10 research outputs found
The water level regime of periglacial lakes during the growth stage (the lakes of the Tavan-Bogdo-Ola mountain massif, South-Eastern Altai)
Get PDFAssessment of the dynamics of high-altitude glacial lakes is becoming increasingly important in the context of modern climate instability. The formation of new periglacial lakes and the growth of existing lakes as a result of the reduction of glaciers are recorded almost all over the world, including Russia. A rapid increase of a periglacial lake size may lead to the formation of an outburst flood. In this context, in order to prevent outburst floods, it is necessary to investigate outburst hazard lakes at all stages of their development. The periglacial lakes of the Altai mountains have been little-studied in comparison with other mountainous areas. At the same time, they are also characterized by the formation of new lakes during the period of climate nonstationarity. It was confirmed by the identified statistically significant trends in average monthly air temperatures during the ablation period. Based on the analysis of multi-temporal satellite images, it was found that the number of new periglacial lakes in the high-altitude territories of the Altai Republic (Katunsky ridge, North-Chuya ridge, South-Chuya ridge and the Tavan-Bogdo-Ola mountain massif) is increasing exponentially. For a more detailed survey and field hydrological studies, the authors chose the recently formed periglacial Lake Barsovo and periglacial Lake Gachi-Kol. Both lakes located within the northen slope of the Tavan-Bogdo-Ola mountain massif. Field observations, which were carried out in July-August 2021, have shown that both lakes are currently at the transgressive stage of development (growth stage). The transgressive phase of the lakes development is characterized by a rapid increase in size by the end of the warm period and a complex level regime on both diurnal and annual scales, due to the fact that both lakes are adjacent to the glacier
Characteristics of the hydrological regime of the periglacial moraine lakes in the Altai
No full textIn the last decade glaciers of Inner Asia have been shrinking with acceleration, and the number of glacial lakes has been growing significantly, including those with a high probability of outburst and high-water discharge. The hydrological regime of lakes in the Altai is understudied in comparison with lakes in other high mountain countries. The article is based on our extensive field material on hydrological and morphometric characteristics of moraine lakes collected in the Russian and Mongolian parts of the Altai Mountains and combined with the Earth remote sensing data. We have proposed detailed indicators (criteria) of transgressive, regressive and post-regressive stages of lake development. It allows allow to determine at a qualitative level at what stage a lake is at and to assess its further development. The characteristics of hydrological regime of Altai lakes at different stages of development are described for the first time. Based on the criteria proposed, the classification of glacial and moraine lakes in the Altai high mountains was carried out. It shows that at present most of the lakes are in the transgressive stage. Over the last 22 years, the number of lakes has increased significantly: on the territory of the North Chuya Ridge – from 28 to 60, on the South Chuya Ridge – from 39 to 73, on the Katun Ridge – from 57 to 89, on the territory of the Tavan-Bogdo-Ola massif – from 11 to 19, and on the territory of the Mongun-Taiga massif – from 8 to 11 lakes
The outburst of dammed lake Maashey (North-Chuya ridge, Central Altai)
No full textThe dammed lakes are widespread in mountainous areas and usually occur when river flow is blocked by landslides, rock glaciers, etc. Among such lakes, the most dangerous are those located in the periglacial zone and blocked by rock glaciers. Continued deglaciation of mountainous areas under changing climate conditions contributes to accumulation of large volumes of melt water in lakes, which may increase pressure on the dam, cause its failure and subsequent outburst flood. In this article we describe the development of such a lake before its outburst and the process of its outburst. The object of study was Maashei Lake (North Chuya Ridge, Central Altai) located in the zone of mountain glaciation and dammed by a rock glacier, where the lake outburst occurred in July 2012. The lake area before the outburst was 259 × 103 m2 and water volume 1.21 × 106 