Ninth International Conference on Permafrost ... - IARC Research

More documents

Recommendations

Info

Estimation of the Extent of Near-Surface Permafrost in the Mackenzie Delta,Northwest Territories, Using Remote SensingT.-N. Nguyen, C.R. Burn, D.J. KingDepartment of Geography and Environmental Studies, Carleton University, Ottawa, ON, CanadaS.L. SmithGeological Survey of Canada, Natural Resources Canada, Ottawa, ON, CanadaIntroductionBased on air temperature, permafrost should be continuousin the Mackenzie Delta (MD), northwest Canada (Henry &Smith 2001). However, the most recent Permafrost map ofCanada, using sparse ground temperature data, classifiesthe MD as having discontinuous permafrost (Heginbottomet al. 1995). There has been little fieldwork investigatingpermafrost extent within the delta, yet, the determination ofnear-surface permafrost (NSP) extent, defined in this studyas permafrost within 3 m from ground surface, is importantfor land-use planning, as terrain behaviour varies betweenfrozen and unfrozen ground (Smith et al. 2001).The objectives of this research were (1) to assess if thespatial distribution of near-shore vegetation associations canbe used to predict NSP presence in the MD and, if so, (2)to apply remote sensing techniques to map these vegetationcommunities and estimate the proportion of ground underlainby NSP.Vegetation and Permafrost in Mackenzie DeltaThe MD stretches 200 km north–south and 60 km east–west (Mackay 1963). It is an alluvial landscape intersectedby a network of channels and thousands of lakes, and issubjected to annual flooding. Spatial variation in channelshifting, flooding, and sedimentation is expressed by patternsof vegetation (Gill 1973).Horsetail (Equisetum spp.) communities are the typicalemergent plant associations, while Willow-horsetail (Salix-Equisetum) communities can be found with increasingdistance from stream channels. Alders (Alnus spp.) arelocated at slightly higher elevations than the Willowhorsetailcommunities, since alder species are less tolerantof sedimentation. Spruce (Picea glauca) forests representthe climax community south of tree line. North of tree line,sedges (Carex spp.) and horsetails are common adjacent tochannels, and Willow-horsetail and Salix richardsonii arewidespread on more elevated sites (Pearce 1998).In the MD, the thermal effect of water bodies and theshifting nature of channels affect the age, distribution,temperature, and thickness of permafrost (Smith 1975). Onpoint bars, taliks have been recognized near channels byvarious authors (Gill 1973, Smith 1975). The presence ofa talik, where winter freeze-back does not reach the top ofpermafrost, is due to the slow establishment of permafrostbeneath newly exposed ground, and to deep snowdriftsblown off the channels and trapped in near-shore willowstands (Dyke 2000).Vegetation and Permafrost SamplingField sites were selected so that several representativevegetation classes were present at each site. A line transectmethodology was adopted for vegetation sampling andpermafrost probing. A total of 52 transects were laid insummer 2006. The majority of transects were between 100m and 200 m long depending on the width of the vegetationzones found at each site. Transects were establishedperpendicular to the shoreline and crossing the successionalsequence of vegetation (Fig. 1). Vegetation was sampledusing point and line-intercept methods and was identified atthe genus level for shrubs and trees, and at the functionaltypelevel for herbs. Plant presence and frequency werecalculated to provide an indication of how dominant a planttype is in a community. The ground was probed using waterjetdrilling to detect NSP in each vegetation association.Since the active layer thickness rarely exceeds 1.5 m in theMD, NSP was considered absent if unfrozen ground wasrecorded to 3 m depth (Kokelj & Burn 2005).Relation Between Vegetation and PermafrostThere was a clear association between presence ofpermafrost in the upper 3 m and different vegetationcommunities. On point bars and alluvial islands, HorsetailFigure 1. In each 20 m x 20 m plot, the water-jet drilled hole in thecentre was complemented with two others. Each plot was assigned asingle NSP presence or absence label based on the rule of majority.Spruce forests were not the focus of this research since the presenceof permafrost is ubiquitous there with thin active layer thicknesses(Kokelj & Burn 2005).221
Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s tTable 1. Relation between NSP and vegetation associations.Vegetation association Presence of NSP (% of plots)Southern deltaHorsetail (n=8) 0Willow-horsetail (n=19) 0Alder (n=25) 96Central deltaHorsetail (n=11) 9Willow-horsetail (n=20) 10Alder (n=26) 100Northern deltaHorsetail-sedge (n=18) 100Willow-horsetail (n=12) 17Salix richardsonii (n=15) 100and Willow-horsetail communities were not associatedwith NSP. NSP was present beneath all other vegetationassociations and in other land surface types (Table 1).Image Data AnalysisPermafrost cannot be directly imaged by airborne orsatellite-based sensors, but its presence may be inferredfrom surface characteristics, especially vegetation. In thisstudy, SPOT-5 images of the MD, captured in July 2006 witha nominal ground pixel size of 10 m x 10 m, were classifiedfor vegetation characteristics associated with NSP. Usingrelations of these characteristics with field survey data, theproportion of ground underlain by NSP was estimated.In addition to spectral data produced directly by SPOT-5,data transformations such as vegetation indices, textureanalysis and PCA were used to generate additional imageinformation for classification. Training and testing data werechosen randomly among field sampled plots. MaximumLikelihood classifications were used to generate maps ofvegetation associations with accuracies above 80%.Estimation of Near-Surface Permafrost ExtentTo estimate the extent of NSP in the MD, the land surfacewas categorized into three types: (1) Alluvial islands (AI),(2) Point bars (PB), and (3) all other types. PB occupiedabout 18% of the land surface and the extent of AI in thesouthern delta was calculated to be about 5%. The extent ofNSP in the delta is:idjLn∑∑PV) )*(((1)k kk===111where d are the delta regions, L the land surface types, nthe vegetation classes underlain by NSP, V the land fractionoccupied by n, and P the land fraction occupied by L.In the southern delta, 93% of the land surface was foundto be underlain by NSP. Zones with presence of NSPrepresented 95% and 96% of the land surface in the centraland northern delta, respectively.Conclusions1. On point bars and alluvial islands, Horsetail andWillow-horsetail communities were not associated with NSP.NSP was present beneath all other vegetation associationsand in other land surface types.2. Zones with presence of NSP represent 93%, 95%, and96% of the land surface in the southern, central, and northerndelta, respectively. This indicates that the MD is part of thecontinuous permafrost zone.3. The technique developed in this study was useful in themapping of NSP over large areas in a dynamic environmentand could form the basis of a mapping tool that could beused to aid in land-use planning.ReferencesDyke, L.D. 2000. Shoreline permafrost along the MackenzieRiver. In: L.D. Dyke & G.R. Brooks (ed.), ThePhysical Environment of the Mackenzie Valley,Northwest Territories: a Baseline for the Assessmentof Environmental Change. Ottawa: Geological Surveyof Canada Bulletin 547: 143-151.Gill, D. 1973. A spatial correlation between plant distributionand unfrozen ground within a region of discontinuouspermafrost. Proceedings of the Second <strong>International</strong><strong>Conference</strong> on Permafrost, Yakutsk, U.S.S.R., July13-28, 1973: 105-113.Heginbottom, J.A., Dubreuil, M-A. & Harker, P.A. 1995.Permafrost. National Atlas of Canada, 5 th ed.Henry, K. & Smith, M.W. 2001. A model-based map ofground temperatures for the permafrost regions ofCanada. Permafrost and Periglacial Processes 12:389-398.Kokelj, S.V. & Burn, C.R. 2005. Near-surface ground icein sediments of the Mackenzie Delta, NorthwestTerritories, Canada. Permafrost and PeriglacialProcesses 16: 291-303.Mackay, J.R. 1963. The Mackenzie Delta Area, N.W.T.,Canada. Department of Mines and Technical