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Sediment load of the main rivers of Lake Baikal in a changing
environment (east Siberia, Russia)
T.G. Potemkina
*
, V.L. Potemkin
Limnological Institute of the Siberian Branch of RAS, Ulan-Batorskaya st., 3, Irkutsk 664033, Russia
article info
Article history:
Available online xxx
Keywords:
Water runoff
Sediment flow
Changing environment
Lake Baikal
abstract
The results of the analysis of discharge and sediment flow changes of the main rivers flowing into Lake
Baikal are presented. Long-term observation record of sediment flow is divided into two periods differing
in average values and scale fluctuations of annual average values. During the first period, the dynamics of
sediment flow of rivers was determined by hydro-climatic factors, i.e. fluctuations of sediment flow, in
general, are synchronous to fluctuations of water flow. During the second period (from the mid-1970s)
there is a downward trend of sediment flow change (decrease by 49%e82%) against the background of
increased discharge of rivers. This trend is caused by both anthropogenic influence, and natural processes
connected to global and regional changes of climatic characteristics. In general, natural processes of
sediment flow changes in the different areas of Baikal basin are altered by anthropogenic factors to a
greater or lesser extent. The present article can be used as analytical material for further research and
forecast of sediment flow changes in the Baikal basin as well as in other rift-valley lakes of the world.
©2014 Elsevier Ltd and INQUA. All rights reserved.
1. Introduction
The decrease of river sediment load into the sea and the
consequent impacts on the coastal environment have become a
global topic in recent years. It is of great importance in geo-
morphology, biogeochemistry, and engineering. The sediment
flux into the sea from rivers is associated with chemical con-
stituents, such as trace elements, persistent organic pollutants,
and nutrients. Therefore, the fluxes of water and sediment from
rivers affect the coastal seas and the health of marine ecosys-
tems. Formation of river sediment load is determined by inter-
action of a number of natural factors (relief, surface roughness,
composition of rocks, nature of soil and flora, climate condi-
tions). Quite a significant and, at times, a leading factor of
multidirectional changes of sediments volumes is human activ-
ity, differing in type and intensity.
Many researchers have assessed the global river sediment flux
to the coastal oceans (Holeman, 1968; Milliman and Meade,
1983; Milliman and Syvitski, 1992; Hay, 1998; Syvitski, 2003;
Syvitski et al., 2003; Walling and Fang, 2003). Walling and
Fang's (2003) analysis of long time series data on sediment
load from the large rivers of Asia, Europe and North America
shows that approximately 50% of the rivers exhibit statistically
significant upward or downward trends, with the majority
showing declining trends. The sediment flux of most European
rivers has decreased, in some cases sharply, in the past 50 years
(Milliman, 2001). In Russia, 12 of the 20 rivers studied by
Bobrovitskaya et al. (2003) decreased in sediment flux. Human
activity, in particular dam construction, has been identified as
the main cause of the decreasing trend in riverine sediment load
(Vorosmarty et al., 2003; Syvitski et al., 2005; Walling, 2006; Dai
et al., 2008, 2009). The sediment flux is also sensitive to other
factors such as climate change. However, the manner in which
river sediment loads respond to climate change is not well un-
derstood, and related assessment regarding the effect of climate
change on sediment loads is lacking. Global climate changes,
particularly rises in temperature, are known to have effects on
precipitation variability (Allen and Ingram, 20 02; Barnett et al.,
2005), surface runoff (Nijssen et al., 2001; Milliman et al.,
2008), glacial and fluvial processes (Goudie, 2006), soil erosion
(Michael et al., 2005), elevation ranges of common montane
plants (Loarie et al., 2008;http://onlinelibrary.wiley.com/doi/10.
1002/ece3.720/full;Brusca et al., 2013)andsedimentloads
(Syvitski et al., 2003;Meade and Moody, 2010). However, little
work has been done on the observed impacts of climate change
on sediment loads in rivers (Syvitski et al., 2003; IPCC, 2007; Dai
et al., 2008; Knight and Harrison, 2009; Lu et al., 2010, 2013), due
to a lack of data and difficulty in sediment modelling (Lu, 2004).
*Corresponding author.
