Glacier dammed lakes impacting different Alaskan drainages after 30 years of warming temperatures

Transcription

1 Glacier dammed lakes impacting different Alaskan drainages after 3 years of warming temperatures Dave Wolfe A remote sensing thesis project from Alaska Pacific University, Anchorage, Alaska

2 Globe image Go Glacier dammed lakes of Alaska Study Area ogleearth Study Area Baseline data report: Post and Mayo, 1971 What was studied and why o What are glacier dammed lakes & why should we care Basic results o Changes in lakes o Changes in drainages o Patterns in the changes? Map Sheet 2 USGS 1971

3 Glacier dammed lakes of Alaska Definitions Glacier Dammed Lakes are: ice marginal, and dammed by active glacier ice Imagery data: Lakes: YakutatC1 3 & C1 N1 Status: Persistent since 1971 and New Dam: Battle Glacier Region: St. Elias Mountains GDL Slide modified from USGS Image 25 DigitalGlobe (Cat. ID B), from Google Earth

4 Glacier dammed lakes dynamic changing phenomena Lake level fluctuations: 4 views of 1 lake over 3 years ASTER satellite image 23: Filling 25: Full Spring 26: Drained ASTER satellite image Image 25 DigitalGlobe, from Google Earth Glacier dammed lakes are special hydrologic natural hazards because: drainage rate can increase exponentially, and they refill after draining Lake: TalkeetnaD2-13 Status: New since 1971 Dam: Tokositna Glacier Region: NW Alaska Range (WARN) Imagery: Google Earth and ASTER ASTER sa atellite image Fall 26: Refilling

5 Digital Globe 7/25, from Google Earth Lake full summer 25

6 km st and 2nd Order glaciers Harvard Glacier 4 th Order glacier

7 Glacier dammed lakes of Alaska Symbology of change Historic Map 1. Lake in 1971 Current Lake Status Lake is Absent 2. No Lake in New Lake since 2 Scale: 1:98, N Post and Mayo (1971) map Sheet 2 ASTER satellite image acquired 18 September 26

8 Glacier dammed lakes of Alaska Changing Over Time Focus areas in following slides

9 Glacier dammed lakes of Alaska Why Should We Care? Lake releases can flush glacier stored waters, increasing flood volume/duration (subglacial, supraglacial, englacial) Channel scour measure to 3 m in Alaska Sediment or ice flows contribute to damages Sheep Cr. bridge, Richardson Hwy., before & after a glacier dammed lake flood (The bridge is in the same location in both photos!) September 1945 flood, DOT photo Images from Post and Mayo (1971) The flood deposited debris over 7m deep at the bridge from upstream scour.

10 Glacier dammed lakes of Alaska Why Should We Care: Wortmans Trans Alaska oil Pipeline, descending Thompson Pass 1971 USGS map New glacier dammed lake ASTER satellite image ASTER satellite image Sheep creek hazard lakes are absent since 2; new lake hazard could impact the Trans Alaska Pipeline by scour

11 Skilak Glacier lake Late fall or winter release every 1-3 years Januaryy 1969 and 27 releases each had very small hydrograph signals each broke up river ice ice jams caused extensive flood damage 95 km to ice jam 3 km 1 km2 lake 3 km below.7 km2 glacier dammed lake -- new roads Historic Recent

12 Glacier dammed lakes of Alaska Why should we care: Tazlina Example a) 1 km to Oil Pipeline Oil Pipeline and b) 12 km to Oil Pipeline highway bridges c) 156 km 2 moderating lake c b 27 winter release ice jam damage a

13 N kes Glacier dammed lakes of Alaska Results: change in numbers Numbers of Historic and Current glacier-dammed lakes. 275 Lake basins reviewed: 7 + Lake damming glaciers: 2+ Historically: 183 Currently: Curr rently unfi illed basin ns: Absent lakes: 263 from 17 glaciers; 54 no longer dam any lakes Number of Lak 1 Persistent lakes: New lakes: 141 beside 71 glaciers; 31 newly lake damming Absent Persistent New Historic N = 538 Current N = 416 X axis: Lake status: > 2 compared to 1971

