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Glacial Flooding & Disaster Risk Management Knowledge Exchange and Field Training July 11-24, 2013 in Huaraz, Peru HighMountains.org/workshop/peru-2013

Comparison of  recently  formed  glacial  lakes  in  the  Bolivian   Andes  and  the  Southern  Alps  of  New  Zealand  -­‐  Differences  and   similarities   Dirk Hoffman Bolivian Mountain Institute – BMI Email: dirk.hoffmann@bolivian-mountains.org

Abstract As   mountain   glaciers   recede,   there   is   the   potential   for   the   formation   of   glacial   lakes,   depending   on   the   conditions   of   the   terrain   as   well   as   the   characteristics   of   the   moraines.   These   newly   formed   glacial   lakes   have   been   recognized   in   high   mountain   regions  around  the  world  as  posing  a  considerable  risk.   In  the  Bolivian  Andes  glacial  lakes  have  not  yet  received  much  attention,  neither  by  the   local  population  nor  by  researchers.   A  first  documented  case  of  a  GLOF  (Glacial  Lake   Outburst   Flood),   which   in   November   2009   destroyed   numerous   fields,   various   kilometers   of   a   rural   road   and   killed   some   farm   animals   has   made   it   clear   that   Bolivian   glacial  lakes  –  even  though  relatively  small  in  size  -­‐  are  potentially  dangerous.   In  New  Zealand’s  Southern  Alps,  glacial  lakes  are  not  as  numerous,  but  larger  in  size.   They  can  be  found  most  prominently  on  the  lower  parts  of  the  tongues  of  the  12  long   valley  glaciers.  There  is,  however,  no  known  case  of  a  glacial  lake  outburst  flood,  and   lakes  are  widely  considered  as  not  being  dangerous.   This  paper  explores  the  differences  and  similarities  of  recently  formed  glacial  lakes  in   the  Bolivian  Andes  and  those  in  the  Southern  Alps  of  New  Zealand,  focussing  especially   on  the  risks  associated,  and  management  options  resulting  thereof.   Key  words   Glacial   lakes,   climate   change,   glacial   retreat,   Bolivia,   New   Zealand,   Andes,   Southern   Alps  

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Introduction Wherever  mountain  glaciers  recede,  there  is  the  potential  for  the  formation  of  glacial   lakes,  depending  on  the  conditions  of  the  terrain  as  well  as  the  characteristics  of  the   moraines.   These   newly   formed   lakes   often   pose   a   considerable   risk   to   human   settlements   and   infrastructure   downstream,   which   is   not   always   recognized   and   managed  adequately.     In  January  and  February  of  this  year,  I  undertook  a  climate  change  study  tour  to  New   Zealand,  organized  with  the  Bolivian  Mountain  Institute  –  BMI.  One  objective  had  been   to  investigate  how  climate  change  impacted  the  Southern  Alps  of  New  Zealand,  and  to   gain  insides  into  how  potentially  dangerous  glacial  lakes  were  managed.  –  I  was  in  for  a   surprise.     Glacier  retreat  and  glacial  lakes  in  Bolivia   Climate   change   is   a   reality   in   the   Bolivian   Andes.   Temperature,   precipitation   and   humidity  have  changed  considerably  over  the  last  50  years.  Temperature  increase  has   been  about  0.3°  C  per  decade  at  the  end  of  the  20th  century.   Bolivia  is  home  to  around  20%  of  the  world’s  tropical  glaciers,  with  Peru  holding  about   70%,  Ecuador  and  Columbia  combined  4%,  and  the  rest  of  the  world  less  than  1%.  As  in   most  regions  of  the  world,  accelerated  melting  of  glaciers  set  in  around  1980.  At  this   time   Bolivia   held   566   km²   of   glacier   area   in   its   cordilleras.   Due   to   global   warming,   Bolivia’s  tropical  glaciers  are  retreating  at  an  unprecedented  rate.   Recent   investigations   of   glacial   recession   indicate   that   glacier   surface   and   area   have   been  reduced  by  about  50%  during  the  last  35  years  (Soruco  et  al.  2009).  Hundreds  of   glacial  lakes  have  subsequently  formed  at  the  tip  of  the  tongue  of  the  glaciers,  which   might   grow   to   considerable   size   depending   on   local   terrain   conditions.   These   glacial   lakes  are  often  dammed  by  moraines  made  up  of  loose  material  that  might  yield  to  the   pressure  of  the  water  and  break,  releasing  enormous  amounts  of  water  downstream.   In  the  Bolivian  Andes  glacial  lakes  have  not  yet  received  much  attention,  neither  by  the   local  population  nor  by  researchers.  The  recent  glacial  lake  inventory  and  preliminary   risk   assessment   realized   in   2011   by   Daniel   Weggenmann   for   the   Apolobamba   mountain   range   is   the   first   work   of   its   kind   (an   inventory   for   the   Cordillera   Real   is   presently   being   prepared   by   other   researchers).   The   results   of   the   Apolobamba   glacier   lake  inventory  show  that  the  total  number  of  contemporary  glacial  lakes  went  up  from   174   to   216   in   the   period   from   1986-­‐2008,   while   total   lake   area   grew   by   approximately   2.5  km²  (Weggenmann,  2011).      

