Glacier lake outburst floods and glacier surges in Central Asia
Almaty (population 1.2 million) is subject to the risk of floods tion between meteorological services in glacier flood hazard
from torrential rainfalls and glacial lake outbursts. A glacier-in- detection.
duced debris flow in July 1973 in the mountains south of Almaty
deposited over 4 million m
3
of debris into the safety dam, which The increasing number of glacial and moraine lakes in Central
had been specially constructed to prevent the catastrophic im- Asian mountains is a matter of great concern
35,39
. One of the
pacts of such floods. Before this dam was built in 1967, debris surging glaciers that poses a potential threat is the 15 km long
flows caused many casualties and severe destruction in 1921 Medvezhi (Bear) Glacier in the Pamirs mountains of Tajikistan
and 1956
35,36
. (Figure 6B.7). Its surges have repeatedly caused lake forma-
tion, outburst and subsequent floodings. In 1963 and 1973, the
In July 1998, a glacier lake outburst flood in the Shahimardan surge of the glacier was so significant (1 to 2 km increase in
Valley of Kyrgyzstan and Uzbekistan killed over 100 people
37
. length) that the ice dam exceeded 100 m in height and dammed
In August 2002, another such event in the Shakhdara Valley of a lake of over 20 million m
3
of water and debris
40
. The outburst
the Tajik Pamir Mountains claimed 23 lives
38
. In both cases the of that lake generated a series of large flood waves. Due to early
local communities did not receive early warnings and were not warning and monitoring, there were no victims, although infra-
prepared. These tragic lessons have prompted better coopera- structural damage was significant.
Stable Glacier surge and
glacier formation
of ice dam
Area of ice
accumulation
Ice fall
Glacier body
0 2 km
Glacier terminus
Direction of outburst
flood (GLOF)
Glacier lake
Figure 6B.7: Forma-
tion of lakes and
glacier lake outburst
floods (GLOFs) by
Medvezhi Glacier,
A
b
d
u
k
a
go
r
Pamirs.
Source: Tajik Agency
on Hydrometerology
CHAPTER 6B GLACIERS AND ICE CAPS 125