2016 International Conference on Environment, Climate Change and Sustainable Development (ECCSD 2016) ISBN: 978-1-60595-358-8

Dynamics of the Hydrological Regime on the Rivers of the Baikal Region on the Background of Climate Change Natalia KICHIGINA * V.B. Sochava Institute of Geography SB RAS, 664033 Ulan-Batorskaya, 1, , *Corresponding author

Keywords: Climate change, Tendency of river run-off, Baikal region.

Abstract. The second half of the last century and beginning of this century characterized by targeted climate change. It is reflected on hydrological regime and the factors of river flow formation. The regional features of the hydrological regime dynamics of the Baikal region on the background of climate change are considered in article. The long-term fluctuations of river run off are analyzed. The evaluation of long-term cyclic fluctuations of river runoff with use the integral difference curves is executed. These curves reflect annual fluctuations of river run off and indicate to long-term exhaustion or accumulation of water in watersheds. Groups of the rivers with similar alternations of low water and high-water periods are allocated. Trends in runoff are analyzed. Trends of monthly average and annual river flow series for period till 1961 to present were considered. The increase in air temperature is mainly due to the winter months leads to intra annual redistribution of river flow. The majority of statistically significant trends of river run off are observed during the cold period of year.

Introduction A fair amount of recent attention has been focused on the issue relating to climate fluctuation and their consequences [1, 2]. The evidence reported in them for the influence of climate change on the hydrological regime of rivers is largely considered on the macro level. However, the regional manifestation of climate change has a number of intrinsic properties associated also with local physical–geographical conditions [3,4]. Baykal region is located in the center of the Eurasian continent, at a great distance from the oceans, which is the huge inertial accumulator of solar energy. Its largely determines the direction and speed of the warm oceanic and air masses on Earth, which affect the climate of the planet. Features of physical–geographical position of the region and sharply continental climate have to define the features of climate change. The instrumental observations showed a persistent long-term tendency towards a rise in mean annual temperature (0.4˚ C/10 years), with the largest contribution coming from changes in the winter months [5]. The maximum air temperature changes were recorded in February (0.62– 1.94˚C/10 years). Minimum statistically significant trends were recorded in the summer months. The tendencies for a change in the monthly amount of precipitation are insignificant, because they are 10–100 times lower than the international variability. At the same time, much research points to an increase in precipitation at the global (planetary) level, as well as in a large number of the individual regions of the Russia and neighboring countries [6, 7]. The study of regional features of Baikal region rivers flow, the laws of their long-term fluctuations and intra annual redistribution, extreme values, taking into account the local geographical features of the runoff formation in the background of global climate change gets us closer to solving the problems associated with both economic and environmental tasks.

Objects and Data The Baikal region includes three subjects of the Russian Federation, united by belonging to the basin of the Lake Baikal, it is the Irkutsk Region, the Republic of and the Chita region. In the hydrographic relation the Baikal region includes the Lake Baikal basin, nearly all of the River basin, Upper Lena River basin (with Vitim and Olekma River basins) and the upper parts of the Lower Tunguska. The objects of our study were the run-off series in majority for rivers with a catchment area not greater than 100 km 2. Such rivers flows are formed in a more or less homogeneous physical- geographical condition within the same geographical zone. River run off cross-sections were selected in such a way as to reflect the full range of physical-geographical features of the territory. We used information on run-off obtained from hydrological gauging stations to assess changes in the hydrological regime. We examined the data series for mean annual and monthly run-off. Besides we examined run off series of genetically homogeneous phase of water regime – spring snow melt and summer rainfall maxima, annual and summer minima. Analysis of run-off trends was undertaken mainly for an identical 55-year-long period of instrumental observation, from 1961 to 2014, except the Lower Tunguska, where the period from 1961 to 1999 was conceded (due to lack of data). We used information from Baikal region rivers, including 15 gauging stations within the Lena basin, 10 gauging stations within the Angara basin, 12 gauging stations within the Lake Baikal basin, 3 gauging stations within the Lower Tunguska. We used long-term observational data from the Irkutsk and Ulan-Ude Administration for Hydrometeorology and Environmental Monitoring, and data from handbooks of the series Surface Water Resources of the USSR, the State Water Cadastre, as well as data from hydrological yearbooks.

