Teiji Watanabe: GLOF and glacier-related hazards and risk in Tajikistan

GLOF and glacier-related hazards and risk in Tajikistan Managing Climate Change in High Mountain Glacial Watersheds, Huaraz, Peru, 11-14July 2013

Tetsuya Komatsu and Teiji Watanabe Faculty of Environmental Earth Science

â– Previous studies on glacier hazards (Review) & Satellite image analysis (1) Geomorphological characteristics (2) History of glacier hazards â– Suggestions

Previous studies Settlements: on the younger terrace or on the alluvial fan/cone (Watanabe, 2000)

Annual precipitation L:Darjomch Lenin Peak (7,143 m),(ca.

I: Ismoil Somoni village 2,170 m) (7,495 m), KM: Karl Marx (6,723 m)

located on a young (3–5 ka?) river terrace (5 – 38 m higher from the river)

(UNEP, 2002)

Misau located on an alluvial cone

Previous studies Institute of Geography, USSR Academy of Sciences ・6,730 glaciers（7,403 km2）． ・630 glaciers have ‘surging’ history ・20 surge glaciers advanced their terminus.

Kotlyakov et al. (2010)

BOKU University’s group: GLOF studies in the SW part of Tajik Pamir ・Identified 172 glacial lakes (≥2,500 m2) ・Most were formed after 1968 Mergili and Schneider (2011), Mergili et al. (2012)

Case 1ďźšGLOF danger (1) For comparison: Imja Glacier Lake ~1 km2 0.01 km2

0.05 km2

0.04 km2 0.06 km2

Case 2：GLOF danger （2）

1.88 km2

0.46 km2

0.18 km2

Case 3ďźšCascading glacial lake outburst

1.26 km2

0.13 km2

0.02 km2

5140 m asl

4080 m asl

ca. 600 m

2570 m asl

Short distance from glacier to settlement: 5 – 20 km Simple application of early warning may not be appropriate

Confirmed glacier-related hazards （１）Hazard by glacier surge (2 glacier detachments, 2 valley blocking) （２）Hazard by GLOF (1 case) Blue: Surge glacier Yellow: Debris-flow hazard by surging Red: GLOF & glacial-lake hazard by surging Didal Glacier 1974

Bear Glacier 1963, 1973, 2011 Ravak Glacier 20 July 1967 200 m advanced

Dasht Lake 7 Aug. 2002

Glacier surge and GLOF: Bear Glacier NASA Earth Observatory (2011)

・Surged in 1951, 1963, 1973, 1989, 2001 and 2011． ・The surged terminus blocked the valley in 1963, 1973, 1989 & 2011． ・The dammed lake damaged infrastructure downstream.

Base image and the termini on 2 May & 3 June: NASA Earth Observatory （2011）

GLOF: The Dasht 2002 event • Outburst of a glacial lake (4,400 m, 0.03 km2） on 7 August 2002． • Reached Dasht village (2,600 m), 10.5 km downstream, in 45 minutes. Killed 25 village people.

2 km

Shakhdara Valley

Photo：Schneider and Mergili (2010)

Dasht lake

ca. 200 m

Mergili et al. (2012): GLOF occurred by collapse of ice-cored moraine in 2002 Google Earth image: 31 August 2008

Development of Dasht Lake: 32,000 m2 (2002) ‘Guerrilla glacial lake’ Repeatedly appeared Rapidly enlarged Short-lived No surface outlet

Hazards assessment studies （1） Schneider et al. (2010)： danger evaluation of 209 villages （2） Mergili and Schneider (2011)： danger evaluation of 408 lakes

Glacier hazards expected ăƒťStudied in six basins only. ăƒťGlacier detachment, GLOF (debris flow?)

Mergili and Schneider (2011): seven classes of outburst danger 408 lakes Extremely high: 0 Very high: 6 High: 34 0.15 km2

0.46 km2

Especially dangerous: downstream of 3 lakes

0.33 km2 Mergili and Schneider ďźˆ2011

Considerations needed □Missing area of studies • Inventory of glaciers for the whole area

□Regular monitoring • Hanging glaciers: crack • Surge-type glaciers: surging • Glacial lakes: development (guerrilla glacial lakes) ・Repeat appearance, rapid enlargement, & short life ・Tien Shan: 2.5 months from lake appearance to burst

□Mitigation

• Consideration of settlement locations and distance to the source area

Epicenter distribution, Pamir Main Pamir Thrust (northern area) Hindu Kush-Pamir seismic zone (SW area) 　

Gordon et al. (2012)　

SW valleys in the Tajik Pamir: Landslides

20

New monitoring

Frequency

Resolution

Data handling

Cost

Helicopter

○ (weather dependent）

○

×

×

Landsat, ASTER

× （16-day cycle）

△ （15 m）

○

○

Ikonos

× （11-day cycle）

○ （~2 m）

○

×

Ultra-micro satellite

○ （1-day cycle)

○ （~5 m）

○

？ (USD 1 million

Ultra-micro satellite, <50 kg

http://www.astro.mech.tohoku.ac.jp/RISING-2/