The return periods of Karakoram glacier surges are poorly quantified. Here,
we present evidence of an historic surge of the Khurdopin Glacier that began
in the mid-1970s and peaked in 1979. Measured surface displacements reached
>5 km a<sup>−1</sup>, two orders of magnitude faster than during
quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to
a return period of 20 years. Surge evolution in the two events shows
remarkable similarity suggesting a common trigger. Surge activity in the
Karakoram needs to be better understood if accurate mass balance assessments
of Hindu-Kush–Karakoram–Himalaya glaciers are to be made

A. Luckman

D. J. Quincey

The return periods of Karakoram glacier surges are poorly quantified. Here,
we present evidence of an historic surge of the Khurdopin Glacier that began
in the mid-1970s and peaked in 1979. Measured surface displacements reached
>5 km a−1, two orders of magnitude faster than during
quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to
a return period of 20 years. Surge evolution in the two events shows
remarkable similarity suggesting a common trigger. Surge activity in the
Karakoram needs to be better understood if accurate mass balance assessments
of Hindu-Kush–Karakoram–Himalaya glaciers are to be made

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The Cryosphere, 8, 571–574, 2014www.the-cryosphere.net/8/571/2014/doi:10.5194/tc-8-571-2014© Author(s) 2014. CC Attribution 3.0 License.The CryosphereOpen AccessBrief Communication: On the magnitude and frequency ofKhurdopin glacier surge eventsD. J. Quincey1 and A. Luckman21School of Geography, University of Leeds, Leeds, LS2 9JT, UK2Department of Geography, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP, UKCorrespondence to: D. J. Quincey (d.j.quincey@leeds.ac.uk)Received: 24 September 2013 – Published in The Cryosphere Discuss.: 24 October 2013Revised: 17 January 2014 – Accepted: 27 February 2014 – Published: 3 April 2014Abstract. The return periods of Karakoram glacier surgesare poorly quantiﬁed. Here, we present evidence of an his-toric surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacementsreached >5kma−1, two orders of magnitude faster than dur-ing quiescence. The Khurdopin Glacier next surged in thelate 1990s, equating to a return period of 20 years. Surgeevolution in the two events shows remarkable similarity sug-gesting a common trigger. Surge activity in the Karako-ram needs to be better understood if accurate mass balanceassessments of Hindu-Kush–Karakoram–Himalaya glaciersare to be made.1 IntroductionGlaciers in the Karakoram experienced signiﬁcant recessionfor the vast majority of the twentieth century, apart fromsome short-term advances during the 1970s (Hewitt, 2005).However, in the late 1990s and the ﬁrst part of the twenty-ﬁrst century many were shown to be in balance or gainingmass (Gardelle et al., 2012; Kääb et al., 2012), and the ma-jority had either stable terminus positions or were advancing(Scherler et al., 2011; Bhambri et al., 2013). A number ofstudies have cited recent (decadal) climatic patterns as be-ing responsible for this anomalous behaviour, but the pic-ture is somewhat complicated by the large number of surgingglaciers in the region (Copland et al., 2011). Surging glacierscyclically store ice mass at elevation during periods of qui-escence and discharge it down-glacier during periods of ac-tivity, making it difﬁcult to differentiate between the inﬂu-ences of external climatic forcing and internal ice dynamicson individual glacier behaviour. Variations in the distributionof ice volume with elevation may also impact on short-termglacier mass balance (Tangborn, 2013), although recent workin the Pamir and Karakoram found no signiﬁcant differencebetween the mass balances of surge-type and non-surge-typeglaciers over a 10-year period (Gardelle et al., 2013).Recent studies have quantiﬁed dramatic changes inKarakoram-wide glacier velocities (Heid and Kääb, 2012)and, more speciﬁcally, have quantiﬁed individual surge mag-nitudes by tracking surface features between multitemporalsatellite images (Quincey et al., 2011; Mayer et al., 2011).Thisworkhasdemonstratedthatsurfacevelocitiesmayreachupto2kma−1,albeitforshortperiods,andthatsurgecharac-teristics (e.g. presence/absence of a surge front; impact/lackof impact on the glacier terminus position; presence/absenceof a debris cover) can differ greatly between individualglaciers. There remains conjecture as to the trigger mecha-nism behind these surges, with remote observations of theirtiming and evolution suggesting a change in thermal condi-tions may be responsible (Quincey et al., 2011), but a com-bined observation–modelling approach suggesting a switchin subglacial drainage may be the cause (Mayer et al., 2011).There is consensus, however, that surge events are increasingin the Karakoram, and that this is likely to reﬂect (either di-rectly or indirectly) recent changes in precipitation and tem-perature in the region (Copland et al., 2011; Hewitt, 2007).Despite these recent advances in knowledge, the return pe-riods of Karakoram glaciers are poorly constrained. Some ofthe ﬁrmest estimates are provided by Hewitt (2007), who ob-served tributary glacier surges around the Panmah Glacier inthe early 2000s and speculated on a recurrence interval of50–100 years for the Drenmang Glacier, while recognisingPublished by Copernicus Publications on behalf of the European Geosciences Union.572 D. J. Quincey and A. Luckman: Brief CommunicationFig. 