrost distribution in the French Alps

BodinX.*,SchoeneichP.*,LhotellierR.*,GruberS.**,DelineP.***,RavanelL.***,MonnierS.****

* Institut de Géographie Alpine, Université de Grenoble** Institut de Géographie, Université de Zurich*** EDYTEM, Université de Savoie**** Laboratoire de Géographie Physique, Université de Paris 12

Inmountainregions,permafrostisimportantforthegeomorphologyofhighaltitudesareasaswellforthewaterresourcesof inhabitedwatersheds.UnderthepresentGlobalWarming, thepossibledegradationofpermafrostduringthecomingdecadescouldhenceprovokevariouskindofslopeinstabilityandchangedrasticallythehydrologicalfunctioning(Kääbetal., 2006).Abetterunderstandingof thedistributionof thepermafrost is thereforeanecessaryprerequisite for furtheranalysisandmitigationofthosehazards.Aspermafrost is inmostcases invisibleand, thoughcovering largeareas, itsdistribution is largelyunknown.Extensivepermafrost “mapping” can be approached only through either empirical, statistical or physically based modelling(Riseboroughetal.,2008).PermafrostmapshavebeenproducedthiswayfortheSwissAlps.AsnosuchmapexistedyetfortheFrenchAlps,thispaperthusintendstopresentanoverviewofthemainavailabledatasetsonthepresenceofpermafrost,inrockfacesaswellwithindebrisaccumulations:inventoriesofgeomorphologicalindicators(rockglaciersandothercreepinglandformsrelatedtothepresenceofgroundice)andin-situmeasurements(BTS,geophysi-calsoundings…).Amongvarioustypesofavailablemodels,astatistico-empiricalonehasbeensetup:itisbasedontherelationbetweenthetwomostimportanttopoclimaticcontrols(solarradiationandairtemperature)oftherockglacierspresence.Thisrelationwascomputedonalithologically,geomorphologicallyandclimaticallyhomogeneoussmallmassif(CombeynotMassif,≈45°N,40km²)whichpresentsnumerousrockglaciersinvarioustopoclimaticcontexts(Bodin,2007).Twoversionsofthemodel,onefortherootofrockglaciers,onefortheirfrontalpart,havebeencombinedtoassessthepotentialpresenceofpermafrostintheentireFrenchAlps.Twovalidationprocedureshavebeenperformedusingindependentrockglaciersinventories:oneintheMercantourMassif(lat.≈44°N),oneintheVanoiseMassif(lat.≈45.5°N).Thecomparisonbetweentrainingsetandvalidationsetshowsagoodcorrespondenceofthealtitudeandaspectoftheactualrockglaciersandofthemodelledfrontandrootareas.Thosefirstresultsarethusencouragingastheyalreadyprovidetopublicandtodecision-makersusablenewinformationaboutperma-frostpresenceintheirterritory.Atfinescales(lowerthanthewatershed),moreinvestigationsareneverthelessnecessarytodetectandcharacterisepreciselythepermafrost,eitherindebrisaccumulationorinrock-face.

REFERENCESBodin,X.2007:Géodynamiquedupergélisoldemontagne:fonctionnement,distributionetévolutionrécente.L'exemple

dumassifduCombeynot(HautesAlpes).PhD,Geography,UniversityofParis-DiderotParis7,272p.Kääb,A.,M.Chiarle,B.Raup&C.Schneider.2006:Climatechangeimpactsonmountainglaciersandpermafrost.Global

andPlanetaryChange.Riseborough,D.W.,N. I.Shiklamonov,B.Etzelmüller,S.Gruber&S.S.Marchenko.2008:Recentadvances inpermafrost

modeling.PermafrostandPeriglacialProcesses19(2).

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Figure1.MapofthepotentialpermafrostdistributionintheFrenchAlps.

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The Flims Rockslide 3D terrain modelling and volume calculations with GIS-application

CaprezJürg*,MaischMax*,vonPoschingerAndreas**

* Geographisches Institut, Universität Zürich-Irchel, Winterthurerstr. 190, CH-8057 Zürich, (j.caprez@geo.unizh.ch), (max.maisch@geo.uzh.ch)** LfU, Lazarettstr. 67, D-80636 München, (Andreas.Poschinger@lfu.bayern.de)

TheFlimsrockslideistobeknownasthelargestmassmovementintheAlps.RecentstudiessupportthehypothesisofanearlyHoloceneageof thismega-eventby radiocarbondates centredaroundcal. 9450BP (Deplazes,Anselmetti&Hajdas2007).AtthatPreborealtimeclimatealreadyhaschangedtowarmerconditionsandthereforeareadvanceofthemainval-leyglacierofVorderrheinaswell as fromsmall local glaciers canbe excluded fromhaving reworked the rockslidearea(Poschingeretal.2006).Despiteofvariousnewfindingsuptonowthepaleogeographicframework,especiallytheformershapeofthepre-existingFlimsersteinispoorlyestablished.

Basedongeologicevidence (geol.maps,profiles) andgeomorphologic considerations (i.e. extrapolationof slopes) in thisstudyaneweffortwasmadetorebuildandreconstructtheformer3D-topographyoftheFlimsareawithinaGIS(GeographicInformation System). This approach allows to determinewith enhanced precision the dimensions of this extraordinaryrockslideeventandtorevealinmoredetailsthevariousprocessesinvolved.

The3Dterrainmodelsyieldedatotalvolumerangingfrom7km3upto7.3km3forthebreakoutzoneoftherockslide.Thevolumeofthedepositionzoneontheotherhandgave,accordingtodifferentscenarios,valuesbetween8.6km3to9.3km3.Inadditionabout1.5km3oftherockmasswaserodedlateronbytheVorderrheinriver.

DuringtheFlimsrockslidethepre-existingvalleyinfill,supposedlysaturatedcompletelybywater,wassqueezedoutandmobilised between Sagens and Bonaduz, subsequently being deposited as a special facies type, known as ”BonaduzerSchotter“(Abele1997).Approximately20percentofthealluvialvalleyfillwasevacuateddirectlybytheimpactoftherocks-lide.Accordingly,thedebrismassdoesnotreachthebasementoftheVorderrheinvalleybutseemstorestonalayerofrelictalluvialsediments.The3D-reconstructionsoftheFlimstopographyresultedalsoinmodellingformerlakeswiththeirmaxi-mumlevels,triggeredanddammedbytherockslideevent.Various3D-visualizationsofthestudyareacertainlywilllaunchfruitfuldiscussionsonthedynamics,theprocessesandthegeologicconsequencesofthisfamousFlimsevent.

REFERENCESAbele,G. 1997: Rockslidemovement supported by themobilisation of groundwater-saturated vally floor sediments.

ZeitschriftfürGeomorphologie,N.F.,41/1,1-20.Deplazes,G.,Anselmetti,F.&Hajdas, I.2007:Lakesedimentsdepositedon theFlimsrockslidemass: thekey todate the

largestmassmovementoftheAlps.TerraNova,Vol19,No.4,252–258.Poschinger,A.v.,WassmerP.&Maisch,M.2006:TheFlimsRockslide:Historyofinterpretationandnewinsights.In:Evans,

S.G.,Sacarascia-Mugnozza,G.,Strom,A.&Hermanns,R.L.(eds.),MassiveRockSlopeFailure.KluwerAcademicPublishers,341-369.

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Figure1:3D-reconstructedterrainsurfaceofthePre-Flimserstein.a)DigitalterrainmodeloftheFlimsrockslideareawiththeFlimserstein

inthebackgroundandthepartiallyerodedrockmassintheforeground.b)ReconstructionofthePre-FlimsersteinandtheVorderrhein

valleybeforetherockslideevent.

6.

Erosion-driven uplift of the modern Central Alps

ChampagnacJean-Daniel*,SchluneggerFritz**,NortonKevin*,vonBlanckenburgFriedhelm*,AbbühlLuca**&SchwabMarco**

* Institut für Mineralogie, Universitat Hannover, Callinstrasse 1, D-30167 Hannover, champagnac@gmail.com** Institute of Geological Sciences, University of Bern, Baltzerstrasse 1-3, CH-3012 Bern.

Wepresentacompilationoffoursetsofdataofmoderntectono-geomorphicprocessesintheCentralAlpsofSwitzerlandthatappeartosuggestthatrockupliftisaresponsetoclimate-drivendenudationintheabsenceofactiveconvergence.Theseare (1) basin-averaged LateHolocene denudation rates determined from cosmogenic nuclides and from suspended riverloads;theseslightlyexceed,butspatiallymimicthepatternofrockupliftratesasdeterminedbygeodeticleveling;(2)thegeodeticreferencepointisalsothegeomorphicbaselevelwithrespecttoerosion;wefurtherpresent(3)acompilationof

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ymodernplatemotionvelocitiesshowsthattherotationpoleoftheAdriaticplateislocatedwithinthearea,hencetheareaisnotunderconvergence;finally(4),weillustratethattheCentralAlpshaveactedasaclosedsystemforHolocenesedimentredistributionuptotheperi-AlpinelakeswhichhaveoperatedasasinkfortheerosionproductsoftheinnerAlps.WhileavarietyofhypotheseshavebeenputforwardtoexplaintheCentralAlpineuplift(e.g.lithosphericforcingbyconver-genceormantleprocesses;icemelting)weshowwithanumericalisostaticmodelthatthecorrelationbetweenerosionandcrustal uplift rates reflects a positive feedback between denudation and the associated isostatic response to unloading.Thereforeerosiondoesnotpassivelyrespondtoadvectionofcrustalmaterialasmightbethecaseinactivelyconvergingorogens.Otherforcesneedtobeconsideredtodrivesurfaceerosion.WesuggestthatthegeomorphicresponseoftheAlpinetopographytoglacialerosionandtheresultingdisequilibriumformodernchannelizedandassociatedhillslopeprocessesexplainsmuchofthepatternofmoderndenudationandhencerockuplift.Therefore,inanon-convergentorogensuchastheCentralEuropeanAlps,theobservedverticalrockupliftisprimarilyaconsequenceofpassiveunloadingduetoerosi-on.

REFERENCES:Anderson,H.andJackson,J.,1987.ActivetectonicsintheAdriaticregion.GeophysicalJournalRoyalAstronomicalSociety

91,937–983.Battaglia,M.,Murray,M.H.,Serpelloni,E.andBurgmann,R.,2004.TheAdriaticregion:Anindependentmicroplatewithin

theAfrica-Eurasiacollisionzone.GeophysicalResearchLetter31,L09605,doi:10.1029/2004GL019723.Calais,E.,Nocquet,J.,Jouanne,F.andTardy,M.,2002.CurrentstrainregimeintheWesternAlpsfromcontinuousGlobal

PositioningSystemmeasurements,1996–2001.Geology30,651-654.Norton, K.P., von Blanckenburg, F., Schlunegger, F., Schwab,M. and Kubik, P.W., 2008. Cosmogenic nuclide-based

investigation of spatial erosion and hillslope channel coupling in the transient foreland of the Swiss Alps.Geomorphology,95,474–486

Wittmann,H.,vonBlanckenburg,F.,Kruesmann,T.,Norton,K.P.,andKubik,P.,2007.Therelationbetweenrockupliftanddenudation fromcosmogenicnuclides in river sediment in theCentralAlpsof Switzerland. JournalofGeophysicalResearch-EarthSurface112,doi:10.1029/2006JF000729.

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First results of firn temperature measurements in 2008 on Colle Gnifetti, Monte Rosa, Switzerland

DarmsGian*,HoelzleMartin**

*Glaciology, Geomorphodynamics & Geochronology, Department of Geography, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (gian.darms@gmail.com)**Department of Geosciences, University of Fribourg, Chémin de Musée 4, CH-1700 Fribourg(martin.hoelzle@unifr.ch)

Attheendofthe19thcenturyandintothebeginningofthe20thcentury,itwasassumedthatallglaciersintheAlpsaretemperate,although(Vallot1893,1913)observedintheMontBlancareathatcoldfirnonhighaltitudemountaintopsiswidespread.Inthe1950s,Fisherpublishedseveralarticles(1953,1954,1955,1963)aboutcoldfirnobservationsintheMonteRosaareaasdidHaefeli&Brentani(1955)fortheJungfrauarea.Inthe1970s(Lliboutryetal.1976)and(Haeberli1976)werethefirstscientistswhosystematicallyinvestigatedthedistributionofcoldiceandfirnintheAlps.Inthelast20years,re-searchactivitieshavestartedtoincreaseinthecoldhigh-mountainaccumulationareasintheAlps,manystudieshavebeenundertakeninconnectionwithhazardsandcoredrillings(Aleanetal.1983,Böhlert2005,Haeberli&Funk1991,Laternser1992,Lüthi&Funk1997,Lüthi&Funk2000,2001,Oeschgeretal.1977,Schwerzmann2006,Suter1995,Suteretal.2001a,Suteretal.2001b,Suter2002,Suter&Hoelzle2002,2004,Suteretal.2004,Vincentetal.1997,2007).Currently,therearetwositeswheresuchmeasurementshavebeenrepeatedlymade:ColduDômeintheMontBlancarea(Vincentetal.2007)andColleGnifettiintheMonteRosaarea.ColleGnifettiisaverywind-exposedfirnsaddlewithaccu-mulationratesof0.3to1.2mwaterequivalentperyear(Lüthi2000).OnColleGnifetti,severalboreholesweredrilledinvicinityofthesaddlepointand,untilnow,measurementsweremadein1976,1982,1991,1994,1995,1999,2000,2003and2007.Thissummer(2008),newfield-workhasbeencarriedoutonColleGnifetti.Nineboreholesweredrilledwithasteamdrillandboreholetemperaturesweremeasured.Thesetemperaturesarenowreadytobecomparedwithsomeolderdatatodetectpossiblechanges.

6.6

Snow temperatures: measurement and modelling

FierzCharles&LehningMichael

WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH-7260 Davos Dorf (fierz@slf.ch)

Bothmeasuringandmodellingsnowtemperatureswithinthetopmostcentimetresofthesnowpackisachallenge.Snowpackevolution,andinparticularsnowmetamorphism,heavilydependonthetemperaturedistributionnearthesurfaceofthesnowpack.

Shortwaveradiationpenetratingthesnowpackispicked-upbythesensorsthatheatup.Acarefulsensordesignisthusre-quiredandwepresenttwoofthem:thefirstallowsforhighlydepth-resolvedtemperatureprofileswhilethesecondissuita-bleforaccuratecontinuousmeasurementsoverafewdays.

Dailytemperaturecycleswithinthetop30to50cmareduetobothenergyexchangesatthesurfaceandtoshortwaveradi-ationpenetratingthesnow.SNOWPACK,theSwisssnow-covermodel,treatsthelatterasavolumesourceofheat,alikere-freezing.Wewillshowhowthemulti-bandparameterizationofshortwaveabsorptionimplementedinSNOWPACKcanbeoptimizedbycomparingmodeloutputstoreliablemeasurementsofsnowtemperatures.