E-mail address: tat_pot@lin.irk.ru (T.G. Potemkina).
Contents lists available at ScienceDirect
Quaternary International
journal homepage: www.elsevier.com/locate/quaint
http://dx.doi.org/10.1016/j.quaint.2014.08.029
1040-6182/©2014 Elsevier Ltd and INQUA. All rights reserved.
Quaternary International xxx (2014) 1e8
Please cite this article in press as: Potemkina, T.G., Potemkin, V.L., Sediment load of the main rivers of Lake Baikal in a changing environment
(east Siberia, Russia), Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.029
Baikal is the largest natural fresh water reservoir in the world,
located almost in the center of the Asian continent. The volume of
Lake Baikal is 23,000 km
3
, representing about 20% of the world's
fresh water. The unique water of Lake Baikal is characterized by
purity, transparency, low mineralization (about 100 mg/l), absence
of organic admixtures, and maximum oxygen enrichment. Coasts of
Lake Baikal and surrounding mountains have peculiar fauna, flora,
and microclimate. In 1996, Baikal was included in the UNESCO list
of natural World Heritage sites. Saving the nature of Baikal under
present conditions is the most important problem, especially now,
when there is growing concern about shortage of drinking water
worldwide. The problem of fresh water shortage is associated with
human activity (pollution, degradation of freshwater ecosystems,
uncontrolled urbanization, change in land use, etc., which leads to
reduced water resources) and with climate change. Therefore,
during last decades of global climate change, enhancing anthro-
pogenic pressure on the landscape of the lake Baikal catchment, the
scientific interest in the study of the ongoing changes in the rivers
flow regime and, in particular, sediment flow has increased. The
Baikal basin has a well-developed river system. There are about 500
rivers flowing directly into the lake, but monitoring observations of
sediment flow has occurred only on five main rivers (Selenga,
Upper Angara, Barguzin, Utulik, and Khara-Murin). Rivers bring
into the lake the sediments and nutrients, as well as pollutants. The
present article examines the sensitivity of sediment flow of major
Baikal rivers to environmental change, which in turn requires
consideration of the impact of both human activity and climate
change and their interaction in the formation of sediment flux.
2. Physical setting
Baikal is one of the oldest lakes on the planet and the deepest
lake in the world. Its approximate age is 25e30 million years. The
lake's length is 636 km, width varies from 25 to 80 km, and
maximum depth is 1637 m. The catchment area of Baikal is
545,000 km
2
, 31,500 km
2
excluding the water surface area (Atlas of
Baikal, 1993). Approximately 90% of catchment is located on the
east side of the lake. Approximately 45% of the Baikal catchment
area is in Russia, and the remainder in Mongolia (Fig. 1). The ratio of
water surface area to catchment area of Baikal is 1:17, which means
there is a significant role of the land in the feeding process of the
lake. The main link of this process is river flow.
Baikal is a rift-valley lake, and its basin has mainly mountainous
relief. Altitudes vary from 456 m to 2840 m. Mountain ridges are
elongated parallel to the lake basin, oriented mainly south-west to
north-east.
The lake basin substantially consists of forest-steppe and forest
(taiga) zones. However, highly dissected relief causes altitudinal
belts in the vegetation distribution, from steppe to goltsy (alpine
tundra).
The Baikal basin is located in a boreal climate zone with a
continental type of climate. The climate conditions on the study
territory are determined by the nature of the atmospheric circu-
lation and radiation regime, terrain relief, and the influence of
water masses in the coastal areas of the lake. Average annual air
temperature over a long-term observation period in the Baikal
basin is 3.7
C(Surface Water Resources, 1973). The greatest
Fig. 1. Sketch of the Lake Baikal basin showing the main rivers basins in this study. River basins: Utulik e1; Hara-Murin e2; Upper Angara e3; Barguzin e4; Selenga e5.
Boundary between Mongolia and Russia e6; Boundary of the Lake Baikal basin e7.