1. (a) The Khurdopin Glacier imaged on 6 July 2013 by the Landsat Operational Land Imager, overlaid with centreline from which thedata in Fig. 2 were extracted. (b–e) The surge of 1979 evidenced in multi-temporal Landsat MSS data. Dashed lines correlate with distinctfeatures that can be tracked moving down-glacier (north) in each subsequent image. Note that the surge has minimal impact beyond 15kmfrom the terminus.that the most recent period between surges was between 25and 30 years. Guo et al. (2013) concluded that the returnperiod of the recently surged Yulinchuan Glacier exceededforty years, based on a search of satellite imagery datingback to the early 1970s. An inventory of glacier surges pre-sented by Copland et al. (2011) identiﬁed several Karako-ram glaciers that had surged more than once within the satel-lite era, and suggested their particular quiescent period maybe 25–40 years, while historical accounts of thickening andthinning on the lower Khurdopin Glacier appear to follow anapproximate 20-year cycle (Mason, 1930).2 The Khurdopin Glacier and the surge of 1979In this brief communication, we report on a previously un-documented surge of the Khurdopin Glacier that occurredin the late 1970s, detected in Landsat Multispectral Scan-ner (MSS) imagery. The Khurdopin Glacier is approximately41kminlength,1.5kminwidthandispredominantlydebris-covered for its lowermost 10km (Fig. 1). It is situated in theShimshal Valley in the Northern Areas of Pakistan, and is rel-atively well known for its surge activity, having surged mostrecently around 1998–99 (Copland et al., 2011; Quincey etal., 2011). Its distinctive surface morphology (large, loopedmoraines) is indicative of a glacier that has surged manytimes in the past, and reports of periodic ice dams blockingthe Shimshal River (and associated outbursts from VirjerabLake) may coincide with surge events dating back to the late1800s (Visser, 1926; Todd, 1930; Iturrizaga, 2005).A recent visual analysis of archive Landsat MSS imageryrevealed that the glacier discharged large volumes of icedown-glacier during the late 1970s, peaking in the summerof 1979 (Fig. 1b–e). The surface features of this glacierare so distinctive and coherent that it is possible to trackthem using cross-correlation of image patches between re-peat pairs of images, even with the relatively coarse pixelsize of 60m. The feature tracking method used here is identi-caltothatdescribedinpreviouspublications(Luckmanetal.,2003, 2007), with images ﬁrst being co-registered using largepatch sizes before surface displacements are measured usingsmaller patches. Robust matches were accepted based on thestrength of their signal-to-noise ratio, and centreline veloc-ity proﬁles (Fig. 1a) were then extracted from each veloc-ity ﬁeld. Remaining spurious matches were manually ﬁlteredfrom the centreline proﬁle data. Given the large pixel size ofthe MSS imagery, uncertainty in the extracted velocity datais relatively high (Table S1 in the Supplement). Errors relatemostly to co-registration errors as a result of changing snowextent, variable cloud cover and varying illuminations, but inevery case they are signiﬁcantly lower than the magnitude ofthe measured displacement.Measured velocities indicate that during the early part ofthe 1970s the glacier was in quiescence, with the lowermost6km of the glacier either stagnant or almost stagnant (Fig. 2).The velocity of the glacier began to increase sometime be-tween 1975 and 1977, although even at this time the lower-most 4km of ice remained inactive. Between the summersof 1978 and 1979 the surge involved the lowermost 15km ofthe glacier and during the summer of 1979 the surge peaked(July–August), with surface velocity reaching >5kma−1 ata point 5–6km from the terminus, two orders of magni-tude faster than during quiescence. By September of 1979the peak of the surge had passed, and by 1986, pre-surgevelocities had been resumed. Unfortunately, a lack of im-ageryprecludestheextractionof anyfurthervelocitydatabe-tween September 1979 and June 1986. The data we do have,The Cryosphere, 8, 571–574, 2014 