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Combined LiDAR and photogrammetry for stability-related change detec-tion in glacierised and frozen rock walls - A case study in the Monte Rosa east face

FischerLuzia*,EisenbeissHenri**,KääbAndreas***,HuggelChristian*&HaeberliWilfried*

* Glaciology, Geomorphodynamics & Geochronology, Department of Geography, University of Zurich, Switzerland (luzia.fischer@geo.uzh.ch)** Institute of Geodesy and Photogrammetry, ETH Zurich, Switzerland*** Department of Geosciences, University of Oslo, Norway

Often,rockwallsinhigh-mountainareasareinlargepartscoveredbysteepglaciersandfirnfieldsandareunderpermafrostconditions.Impactsonsurfaceandsubsurfaceiceinsuchflanksfromclimaticandotherchangesstronglyinfluencestressandthermalfieldsinrockandice,geotechnicalparametersaswellasthehydraulicandhydrologicalregimeandmayeven-tuallyleadtoslopeinstabilitiesandenhancedmassmovementactivitysuchasmajoriceandrockavalanches(GruberandHaeberli,2007;FischerandHuggel,2008).Thedynamicsandchangesofsteepglaciersandicecoverinhigh-mountainrockwallsandtheirinteractionswiththeunderlyingbedrockareverycomplexandstillincompletelyunderstood(Wegmannetal.,1998;PralongandFunk,2006;Fischeretal.,2006).

TheMonteRosaeastface,ItalianAlps,isthehighestflankintheEuropeanAlps(2200–4600ma.s.l.)andisaprominentexa-mpleforstrongchangesandinstabilitiesinahighalpinerockwall.Steepglaciersandfirnfieldscoverlargepartsofthewall.SincethelastglaciationsmaximumduringtheLittleIceAge(i.e.sinceapproximately1850)untilthe1980s,theglaci-ationhaschangedlittle.Duringrecentdecades,however,theicecoverexperiencedanacceleratedanddrasticlossinextentandthicknessandsomeglaciershavecompletelydisappearedwithinshorttime(Kääbetal.,2004;Fischeretal.,2006).Overtherecenttwodecades,newinstabilitiesdevelopedinbedrockaswellasinice.Themassmovementactivityincreaseddra-sticallysinceabout1990,culminatinginmajormassmovementsinAugust2005,withaniceavalancheofmorethan1x106m3,andinApril2007,witharockavalancheofabout0.3x106m3.

Acquisitionofhigh-qualitydata is essential tobetterunderstand thepredominantprocessesandhazardsbut isamajorchallengeinsuchhigh-mountainrockwallsareverydifficultduetotopographicconditions,icecover,andterrainthatisdifficultanddangeroustoaccess.Therefore,remote-sensingbasedinvestigationsarefundamentalforanintegrativeassess-mentofchangesinicecoverandbedrockaswellasofslopeinstabilitiesinsuchflanks.

ThemainobjectiveofthepresentedstudyistheinvestigationofchangesinbedrockandglaciationintheMonteRosaeastfacebasedonmulti-temporaldigitalterrainmodels(DTMs)andterrestrialandaerialphotographs.Forthispurpose,high-resolutionDTMsoftheMonteRosaeastfacewerephotogrammetricallygeneratedfromaerialphotographsoftheyears1956,1988and2001.In2007,ahelicopter-bornelightdetectionandranging(LiDAR)scanoftheentireMonteRosaeastfacecouldbeachieved.Furtherhigh-resolutionDTMdatastemsfromanairplane–borneLiDARcampaignin2005.BasedonthecomparisonsofDTMsandphotographsoverthelast50years,thespatio-temporalchangesinsurfacetopographyareevaluatedandquanti-tativeassessmentsofmasswastingandmassaccumulationareperformed.Thisuniquemulti-temporaldatasetgivesaninsightinthecomplexstability,dynamicsandmassbalancecyclesofsteepglaciers.Additionally,complexprocessinterac-tionsbetweendifferentprocessesinbedrockandicecanbedetectedfromtheimagedataavailable.

REFERENCESFischer,L.&Huggel,C.2008:MethodicalDesignforStabilityAssessmentsofPermafrostAffectedHigh-MountainRockWalls,

Proceedingsofthe9thInternationalConferenceonPermafrost2008,Fairbanks,Alaska,USA,29.6.-3.7.2008,1,439-444.Fischer,L.,Kääb,A.,Huggel,C.&Noetzli,J.2006:Geology,glacierretreatandpermafrostdegradationascontrollingfactors

ofslopeinstabilitiesinahigh-mountainrockwall:theMonteRosaeastface,NaturalHazardsandEarthSystemSciences,6,761-772.

Gruber, S.&Haeberli,W.2007:Permafrost in steepbedrock slopesand its temperature-relateddestabilization followingclimatechange,JournalofGeophysicalResearch,112,F02S18,doi:10.1029/2006JF000547.

Kääb,A.,Huggel,C.,Barbero,S.,Chiarle,M.,Cordola,M.,Epinfani,F.,Haeberli,W.,Mortara,G.,Semino,P.,Tamburini,A.&Viazzo,G.2004:GlacierhazardsatBelvedereglacierandtheMonteRosaeastface,ItalianAlps:Processesandmitigation,ProceedingsoftheInterpraevent2004–Riva/Trient,1,67-78.

Pralong,A.&Funk,M.2006:Ontheinstabilityofavalanchingglacier,JournalofGlaciology52(176),31-48.Wegmann,M.,Gudmundsson,G.H.,&Haeberli,W. 1998: Permafrost changes in rockwalls and the retreat ofAlpine

glaciers:athermalmodellingapproach,PermafrostandPeriglacialProcesses,9,23–33.

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Lateglacial glacier evolution of the Greina region (Central Swiss Alps)

FontanaGeorgia*,ScapozzaCristian*,ReynardEmmanuel*

*Institut de Géographie, Université de Lausanne, Anthropole, CH–1015 Lausanne (Georgia.Fontana@unil.ch)

TheGreinaregioniswellknownbecauseofitsimportanceintheSwissnatureprotectionhistory.Inspiteoftheinterestingnaturalfeaturesoftheregion,onlyfewscientificresearcheswerecarriedoutuntilnow,particularlyinthefieldofgeomor-phology.Theaimofthisresearch(Fontana2008)wastoreconstitutethelateglacialglacierevolutionoftheGreinaregion,inordertofillagapinthegeomorphologicalknowledgeoftheCentralSwissAlpsandtomakeavailablebasisscientificinformationforthepromotionoftheGreinageomorphologicalheritage.

Alarge-scalegeomorphologicalmapofthewholeregionwasfirstrealised;specialattentionwasaccordedtothecartographyofglaciallandforms.Onthebasisofthecartographyofmorainesandotherglacier-relateddeposits,areconstitutionofthelateglacialpositionsofglacierswasrealised.

Fourmainlateglacialglacierpositionswereidentified(Figure1).Oneofthesepositionsischaracterisedbyacomplexiceorigin,whereastheotheronescorrespondtoancientpositionsoftheGaglianeraglacierandofadisappearedglacierlocatedNEofthePizzoCoroi.Foreachglacierposition,theEquilibriumLineAltitude(ELA)depressionrelatedtothereferencepha-seof1850(Maisch,1992)wascalculated.ThecomparisonoftheELAdepressionofeachglacierpositionallowedustoesta-blisharegionalregressionsequenceincludingthreephases(Table1).Theresultswerethencomparedwithregionalregres-sionsequencesestablishedbyMaisch(1981)intheEasternSwissAlpsandbyRenner(1982)intheGothardregion(Table1).

Greina

(Fontana, 2008)

ELA dep. (m) Eastern Swiss Alps

(Maisch, 1981)

ELA dep. (m) Gothard

(Renner, 1982)

ELA dep. (m)

Greina 1a 110 Bockten 100-150 Alpe di Cruina 116

Greina 1b 210 Egesen 170-240 Manio 200-240

Greina 2 310-350 Daun 250-350 All’Acqua 280-315

Table1:ComparisonoftheGreinaregionalregressionsequencewithregionalregressionsequencesestablishedbyMaisch(1981)andRenner(1982).

Theglacierpositionsandtheregionalregressionsequenceallowedthereconstitutionofagenerallateglacialglacierevolu-tion of theGreina region. An important change in the general ice-flowdirections certainly happened between the LastGlacial Maximum (LGM) and the Lateglacial. The general ice-flow coming from the Rhin-source ice-cap recognised byFlorineth&Schlüchter(1998)wascertainlysubstitutedbyaregionalice-flow.Thegeneralice-flowhadaNNE-SSWdirectioninthePlaunlaGreinaregionduringtheLGMandaSSW-NNEdirectionduringtheLateglacial.DuringtheGreina2phase,theGaglianera,CoroiandTerriglacierswereconfluentandformedafront inthemiddleof thePlaunlaGreinaregion.Duringthisphase,aglacierlocatedNEofPizzoCoroioccupiedtheCraplaCruschdepression.ConcerningtheGreina1aandGreina1bphases,onlythepositionsoftheGaglianeraglaciercouldbereconstituted.ThefrontoftheglacierwascertainlylocatedWofthePlaunlaGreinaregionduringbothphases.

REFERENCESFlorineth,D.,Schlüchter,C.1998:ReconstructingtheLastGlacialMaximum(LGM)icesurfacegeometryandflowlinesin

theCentralSwissAlps,Eclogaegeol.Helv.,91,391-407.Fontana,G.2008:Analyseetpropositionsdevalorisationd’unpaysagegéomorphologique.LecasdelaGreina.Lausanne,

InstitutdeGéographie(MasterthesispublishedonFebruary28,2008,onhttp://doc.rero.ch).MaischM.1981:GlazialmorphologischeundgletschergeschichtlicheUntersuchungenimGebietzwischenLandwasserund

Albulatal(Kt.Graubünden,Schweiz).Zürich,GeographischesInstitut.Maisch,M.1992:DieGletscherGraubündens.Zürich,GeographischesInstitut.Renner,F.1982:BeiträgezurGletscher-GeschichtedesGotthardgebietesunddendroclimatologischenAnalysenanfossilen

Hölzern.Zürich,GeographischesInstitut.

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Figure1.GeneraliceflowdirectionduringLGMandlateglacialphasesintheGreinaregion.

6.

Geomorphological map of the Greina region (Central Swiss Alps)

FontanaGeorgia*,ScapozzaCristian*,ReynardEmmanuel*

*Institut de Géographie, Université de Lausanne, Anthropole, CH–1015 Lausanne (Georgia.Fontana@unil.ch)

TheGreinaisahighmountainregionlocatedintheCentralSwissAlps.Inspiteoftheinterestinggeomorphologicalfeaturesoftheregion,noscientificresearchwascarriedoutinthisfielduntilnow.Theaimofthisresearchwastorealiseageomor-phologicalmapoftheGreinaregion, inordertoreconstitutethemorphogenesisoftheareaandtomakeavailablebasisinformationforthepromotionofthegeomorphologicalheritageoftheGreinaregion(Fontana2008).

ThegeomorphologicalmapwasrealisedusingtheguidelinesdevelopedattheInstituteofGeographyofLausanneUniversity(Schoeneichetal.1998).Themethodallowstherealisationofmorphogeneticmapsandisparticularlyinterestingformor-phogenesisreconstitutions.

TheGreinaregionpresentsarichgeomorphologicaldiversityincludingstructural,fluvial,gravitative,karstic,glacial,pe-riglacialandorganic landforms.The landformdistribution is largelydependentongeological structure.Fromatectonicpointofview,thenorthernpartofthestudyareabelongstotheGothardMassiv.Thistectonicunitiscomposedofcrystallinerocks,especiallygneiss.Crystallinerocksarequiteresistanttoerosionandstillconservethetracesofglacialerosion.Rochesmoutonnéesandstriationsarethereforeveryfrequent.ThetectonicunitssituatedsouthernoftheGothardMassivincludeitssedimentarycoverandsomelowerPenninicnappes.Theautochthonsedimentarycoverismostlycomposedofdolomiticrocks,whichpresentseveralkarsticlandforms,likedolinesandresiduallandforms.TheparautochtonsedimentarycoverandthelowerPenninicnappesincludeseverallithologies.Calcschistsareveryfrequent:astheserocksaresensitivetotheactionoffrost,erosionalglaciallandformsarequiterare,whereastalusslopesareveryfrequent.Asclaysareaproductofcalcschistsweathering,well-developedsolifluxionlobesarealsovisible.

Thankstothegeomorphologicalmapandtootherfieldobservations,thegeneralmorphogenesisoftheGreinaregionduri-ngtheLateglacialandtheHolocenecouldbereconstituted(fortheLateglacial,seeFontanaetal.2008).DuringtheHolocene,glacialprocessesbecameless important,whereasgravitative, fluvialandperiglacialprocessesstronglyshapethecurrent

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gy evolutionoflandscape.AtthebeginningofHolocene,thewholeregionshouldhavebeenconcernedbyaparaglacialmor-

phogeneticcrisis.Animportantglacialsedimentarystockshouldhavebeenreworkedbyfluvio-glacialandfluvialprocesses,whilerockfallsandlandslidesshouldhavebeennumerous.ThefluvialreworkofglacialsedimentsisattheoriginoftworelictparaglacialalluvialfansoutsideoftheGaglianera(Figure1)andCanalvalleys.Atthesametime,thefrostandgravityactionshouldhavecontributedtothetalusslopeformation.Theriversalsoshapedprogressivelytheirtalwegsandthedis-solutionofdolomiterocksshapedkarsticlandforms.ThecurrentsedimentationlevelislowerthanitwasatthebeginningsofHoloceneandcorrespondstothePianodellaGreina,PlaunlaGreinaandAlpediMotterascioalluvialplains.Concerningglaciers,theirHoloceneevolutionisnotwellknown.Since1850,theypresentastrongregression(Maisch1992)andoccupytodayaverysmallpartoftheirglacialcirque(Fontana2008).

Figure1.TheGaglianeraparaglacialalluvialfan(ontheright),andthecurrentalluvialfan(ontheleft).

REFERENCESFontana,G.2008:Analyseetpropositionsdevalorisationd’unpaysagegéomorphologique.LecasdelaGreina.Lausanne,

InstitutdeGéographie(MasterthesispublishedonFebruary28,2008,onhttp://doc.rero.ch).Fontana,G.,Scapozza,C.,Reynard,E.2008:LateglacialglacierevolutionoftheGreinaregion,Proceedingsofthe6thSwiss

GeoscienceMeeting,thisvolume.Maisch,M.1992:DieGletscherGraubündens,Zürich,GeographischesInstitut.Schoeneich, P.,Reynard,E., Pierrehumbert,G. 1998:Geomorphologicalmapping in theSwissAlps andPrealps,Wiener

SchriftenzurGeographieundKartographie,11,145-153.

