5．DistributionofGlacierLakesintheNepalHimalaya
HowmanyglacierlakesexistinNepalandwherearetheylocated？Thesearethemostbasic
informationconcernedwiththepotentialGLOFhazard．Themapsalreadypublishedareonesource
to obtainsuchinformationbut those are relatively too old toidentify the present status ofthe
glacierlakes．Unfortunately the speed of development of thelakesis remarkably highrate as
discussedinSection6．3．Thoughsatelliteimageriescouldbeusefulforabovepurpose，theyonly

permitidentifyingthelocationofaglacierlakewhoseareaismorethansomecriticalsize；thestateofdangerisneverevaluatedbecauseofthelimitationintheresolution．Theflightobservation
ismostlyaneffectiveandanusefulmeasurebecauseitcouldenableinspectionandidentification
ofthedetailedfeaturesofaglacierlakesuchasitspotentialdangerousnessandalsotopographicalconditions around thelake．

Flightobservationswerefirstconductedinthepre＋mOnSOOnSeaSOnin1991（Yamada，1991）and

OneSetOfobliquephotographsofglacierlakeswasobtained．TheflightsweremadeintheLangtang

KholabasinonApri122nd，1991，andintheBarunKholabasin，atributaryoftheArunriver，antheDudhKoshibasinsincludingtheHonkuandtheHinkuriverbasinsonApri125th，1991andin
theChilimeKholabasin（GaneshHimal），tributaryoftheTrisuliriver，SOuthernpartofManaslu
rangeandapartoftheMarsyangdiriverbasinonMay5th，1991．Theflightswerealsomadeover
theTamaKosibasinonOctober9th，1991；theShorongandRoIwalingHimalon12thMayリ1993．

TheKhumburegionandthe LangtangKholabasincouldberelativelywellobserved amongthe
basins flown over．

The distribution of the glacierlakes observed by the flightin the Khumbu regions，WhichincludesthedrainagebasinsofBarunKhola，Hunku，HinknandDudhKosi，isshownonthe
based ontheGlacierInventory Map ofKhumbu Himal（Higuchiet al．，1978）in Fig．4（Yamada，1993）．TheotherlakescompiledwiththeaidofmapsandsatelliteimageriesareshowninFig．5（Yamada，1996）．ThenumberbesidethelakeinFigs．4and5correspondstothe Photo snumb

ShowninthisChapter．
The remarkablelakes at each basin willbe described below with reference to their aerial

Obliquephotos，ifavailabletoshow．
5．1Tamur River BasimThreeglacierlakes areidentifiedbythe satelliteimageriesin the upstream area of Tamur
RiverasshowninFig．5．Sincetherearenodetailedinformation，aflightobservationisrequired．

5．2Arun RiverIhsinin Nepal
TwoglacierlakeswerefoundontheBarunglacierandontheLowerBarunglacierinBarun

Khola，OneOfthetributariesoftheArunriver，theapproachroutetothefamousMt．Makalu（8m a．s．1．）．The glacierlake on the Barun glacierlooks too smallto cause a serious disaster
downstream．Theglacierlakeformed on the Lower Barunglacier（Photo4；No．4in Fig．4）isdammedbyanice−COredmoraine．Thelakemakescontactwiththecliff−Shapedglacierterminu−19−

TheGlacierLakeanditsOutburstFloodinthe NepalHimalaya

CHO OYUG LACIER LAIくES

ーヽ ヽ〜

A N D
G LA CIE RS
IN
DU DH KO S HI R EG10N
EAS T N E PA L
SAGARMATHA（EVEREST）
8848m，／ニ㌧」チいィごsO∈壬0；

医ヨpeak．ridge且ndrlver
匠≡】Glacler（devrl良一free）

匡…或Gl8Cler（devris−COVered）［妻］Gl且elerl且ke

Fig．4：DetaileddistributionofglacierlakesandglaciersintheDudhKosiregion，
EastNepal．ArrowpointingImjaglacierlakeandDigTsho．Numberbesidea
lakecorrespondingtothePhoto snumberinChapter5．

Whichisstagnantandcoveredwiththickdebris．Sincethelakeseemstobepotentiallydangerou

theinvestigationwasmadein1993（KadotaandMool，1993）．Theoutlineofthelakewillbesta

inChapter6．
BesidestheBarunKhola，glacierlakesofotherareaswereinvestigatedbyNepalElectricity