www.the-cryosphere.net/8/571/2014/D. J. Quincey and A. Luckman: Brief Communication 573Fig. 2. Centreline surface velocities extracted from feature trackingdata before, during and after the surge of 1979.however, demonstrate that there was no clear surge front as-sociated with the 1979 surge, nor did it impact on the glacierterminus position, similar to the event recorded in 1999.Mean surface displacements were also extracted fromsmall (100 pixel) patches around 5km from the terminus ineach velocity ﬁeld to facilitate an analysis of the surge evo-lution in comparison to previously measured events (Fig. 3).Thesedatademonstratethatthesurgetookoftheorderoftwoyears from initiation to reach its maximum, and that the rateof initialspeed-up wascomparable tothose eventspreviouslyrecorded in the region. However, the magnitude of the peakvelocity is more than twice that of any previous surge veloc-ity recorded in recent times (∼2kma−1 during the Kunyangsurge) and more than ﬁve times the maximum displacementmeasured during the Khurdopin surge of 1999. It should benoted, however, that the peak of the 1999 surge may not havebeen fully captured by the Landsat archive. Unfortunately,the lack of post-1979 imagery also precludes any analysis ofhow long it took the glacier to revert to its pre-surge dynamicstate. However, if the 1979 surge followed the evolution ofthose recorded in Quincey et al. (2011) we can estimate itwould have terminated sometime during the winter of 1980–81. This leads, overall, to a surge return period of the orderof 20 years for the Khurdopin Glacier.3 Discussion and conclusionThese data suggest that the thickening and thinning cycles onthe lower Khurdopin Glacier previously reported by Mason(1930) were surge events taking place over an approximatecycle of 20 years. The return period of surges on this glaciertherefore appears to be unchanged since the Little Ice Agedespite climatic changes in the region. Establishing patternsof dynamics on the lower glacier is particularly importantgiven the association of terminus ﬂuctuations with the for-mation and drainage of the Khurdopin–Virjerab Lake (Itur-rizaga, 1997), which has been responsible for some of thelargest ﬂoods in the Shimshal Valley during the last century.Neither of the surge events described here impacted on theterminus position of the glacier, or resulted in lake formation,perhaps because the lower glacier is less advanced and dis-tinctly thinner than previously reported (Visser-Hooft, 1926).It is also noted in Iturrizaga (2005) that the lake does notFig. 3. Surge propagation through a point ∼5km up-glacier fromthe terminus. Note that the shape of the 1979 surge evolution issimilar to those events previously plotted by Quincey et al. (2011)(North Gasherbrum, Kunyang, Khurdopin 1999), but the magnitudeof the maximum measured velocity is >2 times greater.only form during times of glacier advance; sealed subglacialdrainage channels during times of recession can also dam theriver ﬂow.Studies considering surge trigger mechanisms in the re-gion remain inconclusive. Previous work has suggested thatclimatically induced changes in glacier thermal conditionsmay be linked to observed advances and thickening duringthe 1990s (Hewitt, 2005), coinciding with a period of excep-tional surging. Our data show that the evolution of the 1979Khurdopin surge is almost identical to that of the 1999 surge;the gradual acceleration of the glacier over several years be-fore the surge maximum was reached and the maximum ve-locities coinciding with late summer months may thereforeconﬁrm a thermal control (Quincey et al., 2011). Equally, therelatively sudden increase in velocities during the summer of1979, and the absence of a surge front in the velocity data,may indicate that a change in subglacial drainage is the dom-inant control (Mayer et al., 2011). Further observations, bothin situ and from remote sensing, are required if the controlsonglaciersurgingintheregionaretobeproperlyunderstood.To identify and quantify other historic surges that mayhave previously gone undetected, prospects are limited byimage availability and spatial resolution. The Khurdopinsurge was only detected because of its distinctive surfacegeomorphology and its relatively large size; some surgingglaciers in the region are not so heavily debris-covered (e.g.North Gasherbrum), lacking the abundance of surface fea-tures required to be able to detect a surge event, and oth-ers are much thinner (laterally; e.g. Kunyang), and there-fore poorly imaged by coarse resolution sensors. However,as the satellite archive lengthens, and increasing volumes ofimagery become available (e.g. through the declassiﬁcationof Corona and Hexagon imagery acquired in the 1960s and1970s), so the potential for detecting multiple events will im-prove. Being able