6.10

Observation of the Cryosphere – Switzerland’s contri-bution to the Global Climate Observing System GCOS

FoppaNando*,SeizGabriela*,WalterspielJulia*

*Swiss GCOS Office, Federal Office of Meteorology and Climatology MeteoSwiss Kraehbuehlstr. 58, CH-8044 Zurich, (Nando.Foppa@meteos-wiss.ch), www.gcos.ch

Inrecentdecades–especiallyfollowingtheadoptionoftheUNFrameworkConventionofClimateChange(UNFCCC)in1992–thedemandforobservationsofclimatechangeandthecloserlinksbetweenclimateobservationandclimateresearch/mo-delinghassteadilyincreased,leadingtotheestablishmentoftheGlobalClimateObservingSystem(GCOS).

GCOSisaninitiativeoftheWorldMeteorologicalOrganization(WMO),theIntergovernmentalOceanographicCommission(IOC)oftheUNESCO,theUNEnvironmentalProgramme(UNEP)andtheInternationalCouncilofScience(ICSU).GCOSis

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designedtoensurethattheobservationsandinformationneededtoaddressclimate-relatedissuesareobtainedsystemati-callyandmadeavailabletoallpotentialusers.Inparticular,GCOSfollowstheaimsandrequirementsofsystematicobserva-tionasspecifiedintheUNFCCCandtheKyotoProtocol.

InSwitzerland,theSwissGCOSOfficeattheFederalOfficeofMeteorologyandClimatologyMeteoSwisswasestablishedin2006,followingtheratificationoftheKyotoProtocolin2003,tocoordinateclimateobservationsatthenationallevelandtofosterinformationexchangeandcollaborationamongthevariousinstitutions.In2007,theSwissGCOSOfficehascompiledthefirst-everinventoryofthecountry’slong-termclimatologicaldataseriesoftheatmosphereandthelandsurface,entitled“NationalClimateObservingSystem(GCOSSwitzerland)”(Seiz&Foppa,2007).Switzerlandhasalongtraditionintheobser-vation of cryospheric parameters, includingmore than 100 years of glacier and snowdepthmeasurements, the longestCentralEuropeanlakeicecoverrecords,thepermafrostmonitoringnetworkPERMOS,theworld’slongestsnowwaterequi-valentseriesforcatchmentareas,andisadditionallyhostingtheimportantWorldGlacierMonitoringService.

OurpresentationwillgiveanoverviewaboutGCOSingeneralandabouttheSwissGCOSactivities. ItwillhighlighthowlocalmeasurementsofdifferentcryosphericparametersinSwitzerlandcontributetotheGlobalClimateObservingSystemandtheadded-valueofsatellite-basedobservationsofthecryospherewithinGCOS.

REFERENCESSeiz,G.,&Foppa,N.2007:NationalClimateObservingSystem(GCOSSwitzerland).PublicationofMeteoSwissandProClim,

92p.,(availableinGerman,FrenchandEnglishunderhttp://www.gcos.ch)

6.11

Replica method for three-dimensional X-ray microtomographic imaging of snow

FreiEsther,HeggliMartin&SchneebeliMartin

WSL Institute for Snow and Avalanche Reserach SLF, Flüelastrasse 11, CH-7260 Davos Dorf (heggli@slf.ch)

Snowmicrostructureisacrucialfactordeterminingmanypropertiessuchasmechanicalstrength,thermalconductivity,oropticalproperties.Therearebasicallythreetechniquesusedtomeasurethefullthree-dimensionalmicrostructureofsnowsamples: serial sectioning, direct X-ray computer tomography (micro-CT), ormicro-CT of 1-chloronaphthalene cast snow.Samplesthatneedtobetransportedorstoredmustbeconservedbycastingthesnowwithasolidifyingsubstance,e.g.1-chloronaphthaleneordiethylphthalate (DEP).Chloronaphthalene,whilehavingagoodX-raycontrast, isquite toxicandsmellsbad.

ImageprocessingofserialsectionsofDEPcastsnowisoftenverydifficult,duetotheformationofDEPcrystalsthatappearopticallyverysimilartoicecrystals.Micro-CTwassofarnotapplicabletoDEPcastsnowsamplesbecausethereishardlyanyabsorptioncontrastbetweeniceandDEP.

WedevelopedanewreplicamethodthatallowsinvestigatingthemicrostructureofDEPcastsamplesbymicro-CT.Thesam-plingandcastingprocesscanbedoneasusual.Beforethemicro-CTmeasurement,theiceneedstoberemovedfromthecastsamples.ThevapourpressureofDEPisaboutamilliontimessmallerthanthatofice,whichallowssublimatingtheicese-lectively.Keepingthesampleundervacuumacceleratesthesublimationprocessdrasticallytoafewdays.ThisleavesbehindtheDEP,whichformsanexactnegativeimageofthesnow.Theporousstructurecannowbemeasuredinthemicro-CT.Anumericalinversionofthesegmentedmicro-CTimagesyieldsadigitalreplicaoftheoriginalsnowstructure.

Theaccuracyofreplicationwastestedbycomparingthedigitalreplicatotheoriginalsnowstructure.Thestructuralpara-metersofthetwostructureswerecomparedtoeachother.Thereplicationofthesnowmicrostructurewasverygoodwithrelativeerrorsbelow5%.Thepresentedreplicamethodiscomparablystraightforwardand,forthesnowtypestested,themicrostructureisaccuratelyreproduced.

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The ice ridge at Murtèl/Corvatsch: Studying a (c)old archive

FreyHolger*,BusarelloClaudio**,FrauenfelderRegula***,HaeberliWilfried*,HoelzleMartin****,MayBarbara*****,RauSebastian*****,WagenbachDietmar*****&WagnerStefan******

*University of Zurich, Department of Geography, Winterthurerstr. 190, CH-8057 Zurich (holger.frey@geo.uzh.ch)**SwissRE, Mythenquai 50/60 P.O. Box, CH-8022 Zurich***Norwegian Geotechnical Institute, P.O. Box 3930 Ullevål Stadion, NO-0806 Oslo, Norway****University of Fribourg, Department of Geosciences, Chemin du Musée 4, CH-1700 Fribourg *****University of Heidelberg, Institute of Environmental Physics, Im Neuheimer Feld 229, D-69120 Heidelberg,******Bitzi-Bendel, CH-9642 Ebnat-Kappel

Coldcornice-,crest-andplateau-typeminiatureicecapsofthenorthernhemisphereareknowntocontainold(HolocenetoevenPleistocene)icelayers.Thesesmallbuthighlyinterestingpaleoglaciologicalandpaleoclimaticalarchives,however,arestilllargelyunexploredandtheirfutureresponsetotherapidwarmingoftheatmosphereremainstobeinvestigated.Onthenorth-south-orientediceridgeMurtèl/Corvatsch(3300–3500m.a.s.l)intheUpperEngadin,systematicstudiesareper-formed since several years (Haeberli et al. 2004). In this contributionwe like to sumup the investigationsand findings,presentnewresultsanddiscusspotentialfutureresearchquestions.

Refreezingofmeltwateristhemainaccumulationprocess,resultinginsmallaccumulationrates.Temperaturesinborehol-esandatthemarginalice/rock-contactrevealthattheridgeconsistsofcoldiceandisfrozentothepermafrost-bedrock(nobasalsliding).Finiteelementsmodellingshowsthatonlyverysmallflowvelocitiescanbeexpectedundertheridgewherethesurfaceslopetendstowardszero.Thesetwofindings(smallaccumulationratesandprobableicevelocitiesclosetozeroattheice/rockinterface)indicatethatbasalicelayersmayhaveaconsiderableage(millennia).Theseassumptionsaresup-portedbyaC14datefromanicecoredrilleddowntothebedrockin2007,whichhowever,sincebeingapreliminaryresult,needstobeconfirmedbyfurtheranalyses.

AGPSsurveywasperformedin2000andrepeatedin2007.Comparisonofthetwodigitalelevationmodels(DEM)showedanaveragesubsidenceofthesurfaceofabout5m(≈0.7m/y)withamaximumloweringof>15mandageometricdistortionoftheridge.AnalysesoftheTritiumcontentshowthattheiceatthesurfacein2007datesbacktoaround1960,whichmeansthattheiceaccumulatedinthelastfourtofivedecadeshasalreadymeltedaway.Groundpenetratingradar(GPR)measure-mentsfrom2001indicateicethicknessesofabout30m(±20m)undertheridgeandmoreshallowpartsattheglaciermar-gins.Continuationorevenaccelerationofrecentthinningrateswould,hence,leadtovanishingoftheglacierwithinde-cades.

REFERENCESHaeberli,W.,Frauenfelder,R.,Kääb,A.&Wagner,S.2004:Characteristicsandpotentialclimaticsignificanceof“miniature

icecaps”(crest-andcornice-typelow-altitudeicearchives).JournalofGlaciology,50(168),129-136.

6.13

Application of operational geophysical monitoring systems on alpine permafrost

HauckChristian*&HilbichChristin**

*Department of Geosciences, University of Fribourg, Chemin de Musée 4, CH-1700 Fribourg (christian.hauck@unifr.ch)**Geographical Institute, University of Jena, Löbdergraben 32, D-07743 Jena

Determiningthesubsurfaceiceandunfrozenwatercontentincoldregionsareimportanttasksinallkindofcryosphericstudies,butespeciallyonperennial(permafrost)orseasonalfrozenground,wherelittleinsightscanbegainedfromdirectobservationsatthesurface.Intheabsenceofboreholes,geophysicalmethodsareoftentheonlypossibilityfor“visualising”the subsurface characteristics, and their successful application in recent years lead tomore andmore sophisticated ap-

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yproachesincluding2-and3-dimensionalmonitoringandevenquantifyingtheiceandunfrozenwatercontentevolutionwithinthesubsurface(foranoverviewseeHauck&Kneisel2008).

Duetothestrongsensitivityofelectricalresistivityandpermittivitytothephasechangefromunfrozenwatertoice,theapplicationofelectricalandelectromagnetictechniqueshasbeenespeciallysuccessful.Withinthesemethods,ElectricalResistivityTomography(ERT)isoftenfavouredduetoitscomparativelyeasyandfastdataprocessing,itsrobustnessagainstambientnoiseanditsgoodperformanceeveninharsh,coldandirregularenvironments.NumerousrecentstudieshavenowshownthatERTisprincipallysuitabletospatiallydelineategroundice,differentiatebetweenice-poorandice-richoccur-rences,monitorfreezing,thawingandinfiltrationprocesses,andevendeterminetheoriginoftheice,i.e.adifferentiationbetweenburiedglaciericeandsegregationice,duetotheirdifferentioncontents(yieldingareducedelectricalresistivityforthelatter).

Inthecontextofapossibleincreasedfrequencyofextremeweatherperiods,suchasthehotsummer2003intheEuropeanAlps,amonitoringofcryosphericcomponentssuchasthemountainpermafrostevolutionbecomesmoreandmoreimpor-tant(Hilbichetal.2008a).Commonobservationtechniquesareusuallybasedonthethermalaspects,asinexistingperma-frostboreholetemperaturemonitoringnetworks.Concerningtheimpactsofchangingclimateparameters,notonlytempe-raturebutespeciallytheiceandwatercontentofthesubsurfaceplaysanimportantrole,especiallyforpermafrostobserva-tionpurposes.

Insummer2006theinstallationofasemi-automaticERTmonitoringsystemhasbeencompletedat4permafrostsitesintheSwissAlps(inco-operationwiththeSwisspermafrostnetworkPERMOS,VonderMühlletal.2007).Thisgeophysicalmonito-ringnetworkserves to investigate thesensitivityofcharacteristicmorphological sites toextremeatmospheric forcing inordertoestimatethelong-termevolutionduetoclimateinducedwarming.Monitoringprofilesarelocatedatarockglacier(Murtél,UpperEngadine),steepslope(Schilthorn,BerneseAlps),talusslope(Lapires,Valais)andfrozenbedrock(Stockhornplateau,Valais)(Hilbichetal.2008b).ThegeophysicalmonitoringstrategyincludesrepeatedERTmeasurementswithamon-thlytoseasonalresolutionoverseveralyears,aswellasannualrefractionseismicmeasurementsatallsites.Whereasrelativeresistivitychangeswithtimecanbeattributedtofreezeandthawprocesses,combinedERTandrefractionseismictomogra-phywillservetodeterminetotalfractionsofice,unfrozenwaterandairwithintheporespaceoftherespectivesubsurfacesections(Haucketal.2008).

REFERENCESHauck,C.&Kneisel,C.(Eds)2008:Appliedgeophysicsinperiglacialenvironments.CambridgeUniversityPress.Hauck,C.,Bach,M.&Hilbich,C.2008:A4-phasemodeltoquantifysubsurfaceiceandwatercontentinpermafrostregions

basedongeophysicaldatasets.NinthInternat.Conf.onPermafrost,Fairbanks,Alaska,2008,6pp.Hilbich,C.,Hauck,C.,Hoelzle,M.,Scherler,M.,Schudel,L.,Völksch,I.,VonderMühll,D.&MäusbacherR.2008:Monitoring

mountainpermafrost evolutionusingelectrical resistivity tomography:A7-year studyof seasonal, annual, and long-termvariationsatSchilthorn,SwissAlps,J.Geophys.Res.,113,F01S90,doi:10.1029/2007JF000799.

Hilbich,C.,Hauck,C.,Delaloye, R.&Hoelzle,M. 2008:A geoelectricmonitoringnetwork and resistivity-temperaturerelationshipsofdifferentmountainpermafrostsitesintheSwissAlps.NinthInternat.Conf.onPermafrost,Fairbanks,Alaska,2008,6pp.

VonderMühll,D.,Noetzli,J.,Roer,I.,Makowski,K.&Delaloye,R.2007.PermafrostinSwitzerland2002/2003and2003/2004,GlaciologicalReport(Permafrost)No.4/5oftheCryosphericCommission(CC)oftheSwissAcademyofSciences(SCNAT)andDepartmentofGeography,UniversityofZurich,106pp.

6.1

Thermal conductivity of snow: How to find a better parameterisation?

HeggliMartin,KöchleBernadette,PinzerBernd&SchneebeliMartin

WSL Institute for Snow and Avalanche Reserach SLF, Flüelastrasse 11, CH-7260 Davos Dorf (heggli@slf.ch)

Thethermalconductivityofsnowisanimportantparameterintheenergybalanceofsnow-coveredareas.Thisenergybalan-ceisakeytounderstandingtheresponseofarcticregionstochangingglobalclimate.Thethermalconductivityandtheheatflowthroughsnowalsodeterminethetemperaturegradientmetamorphismwhichmodifiesthemicrostructureofsnow(Schneebeli&Sokratov2004;Kaempferetal.2005).Asaconsequence,mechanical,thermophysical,chemical,andopticalpropertiesofthesnowarechanged.Formodellingthemetamorphismofsnow,itisessentialtousearealisticparameterisa-

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gy tion for the thermal conductivity. Anunderstanding of the relationship betweenheat flow and snowmicrostructure is

crucial for improvingmodels in climatology, interpretations of chemical signals in firn and ice, and for avalanche re-search.