Authority（NEA）withintheterritoryofNepalaboveArun3andtheUpperArunProjectsitesfor

ahydoLpOWerdevelopment（NEAReport，1987）．TwolakesnearKepuPokhariwerevisitedonfootoidentifytheGLOFpotential，Whichislocatedintheheadwater of Chhokang Khola，thefir

tributaryontherightbanksideofArunriverafteritentersNepalfromTibet．Aflightobservation
WaSalsomadeofTingeDangaPokhariconsistingoffourlakeslocatedintheupperreachofthe
MedokChhejeKhola，thefirsttributaryontheleftbanksideofArunriverafteritentersNepal
from Tibet．Thoselakes were concluded to be safe．
−20−

DistributionofGlacierLakesintheNepalHimalaya

Fig．5：DistributionofglacierlakesfoundsofarexcepttheDudhKosiregionshownin Fig．4．Thepotentially dangerousglacierlakebeingpointed by an arrow．
NumberbesidethelakecorrespondingtothePhoto snumberinChapter5．

Photo4：GlacierlakeformedontheLowerBarunglacierintheBarunKholabasin（No．4inFig．4）．

−21−

TheGlacierLakeanditsOutburstFloodintheNepalHimalaya

5．3DudllKosiIhsin
5．3．1Hunku Khola Basin

Sixteenglacierlakeswereobservedbytheflight・Someofthemwerealreadyseparatedfrom
themotherglacierandlookssafety・Theremarkableonesareonlyintroducedhere・Theglacierlake。ntheterminusofHunkuglacierlocatedattheheadwateroftheHunkuriverisshowni
photo5（No．5inFig．4）．Thelakestillcontactswiththemotherglacier・Photo6（No・6inFig・4）
showsChamlangTsho（1eftinthephoto）andanunnamedglacierlake（rightinthesamephoto）
f。rm。dattheglaciertongues．Boththelakesarenowseparatedfromthemotherglaciers・FoursmallglacierlakeswereformedinfrontoftheNaulekhglacierlocatedontherightbanksideof
theHunkuriver，WhichareshowninPhoto7（No・7inFig・4）；allthelakesareseparatedfromthe
motherglacier．

Photo5：GlacierlakeformedontheHunkglacierintheHunkriverbasin（No・5inFig．4）．

−22

Distribution ofGlacierLakesinthe NepalHimalaya

Photo6：Glacierlake，ChamlangTsho，andanunnamedglacierlakeinthe Hunku
riverbasin（No．6inFig．4）．

−23−

The Glacier Lake and its Outburst Flood jn the Nepal Bimalaya
5．3．2Hinku Khola Basin

AtotalofthreelargeandfoursmallglacierlakeswereidentifiedasshowninFig．4．Photo8Showsaglacierlake，SabaiTsho，formedonthetongueoftheSabaiglacier（No．8inFig4）；t

VerySteepmOtherglacierapproachesthelake．Theglacierlake，DudhKundontheSanuglacieriShowninPhoto9（No．9inFig．4）．PhotolOshowstheglacierlakeattheendoftheMojangglaci

alsoontheleftbanksideoftheHinkuriver（No．10inFig．4）．Boththelakesareseparatedfr

theglaciers．

Photo8：Glacierlake，SabaiTsho，formed below the Sabai
glacierinthe Hinkuriverbasin（No．8in Fig．4）．

24

DistributionofGlacierLakesintheNepalHimalaya

Photo9：Glacierlake，DudhKund，formedbelowtheSanuglacierintheHinkuriver
basin（No．9inFig．4）．

PhotolO：GlacierlakeformedbelowtheMojangglacierintheHinkuriverbasin（No．
10inFig．4）．

−25−

TheGlacierLake anditsOutburst Floodinthe NepalHimalaya
5．3．3Dudh KosiBasin above Namche Bazar