m3. As a result of the outburst, the lake was completely drained. We analyzed the published works on Lake Maashei, materials of our own field studies in the lake basin combined with remote sensing data. We hypothesized that the mechanism of the outburst occurred in 2012 was caused by the water erosion of the filtration channel in the dam body. The mechanism of this outburst was numerically simulated using the method presented in this article. The modeling allowed to reproduce the outburst flood hydrograph, to estimate such characteristics as maximum water discharge, volume of the outburst flood, water flow velocities and the size of the formed breach. Estimated maximum discharge was 694 m3s−1, flow velocities varied from 0.2 to 5-7 m s−1, and the outburst flood period was about 5.5 hours. The breach was formed to the full height of the dam (10 m). Its calculated morphometric characteristics were as follows: average width 47.5 m (measured 41.5m), скоss-section area 476 m2 (measured 415 m2). The discrepancy between the modeled and measured values was about 15 %
The Use of Isotope Indicators in Hydrological Studies in the Taldura River Basin, Central Altai
No full textStable isotopes investigation was carried out in the territory of the Yuzhno-Chuya Ridge (Central Altai) during the ablation season of 2022. Samples were taken to determine the contribution of meltwater and precipitation to feeding of water bodies. The main research objects are Nekrasov glacier – Tamozennoye Lake system and Taldura River. In the basin of Lake Tamozennoye, the average ice δ18O of the Nekrasov glacier (‒17.3%) was obtained. Based on the isotopic composition of ice and precipitation, it was estimated that in the stream flowing into Lake Customs, the contribution of glacier meltwater varies from 28 to 67%, on average 54%. For a stream flowing out of a lake, the proportion of meltwater is higher: 48–72, 61% on average. First of all, meltwater enters the lake by filtration through the moraine, and not by surface runoff. Along the Taldura River, δ18O does not change significantly (δ18O –16.58 … –16.84%) for 38 km before the Taldura River confluence into the Chagan River. This indicates the complete predominance of glacier meltwater in the river feeding in the middle of the ablation season. Repeated sampling of water from the Taldura River 5 km from the edge of the glacier showed, that the effect of precipitation can be traced in the isotopic composition of river water, but it does not exceed 20%
Shrinking of the glaciers of East Altai (Shapshal Center) after the maximum of the Little Ice Age
Get PDFBased on the analysis of remote data and field observations, we reconstructed the glaciation of the Shapshal Center (Eastern Altai) for the maximum of the Little Ice Age (LIA) and by the state of the glaciers as of 2001. At the maximum of the LIA, glaciation was represented by 358 glaciers with a total area of 84.43 km2. It was found 87% reduction of the total area of glaciers in the interval from the LIA maximum to 2015. During the reduction, valley glaciers disintegrated and glaciers in the Kargy River basin disappeared. The moraines of the LIA have low lake coverage (0.17% of area), therefore a probability of their breakthrough is low. We obtained data on the retreat of the Mushtuk Glacier (№ 78), the largest one of the Shapshal center, in five time slices from the LIA maximum. The highest retreat rates were reconstructed in the interval 1989–2001, but in the interval 2010–2016 the average rates decreased to 5 m/year. Changes in the mass balance index of the Mushtuk Glacier between from 1961 to 2018 were calculated. A sharp decrease in the mass balance in the 1990s and stabilization of values at a low level after 2001 were found. According to the calculations, the response time of the Mushtuk Glacier was about 9 years. If the current climatic conditions persist, there is reason to assume stabilization of glaciers in the coming years
The state of the Shapshalsky glacierization center (Eastern Altai) in 2015