Availabledatafortheeffectivethermalconductivityofsnow,keff

,aremostlybasedonmeasurementswithatransientmethodusinganeedleprobe(e.g.Sturmetal.1997).Theyrelatekeffempiricallytothedensity.However,themeasuredvaluesdifferbyuptoafactoroffiveforsnowwiththesamedensityandthesamegrainshape.Thus,alargeuncertaintyisintroducedintomodels thatuseaparameterisationbasedonthesemeasurements.Furthermore,newmeasurementsusingasteadystatemethodwithheatfluxplatessuggestvaluesofk

eff,thataresignificantlyhigherthanthosemeasuredbySturmetal.

(1997).Forsnowsampleswithadensityof200-300kgm-3,akeff

,of0.2-0.3Wm-1K-1wasmeasured.

Inourstudy,wesystematicallycomparemeasurementsofkeff

,withaneedleprobe(transientmethod)andwithheatfluxplates(steadystatemethod)fordifferentsnowtypesandsnowdensities.Themicrostructureofthesnowsamplesischaracte-rizedwithmicrocomputertomography(micro-CT).Basedontheassumptionthatthebondsbetweengrainsaremoreimpor-tant than the density of the snow,Dadic et al. (2008) suggest a correlation between the penetration resistance and thethermalconductivityofsnow.WetestthiscorrelationbymeasuringthepenetrationresistanceofthedifferentsnowtypesusingtheSnowMicroPen(SMP),ahighresolutionpenetrometer(Schneebeli&Johnson1998),andcorrelatingthesemeasure-mentstothemeasuredthermalconductivity.

Contactproblemsbetweentheprobeandthesnowsamplemaybeapotentialexplanationfortheobserveddifferencesbet-weenthemeasurementmethods.Thiseffect isexpectedtobeespeciallypronouncedinfragilesnowtypessuchasdepthhoar.Thecontactgeometrybetweentheprobeandthesnowsampleisinvestigatedusingmicro-CT.

REFERENCESDadic, R., Schneebeli,M., Lehning,M.,Hutterli,M.A.&OhmuraA. 2008: Impact of themicrostructure of snowon its

temperature:AmodelvalidationwithmeasurementsfromSummit,Greenland.J.Geophys.Res.113,D14303.Kaempfer,T.U.,Schneebeli,M.&Sokratov,S.A.2005.Amicrostructuralapproachtomodelheattransferinsnow.Geophys.

Res.Lett.32,L21503.Schneebeli,M.&Johnson,J.B.1998.Aconstantspeedpenetrometerforhigh-resolutionsnowstratigraphy.Ann.Glaciol.26,

107-111.Schneebeli,M.&Sokartov,S.A.2004.Tomographyoftemperaturegradientmetamorphismofsnowandassociatedchanges

inheatconductivity.Hydrol.Process.18,3655-3665.Sturm,M.,Holmgren,J.,König,M.&Morris,K.1997:Thethermalconductivityofseasonalsnow.J.Glaciol.43,26-41.

6.1

Thermal and electrical properties of a periglacial talus slope

LambielChristophe*,ScapozzaCristian*,PieracciKim*,BaronLudovic**&MarescotLaurent***

*Institute of Geography, University of Lausanne, Anthropole, CH-1015 Lausanne (christophe.lambiel@unil.ch)**Institute of Geophysics, University of Lausanne, Amphipôle, CH-1015 Lausanne***Institute of Geophysics, ETH-Swiss Federal Institute of Technology, 8093 Zurich

LesAttelastalusslopeislocatedonthewesternflankoftheMontGelé(3023ma.s.l.),inVerbierarea.Thiscone-shapedland-formisaffectedbysolifluctionintheupper-midpartoftheslope,whereasbulgingsuggeststhepresenceofcreepingper-mafrostinthelowerpartoftheslope.

Inordertodeterminethespatialextensionandthecharacteristicsofthepermafrostwithintheslope,severalthermalandgeoelectricalmeasurementshavebeencarriedout(Lambiel2006).

GroundsurfacetemperaturesmeasuredinMarch2005atthebaseofthesnowcover(BTSmethod)displayedvaluescolderthan-6°Cbelow2700ma.s.l.(Fig.1).Intheupperportionoftheslope,temperatureswerewarmer(upto-1°C).Accordingtothesevalues,permafrostmaybepresentinthelowerpartoftheslope,whereastheprobabilityof itspresencedecreasesupslope.

Insummer2007,48permanentelectrodeswereinstalledeach4metersalonganupslope-downslopeprofileinordertomo-nitortheundergroundresistivityusingtheElectricalResistivityTomography(ERT)technique(Fig.1).TheERTprofile(Fig.2)showsthatthehighestresistivitiesarelocatedinthelowerpartoftheslope.Fromthedistanceof85meterstothefootof

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ytheslope,aresistivebodywithvalueshigherthan25kΩmandthicknessofabout15metershasbeenimagedbybothappa-rentresistivityandinversedresistivity.ItcorrespondstothecoldBTStemperatures(Fig.1)andcanbeinterpretedasaper-mafrostlens.InthemiddleoftheERTprofile,thelowerresistivities(<10kΩm)measuredbelow15-20mdepthareinterpre-tedasunfrozensediments.Intheuppersection,theresistivebodyisstillpresent,butisfoundatgreaterdepthandthere-sistivityvaluesarelower(12-20kΩm).Thismaybeinterpretedeitheraslow-resistivitypermafrostorasporoussediments.Intheuppermostpartoftheprofile,theresistivitieslowerthan4kΩmindicatetheabsenceoffrozensediments.

ThepermafrostdistributionpatternevidencedinLesAttelastalusslopeisconformtothemeasurementscarriedoutinotheralpinetalusslopes(e.g.OttoandSass2006,LambielandPieracci2008).Permafrostappearslikelyinthelowerpartoftheslopes,whereasitisgenerallyabsentupslope.Inordertogetdirectinformationonthegroundcharacteristicsandthermalregime,3boreholeswillbedrilledalongtheERTprofile.

REFERENCESLambiel, C. 2006: Le pergélisol dans les terrains sédimentaires à forte déclivité: distribution, régime thermique et

instabilités.Thèse,UniversitédeLausanne,InstitutdeGéographie,coll."TravauxetRecherches"n°33,260p.Lambiel,C.,Pieracci,K.2008:Permafrostdistributionintalusslopeslocatedwithinthealpineperiglacialbelt,SwissAlps.

PermafrostandPeriglacialProcesses,19:293–304.Otto,J.C.,Sass,O.2006:ComparinggeophysicalmethodsfortalusslopeinvestigationsintheTurtmannvalley(SwissAlps).

Geomorphology76:257-272.

Figure1.BTSmeasurementsinMarch2005(blackdots)andlocationoftheElectricalResistivityTomographyprofile(blackline)inLes

Attelastalusslope.

Figure2.ElectricalresistivitytomograminLesAttelastalusslope,July2008.ThecolourscalerepresentsinvertedresistivitiesinΩm.

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Modelling of glacier bed topography from glacier outlines and DEM data in a GIS

LinsbauerAndreas*,PaulFrank*,HoelzleMartin*&HaeberliWilfried*

* Department of Geography, University of Zurich, Winterthurerstr. 190, CH-8057 Zürich (alinsbau@geo.uzh.ch)

Duetotheongoingandexpectedfutureincreaseinglobalmeantemperature,theAlpineenvironmentwillcontinuetogetfurtherawayfromequilibrium.Thiscouldhavelargeenvironmentalandsocietalimpacts.Glaciersareapartofthehigh-mountaincryosphere,andtheirchangesareconsideredtobethebestnaturalindicatorsofclimaticchanges.Theobservati-onof thehigh-mountainenvironmentand itsglaciers formsthusan importantpart inglobalclimaterelatedobservingprograms. The calculationandvisualizationof futureglacierdevelopment is thusan important taskof communicatingclimatechangeeffectstoawiderpublic(Pauletal.,2007).

One of themost challenging topics in the assessment of climate change impacts on future glacier development is theunknownglacierbedandtherelateduncertaintiesinglaciervolumeestimations(DriedgerandKennard,1986).Inthisre-spect,anestimatedtopographyoftheglacierbedwouldfacilitatethecalculationofglaciervolume,thedetectionoflocaldepressions,andthevisualizationoffutureice-freegrounds.Whileseveralmethodsexisttoobtainaglacierbedfrommo-dellingcombinedwithmeasurements(e.g.Hussetal.,2008),thegoalofthisstudyistheapplicationofasimplebutrobustmethodwhichautomaticallyapproximatesaglacierbedforalargesampleofglaciers,usingonlyfewinputdatasuchasadigitalelevationmodel(DEM),glacieroutlines,andasetofflowlinesforeachglacier(Fig.1).Itisbasedonthecalculationoftheicethicknessalongselectedpointsoftheflowlinefromtheshallowiceapproximation(SIA)followingHaeberliandHoelzle(1995)andsubsequentspatialinterpolationusingaroutine(topogrid)thatisimplementedinageographicinforma-tionsystem(GIS)andwasdevelopedbyHutchinson(1989).

Sensitivitytestswithsimplegeometricformsonflatandinclinedsurfaceshelpedtoconstrainthemodelparameters.Thisincludesthespecificationsfortopogridaswellastherulesfordigitizingtheflowlines.ForSwitzerland,theyformtheonlypartoftheinputdatathathavetobenewlycreated.ThemodelwastestedwithrealdatafromtheBerninaregionwhichleadtosomemodificationsoftheflowlinedigitizingandinterpolationprocess.Finally,thereconstructedbedsarecomparedtoglacierbedsor thicknessmeasurements for threeglaciers (Morteratsch,Gorner andZinal)whichhavebeenobtained inpreviousstudies.

Thecomparisonrevealedthatthemethodhasalargepotential,butfurtherimprovementscouldbeintegratedaswell.Thegeneraldepthdistributionofthereconstructedglacierbedsisinafairlygoodagreementwiththeresultsfromtheotherstudiesandcalculatedglaciervolumesorthelocationoflocaldepressionsdoagreeaswell.However,thereisatendencytounderestimateglacierthicknessandlocallysomestrongdeviationsexist.Currently,meanslopeistheonly(andthusaverysensitive)variablefortheicethicknesscalculation.Hence,itmightbepossibletoimprovetheperformanceofthemethodbyintegratingsomebasiclawsofglacierflowandfurthergeomorphometry-dependentsmoothingoftheglaciersurface(e.g.Hussetal.,2008).However,themethodasawholeshouldstayassimpleaspossibletofacilitateitsautomatedandlargescaleapplication.

Theapplicationofthe(improvedandlocallycalibrated)methodtoallglaciersintheSwissAlpsdoesonlyrequirethatglacierflowlinesaredigitizedaccordingtotherulesoutlinedinthisstudy.IncombinationwithfurtherGIS-basedmodels(e.g.Pauletal.,2007)theherepresentedmethodwouldallowtocalculateandvisualizeimpactsofclimatechangeonglaciersandtheirroleasawaterresourceforSwitzerland.

REFERENCESDriedger,C.&Kennard,P. 1986:Glacier volumeestimationoncascadevolcanos: ananalysis andcomparisonwithother

methods.AnnalsofGlaciology,8,59–64.Haeberli,W.&Hoelzle,M.1995:Applicationofinventorydataforestimatingcharacteristicsofandregionalclimate-change

effectsonmountainglaciers:apilotstudywiththeEuropeanAlps.AnnalsofGlaciology,21,206–212.Huss, M., Farinotti, D., Bauder, A. & Funk, M. 2008: Modelling runoff from highly glacierized alpine drainage basins in a

changing climate. HydrologicalProcesses,22(19),3888–3902.Hutchinson,M.1989:Anewprocedureforgriddingelevationandstreamlinedatawithautomaticremovalofspuriouspits.

JournalofHydrology,106,211–232.Paul,F.,Maisch,M.,Rothenbühler,C.,Hoelzle,M.&Haeberli,W.2007:Calculationandvisualisationoffutureglacierextent

intheSwissAlpsbymeansofhypsographicmodelling.GlobalandPlanetaryChange,55,343–357.

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Figure1:Schematicflowchartanddetailsoftheglacierbedmodelling.

6.1

Transient response of idealized glaciers to climate variations

MartinLüthi

VAW Glaciology, ETH Zürich, CH-4092 Zürich (luethi@vaw.baug.ethz.ch)

Variationsofglacierlengthandvolumeunderclimatevariationsareinvestigatedwithmodelglaciersonasimplebedrockgeometry.Underperiodicclimateoscillationsthewell-knownphaselagsof lengthandvolumeareobtained,after initialtransientshavediedout.Therelationbetweenglaciermassbalance(localortotal)andclimateisstronglyinfluencedbythetransientresponseforforcingperiodsshorterthanthevolumetimescale.Thesetransientsaresurprisinglylarge,andleadtounexpectedtrajectoriesinphasespace.Underperiodicoscillationsthelocalicethicknessfollowstheclimateforcingwithatypicalphasedelayof60˚(accumulationarea)to180˚(glacierterminus),whileglacierlengthiscompletelyoutofphaseforforcingperiodsbelowthevolumetimescale.Theevolutionofthemodelglaciercanbeapproximatelydescribedwithaforced,linearlydampedharmonicoscillatorwhichistypicallyunderdamped.Approximateexpressionsforthevolume-andareatimescalesareexplicitlyderived,asarevolume-lengthscalingrelations.

Phasespacediagramofvolumechangevs.lengthchangeofamodelglacierunderclimateforcingwith50yearperiod.Onlyafter5cli-

matecyclestheglacierresponseapproachesthelimitingcyclearoundthesteadystate(blackdot).Obviouslyclimateandglacierreaction

arenotcloselyrelated.

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Airflow velocity measurements in ventilated porous debris accumulations

MorardSebastien*,DelaloyeReynald*

*Geography, Dept. Geosciences, University of Fribourg, Chemin du Musée 4, CH-1700 Fribourg (sebastien.morard@unifr.ch, reynald.delalo-ye@unifr.ch)

Themechanismofdeepaircirculation(the“chimneyeffect”)isknowntobeafrequentphenomenonmaintainingverycoldgroundconditions,andsometimespermafrost,inporousdebrisaccumulations(talusslope,relictrockglacier)locatedseve-ralhundredmetersbelowtheregionalpermafrostlimit.Temperaturemeasurementsatthegroundsurface(Morardetal.2008)andinborehole(Delaloye&Lambiel2007)revealedthatthegroundthermalregimeisstronglyinfluencedbythead-vective-heateffectoftheairflow.Inordertobetterunderstandtheprocessesbywhichinternalventilationcausesastrongovercoolingofthelowerpartofdebrisaccumulations,experimentalcontinuousairflowvelocitymeasurements(usinganemometersandanairdifferentialpressuresensor)havebeencarriedoutrecentlyinthreesites:intheCreux-du-Vantalusslope(Juramountains,1250ma.s.l.),intheDreveneuse-d’enBastalusslope(ValaisPrealps,1560ma.s.l.)(Delaloye&Lambiel2007)andintheGrosChadouarelictrockglacier–talusslopecomplex(FribourgPrealps,1570ma.s.l.).