ThisbasinisknownastheheartoftheNepalHimalaya，WherethefamousgreatHimalayan

peaksover8，000mincludingMt．Everest（officiallynamedSagarmathainNepalandQomolangminTibet）arelocated．Thebasinswerefullyflownoverand21glacierlakeswereobserved．
Imja glacierlake（No．1inFig．4）and Ngozumpa glacierlakes（No．2in Fig．4）alreadyintroducedasatypicalmoraine−dammedlakeandaice−dammedlake，reSpeCtivelyinSection3

arelocatedinthisregion．TheglaciertongueoftheImjaglacierisstagnantandcoveredwiththickdebris．Thelakecontactswiththecliff−Shapedglacierend．TheImjalakewⅢbediscussedindetailinChapter6．DigTshopreviouslyreportedasaglacierlakeburstinthepastisalsolocatedinthis
region（No．3inFig．4）．ItissurethatthepondsontheNgozumpaglaciertonguehavebeenquickly
growingyearafteryear；theyseemtohaveapossibilitytobecomeaglacierlakeinthenear−future・AcrescentrshapedglacierlakeinfrontoftheDuwoglacierisshowninPhotoll（No．11inFig．4）．

Thelakeisalreadyseparatedfromthemotherglacier．

Photoll：Crescen卜shapedglacierlakeformedinfront ofthe
DuwoglacierintheImjaKholabasin（No．11inFig，4）．
−26

DistributionofGlacierLakesintheNepalHimalaya

5・3・4LumdingKholaBasin
Onlyoneglacierlake，TshoOg，isfoundontheLumdingglaciertongueasshowninPhoto12（No・12inFig・4）・OnemorelakeseentothenorthoftheLumdingglacier，LumdingTshoTeng，may
beasafetyclrquelake．

Photo12：Glacierlake，TshoOg，formedontheLumdingglacierintheLumdingriverbasin（No．12inFig．4）．

5．3．5Solu KhoFa Basin

IntheheadwaterareaoftheDudhKundKhola，atributaryoftheSoluKhola，manylakescan

beseen．Anice−dammedlakeisonlyobservedasaglacierlakeontheleftsideoftheDudhglacier（Photo13；No．13inFig．4）．Thelakeis dammedbythethicklateralmoraines andt
glacier．Theyareevaluatedassafe．
−27−

TheGlacierLakeanditsOutburst Floodinthe NepalHimalaya

Photo13：Ice−dammed glacierlake beside the Dudh KundglacierintheDudhKundKholabasin，atributaryoftheSolu Khola（No，13in Fig．4）．

5．4Tama KosiBasin

Onlyoneglacierlake，TshoRolpa，CanbefoundwithintheterritoryofNepalinthebasin．TlakeislocatedattheuppermostreachoftheRoIwalingKholaandformedontheterminusofthe
TrakardingglacierbelowtheTrambauglacierasshowninPhoto14（No．14inFig．5）and thecoverphotograph．ThelakecanbeeasilyfoundinSchneider sMapof RoIwalingHimal onascale
ofl：50，000editedin1981．Thelakehasbeeninvestigatedindetail（Moolet．alリ1993；Kadota，1994；Yamada，1995：Yamada，1996）；ThedetaileddescriptionwillbegiveninChapter6．

DuringtheflightmanypondswereobservedonthetongueoftheDrogpaNagtsangglacieras

showninPhoto15takenin12thMay，1993，WhichwaslocatedintheTibetanside，justbehindMt．
KangNachuga（5736ma．s．1．inSchneiderMap）northofNaaGaon（seeFig．10）・Thepondsmaybe

theembryosofafutureglacierlake．

28一

DistributionofGlacierLakesintheNepalHimalaya

Photo14：Morainedammedglacierlake，TshoRolpa，formedontheterminusofthe
Trakardingglacier，RoIwalingKhola，atributaryofTamaKosi（No．14inFig．
5）．

Photo15：Ponds seeming to be typicalembryos ofthe futureglacierlake on theDrogpa Nagtsang glacierlocatedin Tibetan side behind the Gaurisankar
Himal．

−29一

The Glacier Lake anditsOutburst Floodin the NepalHimalaya

5．5Langtang KholaandChilimeKholaBasin

ThefullareaintheLangtangKhola（LangtangHimal）basinandapartialareaoftheChilime
Kholabasin（Ganesh Himal）were observed．No remarkableglacierlakeswere found．The mostnoticeablelakeisshowninPhoto16（No．16inFig．5），WhichwasaverysmallglacierlakeundthehangingglacierofKhyimjungglacierlocatedattherightbanksideoftheLangtangKhola．The
endmoraine、dammighthaveburstonceandthedeepbreachcanbenoticed．