14 Glacier dammed lakes of Alaska Changing Drainages

15 Glacier dammed lakes of Alaska Environmental Influences on lake / glacier change Combined global land, air, and sea surface temperatures , relative to mean. Inset: Alaska temperatures Time period between inventories 2 Data from 19 first-order weather stations. rkshops/23/ /salmontools/ edu/wor e.pdf tp:// turns/aksalmonfuture Time period between inventories - 2 htt re (Global data source: U.K. Meteorological Office Climate Change and its impacts: A global perspective.)

16 Glacier dammed lakes of Alaska: Examples of ablation by downwasting Red lines: digitized perimeters of glacier extent from 1971 map; dashed lines highlight recent glacer ice perimeters

17 Num Num Num Num N N Graphs: Proportional Change in Glacier Dammed Lake Status Types by analysis region WARN EAKR Number of Basins 3 Number of Basins b A P N H=68 R=32 c A P N H=46 R=27 TALK f b c d g h e i WRST Number of Basins d 15 A P H= 8 N R=8 a a. Total Change in Mean Annual Temperature (Celsius) Number of Basins e 15 A P N H=37 R=45 WARS mber of Basins 6 KENI CHUG STEL mber of Basins mber of Basins mber of Basins f 15 A P N H=63 R=33 g 15 A P N H=69 R=6 h 15 A P N H=13 R=11 i 15 A P N H=125 R=11

18 Glacier Dammed Lakes of Alaska changes in icedam aspects Glacier Aspects origin termi ini WNW West WSW WNW West WSW NW SW NW SW NNW SSW NNW SSW North South North NNE SSE NNE NE SE NE ENE East ESE ENE East South SSE SE ESE Ice dam aspect determination example N Ice dam faces North Ice dam faces ESE Persistent & New ice dams strongly favor colder (N, NE, E) aspects Aspects of Absent Ice dams Aspects of Persistent Ice dams Aspects of New Ice dams NNW NW WNW West North NNE NE ENE East NW WNW West NNW North NNE NE ENE East NNW NW WNW West North NNE NE ENE East WSW ESE WSW ESE WSW ESE SW SSW South SSE SE Historic Lakes SW SSW South SSE SE Current Lakes SW SSW South SE SSE

19 Glacier dammed lakes of Alaska significant (p=.5) change over 3 years Compared to absent lakes, new lakes were: > 3 m higher in elevation; > 2 m closer to the mean glacier altitude; 2 % farther up-glacier 12 km farther from the damming glacier terminus Percentage of lake absence due to: downwasting of damming glacier: 7% ; terminus retreat of damming glacier : 3%. Glaciers damming new lakes averaged: 11% longer than those damming absent lakes a full order higher (more complex) at terminus

20 Glacier dammed lakes of Alaska Summary The hazard from these lakes continues form of the hazard may change as different drainages are affected as lakes release from farther up glacier flushing as lakes release when winter river ice is present These data are a messenger of change with implications for infrastructure and development that t may be useful in modeling further lake change across the cryosphere Himalayas, Swiss Alps, etc

21 Glacier dammed lakes of Alaska Acknowledgements This research was assisted by grants from :Alaska Pacific University :Alaska Section, AWRA and NASA IPY research collaboration, Dr. Jeff Kargel, PI, U of Arizona, Tucson (Satellite, Airborne, and Ground-based Assessment of Cryosphere Changes in the Copper River/Chitina Basins and Adjoining Ranges (Alaska) from Late Maximum to Now, NASA International Polar Year: ROSES 26); and by data from NASA (LPDAAC); US Forest Service; GeoGratis Canada; UA Fairbanks GeoData Center, Alaska Weather Research Center, and Geophysical Institute; US National Park Service; and State of Alaska DEC Additional thanks to: Austin Post, USGS, retired; APU faculty: Jason Geck and Dr.s M. Loso, R. Dial, L. Cornick LPDAAC (Land Processes Distributed Active Archive Center staff)