T.G. Potemkina, V.L. Potemkin / Quaternary International xxx (2014) 1e82
Please cite this article in press as: Potemkina, T.G., Potemkin, V.L., Sediment load of the main rivers of Lake Baikal in a changing environment
(east Siberia, Russia), Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.029
amount of precipitation falls in the mountain area (average annual
amount is 1293 mm), and the minimum (250e300 mm) in valleys
of the rivers Selenga, Barguzin, and Uda, on Olkhon island, and the
Selenga delta. Typically, 80e90% of the annual precipitation occurs
during the warm season (MayeSeptember).
Permafrost is widespread in the lake basin. Most of the basin
consists of discontinuous permafrost area (thickness to 50 m) and
the area of the change from discontinuous to continuous perma-
frost (thickness 50e100 m). Areas of continuous (thickness is over
100 m) permafrost are located in the easternmost and north-east
territory of the lake basin.
The largest rivers by length, water, and sediment load eSelenga,
Upper Angara and Barguzin ewere selected in the large feeding
province of Baikal. Their basins re connected to the water-body only
through river estuaries. Rivers of the coastal area and the facing-
the-lake mountainsides area are grouped into the small feeding
province. Most rivers of the small province are mountain rivers. The
climate conditions of the small feeding province are local and
determined by the high influence of the Baikal water body. Utulik
and Khara-Murin rivers were selected in the small feeding prov-
ince: they are notable for relatively long-term observation periods.
According to the ratio of the main feeding sources, the Utulik and
Khara-Murin rivers are dominated by rainfall runoff, and the Bar-
guzin and lower Selenga have nearly equal amounts of rain and
melt water (snow). Melt water runoff dominates the Upper Angara
(Surface Water Resources, 1973). Average values of water and
sediment flow of the examined rivers over the observation period
are presented in Table 1. Rivers bring detrital material from the
water catchment basin as well as contaminants. Natural and
anthropogenic changes of the lake basin clearly affect the water and
sediment flow regime. At the same time, water-catchment areas of
major rivers, where suspended sediment discharge is measured,
cover over 90% of the Baikal basin: Selenga (82.8%), Barguzin (3.7%),
and Upper Angara (3.6%). Therefore, the ongoing changes in the
entire Baikal basin are objectively characterized by the long-term
data of water and sediments flow of these rivers.
3. Materials and methods
The monitoring observations (by Federal Service for Hydromete-
orology and Environmental Monitoring) of water and sediment flow
of the main Baikal rivers have been analyzed in the study. Data of air
temperature, geology, and precipitation, and cartographic documents
also were analyzed. Previous research (Potemkina and Fialkov, 1993;
Potemkina, 1998, 2004, 2011a,b; Potemkina et al., 2012) and scienti-
fic publications have been used in the study. Long-term records of
annual water (further eWD) and suspended sediment discharges
(further eSSD) cover the periods: on Selenga river e19 34e2011 (WD)
and 1941e2011 (SSD); on Barguzin river e1933 e2011 (WD) and
194 3e2011 (SSD); on Upper Angara river e1939e2011 (WD) and
194 6e2011 (SSD); on Utulik river e1941e2011 (WD and SSD); on
Khara-Murin river e1971 e2011(WD) and 1972e2011 (SSD).
Dynamics charts of the annual water and suspended sediment
discharge over the observation periods were analyzed, trends
determined, and correlation coefficients between WD and SSD
calculated. The long-term SSD observation was divided into two
periods, differing in average values and their scale fluctuation. In
the first period, the synchronous fluctuations of WD and SSD are
marked. The second period was marked by a significant decrease in
the flow of suspended sediment. The annual water discharges of
rivers in the second period did not change significantly.
Changes of annual values of WD and SSD were detected and
correlation coefficients between them calculated for the selected
periods. For validation estimation of the difference between values
over the observation periods, the statistical Student t-test was used.
Movement of bed load sediments was not considered because its
percentage relative to the flow of suspended sediments is small
(about 4% for the plain rivers and 20e25% for the mountain ones)
and does not change the long-term dynamics (Gusarov, 2004;
Panin, 2005).
4. Results and discussion
4.1. Change in water and sediment discharges
The analysis of annual water and sediment discharge dynamics
over the observation period in the investigated rivers of small and
large feeding provinces of Baikal (Fig. 2) has revealed the following
trends. There are negative trends of annual suspended sediment
flow in all rivers, and a reduction of volume of fluvial material has
place. The changes of discharge in the rivers Barguzin, Upper
Anagara, Utulik have positive trends, and in Selenga and Khara-
Murin rivers, slightly negative trends.