Photo16：GlacierlakeformedbelowtheKhyimjungglacierin

theLangtangKholabasin，atributaryoftheTrisuliriver（No．16inFig．5）．

5．6BurhiGamdakiBasiII
ThebasinwasnotyetobservedbytheflightbutMr．Yoneyama，WhobelongstotheAcademic

Alpine Club of Hokkaido University，Japan，tOOk a terrestrialphotograph of the glacierlake

formedonManasuluglaciertongue asshowninPhoto17（No．17in Fig．5）takenin around198（personalcommunication）．Thelakeisdammedbythemoraines．Uplakeendcontactswiththecliff−Shapedmotherglacierend．Thereisnootherinformationofaglacierlakeinthisbasin，yet．
一30DistributionofGlacierLakesintheNepalHimalaya

Photo17：GlacierlakeformedontheManasluglacierinthe BurhiGandakibasin（No．17inFig．5）．ThephotographbeingtakenbyS．Yoneyamain1982．

5．7MarsyangdiBasin
Thebasinwasalsopartiallycoveredbyflightobservationoveronlyinthesouthernareasof
Mt．Manaslu（8156ma．s．1．）totheuppermostreachoftheMarsyangdiriverviatheHimlungHimal

OVertheDudhKholaandthePhuKhola．TheglacierlakeontheterminusoftheThulagiglacierisshowninPhoto18（No．18inFig．5），locatedatthesouth−WeStOfMt．Manaslu，uppermOStreaCh
OftheDhanaKhola；thelakestillcontactswiththecliffShapedglacierend，Whichisstagnant
COVeredwiththick debris；thelakewi11bealso discussedin Chapter6．Twoicedammedlakes

formedbesidetheHimlunSouthglacierandtheKicakekholaglacierarefoundasshowninPhoto

19（No．19inFig．5）attheupperreachofDudhKhola，nOrth−WeStOfMt．Manaslu．Aglacierformedunderanamelessglacieronthesouth．westslopeofMt．KangGuru（7，010ma．s．1．）
inPhoto20（No．20inFig．5）．AsmallmorainedammedlakeisfoundneartheMananVillageat

rightbankoftheMarsyangdiriverontheterminusoftheGangapurnaglacierasshowninPhoto

21（No．21in Fig．5）；thelakeis already separated from the motherglacier．The famouslake，
Tilitsho（Photo22：No．22inFig．5），locatedontheheadwaterofMarsyangdiisalsoaglacierlake
dammedbymoraine；thelakecontactswithasheetShapedglacierendbelowMt．TilitshoHimal（7134m a．s．1．）、
5．8KaliGandakiBasin

Severalglacierlakes are seenin the headwater of the Kaligandakiriverin the satellite

imageries．Oneofthemburstin1995asmentionedinSection4．4．Thedetailedinformationoft
lakes stillremains unknown．

Glacierlakes developinthe eastern part thanin the western partin the NepalHimalaya
becausetheglaciersaremuchdevelopedintheformerregions．
−31−

TheGlacierLakeanditsOutburstFloodin the NepalHimalaya

Photo18：GlacierlakeformedonThulagiglacierin the Dhana Khola basin，a tributary ofMarsyangdiriver（No．18in Fig．5）．

Photo19：Twoicedammed glacierlakesformed
beside the Himlun South glacier and theKicakekhola glacier in the Dudh Kholabasin，a tributary of Marsyangdiriver（No．
19in Fig．5）．

Photo20：Glacierlakeformedonanunnamedglacierflowing
downalongthesouthWaStSlopeofMt．KangGuruat
lefthandside ofthe Marsyangdiriver（No．20inFig．5）．

一32−

DistributionofGlacierLakesintheNepalHimalaya

Photo 21：Smallmorainedammedlake on theterminus of the Gangapurna glacier at therightbankoftheMarsyangdirivernearthe
ManangVillage（No．21in Fig．5）．

Photo22：Glacierlake，Tilitsho，intheheadwaterofMarsyang−
diriver（No．22in Fig．5）．

33−