22 1951 Imagery data: Lake: BeringGlacD6-1 Iceberg Lake Status: Persistent since 1971 First complete drainage in over 1,5 years: 1999 Dam: Tana Glacier tributary Region: Chugach Mountains Photo: Kirk Stone, 1951; Kargel and Wolfe, 28 28

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24 Supra-glacial Lakes Lakes not considered in this or the previous study include those that are: supraglacial subglacial ProglacialP l i l All tend to be on the lower glaciers reaches. Sub-glacial Lakes Pro-glacial Lakes

25 Glacier dammed lakes of Alaska: Example of lake loss by retreating terminus Historic Lake 1971 Melbern Glacier and GDL (Post and Mayo 1971). Black areas: solid = lake in 1971; dashed black line = predicted future lake. Current Status: absent 26 AS STER satellite ima age acquired 23 February Icedam (failing at final jokulhlaup) LandSat7 ETM, path 6 row 19 acquired 13 Aug 21 Image Google Earth

26 Sheep creek hazard lakes are absent since 2; new lake hazard could impact the Trans Alaska Pipeline corridor by scour Flood scour measured to 8 feet in depth. The pipeline is buried at 1 feet. New lake above narrow canyon New lake descending to Lowe River, across from Sheep Creek USGS map Sheep Cr. bridge, Richardson Hwy GDL flood, DOT photo Trans Alaska oil Pipeline, descending Thompson Pass ASTER satellite image

27 Origin aspect, newly damming glaciers Glacier aspect at lake Terminus aspect, newly damming glaciers WNW NNW NW North 1 5 NNE NE ENE WNW NNW NW North 1 5 NNE NE ENE WNW NNW NW North 1 5 NNE NE ENE West East West East West East WSW SW SSW South SE SSE ESE WSW SW SSW South SE SSE ESE WSW SW SSW South SE SSE ESE Origin aspect, former dammimg glaciers Glacier aspect at former lake Terminus aspect, former damming glaciers WNW NNW NW North NNE NE ENE WNW NNW NW North NNE NE ENE NNW NW WNW North 15 NNE 1 NE 5 ENE West East West East West East WSW ESE WSW ESE WSW ESE SW SSW South SE SSE SW SSW South SE SSE SW SSW South SE SSE

28 Ice dam aspects, former damming glaciers Ice dam aspects, newly damming glaciers North 15 NW NNW 1 WNW 5 West WSW SW SSW NNE NE ENE East ESE SE SSE South NW NNW WNW West WSW SW SSW North 1 5 NNE NE ENE East ESE SE SSE South

29 Arctic Ocean Arctic Ocean c f b d h e i a g

30 Glacier dammed lakes of Alaska Study Area Globe image GoogleEarth Presentation Outline: o What was studied and why o What are glacier dammed lakes & why should we care about them o Basic results o Changes in lakes o Changes in drainages o Patterns in the changes?

31 Glacier Aspects Aspects of damming glacier origin NW NNW North NNE NE WNW West 1 5 ENE East Expected Ice dam Aspects WSW SW SSW South SSE SE ESE Aspects of damming glacier termini WNW West NW NNW North NNE NE 1 ENE 5 East NNW NW WNW West WSW SW SSW North NNE 3 NE South SSE SE ENE East ESE WSW ESE SW SE SSW South SSE

32 Glacier dammed lakes (GDLs) of Alaska recurring natural hazards Before e and after a Glacier Lake Outburst Flood Bridge is in same place in both photos (Kuentzel 197). Sheep Creek, Alaska

33 Questions?

34 Imagery data: Lake: BeringGlacD6-1 Iceberg Lake Status: Persistent since 1971 Dam: Tana Glacier tributary Region: Chugach Mountains Photo: Kirk Stone, 1951; Chris Larsen