to quantify Karakoram surges and their re-turn periods is important not only for advancing glaciologicalknowledge, but also because of its relevance to questions offuturewateravailabilityandlongertermlandscapeevolution.This latter application will be the focus of future work.www.the-cryosphere.net/8/571/2014/ The Cryosphere, 8, 571–574, 2014574 D. J. Quincey and A. Luckman: Brief CommunicationSupplementary material related to this article isavailable online at http://www.the-cryosphere.net/8/571/2014/tc-8-571-2014-supplement.pdf.Acknowledgements. We acknowledge the provision of SPOT HRVdata through ISIS project number 667.Edited by: T. BolchReferencesBhambri, R., Bolch, T., Kawishwar, P., Dobhal, D. P., Srivastava,D., and Pratap, B.: Heterogeneity in glacier response in the upperShyok valley, northeast Karakoram, The Cryosphere, 7, 1385–1398, doi:10.5194/tc-7-1385-2013, 2013.Copland, L., Sylvestre, T., Bishop, M. P., Shroder, J. F., Seong,Y. B., Owen, L. A., Bush, A., and Kamp, U.: Expanded andRecently Increased Glacier Surging in the Karakoram, Arct.Antarct. Alp. Res., 43, 503–516, 2011.Gardelle, J., Berthier, E., and Arnaud, Y.: Slight mass gain ofKarakoram glaciers in the early 21st century, Nat. Geosci., 5,322–325, 2012.Gardelle, J., Berthier, E., Arnaud, Y., and Kääb, A.: Region-wideglacier mass balances over the Pamir-Karakoram-Himalaya dur-ing 1999–2011, The Cryosphere, 7, 1263–1286, doi:10.5194/tc-7-1263-2013, 2013.Guo, W., Liu, S., Wei, J., and Bao, W.: The 2008/09 surge of centralYulinchuan glacier, northern Tibetan Plateau, as monitored byremote sensing, Ann. Glaciol., 54, 299–310, 2013.Heid, T. and Kääb, A.: Repeat optical satellite images revealwidespread and long term decrease in land-terminating glacierspeeds, The Cryosphere, 6, 467–478, doi:10.5194/tc-6-467-2012, 2012.Hewitt, K.: The Karakoram Anomaly? Glacier Expansion and the‘ElevationEffect’,KarakoramHimalaya,Mt.Res.Dev.,25,332–340, 2005.Hewitt, K.: Tributary glacier surges: An exceptional concentrationat Panmah Glacier, Karakoram Himalaya, J. Glaciol., 53, 181–188, 2007.Iturrizaga, L.: The valley of Shimshal – a geographical portrait of aremote high mountain settlement and its pastures with referenceto environmental habitat conditions in the North West Karako-rum, GeoJournal, 42, 305–328, 1997.Iturrizaga, L.: New observations on present and prehistoricalglacier-dammed lakes in the Shimshal valley (Karakoram Moun-tains), J. Asian Earth Sci., 25, 545–555, 2005.Kääb, A., Berthier, E., Nuth, C., Gardelle, J., and Arnaud, Y.:Contrasting patterns of early twenty-ﬁrst-century glacier masschange in the Himalayas, Nature, 488, 495–498, 2012.Luckman, A., Murray, T., Jiskoot, H., Pritchard, H. D., and Strozzi,T: Automatic ERS SAR feature-tracking measurement of out-let glacier velocities on a regional scale in East Greenland, Ann.Glaciol., 36, 129–134, 2003.Luckman, A., Quincey, D. J., and Bevan, S.: The potential of satel-lite radar interferometry and feature tracking for monitoring ve-locity rates of Himalayan glaciers, Remote Sens. Environ., 111,172–181, 2007.Mason, K.: The glaciers of the Karakoram and neighbourhood. Rec.Geol. Surv. India, 63, 214–278, 1930.Mayer, C., Fowler, A. C., Lambrecht, A., and Scharrer, K.: A surgeof North Gasherbrum Glacier, Karakoram, China, J. Glaciol., 57,904–916, 2011.Quincey, D. J., Braun, M., Glasser, N. F., Bishop, M. P., Hewitt, K.,and Luckman, A.: Karakoram glacier surge dynamics, Geophys.Res. Lett., 38, L18504, doi:10.1029/2011GL049004, 2011.Scherler, D., Bookhagen, B., and Strecker, M. R.: Spatially variableresponse of Himalayan glaciers to climate change affected bydebris cover, Nat. Geosci., 4, 156–159, 2011.Tangborn, W.: Mass balance, runoff and surges of Bering Glacier,Alaska, The Cryosphere, 7, 867–875, doi:10.5194/tc-7-867-2013, 2013.Todd, H. J.: The Correspondence: Gilgit and Hunza River Floods,Himalayan J., 2, 173–175, 1930.Visser, Ph. C.: Explorations in the Karakoram, Geogr. J., 68, 457–468, 1926.Visser-Hooft, J.: Among the Karakorum Glaciers in 1925, withContributions by Ph. C. Visser, Edward Arnold and Co. London,1926.The Cryosphere, 8, 571–574, 2014 www.the-cryosphere.net/8/571/2014/

The Cryosphere

Brief Communication: On the magnitude and frequency of Khurdopin glacier surge events

Abstract. The return periods of Karakoram glacier surges are poorly quantified. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacements reached &gt;5 km a−1, two orders of magnitude faster than during quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to a return period of 20 years. Surge evolution in the two events shows remarkable similarity suggesting a common trigger. Surge activity in the Karakoram needs to be better understood if accurate mass balance assessments of Hindu-Kush–Karakoram–Himalaya glaciers are to be made.
