Ninth International Conference on Permafrost ... - IARC Research

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Examining the Temporal Variation in Headwater Drainage Networks and Potentialfor Thermokarst Using Remote Sensing in the Imnavait BasinErin D. TrochimUniversity of Alaska FairbanksDouglas L. KaneUniversity of Alaska FairbanksAnupma PrakashUniversity of Alaska FairbanksIntroductionSurficial drainage networks underlain by a confining layersuch as permafrost are characterized by significant amountsof overland flow, manifesting features such as water tracksand incised channels as the dominant complex. Variations inrouting can occur in the Arctic fresh water hydrological cycleas feedback mechanisms between vegetation and permafrostdistribution. Predicting and characterizing potential responseis an important component for engineering infrastructureappropriate for the climatic conditions. The Imnavait basinnorth of the Brooks Range in Alaska is part of a long-termmonitoring effort, and provides an opportunity to pairhydrological studies and high-resolution topography modelswith remotely sensed data, to create a qualitative, spatiallydistributed perspective.Water tracks are saturated areas mantled with organicsoils which may or may not connect to the channel network(McNamara et al. 1999). Flows are perpendicular to elevationcontours, and they often develop a parallel distribution withspacing of approximately tens of meters. The vegetationassociated with water tracks is proportional to quantity ofwater typically present within the channel (Walker et al.1994). Well-developed water tracks contain the Eriophorumangustifolium-Salix pulchra willow community while watertracks of intermittent flow, which are poorly defined, containshrub facies of the Sphagno-Eriophoretum vaginati. subass.typicum.Thawing of ice-rich permafrost or thermokarsting(van Everdingen 1998) in foothills or mountainous areastypically occurs along water tracks; determining the thermalregime of the water tracks will allow the prediction of (if)when a thermokarst may occur. Assessment of whether thewater tracks are experiencing shrub expansion, one of thestrongest indicators of ecosystem change due to climatechange measured to date (Stow et al. 2004), is important forprediction of the future thermal state. Changes in vegetationcan result in feedbacks to the thermal state of the associatedpermafrost, as an increase in density and spatial expansionlower the albedo and allow more energy to be absorbed intothe ground (Callaghan et al. 2004). Coupling this effect withpotential alterations to landscape as a result of thermokarstactivity, including changes in groundwater flow and storage,relief, and discharge patterns and amounts (Grosse et al.2006), results in the potential to significantly alter thelandscape.The Imnavait basin covers an area of 2.2 km 2 . Till froma glacial advance in the middle Pleistocene covers theslopes (Hamilton 1989). Thick permafrost reaching 300 mdeep (Osterkamp & Payne 1981), and lack of springs in thebasin effectively isolate the basin from deep groundwatersources. Maximum depths of thaw are typically 25 to 50 cm,but can extend to 100 cm with variation in environmentalfactors including soil type, slope, aspect, and soil moisture(Hinzman et al. 1991).Aerial photographs from July of 1956, 1978, and 2007were georeferenced and used to digitize water tracks intothree classes to examine the temporal variation in both areaand texture over this 61-year period. Water tracks that wereleast, moderately, and well developed were buffered by 2,5, and 7.5 m, respectively, to approximate area. Zonal GISanalysis using a 5 m digital elevation model acquired in2001 was used to examine the variations in slope, aspect,and elevation.300000Poorly DevelopedMod. DevelopedWell Developed200000Sum Area (m 2 )100000Figure 1. Water tracks in the Kuparuk River basin.01956 1978 2007Figure 2. Imnavait Basin water track distribution: 1956, 1978, and2007.315
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. Zonal GIS analysis of water track distribution.Elevation (m)Aspect(°)Slope(°)Develop. of WT Mean Min Max Mean MeanPoorlyMod.Well1956 900.64 874.75 951.13 235.43 4.711978 906.91 878.74 946.2 226.46 4.942007 903.19 873.67 946.72 204.72 4.341956 895.52 873.88 905.44 229.88 3.981978 907.72 897.01 943.24 256.73 5.232007 899.71 871.83 943.55 224.89 4.861956 0 0 0 0 01978 899.1 872.01 930.11 206.99 4.782007 901.25 874.1 932.03 222.98 5.71Changes in the distribution of the poorly and moderatelydeveloped water tracks both exhibited significant positivelinear trends with R 2 values >0.90. The well-developed watertracks show an initial increase from 1956 to 1978 and thena decrease from 1976 to 2007. This may be due to changesin precipitation and soil moisture, which negatively affectedspecies distribution or gradual channel incision whichrestricted saturated flow to a smaller area.The mean elevation of water tracks varies with time,climbing initially in 1978 and then decreasing in 2007. Thissuggests that water tracks initially extend in distribution upthe slope, and then expand in density in the lower elevationsby 2007. Overall, water tracks in the Imnavait show asouthwest (202.5–247.5°) aspect with significant variationonly in the moderately developed classes with a shift in1978 to west (247.5–292.5°). Well-developed water tracksshow an increase in mean slope angle with time, supportingthe notion that a decrease in overall precipitation or deeperactive layer permitting more infiltration would restrictoverland flow to the steeper areas.Analysis of water track distribution and density from1956 through 2007 showed an increase in both poorly andmoderately defined tracks, while the well-developed watertracks decreased in area. This trend corroborates climatewarming and may indicate increased amounts of solidprecipitation as snow which leave the ground more saturatedin the early growing season and, coupled with warmingweather, provide ideal conditions for shrub expansion.The effect of the change in climatic conditions and thecorresponding shrub expansion in this area on the permafrostwill be examined in future work.ReferencesCallaghan, T.V., Bjorn, L.O., Chernov, Y., Chapin, T.,Christensen, T.R., Huntley, B., Ima, R.A., Johansson,M., Jolly, D., Jonasson, S., Matveyeva, N., Panikov,N., Oechel, W., Shaver, G., Schaphoff, S. & Sitch,S. 2004. Effects of changes in climate on landscapeand regional processes, and feedbacks to the climatesystem. Ambio 33(7): 10.Grosse, G., Schirrmeister, L. & Malthus, T.J. 2006.Application of Landsat-7 satellite data and a DEMfor the quantification of thermokarst-affected terraintypes in the periglacial Lena-Anabar coastal lowland.Polar Research 25(1): 51-67.Hamilton, T.D. 1989. Late Cenezoic glaciation of the CentralBrooks Range. In: T.D. Hamilton, K.M. Reed & R.M.Thorson (eds.), Glaciation in Alaska: The GeologicRecord, Vol. 99. Anchorage, AK: Alaska Geol. Soc.,9-49.Hinzman, L.D. & Kane, D.L. 1991. Snow hydrology of aheadwater arctic basin. 