There are two periods in the long-term course of sediment flow
in the investigated rivers. On the Selenga and Barguzin, the break
point of these two periods is the beginning of the 1980s. This
concurs with the two phases of discharge changes in the Baikal
basin: low-water (1974e1982) and high-water (1983e1996). These
phases are most noticeable in the Selenga and Barguzin, less
noticeable in the Utulik and Khara-Murin, and not apparent in the
long-term course of discharge in the Upper Angara. The conditions
of river runoff are different and depend on relief features and
climate characteristics in different parts of the Baikal water catch-
ment area. The break point for the Upper Angara river was 1973:
after that (in the second period) there is a rapid change of sediment
flow regime. The break point for Utulik river is 1973, and for Khara-
Murin 1982, separating two phases of discharge in the lake basin.
During the first period, the dynamics of sediment flow in the rivers
of large feeding province is consistent with the general course of
water runoff, as indicated by high correlation coefficients between
SSD and WD (Table 2). During the second period, there is a signif-
icant decrease of suspended sediment flow in the course of slightly
changing discharge. Correlation coefficients decreased in the sec-
ond period (Table 2). The correlation between WD and SSD in the
second period for Selenga is significant, for Barguzin it is very weak,
and it is not available for Upper Angara. For the rivers of the small
feeding province (Utulik and Khara-Murin), the correlation be-
tween water flow and sediments flow is insignificant. The obser-
vation record on Khara-Murin river is quite short and mostly falls
within the second period (when correlation coefficients between
WD and SSD are not high). Only 11 years of the observation record
fall within the first period. The prevailing feeding source of Utulik
and Khara-Murin rivers is rainfall runoff, which may cause mud-
flows of variable intensity and, therefore, increases the annual
volume of river sediment. There is a high influence of random
disastrous phenomena (rainstorms, mudflows) on annual sediment
dynamics of these rivers.
Table 1
Characteristics of the main Baikal rivers.
River River length/water
catchment area, km/km
2
Average over observation period
Water flow,
km
3
y
1
Sediment flow,
10
3
ty
1
Large feeding province
Selenga 1024/447,060 27.9 1701
Upper Angara 438/21,400 8.44 258
Barguzin 480/21,100 3.97 101
Small feeding province
Khara-Murin 86/1150 0.72 13
Utulik 86/965 0.52 35
T.G. Potemkina, V.L. Potemkin / Quaternary International xxx (2014) 1e83
Please cite this article in press as: Potemkina, T.G., Potemkin, V.L., Sediment load of the main rivers of Lake Baikal in a changing environment
(east Siberia, Russia), Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.029
Table 3 shows that in the second period, sediment flow of rivers
showed 49%e82% decreases comparing to the first period. The
discharge of rivers, at the same time, either increased or slightly
decreased. The trend of sediment flow decrease in the Selenga and
Barguzin rivers began with the low-water phase (1974e1982).
During that phase as well as during the whole first period, fluctu-
ations of the annual flow were mainly caused by hydro-climatic
factors. In the second period, anthropogenic activity influenced
natural processes. Its effect in the Selenga and Barguzin basins was
not identical, as indicated by correlation coefficients between WD
and SSD. Anthropogenic factors, contributing to decrease of sedi-
ment volume, were caused by regression of agriculture during so-
cioeconomic macro-reformations in Russia. In Buryatia, which
covers about 34% of Baikal basin area, plough lands were reduced
by 84% by 1999 (compared to 1983), and pasture-land area reduced
by 2.6%, haying territories expanded by 9.3%, and the countryside
population decreased (Raldin et al., 2003). These processes have
contributed to the weakening of the erosion in the Barguzin and
Selenga rivers basins and therefore to the decrease of suspended
sediment discharge. In the Selenga river, the decrease of the in-
tensity of erosion processes (due to socioeconomic reformations)
had less effect than in Barguzin basin, where more territory was
more used for agriculture. Correlation coefficients between WD and
SSD in the Selenga river (Table 2) demonstrate the high influence of
hydro-climatic factor on river sediment flow (during the whole
second period and during the long-term observation period).