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The return periods of Karakoram glacier surges are poorly quantified. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid1970s and peaked in 1979. Measured surface displacements reached >5kma−1, two orders of magnitude faster than during quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to a return period of 20 years. Surge evolution in the two events shows remarkable similarity suggesting a common trigger. Surge activity in the Karakoram needs to be better understood if accurate mass balance assessments of Hindu-Kush–Karakoram–Himalaya glaciers are to be made

Adrian Luckman

Cronfa at Swansea University

 Cronfa -  Swansea University Open Access Repository   _____________________________________________________________   This is an author produced version of a paper published in :The Cryosphere                                    Cronfa URL for this paper:http://cronfa.swan.ac.uk/Record/cronfa21914_____________________________________________________________ Paper:Quincey, D. & Luckman, A. (2014).  Brief Communication: On the magnitude and frequency of Khurdopin glaciersurge events. The Cryosphere, 8(2), 571-574.http://dx.doi.org/10.5194/tc-8-571-2014        _____________________________________________________________  This article is brought to you by Swansea University. Any person downloading material is agreeing to abide by theterms of the repository licence. Authors are personally responsible for adhering to publisher restrictions or conditions.When uploading content they are required to comply with their publisher agreement and the SHERPA RoMEOdatabase to judge whether or not it is copyright safe to add this version of the paper to this repository. http://www.swansea.ac.uk/iss/researchsupport/cronfa-support/  The Cryosphere, 8, 571–574, 2014www.the-cryosphere.net/8/571/2014/doi:10.5194/tc-8-571-2014© Author(s) 2014. CC Attribution 3.0 License.The CryosphereOpen AccessBrief Communication: On the magnitude and frequency ofKhurdopin glacier surge eventsD. J. Quincey1 and A. Luckman21School of Geography, University of Leeds, Leeds, LS2 9JT, UK2Department of Geography, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP, UKCorrespondence to: D. J. Quincey (d.j.quincey@leeds.ac.uk)Received: 24 September 2013 – Published in The Cryosphere Discuss.: 24 October 2013Revised: 17 January 2014 – Accepted: 27 February 2014 – Published: 3 April 2014Abstract. The return periods of Karakoram glacier surgesare poorly quantified. Here, we present evidence of an his-toric surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacementsreached > 5 km a−1, two orders of magnitude faster than dur-ing quiescence. The Khurdopin Glacier next surged in thelate 1990s, equating to a return period of 20 years. Surgeevolution in the two events shows remarkable similarity sug-gesting a common trigger. Surge activity in the Karako-ram needs to be better understood if accurate mass balanceassessments of Hindu-Kush–Karakoram–Himalaya glaciersare to be made.1 IntroductionGlaciers in the Karakoram experienced significant recessionfor the vast majority of the twentieth century, apart fromsome short-term advances during the 1970s (Hewitt, 2005).However, in the late 1990s and the first part of the twenty-first century many were shown to be in balance or gainingmass (Gardelle et al., 2012; Kääb et al., 2012), and the ma-jority had either stable terminus positions or were advancing(Scherler et al., 2011; Bhambri et al., 2013). A number ofstudies have cited recent (decadal) climatic patterns as be-ing responsible for this anomalous behaviour, but the pic-ture is somewhat complicated by the large number of surgingglaciers in the region (Copland et al., 2011). Surging glacierscyclically store ice mass at elevation during periods of qui-escence and discharge it down-glacier during periods of ac-tivity, making it difficult to differentiate between the influ-ences of external climatic forcing and internal ice dynamicson individual glacier behaviour. Variations in the distributionof ice volume with elevation may also impact on short-termglacier mass balance (Tangborn, 2013), although recent workin the Pamir and Karakoram found no significant differencebetween the mass balances of surge-type and non-surge-typeglaciers over a 10-year period (Gardelle et al., 2013).Recent studies have quantified dramatic changes inKarakoram-wide glacier velocities (Heid and Kääb, 2012)and, more specifically, have quantified individual surge mag-nitudes by tracking surface features between multitemporalsatellite images (Quincey et al., 2011; Mayer et al., 2011).This work has demonstrated that surface velocities may reachup to 2 km a−1, albeit for short periods, and that surge charac-teristics (e.g. presence/absence of a surge front; impact/lackof impact on