E3S Web of Conferences 415, 03003 (2023)
DFHM8

https://doi.org/10.1051/e3sconf/202341503003

The July 2015 Debris flow in Barsem, Western Pamir (GBAO)
Tajikistan: description and causes
Avzalshoev Zafar1* and Taro Uchimura2
1
2

PhD Candidate, Geotechnical and Geosphere Research Group: GREG, Saitama University, Saitama, Japan
Professor, Geotechnical and Geosphere Research Group: GREG, Saitama University, Saitama, Japan

Abstract. Tajikistan is a landlocked country in the Central Asia republics of the former Soviet Union.
Tajikistan is prone to many natural disasters. Most commonly in Tajikistan, mudflows occur in the Southand North parts of the country. The 2015 Barsem mudflow caused significant damage to the entire village,a territory of the Western Pamir Gorno-Badakhshan Autonomous Region (GBAO), Tajikistan; fortunately,
no human casualties. The total volume of debris flow is about 4.9 million m3. Typically, precipitation above
15-20mm per day in arid areas causes mudflow. Accumulated water during the intensive melting of theglacier and snowfields was saturated with water by the moraine sediment blocking its paths (which served
as a dam for the lake that formed). Several studies indicate that mudflow triggers excess pore pressure orliquefaction of the soil; consequently, sudden and high shear resistance losses eventually generate a mudflow[5][6]. Although mudflows and landslides occur annually, after the 2015 Barsem mudflow, it becomes clearthat the intensity and frequency of new events are increasing. Consequently, the author strongly believes
establishing and implementing an early warning system can be essential.

1 Introduction
This article aims to describe potential reasons andgeotechnical aspects of the Barsem mudflow in July
2015. Tajikistan is a landlocked country in the Central
Asia republics of the former Soviet Union. Barely 10percent of its territory is suitable for agriculture, and theremaining 90 percent is mountains varying from several
hundred meters to 6000-7000 meters above sea level [1].
Tajikistan is prone to many natural disasters,including earthquakes, liquefaction, landslides, mudflow, and avalanches. The primary transportation
system between the cities in the country is by roads.
Therefore, annual economic loss from mudflow andlandslides is growing significantly by thousands ofkilometers of road damage, bridges, buildings, and othertypes of equipment. Especially recently, the last decade,due to climate change and global warming that induces
heavy rainfall and glaciers melting.
From the perspective of the past, geologists distinguishthe main hazard as earthquakes. Thus, more studies in
the past focused on earthquake data analysis anddamages—however, more studies and investigations arerequired on mudflow and landslides.
Although landslide hazard analysis has a long history
in Central Asia, mainly the earlier publications were in
Russian (Fedorenko 1988), eventually stuck around, andwere either never published or buried. In addition to that,a large amount of data was stored and never shown due
to security requirements. Even if it was publishedsomewhere, most figures were presented without

identification, making them almost useless for further
studies [2].
Therefore, in this paper author would like to focus onsuch hazards as mudflow from the geotechnicalperspective and as an example of the most extensive andmost recent case study, the Barsem 2015.
The increase in rainfall intensities over the past
decades and the glacier melting frequency of landslides
and mudflows are dramatically increasing. Therefore,
for mountain regions like Western Pamir GBAO, it iscrucial to implement a monitoring system, as typically,
precipitation above 15-20mm per day in arid areas
causes mudflow [4].

Fig. 1. Mudflow map of Tajikistan. (Author. N.R.Ischuk
2016).

* Corresponding author: zavzalshoev@gmail.com© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0(https://creativecommons.org/licenses/by/4.0/).

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Mudflows threaten about 85 percent of the territory,
and 32 percent are in the high mudflow risk zone [1].
Figure 1 illustrates “Mudflow hazards and distributionin Tajikistan” on a scale of 1-500,000. The updated map
by N.R. Ischuk (2016) and is based on the old maps fromSoviet times by Lim et al. (1984) and Tukeev and Uskov(1984).
The existing map was validated through satellite
imagery in Google Earth software by further study of thedata with Geographic Information system tools N.R.
Ischuk (2016)

2 Overview of the disaster
2.1 Location

Fig. 3. Barsem air temperature graph. (July 2015).

Village Barsem is located on the right side of Gundriver at a distance of 16 km northeastward from thecenter of Shugnan district (Barkhorog), at the outfall of
the Barsemdara gully.
The elevation of the Barsemdara water flow is
2389m above sea level. Inhabitant is located about 90m
above the river bed.
Figure 2 is a 3D extracted from a google map image of
the Barsem valley in June 2022.

2.3 Glacier
Pluvial, slope, and glacial deposits represent theupper-quaternary (Figure 4) sediments.
The sediments are composed of boulders’ loose
sediments deposited by debris flows.
Within the village, the area is composed of alluvial andglacial sediments (pebbles, sand, clay sand) spread in
the floodplain and terrace above the floodplain of theGund river. Boulders and pebble stone materials cover
the central and southwestern areas of the village. In
addition to that, different constructions cover the surfaceof the deck.

Fig. 2. Google map 3D image of the Barsem territory.

2.2 Weather and precipitation
July is a mild summer month in Barsem with anaverage temperature of 15.4°C and min 6.3°C.
According to the Navobod hydrometeorologicalstation (Figure 3), the air temperature in July gradually
increased from 26°С to 35°С (on July 16, 2015, there
was a maximum temperature).
Precipitation was observed only on July 14 in theamount of 1.0 mm. However, rainfall for the rest of thedays was July 17.
Additionally, CBC News reported that July 2015 was
the hottest day on the earth. The abnormal temperature
increases in all different parts of the world beat theprevious global mark.

Fig. 4. Higher part of the Barsemdara mountain (Focus
Humanitarian Assistance takes photos).