Get PDFCatalogues and maps of glaciers (for 2015) of Shapshal Glacier Center, located in the eastern part of the Russian Altai, have been created based on the first field glaciological observations and space images interpretation. In total 123 glaciers with the total area of 14.07 km2 have been allocated. In comparison with the data from the Glacier Inventory of the USSR (1955–1965), the total area of the glaciers has decreased by more than 2 times. The lower limit of glacier development is 2475 m, to the south-east of the region it rises by 1 km, the height of the firm line rises from 2860 m to 3460 m, respectively. Small glaciers prevail (70% of glaciers have an area less than 0.1 km2, the area of the largest glacier is 0.9 km2). In terms of quantity and area, cirque glaciers predominate, there are no valley glaciers. The largest numbers of glaciers have northern and northeastern exposure, with the largest areas of glaciers concentrated on the north-eastern slopes. The highest glaciation intensity has been detected on the eastern slope of the Skalistiy Ridge and the northeastern slope of the southern part of the Shapshalsky Ridge in the upper reaches of the Chon-Khem River, which are optimal for glaciers by a combination of mountain heights and position relative to moisture-bearing atmospheric flows. To the west of these areas, intensity of glacierization decreases due to lower mountain heights, to the east – due to lower precipitation. In general, with low (0.1 km−1 and less) intensity of glacierization, the Shapshal Centre is an area of dispersed glaciation, most glaciers of which are on the verge of disappearance
Reduction of glaciers of the South Chuya Range (Altai) since the maximum of the Little Ice Age
No full textThe extent of glaciation of the South Chuya Range in the LIA and the analysis of its subsequent gradual reduction were assessed. Based on interpretation of Corona, Landsat-7, Sentinel-2, World View-3 satellite images and analysis of field data, the reconstruction and cataloging of glaciers for the LIA maximum, for 1962 and 2000/21 were carried out. For each time slice, the morphology of glaciers, their altitudinal and aspect distribution were analyzed, and the changes that occurred in the glaciation pattern were revealed. The range area covered by glaciers at LIA maximum is estimated as 313.19 km2. The estimate of the glacier area for 1962 is approximately 11 km2 higher than given in the USSR Glacier Inventory. Higher rates of glacier shrinkage after the LIA maximum were identified (61% of area and 59–64% of volume) than in earlier estimates by other authors (21%). The lower limit of glacier extent shifted upward by 300 m, and the altitudinal maximum of ice distribution – by 100 m. Glacier retreat accelerated at each successive stage, reaching in 2000/21 an average rate of about 1.5% per year of their area at the beginning of this last stage. Differences in the distribution of glaciers by their aspect have increased. At the last stages of glacier retreat there was an accelerated degradation of glacier tongues and disintegration of complex valley glaciers into simple valley and cirque-valley glaciers (Bolshoi Taldurinsky, Sofiysky glaciers)
Особенности уровенного режима приледниковых моренно-подпрудных озёр в стадии роста (на примере озёр горного массива Таван-Богдо-Ола, Юго-Восточный Алтай)
Get PDFAssessment of the dynamics of high-altitude glacial lakes is becoming increasingly important in the context of modern climate instability. The formation of new periglacial lakes and the growth of existing lakes as a result of the reduction of glaciers are recorded almost all over the world, including Russia. A rapid increase of a periglacial lake size may lead to the formation of an outburst flood. In this context, in order to prevent outburst floods, it is necessary to investigate outburst hazard lakes at all stages of their development. The periglacial lakes of the Altai mountains have been little-studied in comparison with other mountainous areas. At the same time, they are also characterized by the formation of new lakes during the period of climate nonstationarity. It was confirmed by the identified statistically significant trends in average monthly air temperatures during the ablation period. Based on the analysis of multi-temporal satellite images, it was found that the number of new periglacial lakes in the high-altitude territories of the Altai Republic (Katunsky ridge, North-Chuya ridge, South-Chuya ridge and the Tavan-Bogdo-Ola mountain massif) is increasing exponentially. For a more detailed survey and field hydrological studies, the authors chose the recently formed periglacial Lake Barsovo and periglacial Lake Gachi-Kol. Both lakes located within the northen slope of the Tavan-Bogdo-Ola mountain massif. Field observations, which were carried out in July-August 2021, have shown that both lakes are currently at the transgressive stage of development (growth stage). The transgressive phase of the lakes development is characterized by a rapid increase in size by the end of the warm period and a complex level regime on both diurnal and annual scales, due to the fact that both lakes are adjacent to the glacier.На основе анализа изменчивости гидролого-морфометрических характеристик озёр с применением спутниковых изображений и данных полевых гидрологических наблюдений, выполненных авторами в июле – августе 2021 г., описаны особенности гидрологического режима двух приледниковых озёр с трансгрессивной фазой развития, расположенных на территории горного массива Таван-Богдо-Ола (Республика Алтай)