the glacier terminus position; presence/absenceof a debris cover) can differ greatly between individualglaciers. There remains conjecture as to the trigger mecha-nism behind these surges, with remote observations of theirtiming and evolution suggesting a change in thermal condi-tions may be responsible (Quincey et al., 2011), but a com-bined observation–modelling approach suggesting a switchin subglacial drainage may be the cause (Mayer et al., 2011).There is consensus, however, that surge events are increasingin the Karakoram, and that this is likely to reflect (either di-rectly or indirectly) recent changes in precipitation and tem-perature in the region (Copland et al., 2011; Hewitt, 2007).Despite these recent advances in knowledge, the return pe-riods of Karakoram glaciers are poorly constrained. Some ofthe firmest estimates are provided by Hewitt (2007), who ob-served tributary glacier surges around the Panmah Glacier inthe early 2000s and speculated on a recurrence interval of50–100 years for the Drenmang Glacier, while recognisingPublished by Copernicus Publications on behalf of the European Geosciences Union.572 D. J. Quincey and A. Luckman: Brief CommunicationFig. 1. (a) The Khurdopin Glacier imaged on 6 July 2013 by the Landsat Operational Land Imager, overlaid with centreline from which thedata in Fig. 2 were extracted. (b–e) The surge of 1979 evidenced in multi-temporal Landsat MSS data. Dashed lines correlate with distinctfeatures that can be tracked moving down-glacier (north) in each subsequent image. Note that the surge has minimal impact beyond 15 kmfrom the terminus.that the most recent period between surges was between 25and 30 years. Guo et al. (2013) concluded that the returnperiod of the recently surged Yulinchuan Glacier exceededforty years, based on a search of satellite imagery datingback to the early 1970s. An inventory of glacier surges pre-sented by Copland et al. (2011) identified several Karako-ram glaciers that had surged more than once within the satel-lite era, and suggested their particular quiescent period maybe 25–40 years, while historical accounts of thickening andthinning on the lower Khurdopin Glacier appear to follow anapproximate 20-year cycle (Mason, 1930).2 The Khurdopin Glacier and the surge of 1979In this brief communication, we report on a previously un-documented surge of the Khurdopin Glacier that occurredin the late 1970s, detected in Landsat Multispectral Scan-ner (MSS) imagery. The Khurdopin Glacier is approximately41 km in length, 1.5 km in width and is predominantly debris-covered for its lowermost 10 km (Fig. 1). It is situated in theShimshal Valley in the Northern Areas of Pakistan, and is rel-atively well known for its surge activity, having surged mostrecently around 1998–99 (Copland et al., 2011; Quincey etal., 2011). Its distinctive surface morphology (large, loopedmoraines) is indicative of a glacier that has surged manytimes in the past, and reports of periodic ice dams blockingthe Shimshal River (and associated outbursts from VirjerabLake) may coincide with surge events dating back to the late1800s (Visser, 1926; Todd, 1930; Iturrizaga, 2005).A recent visual analysis of archive Landsat MSS imageryrevealed that the glacier discharged large volumes of icedown-glacier during the late 1970s, peaking in the summerof 1979 (Fig. 1b–e). The surface features of this glacierare so distinctive and coherent that it is possible to trackthem using cross-correlation of image patches between re-peat pairs of images, even with the relatively coarse pixelsize of 60 m. The feature tracking method used here is identi-cal to that described in previous publications (Luckman et al.,2003, 2007), with images first being co-registered using largepatch sizes before surface displacements are measured usingsmaller patches. Robust matches were accepted based on thestrength of their signal-to-noise ratio, and centreline veloc-ity profiles (Fig. 1a) were then extracted from each veloc-ity field. Remaining spurious matches were manually filteredfrom the centreline profile data. Given the large pixel size ofthe MSS imagery, uncertainty in the extracted velocity datais relatively high (Table S1 in the Supplement). Errors relatemostly to co-registration errors as a result of changing snowextent, variable cloud cover and varying illuminations, but inevery case they are significantly lower than the magnitude ofthe measured displacement.Measured velocities indicate that during the early part ofthe 1970s the glacier was in quiescence, with the lowermost6 km of the glacier either stagnant or almost stagnant (Fig. 2).The velocity of the glacier began to increase sometime be-tween 1975 and 1977, although even at this time the lower-most 4 km of ice remained inactive. Between the summersof 1978 and 1979 the surge involved the lowermost 15 