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Graphic 1:  The  ice-­‐dammed  glacial  lake  above  Keara  before  its  outbreak  (left;  Google   Earth  image,  2005)  and  as  seen  today  (right;  photo  by  author,  May  2013).     The   first   and   only   documented   GLOF   incident   in   Bolivia   took   place   on   November   3,   2009  in  the  village  of  Keara  in  the  Northern  part  of  the  Apolobamba  mountain  range,   causing   damage   to   the   local   road,   a   bridge,   killing   farm   animals,   invading   fields   and   eroding  the  river  banks;  fortunately  not  causing  any  human  casualties.   This   incident,   together   with   the   glacial   lake   inventory   and   the   efforts   of   individuals   from   NGOs   and   UMSA   state   university,   helped   to   include   glaciers   and   glacial   lakes   into   the  Social  Monitoring  Program  adopted  by  Apolobamba  Protected  Area  in  2012.     Glacier  retreat  and  glacial  lakes  in  New  Zealand   New   Zealand’s   glaciers   are   almost   exclusively   located   in   the   Southern   Alps   of   its   South   Island,  covering  an  area  of  approximately  1,160  km².  One  of  the  particularities  of  the   Southern   Alps   consists   in   the   extremely   high   rate   of   mountain   uplift   of   around   10   mm/yr,   due   to   plate   movements.   This   figure   is   more   than   double   than   for   other   major   mountain  ranges.   Because   of   the   moderating   effect   of   the   huge   water   mass   of   the   Pacific   Ocean   surrounding  New  Zealand,  global  warming  is  less  pronounced  than  in  other  mountain   ranges   within   large   continental   masses.   Temperature   rise   for   the   Southern   Alps   has   been  calculated  to  be  around  1°  C  (by  1979),  largely  after  the  1950s,  which  at  present   should  stand  between  1.5  –  2  °C.  This  has  led  to  the  retreat  of  New  Zealand  glaciers,   even  though  not  always  in  synchrony  with  the  retreat  patterns  predominating  globally.     “Wholesale  retreat  of  New  Zealand  glaciers  over  most  of  the  20th  century  is  generally   attributed   to   regional   warming   (...).   However,   there   have   been   reversals   within   this   overall  recession  from  glacier  retreat  to  glacier  advance.  These  have  sometimes  been   related   to   regional   precipitation   increases”,   writes   Trevor   Chinn,   New   Zealand’s   foremost  glacier  expert  (Chinn  et  al.  2012).   Total  ice  loss  volume  has  been  calculated  from  54.53  km³  in  1976  to  46.12  km³  in  2008,   which   equals   about   15%.   Up   to   now,   glacial   lakes   have   only   formed   on   the   12   large   valley   glaciers,   characterized   by   low-­‐gradients   and   extensive   debris   cover.   Those   remained   their   areal   extent   until   the   70s,   even   though   notable   down-­‐wasting   took   place.   Because   of   their   slow   response   time,   these   long   glaciers   filter   out   more   of  

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regional climate   as   compared   to   the   overall   warming   of   the   atmosphere   across   New   Zealand.    