The Upper Angara basin is very little used for agriculture
(<1%) (Surface Water Resources, 1973). However, during the
second period the suspended sediment discharge of the river
decreased by 66%, and discharge, at the same time, increased.
The two phases of discharge were not revealed in the long-term
course of the water flow. Hydro-climatic factors were not the
main reason of the start of sediment flow reduction in the 1970s
(Selenga and Barguzin rivers). At this time, the anthropogenic
pressure on the landscape of the Upper Angara basin was strong.
This pressure was caused by the start of Baikal-Amur Mainline
Railway construction. The railway crossed river channels and
floodplains, bridge crossings were built, railway embankments in
floodplains, and dams for different purposes were made, con-
struction camps were settled: all of these made a barrier to
transit of denudation material. Dredging of the channels of the
Kichera and Upper Angara rivers for alluvium for railway con-
struction caused the decrease of sediment transfer into Baikal.
This resulted in reduction of sand supply to the Yarki bar, which
is significantly eroded now (Potemkina, 2011a,b). Dredging of
river alluvium can cause the change of channel operation
(channel deformation, sediment flow) and hydraulic character-
istics (water surface slope, stream velocity). Such a situation,
apparently, was noted in the Upper Angara. A decrease of
mudflow activity in the region also has been noted. According to
the data (Laperdin, 2008) from 1971 to 2007 there were no
disastrous mudflows on the rivers which could change the value
of the average annual sediment discharges. The disturbance of
sediment flow regime is also caused by lowering of the Upper
Angara basin bottom (0.5 cm/y), increasing of swampiness, and
the interception of part of the river sediment by large swamps
(Geology of the BAM zone, 1988). Changes of climatic charac-
teristics in the region, caused by warming, also influence sedi-
ment flux. Thus, a combination of natural processes and socio-
economic activities in the basin of the Upper Angara River
caused a reduction of the river sediment volume and the
establishment of a different regime, confirmed by the use of
Student t-test (at a significance level of 0.95).
In the second period, the volume of sediments in the Utulik and
Khara-Murin rivers decreased by 82% and 70% respectively
(Table 3). The crucial importance in this trend is not an anthropo-
genic factor but natural conditions. Although anthropogenic pres-
sure in the Utulik and Khara-Murin basins has become more
intense, landscapes of most of the territory are close to natural
(large forested area, small ploughed area) and slightly altered by
humans. In the Baikal region, there have been no disastrous mud-
flows for over 40 years. Accumulated denudation material over this
period in the basins can generate, under certain meteorological
conditions, disastrous mudflows that would increase the annual
volume of river sediments. Therefore, during the second observa-
tion period there were small volumes of sediments in Utulik and
Khara-Murin, and the main element in this situation was the nat-
ural conditions and processes.
4.2. Influence of warming processes on river runoff
Warming processes influenced climate characteristics in the
region and the main Baikal rivers' runoff. The mean amount of
global warming was 0.75 C
, while in the Baikal region it was
1.65 C
over 100 years (1907e2006) (Valuation report of climate
change…,2008). Growth rate of warming in the Baikal region is
almost 2 times higher than the growth rate of global temperature.
Climate warming, whose elevated trend was recorded in the second
half of the 1970s, might have caused the increase of evaporation,
reduction of water flow and, as a result, decrease of sediment flow.
However, against the progress of warming over the last 30 years,
there was a phase of increased discharge over most Russian terri-
tory (Shiklomanov et al., 2010). Shiklomanov et al. (2010) notes it
happened due to the rise of humidity, which was mostly caused by
Table 2
Correlation coefficients (K) between water discharge and suspended sediment
discharge over a long-term observation record and its periods.
River Long-term record First period Second period
Years KYears KYears K
Selenga 1941e2011 0.63 1941e1982 0.80 1983e2011 0.69
Upper Angara 1946e2011 0.09 1946e1973 0.70 1974e2011 0.01
Barguzin 1943e2011 0.21 1943e1982 0.62 1983e2011 0.25
Khara-Murin 1972e2011 0.15 1972e1982 0.14 1983e2011 0.29
Utulik 1941e2011 0.32 1941e1973 0.53 1974e2011 0.25
Table 3
Changes of water flow (Q,km
3
y
1
) and sediments flow (R,10
3
ty
1
) over periods.