Windmill and sonic anemometerswereplaced inwindholes located in the lowerpartof the ventilation system. In theDreveneuse-d’enBastalusslope,thewindmillsensorrecordedavelocityof0.1–0.4m/sinsummertime,butstrongeraspi-ration(upto0.8m/s)byverycoldweatherduringasnowfreeperiodinlatefall.IntheCreux-du-Vantalusslope,datafromthesonicanemometerwereverynoisy,butseemalsorangebetween0.05-0.5m/sandsometimes1m/s.IntheGrosChadoua,bothwindsensorsrecordedoutflowvaluesbetween0.5to1.7m/sinsummer,withfastervelocitieswhentheexternaltemperaturerises.Infall,beforetheonsetofasnowcover,whentheexternalairtemperaturecrossedathresholdofabout+4°C,airflowdirectionchangesrapidly.Airflowreversibilityoccurredseveraltimesduringthisperiod,dependingontheoutsideairevolution(figure1).Thewindsensorsdidnotworkproperlyduringwinter.The relation between airflow velocity (U) and the outside air temperature is not linear, but can be expressed as :U = c√(OutsideAirTemperature–ReversibilityThresholdTemperature)(Ohataetal.1994).Cisanempiricalcoefficientdependingupon structural conditions. For the Gros Chadoua, the results fit well with a coefficient c between 0.25 and 0.5. ForDreveneuse-d’enBas,resultsarebetterwithasmallercoefficient(0.10).

Whenthewindholewasdisconnectedfromtheopenairenvironmentbyasnowcover,thedifferentialpressuresensorsre-vealedformostofallthewinterseasonthatthepressurecontrastbetweentheinsideandtheoutsidewasdependantontheexternaltemperature.Thispressurelowatthebaseofthesnowcoverisassumedtobecauseddynamicallybytheascentofrelativelywarmer light air throughout thedebris accumulation. Thisprocess forces the external air topenetrate in thegroundthroughthesnowcoverinthelowermostpartofthesystem.

Figure1.Airflowvelocityanddirection(outfloworaspiration)linkedwiththeoutsideairtemperatureintheGrosChadoua,between25.

Octoberand12.November2007.

Despitetheseinstrumentswerenormallyintendedforopen-airmeasurements,arangeofairflowvelocityhasbeendetermi-ned.Theresultsshowthattheairflowismaintainedbyasimplerelationdeterminedbythepressuregradientresultingfromtemperaturedifferencebetweentheinsideandtheoutsideair.Thecirculationofairinsideporousdebrisaccumulationisalsoacontinuousprocess,evenafterthedevelopmentofasnowcover.

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yREFERENCESDelaloye, R.,& LambielC. 2007:Drilling in a low elevation cold talus slope (Dreveneuse, Swiss Prealps).Geophysical

ResearchAbstracts9:10907.Morard, S.,Delaloye, R.&Dorthe J. 2008: Seasonal thermal regimeof amid-latitude ventilateddebris accumulation.

ProceedingsoftheNinthInternationalConferenceonPermafrost,July2008,Fairbanks,Alaska,1233-1238.Ohata,T., Furukawa,T.&HiguchiK.1994:Glacioclimatological studyofperennial ice in theFuji icecave, Japan,Part1,

Seasonalvariationandmechanismofmaintenance.ArcticandAlpineResearch,vol.26,3.227-237.

6.1

Inventory of geomorphosites of Bavona and Rovana valleys (Ticino)

PaganoLuca

6670 Avegno, luca.pagano@gmail.com

Duringthelastdecade,researchongeomorphologicalheritagehas improvedduetothedevelopmentofgeotourismandgeoparksandtotheactivityoftheWorkinggrouponGeomorphositesoftheInternationalAssociationofGeomorphologists.Severalmethods(seeReynardandCoratza,2007)weredevelopedforassessingthequalityofgeomorphosites–thatisland-formstowhichavaluecanbegivenduetohumanperceptionand/orutilization(Panizza,2001).Theaimistoreducesub-jectivityandtofacilitatetheselectionofthemostrepresentativesites,worthtobeprotectedand/orpromoted.Inspiredbyseveralapproachesdevelopedduringthelastdecade,Reynardetal.(2007)developedattheInstituteofGeographyofLausanneUniversityanassessmentmethodofgeomorphosites.Themethodallowsassessingthescientific,ecological,aesthetic,culturalandeconomicvaluesofgeomorphositesandtonotemoredescriptivedatainordertosetupasiteinven-tory.Theassessmentisdividedintwocategoriesofcriteria:thecentral(scientificvalue)andadditional(ecological,econo-mic,aestheticandcultural)values.TheassessmentmethodwasappliedontwoalpinevalleysintheSouthernSwissAlps.Moreprecisely,wefocusedonthese-lectionandtheassessmentofBavonaandRovanavalleys’geomorphosites(MaggiaValley,Ticino).28landformswithascien-tificcentralvaluewereidentifiedandstudied.ResultsshowthatCalnegiahangingvalleyobtainsthemostimportantscoreandisjustfollowedbytheBasòdinoGlacier,asmallicecapglacier.Onesite,thefossilproglacialmarginoftheBasòdinoGlacierW,representsanincrediblegeodiversityduetotheglacio-karsticoriginofPiandelGhiacciaiospolje.Aftertheinventorystage,wenotedthat,ontheground,geomorphologyisnotmuchknownincomparisonwiththehighvalueofsomegeomorphosites.Thus,inordertoacknowledgethembythegeneralpublic,weofferedsomeperspectiveswiththeintentionofpromotingthegeomorphologicalheritageoftheregion.Firstly,thedefinitionofcategoriesofprotectionwouldcontributetopreservethevulnerablegeomorphositestowardshumanimpacts.Secondly,weunderlinethevalueofsomeinterestingsitesoftheinventorywiththeideaofpromotingasustainabletouristdevelopment.Geodiversityisindeedpoorlytakenintoaccountforthe(geo)touristdevelopmentoftheregion.

REFERENCES:Pagano, L. 2008: Inventairedes géotopes géomorphologiquesduVal Bavona et duValRovana. Sélection, evaluation et

perspectives.MémoiredeLicence.UniversitédeLausanne.Panizza,M.2001:Geomorphosites,concepts,methodsandexamplesofgeomorphologicalsurvey.Chinesesciencebulletin

46,Suppl.Vol.,4-6.Reynard,E.&Coratza,P.2007:Geomorphositesandgeodiversity:anewdomainofresearch.GeographicaHelvetica62,3:

138-139.Reynard, E. Fontana,G. Kozlic, L. Scapozza, C 2007: Amethod for assessing «scientific» and «additional values» of

geomorphosites.GeographicaHelvetica,62,3:148-158.

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6.20

Evaluation des effets de l’enneigement artificiel sur la chimie du sol: Cas de Crans-Montana-Aminona, Valais

ParisodJulien*,SennClaudia*,PfeiferHans-Rudolf*&VennemannTorsten*

*Institut de Minéralogie et de Géochimie, Faculté des Géosciences et de l’Environnement, Université de Lausanne, Anthropole, CH-1015 Lausanne, Suisse.

Ce travail traitedeséventuels impacts sur la chimiedusoldûà l’utilisationde l’enneigementartificiel, ainsiqu’àcelled’additifquipermetuneproductiondeneigedecultureàdestempératuresplushautes.Lebutestdedéterminers’ilexistedes impacts sur lachimiedusol,parcomparaisondes résultatsd’analyseentredifférentsprofilsde sols, soumisetnonsoumisàl’enneigementartificiel,etd’évaluerl’ampleurdecesdernierss’ilexiste.Laneigeartificielleestproduiteparpul-vérisationd’eaumélangéeàdel’aircomprimée,cequiformedesmicrogouttelettesquivonts’agglomérersurdesnoyauxdecongélationspourformerdescristauxdeneige(Brillaudetal.,2005etCampion,2002).Ilnesembledoncpasqu’unapportenélément,desurcroîtpolluant,soitàcraindre,pourautantquel’eauutiliséenesoitpaspolluée(ouquen’yretrouvepasunouplusieursélémentsdansdesconcentrationsanormalementélevées).Cependant,l’utilisationd’unadditifestparfois

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yprésente,cequiétaitlecaspourunepartiedesinstallationsdudomaineskiabledeCran-Montana-Aminonajusqu’en2007.L’additifleplussouventutiliséestuneprotéinebactérienneappeléeINP(IceNucleationProtein,GraetheretJia,2001)pro-duiteparSnowmax®.Cetteprotéinejouelerôledenoyaudecongélation,etfavoriseainsilaformationdecristauxdeneigeàdestempératuresplusélevées(soitenviron–2°Caulieude-4°Csans).Uneutilisationcroissantedel’enneigementartifi-cielle,liéàl’utilisation,danscertainscas,d’unadditifd’originebactérienne,estbiensouventàl’originedecraintesvis-à-visdel’environnement.Cetravailneprétendpasrépondreàlaquestion«L’utilisationdel’enneigementartificielle,avecousansadditif,est-ilàl’origined’unepollutiondessols?»,mais,seplaceplutôtcommeunpointdedépart,afindedéterminersidesimpactsdirectsouindirectssurlachimiedusolssontimputableàl’utilisationdecettetechnologie,notammentunapportencomposésazotésquiseraitliéàlaprésencedel’additifd’origineprotéinique.Nousavonséchantillonnétrois«ty-pes»desols:soumisàl’enneigementuniquementnaturel,àl’enneigementartificielsansadditifetnatureletàl’enneigementartificielavecadditifetnaturel,ainsiquedifférents«types»deneigeafindevérifierl’originel’apportencertainséléments:neigenaturel,neigeartificiellesansadditifetavec,neigemixtenaturelle-artificiellesansadditifetavec.Nousavonségale-mentéchantillonnédifférenteseauxprovenantderuisseauxalimentésparlafontedeneigenaturelle,artificielleavecetsansadditifafind’éventuellementconstatéuntransfertdansceseaux(Fig.1).Danslebutdepasserenrevueunmaximumd’éléments (chimiques)ainsique lespropriétésdebase (pH,granulométrie),présentsdans lesol,nousavonseffectué lesanalysessuivantes:• compositionenélémentsmajeursettracesparfluorescenceX• compositionioniqueparchromatographiesurextractions• dosageducarbonetotal,organiqueetminéralparcoulométrie(suréchantillonssolides)etanalyseurélémentairedeC

dissout(surextractions)• analysesCHN(suréchantillonssolides)• analysesqualitativesspécifiquementdescomposésprotéiniquesparspectroscopieparfluorescenceUV-Visibleetabsor-

bance• dosagedeprotéinestotalesparlaméthodedeBradford(surlesextractions).Lesrésultatsmontrentqueglobalement,ilexistepeudevariationsdeconcentrationsdesélémentsanalyséspouvantêtrecorrélésavecl’utilisationdel’enneigementartificielquecesoitavecousansadditif.Iln’yanotammentpasd’apportsfla-grantsencomposésazotésmalgré l’utilisationd’unadditifdenatureprotéiniqueetd’originebactérienne.Les seulsélé-mentsdontonpeutredouterunapport,dufaitquedesconcentrationsrelativementélevéesdansleséchantillonsdeneigeartificielleavecetsansadditif,sontlemagnésium,lecalciumainsiquelesulfate.Cependant,cedernierétantunanion,uneretentiondanslessolsestpeuprobable.Cedernierseretrouveenconcentrationsplusélevéesdansleseauxderuisseaux,alimentésparleseauxdefontedeneigemixte,doncavecprésencedeneigeartificielleavecetsansadditif.Ilesttoutefoisdifficiledecorrélercesconcentrationsplusélevéesavecunapportdirectdûàl’utilisationdel’enneigementartificiel,auxvuesdeladynamiquedessystèmesd’alimentationdesruisseaux,etdeladatedeprélèvementdeséchantillons.Nouspou-vonsdoncconclurequ’unimpactsurlachimiedusol(pourlapartdecedomaineexplorédanscetravail),n’estpasclaire-mentobservable,etestdanstouslescaspasd’uneampleurimportante.Cependant,nosrésultatsnousmontrentégalementqu’ilseraitintéressantdefairedesrecherchessedirigeantdansledomainedelabiochimiedusol,plusparticulièrementledéveloppementetl’activitébactérienne.

Figure:1:Schémadesdifférentesvoiespossiblesdetransfertdescomposéschimiquesdelaneigeartificielledanslesdifférentscomparti-

ments

REFERENCESBrillaudM-A.,LuezA.,RodicqM. (2005),NeigedecultureetSnowmax:quels impactssurlasanté,RapportAtelierSanté-

Environnement EcoleNationale de la Santé Publique, Rennes. Récupéré sur http://www.tourisme.gouv.fr/fr/navd/mediatheque/publication.

CampionT(2002),Impactdelaneigedeculture,Rapportdel’Agencedel’EauRhôneMéditerrannéeCorse.Graether S.P., Zongchao Jia. (2001), “Modeling Pseudomonas syringae ice-nucleation protein as aβ-helical protein”.

BiophysicalJournal,80,pp.1169-1173.

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Spatial variability of glacier elevation changes in the Swiss Alps obtained from differencing two DEMs

PaulFrank*&HaeberliWilfried*

* Department of Geography, University of Zurich, Winterthurerstr. 190, CH-8057 Zurich (frank.paul@geo.uzh.ch)

Duringthepast25yearsmassiveglacierthinninghasbeenobservedintheAlps.Thisisdocumentedbydirectmassbalancemeasurementsonnineregularlyobservedglaciersaswellasfieldevidence(e.g.disintegrationofglaciertongues,increasedareasofrockoutcrops,collapsingrockwalls,revisedhikingtrails)atseveralsites(Pauletal.,2007).However,itremaineduncertainhowrepresentativetheninedirectlymeasuredglaciersareforthevolumechangeoftheentireAlps.Apossiblewayofassessingtherepresentativityistosubtracttwodigitalelevationmodels(DEMs)fromtwopointsintimewhichareofsufficientaccuracywithrespecttotheexpectedchanges.