Сокращение ледников Восточного Алтая (Шапшальский центр) после максимума малого ледникового периода
Get PDFBased on the analysis of remote data and field observations, we reconstructed the glaciation of the Shapshal Center (Eastern Altai) for the maximum of the Little Ice Age (LIA) and by the state of the glaciers as of 2001. At the maximum of the LIA, glaciation was represented by 358 glaciers with a total area of 84.43 km2. It was found 87% reduction of the total area of glaciers in the interval from the LIA maximum to 2015. During the reduction, valley glaciers disintegrated and glaciers in the Kargy River basin disappeared. The moraines of the LIA have low lake coverage (0.17% of area), therefore a probability of their breakthrough is low. We obtained data on the retreat of the Mushtuk Glacier (№ 78), the largest one of the Shapshal center, in five time slices from the LIA maximum. The highest retreat rates were reconstructed in the interval 1989–2001, but in the interval 2010–2016 the average rates decreased to 5 m/year. Changes in the mass balance index of the Mushtuk Glacier between from 1961 to 2018 were calculated. A sharp decrease in the mass balance in the 1990s and stabilization of values at a low level after 2001 were found. According to the calculations, the response time of the Mushtuk Glacier was about 9 years. If the current climatic conditions persist, there is reason to assume stabilization of glaciers in the coming years.Реконструированы ледники малоисследованного Шапшальского центра оледенения на Восточном Алтае в максимум малого ледникового периода, проанализирован характер их последующего сокращения. Детально рассмотрено сокращение крупнейшего ледника Шапшальского хребта по пяти временным срезам c 1955 по 2019 г. Проведены расчёты индекса баланса массы ледника и времени его климатического отклика
Состояние Шапшальского центра оледенения (Восточный Алтай) в 2015 году
Get PDFCatalogues and maps of glaciers (for 2015) of Shapshal Glacier Center, located in the eastern part of the Russian Altai, have been created based on the first field glaciological observations and space images interpretation. In total 123 glaciers with the total area of 14.07 km2 have been allocated. In comparison with the data from the Glacier Inventory of the USSR (1955–1965), the total area of the glaciers has decreased by more than 2 times. The lower limit of glacier development is 2475 m, to the south-east of the region it rises by 1 km, the height of the firm line rises from 2860 m to 3460 m, respectively. Small glaciers prevail (70% of glaciers have an area less than 0.1 km2, the area of the largest glacier is 0.9 km2). In terms of quantity and area, cirque glaciers predominate, there are no valley glaciers. The largest numbers of glaciers have northern and northeastern exposure, with the largest areas of glaciers concentrated on the north-eastern slopes. The highest glaciation intensity has been detected on the eastern slope of the Skalistiy Ridge and the northeastern slope of the southern part of the Shapshalsky Ridge in the upper reaches of the Chon-Khem River, which are optimal for glaciers by a combination of mountain heights and position relative to moisture-bearing atmospheric flows. To the west of these areas, intensity of glacierization decreases due to lower mountain heights, to the east – due to lower precipitation. In general, with low (0.1 km−1 and less) intensity of glacierization, the Shapshal Centre is an area of dispersed glaciation, most glaciers of which are on the verge of disappearance.Получены новые карты и каталог ледников мало исследованного Шапшальского центра оледенения на Восточном Алтае. По состоянию на 2015 г. здесь насчитывалось 123 ледника суммарной площадью 14,07 км2. По сравнению с данными 1955–1965 гг. суммарная площадь ледников сократилась более чем вдвое. Преобладают малые каровые ледники северо-восточной и северной экспозиций. Площади ледников и интенсивность оледенения убывают с северо-запада на юго-восток