2. Conceptual analysis andcomputer modeling. Water Resources Research 27(6):1111-1121.McNamara, J.P., Kane, D.L. & Hinzman, L.D. 1999. Ananalysis of an arctic channel network using a digitalelevation model. Geomorphology 29: 339-353.Osterkamp, T.E. & Payne, M.W. 1981. Estimates ofpermafrost thickness from well logs in NorthernAlaska. Cold Regions Science and Technology 5(1):13-27.Stow, D.A., Hope, A., McGuire, D., Verbyla, D., Gamon,J., Huemmrich, F., Houston, S., Racine, C., Sturm,M., Tape, K., Hinzman, L., Yoshikawa, K., Tweedie,C., Noyle, B., Silapaswan, C., Douglas, D., Griffith,B., Jia, G., Epstein, H., Walker, D., Daeschner, S.,Petersen, A., Zhou, L. & Myneni, R. 2004. Remotesensing of vegetation and land-cover change in ArcticTundra Ecosystems. Remote Sensing of Environment89: 281-308.Van Everdingen, R. (ed.) 1998. Multilanguage Glossaryof Permafrost and Related Ground-Ice Terms.Boulder, CO: National Snow and Ice Data Center forGlaciology.Walker, M.D., Walker, D.A. & Auerbach, N.A. 1994. Plantcommunities of a tussock tundra landscape in theBrooks Range Foothills, Alaska. Journal of VegetationScience 5: 843-866.AcknowledgmentsMany thanks to Matt Sprau for field assistance and JasonStuckey of the Toolik Field Station GIS program. Fundingwas provided by a student research grant awarded by theCenter for Global Change & Arctic System Research,University of Alaska Fairbanks.316
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NICOP 2008 Ninth <
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ContentsPreface ...................
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Mapping and Modeling the Distributi
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Satellite Observations of Frozen Gr
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xiiIce Wedge Thermal Regime in Nort
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xivPermafrost Response to Dynamics
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NICOP SponsorsUniversitiesUniversit
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Deep Permafrost Studies at the Lupi
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Effect of Fire on Pond Dynamics in
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Cryological Status of Russian Soils
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Acoustical Surveys of Methane Plume
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Permafrost Delineation Near Fairban
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Preparatory Work for a Permanent Ge
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A Provisional Soil Map of the Trans
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Martian Permafrost Depths from Orbi
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Time Series Analyses of Active Micr
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Impact of Permafrost Degradation on
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DC Resistivity Soundings Across a P
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Modeling Thermal and Moisture Regim
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A Provisional Permafrost Map of the
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Alpine Permafrost Distribution at M
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Cryogenic Formations of the Caucasu
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Modeling Potential Climatic Change
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A Hypothesis: A Condition of Growth
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Modeled Continual Surface Water Sto
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Freeze/Thaw Properties of Tundra So
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Discontinuous Permafrost Distributi
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Thermal Regime Within an Arctic Was
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Seasonal and Interannual Variabilit
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Twelve-Year Thaw Progression Data f
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Continued Permafrost Warming in Nor
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Landsliding Following Forest Fire o
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A Permafrost Model Incorporating Dy
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Seasonal Sources of Soil Respiratio
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Greenland Permafrost Temperature Si
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The Importance of Snow Cover Evolut
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The Account of Long-Term Air Temper
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The Combined Isotopic Analysis of L
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Adaptating and Managing Nunavik’s
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Human Experience of Cryospheric Cha
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HiRISE Observations of Fractured Mo
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A Soil Freeze-Thaw Model Through th
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Mapping and Modeling the Distributi
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First Results of Ground Surface Tem
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Historical Changes in the Seasonall
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Rock Glaciers in the Kåfjord Area,
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Snowpack Evolution on Permafrost, N
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Climate Change in Permafrost Region
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Maximizing Construction Season in a
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Pleistocene Sand-Wedge, Composite-W
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