River First period Second period Changes
Years QRYears QR
D
Q
D
R
D
Q%
D
R%
Selenga 1941e1982 28.0 2110 1983e2011 27.1 1071 0.90 1039 3.2 49
Upper Angara 1946e1973 8.32 416 1974e2011 8.76 142 þ0.44 274 þ5.3 66
Barguzin 1943e1982 3.72 145 1983e2011 4.22 41 þ0.50 104 þ13 72
Khara-Murin 1972e1982 0.72 26 1983e2011 0.71 7.9 0.01 18.1 1.4 70
Utulik 1941e1973 0.52 63 1974e2011 0.52 11 0 52 0 82
T.G. Potemkina, V.L. Potemkin / Quaternary International xxx (2014) 1e84
Please cite this article in press as: Potemkina, T.G., Potemkin, V.L., Sediment load of the main rivers of Lake Baikal in a changing environment
(east Siberia, Russia), Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.029
intensifying of circulation processes in North Atlantic that influ-
enced moisture-transporting cyclones. Baikal has seen a rise of
water inflow into the lake with a positive trend of 300 m
3
/s over
100 years as the climate warmed. This trend was caused by the
change of types of atmospheric circulation processes in the region
and the increase of precipitation (Shimaraev et al., 2002).
The general tendency of atmospheric precipitation change in
the Baikal region (1940e2011) was an increase with a slight posi-
tive trend against a high increase of air temperature, common since
the beginning and mid-1970s for all regions of Eastern Siberia
(Miach et al., 2011; Report on climate features in Russian
Federation, 2011). An exception is the Selenga basin, within
which there are areas with both positive and negative precipitation
trends (Batima et al., 2005). Change of air temperature and pre-
cipitation for the long-term period in the basins of the rivers under
consideration is shown in Fig. 3. There is a positive trend in the
discharge change in Baikal rivers, except for the Selenga. Correla-
tion coefficients between average values of water flow and pre-
cipitation are shown in Table 4. The weakest link between
precipitation and water discharge over a long-term period was
observed on the Upper Angara (0.34). In the second period the
influence of precipitation on runoff in these rivers is markedly
reduced. This is due to warming and changes in atmospheric cir-
culation processes in the region.
Fig. 2. The variability of the annual discharges of water and suspended sediments of
major rivers of Lake Baikal: Selenga, Barguzin, Upper Angara, Khara-Murin, Utulik. The
average annual discharge values of water and suspended sediments, respectively (1, 3);
their current values smoothed for five-year periods (2, 4); (5, 6) linear trends. Vertical
dashed line: the boundary between two periods.
Fig. 3. Variation of air temperature and precipitation in the basin of the Selenga River
at the Ulan-Ude station e1; in the basins of the Utulik and Hara-Murin Rivers at the
Hamar-Daban station e2; in the basin of the Upper Angara River at the Nizhneangarsk
station e3; in the basin of the Barguzin River at the Barguzin station e4.
Table 4
Correlation coefficients between precipitation (P) and water discharge (WD) over a
long-term observation record and its periods.
River Long-term record First period Second period
Years PeWD Years PeWD Years PeWD
Selenga 1936e2011 0.50 1936e1982 0.74 1983e2011 0.31
Upper Angara 1966e2011 0.34 1966e1973 0.83 1974e2011 0.34
Barguzin 1966e2011 0.74 1966e1982 0.90 1983e2011 0.60
Khara-Murin 1971e2011 0.68 1971e1982 0.92 1983e2011 0.53
Utulik 1941e2011 0.56 1941e1973 0.75 1974e2011 0.44
T.G. Potemkina, V.L. Potemkin / Quaternary International xxx (2014) 1e85
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(east Siberia, Russia), Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.029
In addition to precipitation, a change of runoff is affected by
particular natural conditions in river basins. The basin of Selenga
mostly consists of forest-steppe, steppe, and desert natural areas,
where evaporation from the surface of the land exceeds the amount
of precipitation. Warming intensifies evaporation and increases
moisture deficit, which highly worsens the water balance of the
territory and eventually affects the water flow of a river (Batima
et al., 2005). The basins of the Upper Angara, Barguzin, Utulik and
Khara-Murin are surrounded by mountains, with moisture and
permafrost. The warming causes degradation of permafrost, that
helps to bring additional moisture into the rivers. The timing of soil
temperature changes at depths of 80 and 160 cm is mostly similar
to the timing of air temperature changes in the Baikal area. In the
basins of the Upper Angara and Barguzin, values in soil temperature
at a depth of 160 cm in the cold period have become positive. In the
northern permafrost, temperature at a depth of 19e20 m increased
by 0.9 C
over the period 1987e2005 (Miach et al., 2011). In frozen
caves along Lake Baikal, retreat is 3.2e11.7 cm/y, and the rate of
melting varies from 1.7 to 12.9 cm/y (Trofimova, 2006). Thus,
permafrost degradation contributes to changes in water runoff of
Baikal rivers.