km ofthe glacier and during the summer of 1979 the surge peaked(July–August), with surface velocity reaching > 5 km a−1 ata point 5–6 km from the terminus, two orders of magni-tude faster than during quiescence. By September of 1979the peak of the surge had passed, and by 1986, pre-surgevelocities had been resumed. Unfortunately, a lack of im-agery precludes the extraction of any further velocity data be-tween September 1979 and June 1986. The data we do have,The Cryosphere, 8, 571–574, 2014 www.the-cryosphere.net/8/571/2014/D. J. Quincey and A. Luckman: Brief Communication 573Fig. 2. Centreline surface velocities extracted from feature trackingdata before, during and after the surge of 1979.however, demonstrate that there was no clear surge front as-sociated with the 1979 surge, nor did it impact on the glacierterminus position, similar to the event recorded in 1999.Mean surface displacements were also extracted fromsmall (100 pixel) patches around 5 km from the terminus ineach velocity field to facilitate an analysis of the surge evo-lution in comparison to previously measured events (Fig. 3).These data demonstrate that the surge took of the order of twoyears from initiation to reach its maximum, and that the rateof initial speed-up was comparable to those events previouslyrecorded in the region. However, the magnitude of the peakvelocity is more than twice that of any previous surge veloc-ity recorded in recent times (∼ 2 km a−1 during the Kunyangsurge) and more than five times the maximum displacementmeasured during the Khurdopin surge of 1999. It should benoted, however, that the peak of the 1999 surge may not havebeen fully captured by the Landsat archive. Unfortunately,the lack of post-1979 imagery also precludes any analysis ofhow long it took the glacier to revert to its pre-surge dynamicstate. However, if the 1979 surge followed the evolution ofthose recorded in Quincey et al. (2011) we can estimate itwould have terminated sometime during the winter of 1980–81. This leads, overall, to a surge return period of the orderof 20 years for the Khurdopin Glacier.3 Discussion and conclusionThese data suggest that the thickening and thinning cycles onthe lower Khurdopin Glacier previously reported by Mason(1930) were surge events taking place over an approximatecycle of 20 years. The return period of surges on this glaciertherefore appears to be unchanged since the Little Ice Agedespite climatic changes in the region. Establishing patternsof dynamics on the lower glacier is particularly importantgiven the association of terminus fluctuations with the for-mation and drainage of the Khurdopin–Virjerab Lake (Itur-rizaga, 1997), which has been responsible for some of thelargest floods in the Shimshal Valley during the last century.Neither of the surge events described here impacted on theterminus position of the glacier, or resulted in lake formation,perhaps because the lower glacier is less advanced and dis-tinctly thinner than previously reported (Visser-Hooft, 1926).It is also noted in Iturrizaga (2005) that the lake does notFig. 3. Surge propagation through a point ∼ 5 km up-glacier fromthe terminus. Note that the shape of the 1979 surge evolution issimilar to those events previously plotted by Quincey et al. (2011)(North Gasherbrum, Kunyang, Khurdopin 1999), but the magnitudeof the maximum measured velocity is > 2 times greater.only form during times of glacier advance; sealed subglacialdrainage channels during times of recession can also dam theriver flow.Studies considering surge trigger mechanisms in the re-gion remain inconclusive. Previous work has suggested thatclimatically induced changes in glacier thermal conditionsmay be linked to observed advances and thickening duringthe 1990s (Hewitt, 2005), coinciding with a period of excep-tional surging. Our data show that the evolution of the 1979Khurdopin surge is almost identical to that of the 1999 surge;the gradual acceleration of the glacier over several years be-fore the surge maximum was reached and the maximum ve-locities coinciding with late summer months may thereforeconfirm a thermal control (Quincey et al., 2011). Equally, therelatively sudden increase in velocities during the summer of1979, and the absence of a surge front in the velocity data,may indicate that a change in subglacial drainage is the dom-inant control (Mayer et al., 2011). Further observations, bothin situ and from remote sensing, are required if the controlson glacier surging in the region are to be properly understood.To identify and quantify other historic surges that mayhave previously gone undetected, prospects are limited byimage availability and spatial resolution. The Khurdopinsurge was only detected because of its distinctive surfacegeomorphology and its relatively large size; some surgingglaciers in the region are not