FortheSwissAlps,aDEMwith25mspatialresolution(DEM25)wasgeneratedbyswisstopoaround1985.InFebruary2000anear-globalDEMwasacquiredbyinterferometrictechniquesduringtheShuttleRadarTopographyMission(SRTM).ThisDEMisavailableforfreefromanftp-serverat90m(or3")spatialresolution.ItoffersnowtheuniqueopportunitytoassessglacierelevationchangesovertheentireAlpsbysubtractingitfromanearlierDEM(liketheDEM25inSwitzerland).IthastobenotedthatbothDEMscouldhavelargererrorsinthe(snow-covered)accumulationareaofglaciers.FortheDEM25,thestereomatchingofopticalaerialphotographysuffersfrompoorcontrastoversnowandtheSRTMDEMhassomeuncertain-tyduetoavariablesnowpenetrationdepthoftheC-bandradarbeam.

FormainlytworeasonswehavenotcorrectedtheelevationdependentbiasoftheSRTMelevationswhichwasreportedinearlierstudies.OnereasonisthatasimilarbiasresultsasanartefactwhenDEMsofdifferentcellsizearesubtracted(Paul,inpress),theotheristhatahugeportionofglacierswouldgetpositiveelevationchanges(massgains)intheaccumulationarea,whichishighlyunlikelyduringtheperiod1985to1999.

Forthisstudywehavecalculatedglacierspecificelevationchangesfrom1985to1999forabout1050glacierslargerthan0.1km2intheSwissAlps(PaulandHaeberli,2008).Thechangesrefertotheglaciergeometryof1973whichisclosetothe1985glacierextent(Pauletal.,2004)anddigitallyavailableforallglaciersinSwitzerland.Inordertocomparetheresultswiththedirectmeasurements,twomeanvolumechangevalues(inmeterwaterequivalent,mw.e.)arecalculated.Oneis(methodA)thearithmeticmeanoftheindividualmeanchangesofallglaciersandanotheroneis(methodB)themeanvaluefortheentireglacierizedareathatdoesnotconsiderindividualglaciers(allglacierstogetheraretakenasoneglacierentity).

Theanalysisrevealsstrongthicknesslosses(partly>80m)forflat/low-lyingglaciertonguesandastrongoverallsurfacelo-weringalsoforglaciertonguesunderathickdebriscover.Thedifferenceimage(Fig.1)displaysfinespatialdetailsofthechange.

ApartfromtheobviousmassivedownwastingofthetongueofTriftglacier,itclearlyrevealsthatsomeglaciers(e.g.Stein,Kehlen,Damma)havebeenlargerin1985thanin1973asthezoneofthinningisoutsidethe1973extent.Themeancumu-lativemassbalanceofthenineglacierswithdirectmeasurements(-10.8mw.e.)agreeswellwiththemeanchange(methodB)fortheSwissAlpsfromDEMdifferencing(-11mw.e.)andcanthusbeconsideredtoberepresentativefortheAlps.Meanthicknesschangeofindividualglaciersiscorrelatedwiththeirsize,elevation,andexposuretosolarirradiation.Thisimpliesthatmasslossesoflargeglacierscanbeunderestimatedwhentheyaredirectlyinferredfromvaluesmeasuredatthegene-rallymuchsmallerglaciersinthemassbalancenetwork.Indeed,themeanchangewithmethod(A)isonly-7.0mw.e.andthusmuchlessnegativethanthefieldderivedvalue.Inparticularthelargeregionsatlowelevationsfromthelargesticemassescontributetothestrongerloss.

REFERENCESPaul, F. Inpress:Calculationof glacier elevation changeswith SRTM: Is there an elevationdependentbias? Journal of

Glaciology.Paul, F.&Haeberli,W.2008: Spatial variabilityofglacier elevationchanges in theSwissAlpsobtained fromtwodigital

elevationmodels.GeophysicalResearchLetters,doi:10.1029/2008GL034718.Paul,F.,Kääb,A.&Haeberli,W.2007:RecentglacierchangesintheAlpsobservedfromsatellite:Consequencesforfuture

monitoringstrategies.GlobalandPlanetaryChange,56,111-122.Paul,F.,Kääb,A.,Maisch,M.,Kellenberger,T.W.&Haeberli,W.2004:RapiddisintegrationofAlpineglaciersobservedwith

satellitedata.GeophysicalResearchLetters,31,L21402,doi:10.1029/2004GL020816.

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6.22

GlobGlacier: A new ESA project to map the world's glaciers from space

PaulFrank*,KääbAndreas**,RottHelmut***,ShepherdAndrew****&StrozziTazio*****

* Department of Geography, University of Zurich, Winterthurerstr. 190, CH-8057 Zurich (frank.paul@geo.uzh.ch)** Department of Geosciences, University of Oslo, Oslo, Norway*** Environmental Earth Observation (Enveo), Innsbruck, Austria**** School of Geosciences, University of Edinburgh, Edinburgh, Great Britain***** Gamma Remote Sensing, Gümligen, Switzerland

Changesofglaciersandicecapsarekeyindicatorsofclimaticchange,mostlyduetotheirenhancedandwellrecognizablereactiontosmallclimaticvariations.Theyhavethusbeenselectedasoneoftheessentialclimatevariables (ECVs) intheglobalclimateobservingsystem(GCOS)andtheirmonitoringisorganizedinatieredstrategywithintheglobalterrestrialnetworkforglaciers(GTN-G).WithinGTN-G,annualmeasurementsofmassbalance(c.50glaciers)andlengthchanges(c.550glaciers)areperformedandintheworldglacierinventory(WGI)detaileddataexistaspointinformationforabout71'000glaciers,whichisc.40%oftheestimated160'000glaciersworldwide.Thus,(1)thecurrentsampleofglacierswithannualmeasurementsisverysmallandmightbenotrepresentativeforthechangesataglobalscaleand(2)theWGIisnotcomple-teanddifficult touse forchangeassessment (pointdata).Asmeltingglaciersand icecapsmightprovideaneven largercontributiontoglobalsealevelriseinthecomingdecadesthanthetwocontinentalicesheets,thereisanurgentnecessitytogeneratemorecompleteandrepresentativedatasets(GCOS,2006).

WhilethelargepotentialofmultispectralsatellitedataforglaciermappingisalreadyutilizedbytheGLIMSinitiativetocreateadigitaldatabaseofglacieroutlines,thefullpotentialofsatellitedatafordeterminationofglaciermassbalanceorlengthchangesinasystematicwayremaintobeexplored.Astherequiredtechniquesformappingglaciersnowlines,topo-graphy,elevationchangesorvelocityfields(allindicativeformassbalance)doalreadyexist,aremainingchallengeistheirintegratedandsystematicapplicationtoalargesetofglaciers(IGOS,2007).TheherepresentednewESAprojectGlobGlacieraimsatexploringandapplyingtheexistingmethodstoalreadyarchivedsatellitedata inordertocontributetoexisting

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gy databases(GLIMS,WGI)andobservationprograms(WGMS).GlobGlacierisoneofESAsdatauserelement(DUE)activitiesthat

respondstotheneedsofsomemajorusersgroups,whichareactivelyinvolvedindefiningtheproductsandassessmentoftheservice(Volden,2007).

TheproductsthatwillbegeneratedbyGlobGlacierinclude(seeFig.1):glacieroutlinesandterminuspositionsfor20'000unitseach,snowlinesandtopographicinformationfor5000unitseach,elevationchangesfor1000unitsandvelocityfieldsfor200units.Thetechniquestobeappliedvarywiththeproductandthesensorandincludeopticalandmicrowavesatellitedataaswellas laseraltimetry (cf.Pauletal., subm.).Glacieroutlineswillbederivedfrommultispectralsensors (mainlyLandsatTM/ETM+)usingwellestablishedmethods(bandratioswiththreshold)combinedwithmanualeditingandGIS-baseddatafusionatthreedifferentlevelsofdetail:Level0(L0):outlinesenclosingcontiguousicemassesthatarecorrectedformisclassification(e.g.debris,shadow,water);L1:individualglaciersthatresultfromcombiningL0outlineswithhydrologicdivides;L2:outlinesfromL1combinedwithDEMdatatoobtainadetailedglacierinventory.Theterminus positionwillbemarkedwherethecentralflowlinecrossestheglacierterminus.Snow lineswillalsobederivedfromopticalimagerybasedonterrainandatmosphericallycorrectedalbedovalues.Thetopography information isbasicallyderivedfromthefreelyavailableSRTMDEMandcomplementedbyDEMsfromopticalstereosensors(e.g.ASTER,SPOT)andinterferometrictech-niques(e.g.usingERS1/2SARdata)inregionsoutsidetheSRTMcoverage.Elevation changeswillbecalculatedbydifferen-cingDEMsfromtwopointsintimeandbycomparingspotelevationsfromlaseraltimetersatorbitcrossingpoints.Finally,velocity fieldswillbederivedfromfeaturetrackingofrepeatpassopticalimageryorfrommicrowavesensorsusingdiffe-rentialSARinterferometryoroffset-tracking.Thetimeperiodanalysedwilldependontheavailablesatellitedataandvaryfromseasonaltoannualmeans.

REFERENCESGCOS2006: SystematicObservationRequirements for Satellite-basedProducts forClimate - Supplementaldetails to the

satellite-basedcomponentofthe ImplementationPlanfortheGlobalObservingSystemforClimate inSupportof theUNFCCC.GCOSReport107,WMO/TDNo.1338,103pp.

IGOS2007:IntegratedGlobalObservingStrategyCryosphereThemeReport-FortheMonitoringofourEnvironmentfromSpaceandfromEarth.Geneva:WorldMeteorologicalOrganization.WMO/TD-No.1405.100pp.

Paul,F.,A.Kääb,H.Rott,A.Shepherd,T.Strozzi,&E.Voldensubm.:GlobGlacier:Mappingtheworldsglaciersandicecapsfromspace.EarseleProceedings.

Volden,E.2007:ESAsGlobGlacierproject.In:CliCIceandClimateNews,Issue9,8.

Figure1.Schematicoverviewoftheworkflow,theworkpackagesandthegeneratedproductsoftheGlobGlacierproject.

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Rapid permafrost degradation induced by non-conductive heat transfer within a talus slope at Flüela Pass, Swiss Alps.

PhillipsMarcia*,ZenklusenMutterEvelyn*,Kern-LuetschgMartina*

*WSL Institute for Snow and Avalanche Research SLF Davos (phillips@slf.ch)

Talusformationsareanimportanttypeofdebrisstorageinmountainenvironmentsandthedegradationoficewithinthemcanleadtothetriggeringofmassmovementsortostructure instability (PhillipsandMargreth2008).Numeroussurfaceinvestigationshaveshownthattheinnerstructureoftalusformationsandhencetheprocessesoccurringtherecanbecom-plex.However,fewdirectmeasurementsexist,forexampleinboreholes.OneoftheearlieststudiedtalusslopesintheSwissAlpsisaNEoriented,25-35°slopelocatedatFlüelaPass,rangingbetween2380and2600masl.Theslopeisboundedbyarockwallatthetopandbyalakeatthebase.Geophysicalinvestigationsinthe1970sindicatedthepresenceofgroundiceatthebaseoftheslope,thinningupslopeandnotoccurringatthetop(Haeberli1975).Thepresenceofpermafrostwasat-tributedtothepersistenceofavalanchedebrisatthebaseoftheslopeinsummerandlateralsotolocaldifferencesinsurfaceroughness(Lerjenetal.2003).

Two20mdeepboreholesweredrilledatthesitein2002,confirmingthepresenceoficeatthebaseoftheslope(Luetschgetal.2004).BoreholeB1islocatedat2501masl(midslope)andB2isat2394m(nearthebaseoftheslope).Boreholestrati-graphiesshowedthepresenceofvaryingamountsoficebetween3and10mdepthandtheoccurrenceofcoarseblocksin-terspersedwithlargevoidsat9–14mdepthinB1andat10–17mdepthinB2;thematerialpresumablyoriginatesfrompara-/postglacial rockfall deposits or blocky Egesenmoraines, which were subsequently covered with firn/ice and finerclasts.

BoreholetemperaturemeasurementshavebeencarriedoutinB1andB2since2002,using12YSI44008thermistorsandCampbellCR10Xloggersineachborehole.MeteorologicaldatawasobtainedneartotheslopeinaflatareaofFlüelaPass.Duringthemeasurementperiod(2002-2007)activelayerdepthshaveremainedveryconstantat3m,evenduringthesum-mer2003heatwave,pointingtotheongoingpresenceoficebelow3m.In2003thepermafrostbodyinB2was7mthick,between3and10mdepth.ByJuly2008itsthicknesshadhalvedandwaslocatedbetween3and6.5mdepth.Thisrapidpermafrostdegradationwastriggeredfrombelow.

Boreholetemperaturedataalsoindicatetheoccurrenceofthermalanomaliesataround10mdepthinB1andaround15mdepthinB2.Thetemperaturecurvesheredisplayamuchhighervariabilityandamplitudethanthosemeasuredjustaboveandbelow.Thissuggeststheoccurrenceofintra-talusventilationthroughthelargevoidswithinthecoarseblockymaterial,aphenomenondrivenbytheexpulsionoftherelativelywarmerandlessdenseintra-talusairinwinter,leadingtotheaspi-rationofcoldexternalairintothebaseoftheslope(DelaloyeandLambiel2005).Thephenomenonisparticularlyeffectivewithcoldairtemperaturesandlowsnowdepthsandcanalsooccurinsummerwhenairtemperaturesarebelow0°C.

Thepresenceofvoidsandtheevidenceoftheoccurrenceofintra-talusventilationsuggestthatnon-conductiveheat-transferprocesses,inparticularlatentheateffects,arecontributingtotheextremelyrapidthinningofthepermafrosticefrombe-low.Astheintra-talusairisdrawnthroughthesnowcoverintothevoidsandbecausetemperaturegradientinducedvapourmigrationoccursfrombelow,theintra-talusairmusthaveahighmoisturecontent;whenthisaircomesintocontactwiththefrozengroundandthedewpointisreached,condensationwilloccur,releasingenergyandenhancingpermafrostde-gradation.Thelatentheatofcondensationishigh(2.5MJkg-1),solittlevapourisrequiredtocausesignificantwarming.

Furtherinvestigationssuchasgas-tracerexperiments,localmicroclimatologicalmeasurementsandmoredetailedboreholetemperaturemeasurementswillberequiredtoanalyzethecausesandeffectsoftheintra-talusventilationindetail.Theexistingmeasurementsdeliverinterestinginformationonpossiblemechanismsofcurrentlyoccurringpermafrostdegrada-tioninalpinetalusslopes.

REFERENCESDelaloye,R.,andLambiel,C.2005.Evidencesofwinterascendingaircirculationthroughouttalusslopesandrockglaciers

situatedinthelowerbeltofalpinediscontinuouspermafrost(SwissAlps).Norskgeogr.Tidsskr.,59:194-201.Haeberli,W.1975.UntersuchungenzurVerbreitungvonPermafrostzwischenFlüelapassundPizGrialetsch(Graubünden).

