Debris Flows of the Tunkinsky Goltsy Mountains (Tunkinsky District, Republic of Buryatia in Eastern Siberia)

International Journal of IJGE 2016 2(3): 166-179 Geohazards and Environmen t http://ijge.camdemia.ca, [email protected] Available at http://ojs.library.dal.ca/ijge Technical Notes Debris Flows of the Tunkinsky Goltsy Mountains (Tunkinsky District, Republic of Buryatia in Eastern Siberia) Stanislav Makarov 1*, Anna Cherkashina 1, Zhanna Atutova 1, Aleksandr Bardash 1, Nadezhda Voropai 1, Natalija Kichigina 1, Boris Mutin 1, Olga Osipova 1, Natalija Ukhova 2 1V.B. Sochava Institute of Geography, SB RAS, 1 Ulan-Bator Street, Irkutsk, Russia 664033 2Institute of the Earth’s Crust, SB RAS, 128 Lermontova Street, Irkutsk, Russia 664033 Abstract : On the night of June 28, 2014, near the village of Arshan in Tunkinsky district, Republic of Buryatia in eastern Siberia, two types of debris flows were formed as a result of intense storm precipitation: 1) debris floods along the river Kyngarga; 2) debris flows along the valleys originating from the cirques of the southern slope of the Tunkinsky Goltsy range, which went in the south-west direction towards the village. A year later, July 14, 2015, in the village of Arshan a debris flood occurred in the river Kyngarga. During the Holocene debris flows have occurred repeatedly, traces of which are seen in the sections of loose deposits. Their age was defined with the help of radiocarbon analysis of buried soil horizons. A historical analysis of debris flow activity on the territory for more than a century was made using published scientific works. Natural factors for the formation of debris flow situation were considered (synoptic and climatic conditions, hydrology, geology and landscape structure were evaluated). Reasons for the most recent debris flows were defined. A detailed analysis was given of the valleys of a number of rivers where results of debris flows were the most destructive. As a result of the debris flow along the river Kharimta, realignment of the river network took place. Consequences of debris flows for the natural environment and infrastructure of the village of Arshan were evaluated. It is considered that the partial destruction of the village of Arshan is a distinct possibility in the near future due to debris flows from cirque #1. Keywords : debris flow, soil avalanchings, kars (cirques), radiocarbon age, Holocene, Tunkinsky Goltsy Mountains, Arshan village 1 Introduction Sciences 1963 ). The methodological basis for the study of debris flows in the mountains south of The areas of intensive development of debris eastern Siberia was established by Astrakhantsev flows, the main factors of their formation and and Budz (1962) . distribution are presented in the articles of In recent decades, the study of debris flows Siberian scientists ( USSR Academy of Sciences has focused on the mechanisms of their formation 1963 , Astrakhantsev and Ivanov 1964 , in the conditions of intense torrential rainfall, in Astrakhantsev and Budz 1966 , Budz 1969 ). The particular with the use of instrumental most thorough study of debris flows.identified the measurements and modeling techniques geological, geomorphological and hydro- (Takahashi 1981 , Anderson and Sitar 1995 , meteorological factors and conditions of Iverson et al 1997 , Berti et al 1999 , Jakob and formation of debris flows ( USSR Academy of Hungr 2005 , Sassa аnd Wang 2005 , Gregoretti * Corresponding Author: Stanislav Makarov, email: [email protected] , Tel: +7 929 434 4589 Copyright © Canamaple Academia Services, http://press.camdemia.ca DOI: 10.15273/ijge.2016.03.016 166 Debris flows of the Tunkinsky Goltsy Mountains IJGE 2016 2(3): 166-179 and Fontana 2008 , McCoy et al 2010 ). 1340 MJ/m 2 (Belousov et al 2000 ). The territory is characterized by significant amplitude of Synoptic situation seasonal and daily fluctuations in air temperature Debris flows in the village of Arshan have with warm but short summer and cold winter with resulted from the contemporary atmospheric little snow. In summer, cyclonic weather prevails, circulation. To analyze the change in the nature of while in winter the action of the Siberian High general atmospheric circulation we used results in clear, windless and frosty weather. As classification of Northern Hemisphere early as in September mountains are covered by atmospheric circulation by Dzerdzeevsky`s snow which melts in June. Snow cover depth is method ( Dzerdzeevsky et al 1946 ). Classification usually less than 0.5 m over the valley. Closer to criteria are posted on the websites the forest boundary the depth is up to 1-1.5 m. http://igrankononova.narod.ru and www. Precipitation is distributed unevenly over the atmosphericcirculation.ru ( Kononova 2007 ). territory, both in area and in seasons of the year. Debris flow hazardous elementary circulation The great bulk of precipitation falls during the mechanisms (ECM) were ranked for mountain summer; the three summer months (June-August) systems ( Malneva and Kononova 2005 ). In account for up to 72%. Heavy and very heavy Arshan on July 16-17, 1962, and on June 27-28, precipitation has been increasing in Siberia 2014, and during the debris flood in the river during the past five decades ( Groisman and Kyngarga on July 13-14, 2015, the most Gutman 2012 ). hazardous synoptic conditions obtained. In all Location of the Arshan village in the these cases, synoptic conditions favorable for piedmont of the Tunkinsky Goltsy ridge convective cloudiness and heavy precipitation determines the formation of climatic conditions, over the study were: a) surface level diffused different from those that characterize climate of trough combined with upper-level low gradient the central part of the valley. According to the trough (up to 9 km); b) cold front; c) south data of long-term observations (1910-1997), cyclone from Mongolia; d) blocking ridge over temperature at the weather station Arshan (closed Trans-Baikal territory. The village of Arshan was in 1997) is 3-6 °C higher than in the central part centrally located in relation to low pressure of the basin in winter and 2-4 °C lower in the troughs, and heavy rainfall resulted. summer months ( Vasilenko and Voropai 2015 ). Unfortunately, due to the current lack of a Mean long-term annual precipitation in Arshan meteorological station in the village of Arshan, it village is around 480 mm, while at the weather is not possible to estimate, even approximately, station Tunka (center of the basin, 20 km to the the amount of precipitation on June 27-28, 2014, south from Arshan) it is 320 mm. Long-term and July 13-14, 2015. mean precipitation in Arshan was 89 mm in June, The last decade has been identified as an 141 mm in July, and 116 mm in August. The atmospheric circulation transition period in the following years: 1941, 1942, 1962, 1966 and Northern Hemisphere. This transition is 1971 in Arshan have monthly amounts, characterized by an increase in extreme significantly higher (by 250-340 mm) than the precipitation in different sectors of the Northern average. Daily precipitation amount in Arshan Hemisphere, including the territory of Russia, reached maximum in August 1941 – 98 mm, in which, in turn, is leading to an increase in August 1947 and July 1962 – 88 mm. The high flooding and related geohazards ( Kononova mountain areas at Tunkinsky Goltsy ridge have 2014 ). precipitation about two times higher compared to the Arshan station. In Tunka the daily 2 Climatic Conditions precipitation is much lower, for instance maximal daily precipitation for the observation period Climatic peculiarities of the Tunka Basin are (1888-2015) does not exceed 60 mm. The formed under the influence of lateral-zonal and previous debris flood on July 17-18, 1962, was altitudinal gradients. Radiation balance is around caused by abundant precipitation. The Arshan 167 IJGE 2016 2(3): 166-179 Makarov et al weather station recorded 176.6 mm during two are most often in July and August. The greatest days, while the Tunka station only 29.5 mm rises (up to 3-4 m) were observed in 1912, 1938, (Zonov 1962 ). 1941 and 1971 ( Surface Water Resources 1972 ). The greatest flow of significant rain flood of July 3 Hydrologic Characteristics of the River 26, 1971, defined by the flood marks (State Water Kyngarga Cadaster 1978 ) was 94.8 m3/s. According to rough estimates, on July 28, 2014 water level in The river Kyngarga runs from the southern slopes the river Kyngarga rose by 2.5-3 m, relative to of the Tunkinsky Goltsy at an altitude of 2260 m pre-flood level, average stream flow rate could be and flows into the river Tunka at the left, twelve 4.5-5.5 m3/s. Abundance of mud and stone kilometers from its mouth. The length of the river material in the river flow caused high destructive is 26 km. Area of catchment is 231 km 2 and potential of the flood. average slope is 5.95%. Average flow velocity changes from about 1.5 m/s in the upper part to 4 Geologic Aspects 0.02 m/s near the mouth. In the upper reaches of the river there are three waterfalls. The bottom of The southern slopes of the Tunkinsky Goltsy are the river-bed in the upper part is rocky, at the underlain by a 1-2.5 km East-West band, waterfalls composed of crystalline rocks, in the composed of Archaean – lower Proterozoic lower reaches it is of sand, gravel, and peat complex: gneisses, plagiogneisses, crystalline (Surface Water Resources 1972 ). On the left bank schists, and thin intercalated marbles ( Samburg of the river Kyngarga mostly ephemeral streams 1971 ). To the North, closer to the divide, are descend from the cirques. The main tributaries of intrusions formed by foliated paleogranites and the river Kyngarga are the rivers: Malyj Kharimta, gneiss-granites. Then there are strata of rocks Kharimta, and Ulyamkhai. On both sides of the (lower-middle-upper Proterozoic complexes), Kyngarga river valley there are a number of small, composed of limestone, gneisses, schists, and ephemeral channels.

Load more