    Hooker  and  Mueller  lakes  (left);  alluvial  gravel  fan  below  Mueller  glacier  (right);  photos   by  author.     Mainly   during   the   1980s   the   formation   of   small   supra-­‐glacial   ponds   set   in,   which   quickly   lead   to   the   formation   of   glacial   lakes.   What   followed   during   the   1990s   was   the   rapid   expansion   of   these   lakes,   which   for   the   respective   glaciers   marked   “a   tipping   point   once   rapid   frontal   retreat   is   initiated   by   lake   growth”   (Chinn   et   al.   2012).   This   feedback   mechanism   has   started   a   new   dynamic   of   accelerated   lake   expansion   and   accelerated  melting  of  the  glacier  tongue,  which  is  now  under  way.   It   is   important   to   notice,   however,   that   these   glacial   lakes   are   dammed   by   alluvial   outwash   gravel   plains,   and   not   by   brittle   moraines,   which   makes   them   much   more   stable.  It  is  for  this  reason,  that  existing  glacial  lakes  are  not  considered  dangerous,  but   as   a   tourist   attraction.   Research   is   mainly   directed   to   understand   lake   building   and   expansion   processes,   as   well   as   calculating   the   impact   glacial   lakes   have   on   the   rate   of   glacial  recession  at  the  tongues  that  are  in  contact  with  lake  water.     Similarities   The   similarities   between   glacial   lakes   in   Bolivian   and   New   Zealand   high   mountain   regions  can  be  resumed  the  following  way:   •

There is   a   clear   trend   of   glacial   recession   in   both   regions,   largely   in   line   with   worldwide  trends  of  glacial  retreat.  

In both  cases,  a  number  of  glacial  lakes  have  formed  over  the  last  decades  at  the   snouts  of  glaciers.  

These lakes  have  notably,  sometimes  dramatically  increased  in  size.  

Formation of  glacial  lakes  is  an  ongoing  phenomenon.  

Differences  

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Differences between  glacial  lakes  of  the  New  Zealand  Southern  Alps  and  the  Bolivian   Andes  are  numerous;  they  can  be  summarized  as  follows:   •

Ice loss   in   Bolivia   (45-­‐50%)   over   the   last   40   years   was   about   three   times   that   of   New  Zealand  (15%).  

Glacial lakes  in  Bolivia  are  more  numerous  (a  few  hundred  compared  to  12).  

Glacial lakes  in  New  Zealand  are  much  larger  in  size  and  water  volume.  

Some of   the   lakes   in   Bolivia   are   to   be   considered   dangerous;   there   was   a   first   recorded  GLOF  incident  in  2009.  

New Zealand’s  recently  formed  lakes  are  considered  not  to  pose  any  danger,  they   are  even  used  as  a  new  tourist  attraction.  

Besides traditional   settlements   in   glacierized   watersheds,   in   Bolivia   there   are   mining  and  agricultural  activities  taking  place  close  to  glaciers.  

In New   Zealand   there   is   no   native   population   in   high   mountain   areas;   in   certain   places  touristic  infrastructure  is  present.  

Differences in   mountain   geo-­‐morphology   and   topography   are   important:     -­‐   long   valley   glaciers   in   New   Zealand   (absent   in   Bolivia);   -­‐   very   high   rates   of   uplift   in   the   Southern   Alps:   10   mm/yr;   -­‐   lake   levels   in   New   Zealand   are   lowering   over   time;   -­‐  alluvial  outwash  gravel  plains  instead  of  moraine  dams  

Drawing  showing  the  formation  of  large  alluvial  outwash  plains  at  the  heads  of  modern   day  glaciers  and  glacial  lakes  in  New  Zealand;  source:  Chinn       Conclusions   Contrary   to   my   initial   expectations,   differences   are   more   significant   than   similarities   when  comparing  glacial  lakes  in  the  Bolivian  Andes  and  New  Zealand’s  Southern  Alps.  

