“Remote” landslide-related
hazards and their consideration
for dams’ design

Alexander Strom(*) & Anatoly Zhirkevich(**)
(...
The 1963 Vajont disaster highlighted the importance of
slopes stability analysis not only directly at the dam sites
but al...
Examples:
Rogun dam project in Tajikistan;
Kambarata dam project in Kyrgyzstan
Rogun dam project, Tajikistan
In 1993 powerful debris flow blocked Vakhsh River downstream
from the damsite causing severe...
So powerful debris flows from the
Obi-Shur Creek could be
anticipated
Trace of debris flow in the ObiShur gorge. Photograph of 1978.
Estimated discharge 1500-1700 m3/sec

~6m
June 22, 2012. Debris flow in the Obi-Shur Creek stopped by the dam.
Photo courtesy Vadim Panteleev (Hydroproject)

Constr...
Possibility of outburst floods caused by
rivers damming upstream from reservoir
Sites of potential stream damming in the
Muksu River basin (Northern Pamir)
Model of the Baliandkiik River damming by potential
surge of the Fedchenko glacier.
Lake volume – 0.17 km3
Damming of the Muksu River by potential rock avalanche.
Lake volume ~ 0.2 km3
Catastrophic breach of such dams with complete release
of stored amount of water (up to 0.2 km3) would cause
flood wave at...
Kambarata 1 & 2 dam projects, Kyrgyzstan
Position of Kamarata 1 & 2 dam sites and their reservoirs

K2
K1
Possibility of downstream river damming
and Kambarata-1 powerhouse inundation
Rockslide
headscarp on the
left bank of the
Naryn River

Remnant of rockslide body
on the rignt bank terrace of
the Naryn ...
Small scarps (marked by arrows) on top of the
ridge indicating its ongoing instability
Tree trunks on ~5-m high terrace of the Naryn River

Evidence of abnormal flood
exceeding PMF estimates
Assumed peak disch...
Emptied landslide-dammed lake about 80 km upstream
from Kambarata-1 damsite. Its breach released about
2x106 m3 of water

...
Due to limited amount of water that could be released and
significant distance from the Kambarata-1 reservoir breach of th...
Much more severe effects could be anticipated if
rockslide would block main stream of the Naryn
or Kokomeren Rivers, resul...
Evidence of catastrophic outburst flood

~70 m high breached dam in the Kokomeren River valley

Rocky remnant 2 km downstr...
1st phaze – coarse angular boulders
up to 1 m in size left by the flood
wave “in the shadow” of the rocky cliff

Estimated...
Study of the potentially unstable slopes that
can produce river damming downstream
from the HPP and upstream from the
rese...
Thank you for
your attention!
Strom - remote landslide related hazard
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International Conference Vajont2013 - 8 October

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Strom - remote landslide related hazard

  1. 1. “Remote” landslide-related hazards and their consideration for dams’ design Alexander Strom(*) & Anatoly Zhirkevich(**) (*) Geodynamics Research Center - Branch of JSC “Hydroproject Institute” - Moscow, Russia (**) JSC “Hydroproject Institute” - Moscow, Russia
  2. 2. The 1963 Vajont disaster highlighted the importance of slopes stability analysis not only directly at the dam sites but also in the reservoir areas to ensure hydraulic projects safety. However, catastrophic collapse of huge rock/soil mass into reservoir does not exhaust negative effects of landslides that must be taken into consideration in the course of dams design. Severe consequences might result from river channel damming by landslides both downstream from the dam site and far upstream from the reservoir.
  3. 3. Examples: Rogun dam project in Tajikistan; Kambarata dam project in Kyrgyzstan
  4. 4. Rogun dam project, Tajikistan In 1993 powerful debris flow blocked Vakhsh River downstream from the damsite causing severe effects
  5. 5. So powerful debris flows from the Obi-Shur Creek could be anticipated
  6. 6. Trace of debris flow in the ObiShur gorge. Photograph of 1978. Estimated discharge 1500-1700 m3/sec ~6m
  7. 7. June 22, 2012. Debris flow in the Obi-Shur Creek stopped by the dam. Photo courtesy Vadim Panteleev (Hydroproject) Construction of the protection dam in the Obi-Shur Gorge, November, 2011
  8. 8. Possibility of outburst floods caused by rivers damming upstream from reservoir
  9. 9. Sites of potential stream damming in the Muksu River basin (Northern Pamir)
  10. 10. Model of the Baliandkiik River damming by potential surge of the Fedchenko glacier. Lake volume – 0.17 km3
  11. 11. Damming of the Muksu River by potential rock avalanche. Lake volume ~ 0.2 km3
  12. 12. Catastrophic breach of such dams with complete release of stored amount of water (up to 0.2 km3) would cause flood wave at the tail of the Rogun reservoir with mean daily discharge of 2400 m3/sec. It would result in ~1.5 m rise of the maximal reservoir level, which is within the assessment accuracy, considering wind waves and normative dams’ freeboard. Such excessive reservoir level would not provide essential risk for high Rogun dam with large reservoir. However, outburst floods in the catchment areas could pose real threat to hydraulic schemes and their possibility must be investigated.
  13. 13. Kambarata 1 & 2 dam projects, Kyrgyzstan
  14. 14. Position of Kamarata 1 & 2 dam sites and their reservoirs K2 K1
  15. 15. Possibility of downstream river damming and Kambarata-1 powerhouse inundation
  16. 16. Rockslide headscarp on the left bank of the Naryn River Remnant of rockslide body on the rignt bank terrace of the Naryn River
  17. 17. Small scarps (marked by arrows) on top of the ridge indicating its ongoing instability
  18. 18. Tree trunks on ~5-m high terrace of the Naryn River Evidence of abnormal flood exceeding PMF estimates Assumed peak discharge of about 6 000 – 7 000 m 3/sec and, possibly, up to 10 000 m3/sec – 2-3 times more than maximal flood ever recorded in the Naryn River. What could produce such flood?
  19. 19. Emptied landslide-dammed lake about 80 km upstream from Kambarata-1 damsite. Its breach released about 2x106 m3 of water One more landslide-dammed lake of the same size still exist upstream.
  20. 20. Due to limited amount of water that could be released and significant distance from the Kambarata-1 reservoir breach of this lake would not provide any real hazard for high dam with large reservoir. However it poses threat and should be considered for the much smaller Kambarata-2 Project where such flood could provide inflow exceeding the existing spillway capacity.
  21. 21. Much more severe effects could be anticipated if rockslide would block main stream of the Naryn or Kokomeren Rivers, resulting in formation of a large water body up to hundreds millions cubic meters in volume as it had happened here repeatedly in Late Pleistocene and Holocene.
  22. 22. Evidence of catastrophic outburst flood ~70 m high breached dam in the Kokomeren River valley Rocky remnant 2 km downstream overlaid by outburst flood deposits
  23. 23. 1st phaze – coarse angular boulders up to 1 m in size left by the flood wave “in the shadow” of the rocky cliff Estimated peak discharge ~30 000 m3/sec 2nd phaze – finer debris on top
  24. 24. Study of the potentially unstable slopes that can produce river damming downstream from the HPP and upstream from the reservoir must be performed to ensure safety of hydraulic schemes. Such surveys must be included as mandatory activities in the corresponding national and international guidelines.
  25. 25. Thank you for your attention!

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