Accompanied by increased water runoff, sediment load in the
rivers decreases. Warming and permafrost degradation has caused
marked upward displacement (30e60 m) of alpine distribution
limits of woody vegetation during the last 60e80 years in different
regions of the world (Iashina, 2011). In the adjacent Altai-Sayan
mountain country, movement of the upper boundary of the forest
communities by 20e80 m in height and 100e900 m along the slope
is evident (Moiseev et al., 2010). In the area of Lake Baikal, there are
similar processes. Consequently, the treeless zone (goltsy zone)
decreases, which is the source of detrital material for the formation
of river sediments and mudflows. Distribution in this zone of
vegetation reduces formation of detrital material and blocks its
movement, thus creating conditions for reducing the sediment load
of rivers. Thus, the available data of sediment flow of Baikal rivers
indicate that the leading role in reducing sediment runoff belongs
to the natural processes, that are in different parts of the region to a
greater or lesser extent altered by anthropogenic factors (this ap-
plies mainly to the large feeding province).
4.3. Limitations of this study
Changing of the flow of river sediments due to a changing
environment is a widespread global phenomenon. In general, the
prevailing trend is a decrease in runoff sediment. The insight of the
mechanism of the mobilization of riverine sediment is of great
scientific and practical value in view of its importance to change of
the coastline at the river mouths and the receiving water body. In
addition, reducing sediment load has a significant environmental
impact on the aquatic ecosystems, because of the decrease in
sediment-associated nutrient supply.
While human impact and climate change continues to be largely
responsible for the reduction of sediment loads in the Baikal rivers,
there are several limitations associated with our work. This study
attempted to examine all the factors of influence on riverine sedi-
ment, but it is very hard to disentangle different impact factors. It is
difficult to give a quantified portion to each of the impact factors in
view of their contribution to the sediment decrease due to the
complication of the sediment mobilization process and the data
deficiencies. In-depth and more detailed studies are needed. For
example, there are insufficient data on the permafrost thaw and
degradation under a warming climate, which is an important factor
influencing sediment transport. Permafrost has key controls over
various hydrological and geomorphologic processes and phenom-
ena, such as surface runoff and groundwater flow, slope stability,
and rates of river bank erosion. Owing to the large coverage of
permafrost in the Baikal region and the susceptible nature of
permafrost to warming, permafrost thaw and degradation would
be expected to exert important controls on sediment load. Factors
such as changes in vegetation, raising the upper limit of the forest,
reducing intensity of frost weathering of rocks, and variations in
soil erosion caused by climate change may have a significant impact
on the sediment load in the Baikal region. Due to a deficiency or
lack of data on these factors, it is difficult to give a quantitative
assessment. It is also difficult to assess the degree of human activity
on the sediment load (excavation of river alluvium, land use
changes, construction of railways, settlements). Elucidating the
complex relationship of changing environment and sediment
runoff in the future will require conducting additional works.