Zurich.Lerjen,M.,Kääb,A.,Hoelzle,M.,andHaeberli,W.2003.Localdistributionofdiscontinuousmountainpermafrost.Aprocess

studyatFlüelaPass,SwissAlps.InEighthInternationalConferenceonPermafrost.EditedbyS.A.Phillips.Zurich.Swets&Zeitlinger,Vol.1,pp.667-672.

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gy Luetschg,M.,Stoeckli,V.,Lehning,M.,Haeberli,W.,andAmmann,W.2004.TemperaturesintwoboreholesatFlüelaPass,

Eastern SwissAlps: the effect of snow redistributiononpermafrost distributionpatterns inhighmountain areas.PermafrostandPeriglacialProcesses,15:283-297.

Phillips,M., andMargreth, S. 2008. Effects of ground temperature and slopedeformationon the service life of snow-supportingstructures inmountainpermafrost:WisseSchijen,Randa,SwissAlps. In9th InternationalConferenceonPermafrost. EditedbyD.L.KaneandK.M.Hinkel. Fairbanks,Alaska. InstituteofNorthernEngineering,UniversityofAlaskaFairbanks,Vol.2,pp.1417-1422.

6.2

Rockglacier dynamics in the Swiss Alps – comparing kinematics and thermal regimes in the Murtèl-Corvatsch region

RoerIsabelle*,HoelzleMartin*,**,HaeberliWilfried*&KääbAndreas***

* Glaciology, Geomorphodynamics & Geochronology; Geography Department, University of Zurich, Winterthurerstrasse 190, CH – 8057 Zürich (iroer@geo.uzh.ch)** Department of Geosciences, University of Fribourg, Chemiin du musée 6, CH – 1700 Fribourg*** Department of Geosciences, University of Oslo, Postbox 1047 Blindern, NO - 0316 Oslo

Inthecontextoftherecentclimaticchangesandtheirimpactonthecryosphere,permafrostenvironmentsplayakeyroleduetotheirsensitivitytowardsthermalchangesandresultinggeomorphologicalresponse.Theindicativeroleofrockgla-ciersinthesegeosystemswasemphasizedonlyrecently(e.g.,Haeberlietal.2006),butwasuptonowmainlyrestrictedtotemperaturevariationswithinthepermafrostbodyaswellasvariationsinactivelayerthickness.Withinthelastdecade,anincreasingnumberofstudiesmonitoredandquantifiedthecreepbehaviourofrockglaciersintheEuropeanAlpsandobser-vedincreasingsurfacedisplacementssincethe1990s(e.g.,Schneider&Schneider2001,Lambiel&Delaloye2004,Kääbetal.2007).Inthiscontextitisdescribed,thattheAlpinerockglaciersshowarathersynchronousbehaviourandrespondsensi-tivelytorecenttemperatureincrease(Roeretal.2005,Kääbetal.2007,Delaloyeetal.2008).Thereseemstobeastrongindi-cationthattheobservationsarerelatedtoawarmingoftheshearzonewithintheindividualrockglaciers(Arensonetal.2002).The presentation aims at the combined analysis of rockglacier kinematics and thermal characteristics in the Murtèl-Corvatschregion,oneofthebestequippedpermafrostresearchsites.

REFERENCESArenson,L.U.,Hoelzle,M.&Springman,S.2002:Boreholedeformationmeasurementsandinternalstructureofsomerock

glaciersinSwitzerland.PermafrostandPeriglacialProcesses13:117-135.Delaloye,R.,Perruchoud,E.,Avian,M.,Kaufmann,V.,Bodin,X.,Hausmann,H., Ikeda,A.,Kääb,A.,Kellerer-Pirklbauer,A.,

Krainer,K.,Lambiel,C.,Mihajlovic,D.,Staub,B.,Roer,I.&Thibert,E.2008:RecentinterannualvariationsofrockglaciercreepintheEuropeanAlps.In:Kane,D.L.&K.M.Hinkel(eds.)NinthInternationalConferenceonPermafrost(Fairbanks,Alaska)1:343-348.

Haeberli,W.,Hallet,B.,Arenson,L.,Elconin,R.,Humlum,O.,Kääb,A.,Kaufmann,V.,Ladanyi,B.,Matusoka,N.,Springman,S.&VonderMühll,D.2006:Permafrostcreepandrockglacierdynamics.PermafrostandPeriglacialProcesses17:189-214.

Kääb,A.,Frauenfelder,R.&Roer,I.2007:Ontheresponseofrockglaciercreeptosurfacetemperatureincrease.GlobalandPlanetaryChange56:172-187.

Lambiel,C.&Delaloye,R.2004:Contributionofreal-timekinematicGPPSinthestudyofcreepingmountainpermafrost:examplesfromtheWesternSwissAlps.PermafrostandPeriglacialProcesses15:229-241.

Roer, I.,Avian,M.,Delaloye,R., Lambiel,C., Bodin,X., Thibert, E.,Kääb,A.,Kaufmann,V.,Damm,B.&Langer,M.2005:Rockglacier„speed-up“throughoutEuropeanAlps–aclimaticsignal?ProceedingsoftheSecondEuropeanConferenceonPermafrost,Potsdam,Germany,June2005:101-102.

Schneider, B.& Schneider,H. 2001: Zur 60jährigenMessreihe der kurzfristigenGeschwindigkeits-schwankungen amBlockgletscherimÄusserenHochebenkar,ÖtztalerAlpen,Tirol.ZeitschriftfürGletscherkundeundGlazialgeologie37,1:1-33.

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Electromagnetic Prospecting in Alpine Permafrost: Examples from the Southern Swiss Alps

ScapozzaCristian*,GexPierre**,LambielChristophe*&ReynardEmmanuel*

*Institut de Géographie, Université de Lausanne, Anthropole, CH-1015 Lausanne (Cristian.Scapozza@unil.ch)**Institut de Géophysique de l’Université de Lausanne, Amphipôle, CH-1015 Lausanne

WithintheframeworkofgeomorphologicalandglaciologicalinvestigationsoftheLateglacialandHoloceneglacier/perma-frostevolutionintheCantonTicino(SouthernSwissAlps),severalgeophysicalmethods(frequency-domainelectromagneticlateralmappingand2Dresistivityprofiling,direct-currentresistivitysoundings,self-potentialmeasurementsandthermalprospecting)havebeenusedformappingthepermafrostdistributionatthelocalscale(Scapozza2008;Scapozzaetal.2008).Inthiscontext,theapplicationofelectromagneticgeophysicalmethodsintheprospectingofalpinepermafrostisarecentandnotwell-developedapproach(see,forexample,Hauck2001).

Inthisstudy,twofrequency-domainelectromagneticmethodswereused:thefieldgroundconductivity-meterGeonicsEM-31andtheVLF-R(Very-LowFrequencyResistivity)resistivity-meterGeonicsEM-16R.TheGeonicsEM-31operatesatafixedfre-quencyandallowstodeterminethespatialapparentconductivityandinphasevariationsinthesurveyarea(McNeill1980).Theinphaseisproportionaltothemagneticsusceptibilityoftheground.Thedepthofinvestigationdependstothespacingbetweentransmitterandreceiver(3.66mfortheEM-31)andtothefrequency(9.8kHz).Accordingtothepolarisationoftheinstrument,thedepthofinvestigationsisaround6mwiththeverticaldipoles(VD)andaround3mwiththehorizontaldipoles(VH).TheVLF-Rtechniqueuseselectromagneticenergyradiatedbyaverylowfrequency(VLF)transmitter(Cagniard1953).InthisstudytheRhauderfehntransmitter(23.4kHz)locatedinGermany(nearBremen)wasused.Themeasurementofthehorizontalcomponentoftheelectricfield (E)andofthehorizontalmagneticcomponent (H)perpendiculartotheazimuthofthetransmittingstationallowstoknowtheapparentresistivityofthenearsurface.TheratiobetweenHandEgivesaphaseanglethatchangesaccordingtovariationsofresistivitywiththedepth.Thecombinedinversionofapparentresistivityandphaseangledataallowsustorealize2DVLF-Rtomographywithatwo-layerresolution.

Themeasurementcarriedouton thePiancabella rockglacier (BlenioValley) (Fig.1A) showthatpermafrostoccurrence isprobable,withmaximalresistivitiesatthefrontoftherockglacierandadecreaseofthevaluestowardupslope,asexpectedbygeomorphologicalobservationsandothergeophysicalmeasurements(seeScapozza2008).Inparticular,theelectroma-gneticprospectingallowsustoknowapproximatelytheactivelayerdepthandthepermafrostresistivity,asshownintheVLF-Rtomography(Fig.1B).Thisexampleshowsthatelectromagneticprospectinginalpinepermafrostoffersgoodpossibi-litiestomapthespatialapparentresistivity(i.e.thepermafrostdistribution)(EM-31andVLF-R)and/ortoobtaininformationconcerningthestructureoftheprospectedterrains(VLF-Rtomography).

REFERENCESCagniard,L.1953:Basictheoryofthemagneto-telluricmethodofgeophysicalprospecting.Geophysics18,605-635.Hauck,C.2001:Geophysicalmethodsfordetectingpermafrost inhighmountains.MitteilungenderVAW-ETHZürichNo.

171.McNeill, J.D.1980: Electromagnetic terrainconductivitymeasurementsatLowInductionNumbers.Mississauga,Geonics

Ltd.,TechnicalNoteTN-6.Scapozza,C.2008:Contributionà l’étudegéomorphologiqueetgéophysiquedesenvironnementspériglaciairesdesAlpes

Tessinoisesorientales.Lausanne,InstitutdeGéographie(MScThesis,publishedonFebruary28,2008,onhttp://doc.rero.ch/).

Scapozza,C.,Gex,P.,Lambiel,C.&Reynard,E.2008:Contributionofself-potential(SP)measurementsinthestudyofalpineperiglacial landforms: examples from theSouthernSwissAlps. Proceedingsof the9th InternationalConferenceonPermafrost,Fairbanks,AK,29June–3July2008,1583-1588.

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Figure1.A:VLF-R(EM-16R)andEM-31profilesalongthePiancabellarockglacier.B:VLF-RtomographyoftheprofileSCE-VLF08.

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Permafrost Map of the Eastern Ticino Alps

ScapozzaCristian*,MariStefano**,ValentiGiorgio***,StrozziTazio****,GexPierre*****,FontanaGeorgia*,MüllerGuy*,LambielChristophe*,DelaloyeReynald**&ReynardEmmanuel*

*Institut de Géographie, Université de Lausanne, Anthropole, CH-1015 Lausanne (Cristian.Scapozza@unil.ch)**Département des Géosciences, Géographie, Université de Fribourg, Chemin du Musée 4, CH-1700 Fribourg***Sezione Forestale Cantonale, Viale Franscini 17, CH-6500 Bellinzona****GAMMA Remote Sensing, Worbstrasse 225, CH-3073 Gümlingen*****Institut de Géophysique, Université de Lausanne, Amphipôle, CH-1015 Lausanne

Thepermafrostdistributionandcharacteristics intheSouthernSwissAlpsarepoorlyknownbecauseof lackofresearchdedicatedtothismorphoclimaticcontextoftheAlpsduringthelastdecades.Inspiteoftheinterestforthecryospherere-actionstoclimatewarming,onlyfewscientificstudieswerecarriedoutuntilnowintheperiglacialbeltoftheTicinoAlps.WithintheframeworkofgeomorphologicalandgeophysicalinvestigationsontheLateglacialandHoloceneglacier/perma-frostevolutionintheSouthernSwissAlps(seeScapozza&Reynard2007;Scapozza2008;Scapozzaetal.2008),aregionalmodelbasedonaninventoryof75rockglacierswasdevelopedtosimulatethepermafrostdistributionintheEasternAlpsoftheCantonTicino(Fig.1).Themodelusedisbasedontheassumptionthatthepermafrostdistributionattheregionalscaledependsmainlyonaltitudeandorientation(topoclimaticparameters)andthattheminimalaltitudeofactive/inactiverockglacierscanbeusedasanindicatorofthelowerlimitofdiscontinuouspermafrost.Themodelwascalibratedbythermalandgeophysicalprospecting, inorder toasses thepermafrostdistributionat the localscale.Moreover, several siteswereequippedforlong-termstudies.Atthemoment,intheEasternTicinoAlps(Fig.1),thefollowingsstudiesarecarriedout:

-GeomorphologicalmappingandgeophysicalprospectingandmonitoringintheSceruValley.Thegeophysicalprospectingwascarriedoutwithfrequency-domainelectromagneticlateralmappingand2Dresistivityprofiling(GeonicsEM-16RandEM-31),direct-current(DC)resistivitysoundings,self-potentialmeasurements,andthermalprospecting(miniaturegroundtemperaturedataloggersandspringtemperatures)(Scapozza2008;Scapozzaetal.2008).OnthePiancabellarockglacierandontheGanaRossatalusslope,aground-surfacetemperatureandself-potentialmonitoringnetworkwassetup.-Geomorphologicalmapping,direct-current(DC)resistivitysoundings,ground-surfacetemperaturesandreal-timekinema-tic(RTK)GPSmonitoringforstudyingthedynamicsofcreepingpermafrostintheNorthernsideoftheCimadiGanaBianca,particularlyontheStabbiodiLargariorockglacier(Valenti2006;Müller,inprep.).- ERS InSAR (space-borne synthetic aperture radar interferometry) signatures inventory to estimate bothmagnitude andspatialpatternofslopemotionintheperiglacialbeltoftheTicinoAlps,inparticularintheGothardregionandintheBlenioValley.Inthenextyears,thestudyandtheequipmentofotherssitesforpermafrostresearchandmonitoringisplannedintheValBedrettoregionandintheGreinaregion.Thegoalistobetterknownthecryospherereactiontorecentclimatewarminginordertoassessandquantifytheprocessesrelatedwithpermafrostdegradationinhighmountainenvironments.

REFERENCESMüller,G.inprep.:Ladégradationdupergélisolliéeauxchangementsclimatiquesetlesrisquesassociés.Lecasduversant

NorddeCimadiGanaBianca(ValdiBlenio,Tessin).Lausanne,InstitutdeGéographie(MScThesis).Scapozza,C.2008:Contributionà l’étudegéomorphologiqueetgéophysiquedesenvironnementspériglaciairesdesAlpes

Tessinoisesorientales.Lausanne,InstitutdeGéographie(MScThesis,publishedonFebruary28,2008,onhttp://doc.rero.ch/).

Scapozza,C.&Reynard,E.2007:RockglacierselimiteinferioredelpermafrostdiscontinuotralaCimadiGanaBiancaelaCimadiPiancabella(ValBlenio,TI).GeologiaInsubrica10,21-32.

Scapozza,C.,Gex,P.,Lambiel,C.&Reynard,E.2008:Contributionofself-potential(SP)measurementsinthestudyofalpineperiglacial landforms: examples from theSouthernSwissAlps. Proceedingsof the9th InternationalConferenceonPermafrost,Fairbanks,AK,29June–3July2008,1583-1588.