so heavily debris-covered (e.g.North Gasherbrum), lacking the abundance of surface fea-tures required to be able to detect a surge event, and oth-ers are much thinner (laterally; e.g. Kunyang), and there-fore poorly imaged by coarse resolution sensors. However,as the satellite archive lengthens, and increasing volumes ofimagery become available (e.g. through the declassificationof Corona and Hexagon imagery acquired in the 1960s and1970s), so the potential for detecting multiple events will im-prove. Being able to quantify Karakoram surges and their re-turn periods is important not only for advancing glaciologicalknowledge, but also because of its relevance to questions offuture water availability and longer term landscape evolution.This latter application will be the focus of future work.www.the-cryosphere.net/8/571/2014/ The Cryosphere, 8, 571–574, 2014574 D. J. Quincey and A. Luckman: Brief CommunicationSupplementary material related to this article isavailable online at http://www.the-cryosphere.net/8/571/2014/tc-8-571-2014-supplement.pdf.Acknowledgements. We acknowledge the provision of SPOT HRVdata through ISIS project number 667.Edited by: T. BolchReferencesBhambri, R., Bolch, T., Kawishwar, P., Dobhal, D. P., Srivastava,D., and Pratap, B.: Heterogeneity in glacier response in the upperShyok valley, northeast Karakoram, The Cryosphere, 7, 1385–1398, doi:10.5194/tc-7-1385-2013, 2013.Copland, L., Sylvestre, T., Bishop, M. P., Shroder, J. F., Seong,Y. B., Owen, L. A., Bush, A., and Kamp, U.: Expanded andRecently Increased Glacier Surging in the Karakoram, Arct.Antarct. Alp. Res., 43, 503–516, 2011.Gardelle, J., Berthier, E., and Arnaud, Y.: Slight mass gain ofKarakoram glaciers in the early 21st century, Nat. Geosci., 5,322–325, 2012.Gardelle, J., Berthier, E., Arnaud, Y., and Kääb, A.: Region-wideglacier mass balances over the Pamir-Karakoram-Himalaya dur-ing 1999–2011, The Cryosphere, 7, 1263–1286, doi:10.5194/tc-7-1263-2013, 2013.Guo, W., Liu, S., Wei, J., and Bao, W.: The 2008/09 surge of centralYulinchuan glacier, northern Tibetan Plateau, as monitored byremote sensing, Ann. Glaciol., 54, 299–310, 2013.Heid, T. and Kääb, A.: Repeat optical satellite images revealwidespread and long term decrease in land-terminating glacierspeeds, The Cryosphere, 6, 467–478, doi:10.5194/tc-6-467-2012, 2012.Hewitt, K.: The Karakoram Anomaly? Glacier Expansion and the‘Elevation Effect’, Karakoram Himalaya, Mt. Res. Dev., 25, 332–340, 2005.Hewitt, K.: Tributary glacier surges: An exceptional concentrationat Panmah Glacier, Karakoram Himalaya, J. Glaciol., 53, 181–188, 2007.Iturrizaga, L.: The valley of Shimshal – a geographical portrait of aremote high mountain settlement and its pastures with referenceto environmental habitat conditions in the North West Karako-rum, GeoJournal, 42, 305–328, 1997.Iturrizaga, L.: New observations on present and prehistoricalglacier-dammed lakes in the Shimshal valley (Karakoram Moun-tains), J. Asian Earth Sci., 25, 545–555, 2005.Kääb, A., Berthier, E., Nuth, C., Gardelle, J., and Arnaud, Y.:Contrasting patterns of early twenty-first-century glacier masschange in the Himalayas, Nature, 488, 495–498, 2012.Luckman, A., Murray, T., Jiskoot, H., Pritchard, H. D., and Strozzi,T: Automatic ERS SAR feature-tracking measurement of out-let glacier velocities on a regional scale in East Greenland, Ann.Glaciol., 36, 129–134, 2003.Luckman, A., Quincey, D. J., and Bevan, S.: The potential of satel-lite radar interferometry and feature tracking for monitoring ve-locity rates of Himalayan glaciers, Remote Sens. Environ., 111,172–181, 2007.Mason, K.: The glaciers of the Karakoram and neighbourhood. Rec.Geol. Surv. India, 63, 214–278, 1930.Mayer, C., Fowler, A. C., Lambrecht, A., and Scharrer, K.: A surgeof North Gasherbrum Glacier, Karakoram, China, J. Glaciol., 57,904–916, 2011.Quincey, D. J., Braun, M., Glasser, N. F., Bishop, M. P., Hewitt, K.,and Luckman, A.: Karakoram glacier surge dynamics, Geophys.Res. Lett., 38, L18504, doi:10.1029/2011GL049004, 2011.Scherler, D., Bookhagen, B., and Strecker, M. R.: Spatially variableresponse of Himalayan glaciers to climate change affected bydebris cover, Nat. Geosci., 4, 156–159, 2011.Tangborn, W.: Mass balance, runoff and surges of Bering Glacier,Alaska, The Cryosphere, 7, 867–875, doi:10.5194/tc-7-867-2013, 2013.Todd, H. J.: The Correspondence: Gilgit and Hunza River Floods,Himalayan J., 2, 173–175, 1930.Visser, Ph. C.: Explorations in the Karakoram, Geogr. J., 68, 457–468, 1926.Visser-Hooft, J.: Among the Karakorum Glaciers in 1925, withContributions by Ph. C. Visser, Edward Arnold and Co. London,1926.The Cryosphere, 8, 571–574, 2014 www.the-cryosphere.net/8/571/2014/

Brief Communication: On the magnitude and frequency of Khurdopin glacier surge events

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