5. Summary and conclusions
With the meteorological data for the observation period in the
basins of major rivers of Lake Baikal and records of water discharge
and sediment load at these rivers, the effects of climate change and
human impact on sediment loads are established through the re-
lationships among air temperature, precipitation, and water and
sediment discharges. The dynamics of the annual sediment load on
the main Baikal rivers is marked by two periods, differing in
average values and scale fluctuation. During the first period, the
sediment flow dynamics were determined by hydro-climatic fac-
tors. Fluctuations of sediments flow, in general, are synchronous to
fluctuations of water flow. This is confirmed by sufficiently high
correlation coefficients between water discharge and suspended
sediment discharge (0.53e0.80). In the second period, there is a
strong decrease of suspended sediment flow in the course of
slightly changing discharge. On the rivers Selenga, Barguzin, and
Hara Murin, decreased sediment runoff began in 1983, and on the
Upper Angara and Utulik in 1974. During the second period, sedi-
ment load in rivers decreased by 49%e82%. Discharge increased in
the Upper Angara and Barguzin by 5.3% and 13%, respectively,
decreased by 3.2% in Selenga, and the Khara-Murin and Utulik
remained unchanged. Influence of precipitation on water runoff in
the rivers during the first period was significant, as indicated by the
correlation coefficients (0.74e0.92). During the second period, the
relationship between precipitation and water runoff weakened.
Probably, other processes occurred due to warming and changing
atmospheric circulation. Changes in water and sediment runoff
were caused by natural (geological, geomorphological, hydro-
climatic) and anthropogenic (socio-economic reformations,
change of use of land, digging up river alluvium, construction of
roads, housing) factors, which in different parts of the Baikal basin
had different results.
The Selenga river basin is elongated in a southerly direction and
located in different climatic zones. Most of the basin is experiencing
a moisture deficit. Under warming, increased evaporation causes a
moisture deficit increases, which leads eventually to a decrease of
water flow and sediment in the river. The correlation coefficient
between water and sediment flow in the first period (up to 1983)
was 0.80, and in the second period it slightly decreased (0.69). In
the Selenga basin, the sediment flow is quite significantly influ-
enced by hydro-climatic factors. Human activity is contributing toa
decrease of river sediment load.
Barguzin and Upper Angara river basins are within mountainous
terrain with sufficient moisture, and permafrost promotes
involvement of additional moisture under climate warming. In the
Barguzin and Upper Angara, during the second period water flow
increased, but sediment flow significantly decreased by 72% and
66%, respectively. The reason for this trend in the Barguzin basin
was a more significant manifestation of socio-economic
T.G. Potemkina, V.L. Potemkin / Quaternary International xxx (2014) 1e86
Please cite this article in press as: Potemkina, T.G., Potemkin, V.L., Sediment load of the main rivers of Lake Baikal in a changing environment
(east Siberia, Russia), Quaternary International (2014), http://dx.doi.org/10.1016/j.quaint.2014.08.029
reformations against the background of natural processes. The
combination of anthropogenic impact on basin landscape and
changes in natural processes caused the sharp change of sediment
volumes on the Upper Angara. The dominant role in the tendencyof
sediment volume decrease in Khara-Murin and Utulik rivers be-
longs to changing natural processes due to climate warming. In
general, natural processes continue to be largely responsible for the
decrease of sediment load in the main rivers of Lake Baikal.
Although climate change according to preliminary estimates had a
negative 3% contribution on sediment in the Yangtze River (Dai
et al., 2008), in the Baikal region its influence on sediment flow is
probably to a greater extent. Warming in Baikal region is almost 2
times higher than the increase of global temperature. Our results
also indicate that sediment loads respond to climate change more
sensitively than does water discharge. However, the extent to
which sediment load responds to climate change remains largely
unknown due to the complexity of the answer. Quantitative
assessment of the effect of climate change on sediment load is
therefore of critical importance for future research. Earlier obtained
results on sediment balance in Selenga delta, on river sediment
transfer to the coastal area, and their distribution in the lake Baikal
(Potemkina and Fialkov,1993; Potemkina, 1998; Potyomkina et al.,
1998) require revision and additional research due to the changes
of sediment flow of major Baikal rivers. Given that future climate
warming and human activities will cause changes in water and
sediment in river basins, this study can be beneficial for further
research and forecast of sediment flow changes in the Lake Baikal
basin and in other world rift lakes.
Acknowledgments
This study was supported by the Russian Foundation for Basic
Research, grant N11-05-00140-a.
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