Valenti,G.2006:IlpermafrostinTicino.Dati,statisticheesocietà6(2),46-50.

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Figure1.PermafrostandrockglaciersdistributionintheEasternTicinoAlps.

6.2

Conceptualising sediment cascades to enhance dynamic geomorphological mapping

ThelerDavid*,BardouEric**,ReynardEmmanuel*

*Institut de Géographie, Université de Lausanne, Quartier Dorigny, CH-1015 Lausanne (david.theler@unil.ch)**Bureau IDEALP Ingénieurs Sàrl, Rue de la Marjorie 8, CH-1950 Sion

Researchfocusingongeomorphologicalmappingoftenconcernstheestablishmentoflandformsinventoriesatlargescales.Themaindisadvantageofthemapsproducedistheirstaticcharacter.Infact,availablegeomorphologicallegendsystemsarenotalwayssufficientformappingalpineenvironmentswithhighgeomorphologicalactivity.Agoodexampleisillustratedbytorrentialsystemswheredynamicprocesseslikechanneliseddebrisflowsoccurandwherelandformsassociatedtotheseprocessesmaychangeveryfastintimeandspacescales.Assessingsedimentvolumesthatsupplydebrisflowchannelsisoneofthekeyparameterstomitigatedisastersonplacesgeomorphologicallyconcernedbyfluvialprocesses(Zimmermannetal.1997).DataderivedthroughGISspatialanalysisbasedonhighaccuracydigitalelevationmodels(slopes,aspect,hydro-graphicnetworkanddelineationofsubwatersheds)mightbeofhighinterestformappingdynamicgeomorphologicalpro-cessesasshownbyanattemptdoneforBruchitorrentialsystemintheSwissAlps(Theleretal.inpress).ThispaperproposestouseGIStoolscoupledwithaqualitativeconceptualisationofthesystem,whatshouldopennewopportunitiesforgeomor-phologicalmapping.AnexampleispresentedforatorrentialsystemintheSwissAlps.

Thedifferentpartsofthesystemareconceptualisedinordertodepictthesedimenttransfersonamountainflank(Fig.1,

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y2).Sedimenttransferstartsfromthehillslopes(1),wherephysicalweatheringfollowedbygravitationalprocessesarepredo-minant.Thetimeofresidenceofsedimentsisveryvariabledependingonthetopographicsettingandtheintensityofpro-cessesandcouldberelatedtoacomplexstochasticfunction(e.g.Hegg,1997).Sedimentsmayhaveasecondrepositorywhentheyreachtheactivegully(2).Here,thetimeofresidencedependsonwaterrunoff.Itcouldbeexplainedbylesscomplexfunctions,becausetransferisdoneonlythroughtwoprocesses–debrisfloworbedloadtransport.Thesetwophenomenatransfersedimentsveryactivelyandthereforedonotstorethemforlong(3).Whentheyreachthefan(4)sedimentstrans-portedbyactivegeomorphicphenomenacouldeitherbestored (5)or transitdirectly totheeffluent (6).Followingthesepreviousobservationsdebris transferarethenreplaced intotheglobalerosionsystem.Thiscouldhelptohighlightwithwhichpartofthesystemvolumeassessmentmodelareplaying.TheglobalschemecanbesummarisedbyatankcascadeasdepictedinFigure2.Thesizeofthetankisreferredtothepotentialresidencetimeofsediments(thedifferenceinsizeonthegraphmustbeseeninalogarithmperspective).

Figure1.Placeofdebrisflowandbedloadtransportintotheerosivesystem.

Figure2.Tankcascadeforsedimenttransferandlandscapeelementswherethedifferentformulaareapplied.

REFERENCESTheler,D.&Reynard,E. inpress:Assessing sediment transferdynamics fromgeomorphologicalmaps:Bruchi torrential

system,SwissAlps.JournalofMaps2008.Hegg,C., 1997. ZurErfassungundModellierung vongefährlichenProzessen in steilenWildbacheinzugsgebieten,G52.

GeographischesInstitutderUniversitätBern,Bern.Zimmermann,M.,Mani,P.&Romang,H.1997:Magnitude-frequencyaspectsofalpinedebrisflows.Eclogaegeol.Helv.,90,

415–420.

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Glacier volcano interactions and related hazards during the 200 eruptive crisis at Nevado del Huila, Colombia

WorniRaphael*,PulgarínBernardo**,AgudeloAdriana**,HuggelChristian*

*Department of Geography, University of Zurich, Switzerland (raphael_worni@gmx.net)**INGEOMINAS Popayán, Colombia

NevadodelHuila,aglacier-coveredvolcanointheSouthofColombia’sCordilleraCentral,hasnotexperiencedanyhistoricaleruptions.InFebruaryandApril2007thevolcanoeruptedwithtwocomparablysmallphreaticevents.EacheruptionwasaccompaniedbytheformationoflargefissuresintheHuilasummitregionof2kmlengthand50-80mwidthwithconti-nuedstrongfumarolicactivityaftertheeruptions.Theeruptionsproducedlaharsthattravelled150kmdownthePaezRiver,withflowvolumesofseveralmillionm3and≈40millionm3fortheFebruaryandAprilevents,respectively.ThewatercontentoftheAprilflowisestimatedat≈25millionm3.

Theeruptionandglacierrelateddynamicswereanalyzedusingair-bornephotography,QuickBirdandAstersatelliteimage-ry.Itwasfoundthatglacierswerenotaffectedbytheeruptionsinamagnitudethatwouldcorrespondtotheamountofice-meltgeneratedwaternecessarytoproducetheobservedlaharflowvolumes.Instead,indicationsofflowpathssuggestedthatmostofthewaterthatformedthelaharswasexpelledfromthefissures,stemmingfromhydrothermalwaterreservoirs.Channelsofafewmetersdepthincisedinglaciericeprovidedevidenceofwaterflowovertheglacierswithtemperatureslikelyexceeding80°C.Sedimentwasdepositedontheglaciersandfurtherdownstream.DuringtheAprileruptionthelo-wermostpartoftheElOsoglacierfailed,probablyasanavalanchewithabout0.5millionm3ofice.Themechanismthatcausedthisglacierfailureisnotyetwellunderstoodbutcouldberelatedtohotwaterreleasedfromthesummitfissuresthatenteredthebaseoftheglacierandprovokedasuddenreductionofshearstrengthattheglacier-bedrockinterface.

Theunderstandingofthevolcano-iceinteractionsonNevadodelHuilaandrelatedformationoflargelaharsisimportantinviewoftheresultingseverehazards.Theparticularlylargedimensionofthelaharsassociatedwiththe2007eruptionsleavespacefordiscussionastotheoriginofsuchlargeamountsofwater.Aliteraturereviewsuggestedthatdrainageofsimilarlylargehydrothermalwaterreservoirsduringeruptiveactivityisveryrare.Moreinvestigationsarethereforeneededtobetterconstraintherelevantprocesses.AstothefutureconditionsatNevadodelHuila,itismostlikelythatglacierswillcontinuetorespondtoongoingatmosphe-ricwarming.Inthelast20yearsglacierswerefoundtohaveshrunkby30%toacurrentsizeof10.7km2,withanestimatedicevolumeequivalentto410millionm3ofwater.Thecurrentrateofretreatsuggestsglacierscoulddisappearcompletelyinthesecondhalfofthe21stcentury,andhencestillrepresentamajorsourceofhazardwheninteractingwithvolcanicactivi-tyresultinglargelahars.

6.2

Analyses of newly digitised snow series over the last 100 years+ in Switzerland

WüthrichChristian*,BegertMichael*,ScherrerSimonC.*,Croci-MaspoliMischa*,AppenzellerChristof*,WeingartnerRolf**

*Bundesamt für Meteorologie und Klimatologie MeteoSchweiz, Krähbühlstrasse 58, Postfach 514, CH-8044 Zürich, christian.wuethrich@meteoswiss.ch**Geographisches Institut der Universität Bern, Gruppe für Hydrologie, Hallerstrasse 12, CH-3012 Bern

SnowisontheonehandanimportantcommercialfactorespeciallyintheSwissAlpineregion(tourism,hydro-electricity,drinkingwater)andontheotherhandresponsibleforconsiderablehazardslikeavalanches.Inaddition,snowisanexcellentindicatortodetectclimatechange.Hence,high-qualitylong-termsnowseriesarecrucialforreliableanalyses.Inthepresentedstudy12Swisssnowserieswithdailymeasurementssinceatleast1910(onedatingbackto1864,cf.Fig.1)andaltitudesbetween450and2500maslhavebeenanalysed.Theobjectivesweretwofold.First,suitablelong-termsnowserieshavebeenselected,missingdatadigitizedandtheentireseriesqualitychecked.Second,thelong-termsnowseries

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yhavebeenusedfortrendanalysesoveratimeperiod>100years.AsnowdepthreconstructionwiththemethodofBrownandBraaten(1998)usingdailynewsnow,temperatureandprecipitationasinputvariablesperformedwellandmadeitpossibletoanalysedayswithsnowpack(Fig.2).Theresults showthat thesnowcover isvaryingsubstantiallyonseasonalanddecadal timescales,which is in linewithScherrer(2006).Theanalysesofthedecadalnewsnowtrendsduringthelast100yearsshowsunprecedentedlownewsnowsumsinthewinterseasons(DJF)ofthe1990s.The100yeartrendofdayswithsnowpackrevealsasignificantdecreaseforstationsbelow800maslinthewinterseason(DJF)andforstationsaround1800maslinthespringseason(MAM).Similarresultswerefoundforseasonalnewsnowsums.Finallytheresultsofthetrendanalysesarediscussedwithrespecttothetemperaturetrends.

REFERENCESBrown,R.;Braaten,R.;1998:SpatialandTemporalVariabilityofCanadianMonthlySnowDepths(1946-1995);Atmosphere

Ocean36(1),37-54.Scherrer, S.C.; 2006: Interannual climate variability in the European andAlpine region; VeröffentlichungNr. 67 der

MeteoSchweiz,Zürich.

Figure1.NewsnowsumseriesforSilsMaria(1798masl)1864-2005

Figure2.DayswithsnowpackbasedonreconstructedsnowdepthforSilsMaria(1798masl)1864-2005.

6.30

Evidence of warming in disturbed and undisturbed permafrost terrain at Schafberg (Pontresina, Eastern Swiss Alps)

ZenklusenMutterEvelyn*,PhillipsMarcia*,BlanchetJuliette*

WSL, Institute for Snow and Avalanche Research SLF, CH-7260 Davos, Switzerland (zenklusen@slf.ch)

Bothclimateandhumaninfluencesintheformoftechnicalstructuresmayaltergroundtemperaturesinmountainperma-frostsoils(Phillips2006).In1996severalboreholesweredrilledintothepermafrostoftheMuotdaBarbaPeider(Schafberg)ridgeabovePontresinaintheEasternSwissAlps.Thisstudyinvestigatesandcomparesthegroundtemperaturesmeasuredintwooftheseboreholes,B1andB2.

Theboreholesarelocated50mapartat2960maslinaNWorientedsteepscreeslopeandareinstrumentedwith10thermi-storsbetween0.5mand17.5mdepth.Bothlocationsareverysimilarfromaclimatologicalandgeologicalpointofview.The

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gy maindifferencebetweenthetwoboreholesisthatboreholeB1islocatedbetweensnow-retainingavalanchedefensestruc-

tureswhereasB2 is intheundisturbedscreeslope.Asaconsequence, thesnowcoverpersists longeratB1thanatB2 inearlysummer,thusmodifyinggroundtemperaturesthere.

11completeyears(1997-2007)ofdailyboreholetemperaturemeasurementsatSchafberg(Fig.1)anddatadeliveredbyanear-bymeteorologicalstationofferafirstviewofpossibleinfluencesofclimatechangeandtechnicalstructuresonpermafrostgroundtemperatures.

Forbothboreholes,temporaltrendanalysesshowsignificantwarmingforannualminimum,meanandmediantempera-turesatdepthsbelow10mandforannualmaximumtemperaturesinalldepths.Themagnitudeofthesetrendsareallsimi-larandatbothborehole locationsapproximately0.02–0.03°Cperyear,which is less thanthoseregistered forexampleduringthesameperiodinScandinavianmountainpermafrost(Isaksenetal.2007),reflectingtheinfluenceoftheridgeto-pography,highlyvariablesnowcoverandthepresenceofcoarseblocksatthegroundsurfaceatourstudysite.

Analysesof themaximumannualactive layerdepth (definedasbeingthemaximumannualpenetrationof the0°C iso-therm,(Burn1998))revealthattheactivelayerinB2(around2m)isalmosttwiceasthickasinB1,duetosmalllocaldiffe-rencesinstratigraphy,hydrologyandsolarradiation(RistandPhillips2005).Duringthe11-yearmeasurementperiod,theactivelayerdepthsinbothboreholeshaveremainedquiteconstantwithatemporarydeepeningduringtheextremelyhotsummer2003.Concerningtheannualdurationoftheactivelayer,significantpositivetrendswerefoundforbothboreholes.AlthoughtheannualdurationoftheactivelayeratB2isabout50%longerthanatB1,theincreaseoftheannualactivelayerdurationatB2(5daysperyear)islowerthanatB1(6daysperyear).

Thecomparisonofthetemporaloccurrenceofannualmaximum/minimumtemperatureindifferentdepthsgivesaninsightintohowfastthegroundreactstoseasonalwarming/cooling.Coolinginwinteroccurssimilarlyatbothboreholelocationsandnear-surfacewarminginsummerisdelayedduetothepresenceoftheinsulatingscreecover.Summerwarmingcanadditionally bedelayedby 1 to 2monthsdue to the longer lasting snow cover at B1 compared toB2 (e.g. years 1999 to2001).

Insummary,similarwarmingtrendsovertheperiod1997-2007arevisibleinbothboreholes,indicatingtheregistrationofacommonwarminginfluenceatdepth,despitethecoolingeffectofavalanchedefencestructuresatB1insummerthroughthedelayofsnowmeltattheendofsnow-richwinters.

Fig.1:GroundtemperatureseriesintheSchafbergboreholesB1(left)andB2(right),1996-2008

REFERENCESBurn,C.R.1998.Theactivelayer:twocontrastingdefinitions.PermafrostandPeriglacialProcesses,9:411-416.Isaksen, K., Sollid, J.L.,Holmlund, P., andHarris, C. 2007. Recentwarming ofmountain permafrost in Svalbard and

Scandinavia.JournalofGeophysicalResearch,112(F02S04,doi:10.1029/2006JF000522).Phillips,M.2006.Avalanchedefence strategiesandmonitoringof two sites inmountainpermafrost terrain,Pontresina,

EasternSwissAlps.NaturalHazards,39:353-379.Rist,A.,andPhillips,M.2005.Firstresultsofinvestigationsonhydrothermalprocesseswithintheactivelayerabovealpine

permafrostinsteepterrain.Norskgeogr.Tidsskr.,59:177-183.