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They are   based   mainly   on   the   geo-­‐morphological   characteristics   of   the   mountain   ranges  and  its  glaciers.   In   Bolivia,   there   is   a   need   to   realize   glacial   lake   inventories   of   other   mountain   regions,   especially   Cordillera   Real,   expand   monitoring   activities,   and   to   realize   on-­‐site   technical   expert  surveys  of  those  glacial  lakes  identified  as  possibly  dangerous.   In   New   Zealand,   in   contrast,   there   is   presently   no   need   for   management   of   glacial   lakes.  It  might  be  good,  however,  to  analyze  the  possibility  of  rock  avalanches  falling   into   glacier   lakes,   as   well   as   to   take   another   close   look   at   topography   higher   up   to   make  sure  no  dangerous  glacial  lakes  would  form  there  in  the  future.       Acknowledgements   I   would   like   to   thank   Daniel   Weggenmann,   Rodrigo   Tarquino,   Apolobamba   National   Park,  Stefan  Winkler,  Trevor  Chinn,  the  participants  of  the  annual  Snow  &  Ice  Research   Group   (SIRG)   meeting,   and   many   others   for   their   contribution   to   this   work   and   the   time   dedicated   to   discuss   the   situation   of   glacial   lakes   in   the   Bolivian   Andes   and   the   New   Zealand   Southern   Alps.   It   is   my   wish   that   in   the   future   some   more   intense   cooperation  might  result  from  this  first  comparative  exploration.       References   Chinn,  T.  (1996):  New  Zealand  glacier  responses  to  climate  change  of  the  past  century.   New  Zealand  Journal  of  Geology  and  Geophysics,  39:3.   Chinn,  T.,  S.  Winkler,  M.J.  Salinger  and  N.  Haakensen  (2005):  Recent  glacier  advances  in   Norway   and   New   Zealand:   A   comparison   of   their   glaciological   and   meteorological   causes,  Geografiska  Annaler  87  A.   Chin,   T.,   B.B.   Fitzharris,   A.   Willsman   and   M.J.   Salinger   (2012):   Annual   ice   volume   changes  1976-­‐2008  for  the  New  Zealand  Southern  Alps.  Global  and  Planetary  Change   92-­‐93.   Dykes,   R.C.,   M.S.   Brook   and   S.   Winkler   (2010):   The   contemporary   retreat   of   Tasman   Glacier,  Southern  Alps,  New  Zealand,  and  the  evolution  of  Tasman  proglacial  lake  since   AD  2000.  Erdkunde,  Vol.  64,  No.  2.   Haeberli,   W.,   J.J.   Clague,   C.   Huggel   and   A.   Kääb   (2010):   Hazards   from   lakes   in   high-­‐ mountain   glacier   and   permafrost   regions:   climate   change   effects   and   process   interactions.  XI  Reunión  Nacional  de  Geomorfología,  Solsona,  España.   Hoffmann,  D.  (2011):  Participatory  Glacier  Lake  Monitoring  in  Apolobamba  Protected   Area.  A  Bolivian  Experience.  Journal  for  Sustainability  Education,  March  19,  2011.   Hoffmann,  D.  &  Weggenmann,  D.  (2013).  Climate  Change  Induced  Glacier  Retreat  and   Risk  Management:  Glacial  Lake  Outburst  Floods  (GLOFs)  in  the  Apolobamba  Mountain   Range.  In:  Leal  Filho,  W.  (Ed.):  Climate  Change  and  Disaster  Risk  Management,  Springer.  

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Huggel, C.   (2004).   Assessment   of   glacial   hazards   based   on   remote   sensing   and   GIS   modeling,  Zürich,  Univ.  Geographisches  Institut.   Jordan,   E.   (1991).   Die   Gletscher   der   bolivianischen   Anden   eine   photogrammetrisch-­‐ kartographische   Bestandsaufnahme   der   Gletscher   Boliviens   als   Grundlage   für   klimatische  Deutungen  und  Potential  für  die  wirtschaftliche  Nutzung;  mit  34  Tabellen   von  Ekkehard  Jordan,  Stuttgart,  Steiner.   Rabatel,  A.  et  al.  (2013).  Current  state  of  glaciers  in  the  tropical  Andes:  a  multi-­‐century   perspective  on  glacier  evolution  and  climate  change.  The  Cryosphere,  7,  81-­‐102.   Soruco,   A.,   Vincent,   C.,   Francou,   B.   &   Gonzalez,   J.   F.   (2009).   Glacier   decline   between   1963  and  2006  in  the  Cordillera  Real,  Bolivia.  Geophysical  Research  Letters,  36.   Weggenmann,   D.   (2011).   Gletscherseeausbrüche   in   der   Cordillera   Apolobamba   (Bolivien)  –  Analyse  und  Bewertung  des  Risikopotentials  im  Rahmen  des  Klimawandels.   Diploma  (unpublished),  Heidelberg  University.   Winkler,  S.,  Chinn,  T,  Gartner-­‐Roer,  I.,  Nussbaumer,  S.U.,  Zemp,  M.  and  Zumbühl,  H.J.   (2010).   An   Introduction   to   Mountain   Glaciers   as   Climate   Indicators   with   Spatial   and   Temporal  Diversity.  Erdkunde,  Vol.  64,  No.  2.   Salinger,  J.,  T.  Chinn,  A.  Willsman  and  B.  Fitzharris  (2008).  Glacier  response  to  climate   change.  Water  &  Atomosphere  16  (3).    

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Dirk Hoffman: Comparison of recent glacial lakes in Bolivia and New Zealand  

As mountain glaciers recede, there is the potential for the formation of glacial lakes, depending on the conditions of the terrain as well a...

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