Surveys,Geographical Branch, Memoir 8.Pearce, C.M. 1998. Vegetation patterns and environmentalrelationships in an Arctic riparian wetland. In: S.K.Majumdar, E.W. Miller & F.J. Brenner (eds.), Ecologyof Wetlands and Associated Systems. PennsylvaniaAcademy of Science, 258-280.Smith, M.W. 1975. Microclimatic influences on groundtemperatures and permafrost distribution, MackenzieDelta, Northwest Territories. Canadian Journal ofEarth Sciences 12: 1421-1438.Smith, S.L., Burgess, M.M. & Heginbottom, J.A. 2001.Permafrost in Canada, a challenge to northerndevelopment. In: G.R. Brooks (ed.), A Synthesis ofGeological Hazards in Canada. Ottawa: GeologicalSurvey of Canada Bulletin 548: 241-264.222
Page 1:
NICOP 2008 Ninth <
Page 6 and 7:
ContentsPreface ...................
Page 8 and 9:
Mapping and Modeling the Distributi
Page 10 and 11:
Satellite Observations of Frozen Gr
Page 13 and 14:
xiiIce Wedge Thermal Regime in Nort
Page 15 and 16:
xivPermafrost Response to Dynamics
Page 17 and 18:
xvi
Page 19 and 20:
NICOP SponsorsUniversitiesUniversit
Page 22 and 23:
Deep Permafrost Studies at the Lupi
Page 24 and 25:
Effect of Fire on Pond Dynamics in
Page 26 and 27:
Cryological Status of Russian Soils
Page 28 and 29:
Acoustical Surveys of Methane Plume
Page 30 and 31:
Permafrost Delineation Near Fairban
Page 32 and 33:
Preparatory Work for a Permanent Ge
Page 34 and 35:
A Provisional Soil Map of the Trans
Page 36 and 37:
Martian Permafrost Depths from Orbi
Page 38 and 39:
Time Series Analyses of Active Micr
Page 40 and 41:
Impact of Permafrost Degradation on
Page 42 and 43:
DC Resistivity Soundings Across a P
Page 44 and 45:
Modeling Thermal and Moisture Regim
Page 46 and 47:
A Provisional Permafrost Map of the
Page 48 and 49:
Alpine Permafrost Distribution at M
Page 50 and 51:
Cryogenic Formations of the Caucasu
Page 52 and 53:
Modeling Potential Climatic Change
Page 54 and 55:
A Hypothesis: A Condition of Growth
Page 56 and 57:
Modeled Continual Surface Water Sto
Page 58 and 59:
Freeze/Thaw Properties of Tundra So
Page 60 and 61:
Discontinuous Permafrost Distributi
Page 62 and 63:
Thermal Regime Within an Arctic Was
Page 64 and 65:
Seasonal and Interannual Variabilit
Page 66 and 67:
Twelve-Year Thaw Progression Data f
Page 68 and 69:
Continued Permafrost Warming in Nor
Page 70 and 71:
Landsliding Following Forest Fire o
Page 72 and 73:
A Permafrost Model Incorporating Dy
Page 74 and 75:
Seasonal Sources of Soil Respiratio
Page 76 and 77:
Greenland Permafrost Temperature Si
Page 78 and 79:
The Importance of Snow Cover Evolut
Page 80 and 81:
The Account of Long-Term Air Temper
Page 82 and 83:
The Combined Isotopic Analysis of L
Page 84 and 85:
Adaptating and Managing Nunavik’s
Page 86 and 87:
Human Experience of Cryospheric Cha
Page 88 and 89:
HiRISE Observations of Fractured Mo
Page 90 and 91:
A Soil Freeze-Thaw Model Through th
Page 92 and 93:
Mapping and Modeling the Distributi
Page 94 and 95:
First Results of Ground Surface Tem
Page 96 and 97:
Historical Changes in the Seasonall
Page 98 and 99:
Rock Glaciers in the Kåfjord Area,
Page 100 and 101:
Snowpack Evolution on Permafrost, N
Page 102 and 103:
Climate Change in Permafrost Region
Page 104 and 105:
Maximizing Construction Season in a
Page 106 and 107:
Pleistocene Sand-Wedge, Composite-W
Page 109 and 110:
Ni n t h In t e r n at i o n a l Co
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Ni N t h iN t e r N at i o N a l Co
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192: Ni n t h In t e r n at i o n a l Co
Page 217 and 218: Ni N t h iN t e r N at i o N a l Co
Page 241: Ni n t h In t e r n at i o n a l Co
Page 253: Ni n t h In t e r n at i o n a l Co
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
Page 331 and 332:
Page 333 and 334:
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
Page 365 and 366:
Page 367 and 368:
Page 369 and 370:
Page 371 and 372:
Page 373 and 374:
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
370Huang, B. 339Hugelius, G. 105, 1
Page 393:
372
show all

Ninth International Conference on Permafrost ... - IARC Research

Create successful ePaper yourself

Delete template?

Save as template?