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
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
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.
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 effects
So powerful debris flows from the
Obi-Shur Creek could be
Trace of debris flow in the ObiShur gorge. Photograph of 1978.
Estimated discharge 1500-1700 m3/sec
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,
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 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
Position of Kamarata 1 & 2 dam sites and their reservoirs
Possibility of downstream river damming
and Kambarata-1 powerhouse inundation
headscarp on the
left bank of the
Remnant of rockslide body
on the rignt bank terrace of
the Naryn River
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 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?
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.
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
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.
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.
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
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
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.