Methods The assessment of long-term cyclic flow fluctuations with use of integral difference curves is executed. These curves reflect not only the annual fluctuations in flow, but also indicate long-term exhaustion (the descending curve sites) or accumulation (the ascending curve sites) of river flow in the basin. Allocation of water content phase is carried out on the main turning points of curves. The coefficient of a linear trend determined by a method of the smallest squares is used as a measure of run off changes intensity. The statistical significance of the trends is estimated by the statistical test of the null hypothesis of no difference between the regression model and the experimental data from 95% confidence interval. Only data series without gaps or with single gaps were used in processing. Missing values were replaced by an average value, calculated for the corresponding variable. Despite the low accuracy, this method is appropriate due to its simplicity and the small number of gaps. Values with a large deviation from the average value were estimated and also treated as missing values.

Results Integral difference annual flow curves clearly illustrate the long periods of low and high water. They show the general tendency of long-term fluctuations of a flow in river basins. In the central and southern of Lake Baikal basin (Fig. 1, line 1) now is low-water period, which began in 1999. In the north of Lake Baikal basin there is high-water period at the same time (line 3). The Angara basin is marked the small reduction of the flow on the number of rivers (line 4). This low-water period replaced the high-water period, which was here at the beginning of the current decade (2001 - 2006). In Upper Lena basin the high-water period ended which lasted from 2002 to 2012 (line 2). Monthly mean and annual run-off trends were analysed, the statistically significant trends are presented in Table 1.

0,04

v 0,02 С 0,00 (k-1)/

∑ -0,02 -0,04 4 3 5 8 1 7 0 9 2 4 6 91 00 03 93 94 95 96 97 97 98 9 99 0 0 00 1 1937 1940 1 1946 1949 1952 1 195 196 1964 1 1 1973 1976 1 1 1985 1988 1 1 1997 2 2 2 2009 2012 1 2 3 4

Figure 1. Integral difference curves of the river flow, where - k modular coefficient, Cv – variation coefficient: 1 - Selenga-Mostovoi (Lake Baikal basin), 2 - Lena-Zmeinova (Lena River basin), 3 -Verch.Angara-Zaimka (Lake Baikal basin), 4 - Irkut-Tibelti (Angara River basin). Table 1. Statistically significant trends of months average and annual run off for period 1961-2014. River - Months Ann Station I II III IV V VI VII VIII IX X XI XII ual Lower Tunguska- Erbogache - n (till 11.7 1999) 2.51 8 Angara river basin Irkut- 0.01 0.00 0.00 0.01 0.04 0.01 Mondi 18 68 72 0.02 5 34 0.02 69 Irkut- 0.12 0.08 0.24 Tibelti 8 3 0.15 1.01 0.26 0.45 6 0.06 Olha-Olha 3 Kuda- - Granovschi 0.24 0.04 na 6 5 Harat- 0.00 0.02 0.00 0.00 Harat 469 57 7 45 Le na river basin Lena - 0.09 1.05 0.38 0.28 Kachug 5 0.12 9 5 2 Lena- 0.83 1.01 6.32 Zmeinova 6 5 9 7.71 9.97 4.12 1.31 4.3 0.02 Ilikta-Tarel 2 - - Manzurka- 0.02 0.12 0.00 Zuevo 0.01 6 -0.17 4 34 Kuta- - - Maksimov 0.04 0.40 0.15 o 1 -1.74 7 4 Taura - - - - Taura 0.06 0.05 0.22 0.09 8 8 9 5 Kirenga- Shorochov 0.71 0.48 - a 1 5 6.29 2.35 1.68 0.85 Vitim -Ust - Zaza (till 0.52 0.07 2012) 1.61 2.04 7 4 0.01 Vitim- Kalakan (till 2012) China - Troitski 0.23 0.21 0.02 0.05 (till 2012) 0.189 6 1 69 7 Zaza-Ust- - Zaza (till 0.27 0.00 2012) 0.061 8 52 Umurchen - - Umurchtn( 0.04 0.09 0.00 till 2012) 4 0.596 98 72 Kalakan- Kalakan (till 2012) Tsipa -Uiu - 0.26 0.09 (till 2012) 1.88 2 2 Lake Baikal basin Verch Angara- 0.20 0.26 0.56 - 0.84 Zaimka 4 4 0.41 2 2.78 1.85 1.96 1.84 7 0.29 0.66