Snowfields are on the right-hand side of theBarsemdara river (snowfields are an accumulation ofpermanent snow and ice).
The occultation of four glaciers with an area of 0.23 to
0.37 km2 each was observed (Figure 5).
The length of the glaciers is 0.4-1.8 km, including thegenuine part of 0.4-1.8 km. The snow line at altitudes of
4.51-4.66 km. Glacial and diluvial deposits are highly
water-saturated with meltwater from snowfields andglaciers due to high soil permeability (Figure 5).

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The second reason for mudflow triggers an accumulated
dam in the upper part of the glacier, followed by soil
erosion.
Several studies indicate that mudflow triggers excess
pore pressure or liquefaction of the soil; consequently,sudden and high shear resistance losses eventually
generate a mudflow [5][6].
Soil consistency is explained by Atterberg limits,i.e., plastic limit (PL) and liquid limit (LL). If the waterlevel is lower than the LL, the soil is in a plastic state,
but when the water content is higher, the ground is in a
viscous liquid state.
Figure 7 illustrates the Barsem mudflow path. The
red circle line is a glacier at the upper part of themountain. Further on the bottom side is a snowfield.
Thus, it is assumed that loose soil accumulated during
sediment transportation and illuviation over a long time
under the snowfield.
Eventually, after the ground reached a viscous liquidstate and a large amount of the deposits accumulating
for several days started failing after the weather got its
maximum temperature, causing the melting of thesnowfield that worked as a dam collapse.

4Fig. 5. Barsemdara stream glaciers (photos by Focus
Humanitarian Assistance).

3 Mudflow source
Accumulated water got blocked by moraine
sediment during the intensive melting of the glacier andsnowfields. Consequently, the formation of the dam
appeared.
Further water infiltration pierced through themoraine and diluvial scree sediments, increasing suction
and loose shear strength. Therefore, the failure surface
accumulates, and flexible saturated material collapses.
(Figure 6).

Fig. 7. Barsem mudflow source 16 July 2015 (Focus
Humanitarian Assistance takes photos).

Figure 8 demonstrates the consequences of themudflow. Consequently, the only international road forcommunication between cities and the entire country
was destroyed, including residents' houses.
Further, it created an artificial dam immediately after
the mudflow, which soon became an additional threat todownstream villages and the city's center for flooding.
The artificial dam created the “Barsemkul” lake withproperties of 2300-2400 m in length, a depth of 13-17m, and an average width of 128 m. Therefore, theapproximate volume of water in the lake is V= (a x b xh = (2400 x17x128) = 5 222 400 m3 Figure 8.
However, the annual volume of the lake increases due torainfall, snow, and glaciers melting.

Fig. 6. Mudflow source glaciers are melting. (FocusHumanitarian Assistance takes photos).

Several reasons triggered the current mudflow. First,
abnormally high temperatures during July 2015
consequently caused glaciers to melt. Apparently, notwithin one or two days but for a month or more.
Unfortunately, the precipitation of the previous monthof 2015 is unavailable. However, considering themountainous and rainy seasons, from April to May, theauthor firmly believes that rainfall is high.

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low floodplain terraces of the main rivers, at the foot of
the slope, and on the surface of ancient landslide bodies,
which are very vulnerable to natural hazards with local
and remote manifestations.
The ongoing climate change event negatively
impacts different areas of life - ecosystem, health,agriculture, water management, transport infrastructure,energy, and gender.
Secondly, the most significant reason is a lake ofmonitoring data and research.
Although mudflows and landslides occur annually,
after the 2015 Barsem mudflow, it becomes clear thatthe intensity and frequency of new events are increasing.
However, the author strongly believes establishing andimplementing an early warning system can be essential.
Consequently, the early warning system is followed bymonitoring soil properties, precipitation, and watercontent.
Prove of climate change-induced Barsem mudflow
must be addressed. However, from a geotechnicalperspective, increasing water content is followed by anincrease in suction during wetting and a decrease duringdrying casing slope failure. Therefore, a large number ofmudflows and landslides can be eliminated by a propermonitoring system.
The current case study of the Barsem mudflow will
be helpful in the implementation of the early warning
system in future studies, especially for mountainous
regions.

Debris flow blocks the river.

Fig. 8. Mudflow cone formed as a result of a catastrophic
mudflow on July 16, 2015 (Focus Humanitarian Assistancetakes photos).

The overall properties of the Barsem 2015 mudflow arelisted in Table 1.
Table 1. Some properties of the mudflow.
ItemQuantity

Mudflow area

71.35 km2

The total volume of solid runoff is4994540 m3

4994540 m3

The estimated volume of the involved
solid component is 249727 m3

249727 m3

Mudflow cone area

308479 m2

The volume of mudflow mass in thealluvial cone -, with an average
mudflow cone thickness(h = 5m) is 1542395

1.

Mudflow velocity from

5-12 m/s

2.

The author would like to thank AKAH Tajikistan for sharing
pictures, particularly A. Navruzsho. Additionally, the author
would like to thank his supervisor Taro Uchimura for his
continued support.

References

3.
4.

Only the event for July related to climate change inthe territory of GBAO, the Rasht region, and the Sughdregion led to enormous economic damage to thecountry. In addition, seven mudflows in various areas
have been reported only for July 2015.

5.
6.

4 Conclusion
7.
Several factors triggered the region's current and pastnatural disasters.
First, climate change is considered the main factor in
the resurgent natural disaster - the activation of
mudflows, the threat of flooding, and flooding in thePamirs of GBAO, Tajikistan.
Historically and geologically, due to the lack of landin this mountainous region, all the residential areas(villages, towns, and cities), essential facilities, andinfrastructure are located on the alluvial fan of the lateraltributaries of the central valleys. Near the floodplain and4

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