Boletin No.001 TU HUNZA ROTARIO. Elaboro Martha Suarez Buitrago Club Rotario Tunja Hunza
Attabad landslide crisis in Hunza, Pakistan – lessons for ... · Attabad landslide crisis in...
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Attabad landslide crisis in Hunza, Pakistan – lessons for the management of valley blocking landslides
Dave PetleyDurham University, United Kingdom
Thanks to: D. Karim, S. Wali, N. Ali, N. Nasab & K. ShabanFocus Humanitarian Assistance, Pakistan
http://blogs.agu.org/landslideblog/
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Schedule of talk
• Global landslide mortality hazard and risk
• Landslide mortality hazard and risk along the Himalayan Arc
• The 2010 Attabad landslide, Hunza, Pakistan
Powerpoint file on my AGU hosted blog at:
http://blogs.agu.org/landslideblog/
Google: “landslide blog AGU”
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CRED data for landslide fatalities
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1000
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4000
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6000
7000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Cum
ulat
ive
num
ber o
f fat
aliti
es
Year
6587
Other disasters 2002-2009 (CRED database)Earthquake: 429,877 River flood: 37,860Storm: 166,410 Volcano: 221
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0
10000
20000
30000
40000
50000
60000
70000
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90000
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Cum
ulat
ive
num
ber o
f fat
aliti
es
Date
81,833
Landslides from the Kashmir earthquake
Landslides from the Wenchuan earthquake
The (more) true human cost of landslides
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0
0.1
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0.9
Dai
ly a
vera
ge n
umbe
r of N
FLs
200420052006200720082009Average
Monthly occurrence of non-seismic fatal landslides (NFLs)
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Annual cycle in pentads (five day bins)
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10
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25
0 183 365
Num
ber o
f rec
orde
d la
ndsl
ides
Day number
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Trend in occurrence?
R² = 0.4394
R² = 0.7705
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120
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2004 2005 2006 2007 2008 2009 2010
Num
ber o
f NFL
s
Num
ber o
f fat
aliti
es
Landslides
Fatalities
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1. Progressive failure over >7 years, scar height = 1175 m
2. Catastrophic failure event in Jan 2010 with no trigger
3. Emplacement of rockslide onto lake sediments triggered secondary high velocity mudflow event
Cross valley runout = 1300 mDeposit height = 120 to 200 m
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Data driven flood estimation
• Typical values of maximum discharge using this approach:– 14,000 cumecs (Costa and Schuster 1986)– 12,000 - 26,000 cumecs (Walder and O’Connor 1997)
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Management of the hazard
• Initial management response was the construction of a spillway.– Original intention: 30 metres deep– Actual depth at time of overtopping: 15 metres– Final spillway was very narrow and unlined
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Evacuations
• After the landslide, Focus installed sirens in 15 villages
• People in most hazardous areas relocated into camps
• Boat service established on lake, but enormous hardship upstream
• One month before overtopping NDMA evacuated 15,000 people downstream of barrier
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Seepage development
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Volu
me
of s
eepa
ge (c
ubic
met
res
per s
econ
d)
Date
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Prediction of date of overtopping
• NDMA consistently predicted the date of overtopping incorrectly (repeatedly predicted overtopping too early)
• However, final overtopping occurred later than expected because the lacustrine silts deformed, raising the floor of the channel
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Water level rise
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Rat
e of
filli
ng (m
etre
s pe
r day
)
Wat
er d
epth
(met
res)
Date
Water depth (m)Height of lowest point of completed spillwayFilling rate
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Overtopping behaviour
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102.5
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Rat
e of
filli
ng (m
etre
s pe
r day
)
Wat
er d
epth
(met
res)
Date
Water depth (m)Height of lowest point of completed spillwayFilling rate
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Spillway discharge – depth relationship
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111 112 113 114 115 116 117 118
Spill
way
dis
char
ge (c
umec
s)
Lake depth (m)
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Management problems
• Karakoram Highway remains blocked• In 2010 floods, Gilgit-Baltistan was cut off to north and south• Loss of productive land• Loss of cash crop markets• Landslide hazard remains
– Progressive failure– GLOF– Seismic event– Landslide into lake
• Should the lake level be lowered?– FWO attempt through the winter aimed to reduce the spillway
elevation by 35 metres, but achieved less than 4 metres
• 2011 monsoon will start in about six weeks