Bargizin- 0.27 0.22 0.12 0.71 0.96 Barguzin 3 1 0 2 9

Turka- 0.33 0.38 0.39 0.58 0.25 0.30 0.25 Sobolicha 8 5 6 3 2 3 4 0.26 Maksimich a- - - - - Maksimich 0.00 0.00 0.00 0.01 0.00 a 39 32 35 0.003 3 26 - - - - Itansa- 0.01 0.26 0.11 - 0.00 0.00 Turuntaevo 4 5 -0.095 0.12 6 0.099 21 48 - - B.Suchaya- 0.00 0.00 0.01 Suchaya 654 689 06 - - - Selenga- 7.78 - - - 1.22 0.26 - Mostovoi -10.89 5 15.9 17.2 16.05 -6.80 8 1 6.42 ------Pohabiha- 0.00 0.00 0.00 0.01 0.01 0.012 0.00 0.00 Sludianka 4 4 25 28 8 9 59 65 Bolshaya------Pokrovsko 0.00 0.00 0.00 0.00 - 0.03 0.03 0.03 0.03 0.03 0.02 e 62 42 44 96 0.0034 2 9 0 6 28 2 B.Rechka- - - Posolskoe 0.19 0.087 Snegnaya - - Vidrino 0.14 0.87 0.26 Hara- Murin- 0.01 0.04 - Murino 95 0.03 6 0.52 negative statistical significant trends* positive statistical significant trends * statistical significant trends < 0.05 Within the Angara and Upper Lena basins annual run-off changes were directed differently and were not generally statistically significant. A statistically significant positive tendency was observed here on most of the gauging stations considered in the cold season (from October to March–April). Within the Upper Lena river basin, a tendency for run-off reduction in May, Jun and July was observed. At the same time within Vitim River basin a tendency for run-off increasing in May was observed. Within the Angara basins the statistically significant negative tendency of spring snow melts and summer rain fall maxima was predominate (Table 2). At the same time within Upper Lena basin the statistically significant positive tendency of spring snow melts and summer rain fall maxima was predominate in some rivers.

Within the Lake Baikal basin annual run-off changes were directed differently and were statistically significant in some cases. In the north of Lake Baikal basin a statistically significant positive tendency was observed in the cold season (from October to March–April). At the same time within central and southern of Lake Baikal basin a tendency for run-off reduction was predominate for most of months. This is in accordance with the results obtained by the integral difference curves—now here marked low water period. Table 2. Statistically significant trends of run off maxima for period 1961-2014. River - Station Snow melt maxima Rain fall maxima Angara river basin Irkut-Mondi -1.296 Irkut-Tibelti -13.09 Kuda-Granovschina -0.964 Murin-Zagatui -0.137 Haita-Haita -0.304 Ida-Morozova -0.53 Zima-Zulumai -0.811 Kadui-Kadui 0.317 Lena River basin Manzurka-Zuevo 0,25 Kupa-Muka -4,99 Vitim-Kalakan 19,2 China-Troitski 0,71 Zaza-Ust-Zaza 0,12 Umurchen-Umurchtn 3,80 Bagdarin-Bagdarin 0,30

Summary The increase in air temperature is mainly due to the winter months leads to intra annual redistribution of river flow. The majority of statistically significant trends of river run off are observed during the cold period of year. Hence, there emerge more favorable (compared with the mid-20th century) heat balance conditions for flow during the winter and summer–autumn low water period. Winter run-off is determined first of all by underground power. It is possible to assume, that now in the Baykal region during the milder winters, the share of underground power increases because of the lower freezing and earlier thawing of the soil.

References [1] Georgievsky VY, Shiklomanov I. Climate change and water resources. In World Water Resources at the Beginning of the 21st Century, Cambridge University Press, 390–413, (2003). [2] Assessment Report on Climate Change and its Consequences in the Russian Federation, ROSHYDROMET, Moscow, 2008 (in Russian). [3] Groisman PY. Trends in intense precipitation in the climate record, Journal of Climate 18, 1326–1350, (2005). [4] Kundzewicz ZW. Climate change and floods, Bulletin of WMO, July 2006, (2006). [5] Voropay NN, Maksyutova EV, Balybina AS. Contemporary Climatic Changes in the Predbaikalie Region, IOP Publishing Environ, 6 045209, (2011) 19-23. [6] IPCC. Summary for policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change, Cambridge University Press; 1-19, (2012). [7] Semenov VA. Surface Water Resources of the Mountains of Russia and Neighboring Territories, RIO Gorno-Altaisk. un-ta, Gorno-Altaisk, 2007. (in Russian).