Moraine-dammed glacial lakes and threat of glacial debris flows in South-East Kazakhstan

Glacier retreat has caused the emergence of numerous moraine-dammed glacial lakes (MGL) over the last century which have become research foci in many mountain regions of the world. Outbursts of MGLs have caused destructive floods and debris flows, leading to numerous human casualties and significant material damage. The mountains of South-Eastern Kazakhstan have also become prone to lake outburst floods and related debris flows, specifically in the second half of the 20th century. This paper presents and reviews existing surveys and knowledge along with results of own investigations on the formation of MGLs and the characteristics of lake outburst floods and debris flows in the Kazakh part of Tien Shan. We suggest a workflow to identify the most dangerous types of lakes and provide information about their morphogenetic features and hazard criteria. The number of MGLs increased since the 1970s with more than 160 existing in 2018. Forty were identified as being dangerous. Forty-eight lake outbursts occurred since 1950 with all the documented events happened between end of June and end of August. The most dangerous outbursts were caused by ruptures in ice-cored moraine dams. Outbursts of nine MGLs caused disastrous debris flows, with some occurring repeatedly. The number of outbursts clearly decreased since the year 2000 compared to 1970–2000. However, due to ongoing glacier retreat new lakes are forming at higher altitudes. Their greater potential energy makes possible future outbursts more dangerous. Re-evaluation of existing methods to calculate the water volume and peak discharge based on bathymetric measurements and observed outbursts revealed that the applied equations provide suitable approximations and allow supporting mitigation and prevention measures. Finally, the presentation of implemented measures to lower the water level using siphons or artificial flow channels shows that they can reduce the lake outburst hazards. However, they are associated with risks and financial costs and it needs to be carefully considered whether protection measures of the endangered areas are more cost effective.Publisher PDFPeer reviewe

Assessment of evolution and risks of glacier lake outbursts in the Djungarskiy Alatau, Central Asia, using Landsat imagery and glacier bed topography modelling

Changes in the abundance and area of mountain lakes in the Djungarskiy (Jetysu) Alatau between 2002 and 2014 were investigated using Landsat imagery. The number of lakes increased by 6.2 % from 599 to 636 with a growth rate of 0.51 % a−1. The combined areas were 16.26 ± 0.85 to 17.35 ± 0.92 km2 respectively and the overall change was within the uncertainty of measurements. Fifty lakes, whose potential outburst can damage existing infrastructure, were identified. The glacier bed topography version 2 (GlabTop2) model was applied to simulate ice thickness and subglacial topography using glacier outlines for 2000 and SRTM DEM (Shuttle Radar Topography Mission digital elevation model) as input data achieving realistic patterns of ice thickness. A total of 513 overdeepenings in the modelled glacier beds, presenting potential sites for the development of lakes, were identified with a combined area of 14.7 km2. Morphometric parameters of the modelled overdeepenings were close to those of the existing lakes. A comparison of locations of the overdeepenings and newly formed lakes in the areas de-glacierized in 2000–2014 showed that 67 % of the lakes developed at the sites of the overdeepenings. The rates of increase in areas of new lakes correlated with areas of modelled overdeepenings. Locations where hazardous lakes may develop in the future were identified. The GlabTop2 approach is shown to be a useful tool in hazard management providing data on the potential evolution of future lakes

О влиянии гляциологических и гидрометеорологических условий на гляциальную опасность Заилийского Алатау

A need to estimate a hazard of a mudflow stream appearance in the glacial-nival zone of the Northern slope of Zailiyskiy Alatau (Kasakhstan) is now one of the really urgent problems. The objective of this study was to inves‑ tigate influence of glacial and hydrometeorological factors on the condition of snow-glacial zone of Zailiyskiy Alatau and find out a mudflow-forming role of the mudflow centers arising due to climate warming and degra‑ dation of glaciation: periglacial lakes, intramoraine channels and reservoirs, and also talik massifs of morainic deposits. We analyzed glacial processes in the Zailiysky Alatau over a long period using meteorological data of the Almaty weather station and its close correlations with data from weather stations in the mountains. The area of glaciations was found out to be reduced after the maximum of the Little Ice Age. A combined diagram of occurrence of the mudflow manifestations and factors causing them had been constructed on the basis of sta‑ tistical data on the landslide phenomena. Glacial mudflows were the most frequent in 1960–1990, and later on activity of them became weaker. We believe, that in the next 10–20 years, the glacial mudflow hazard in Zailiys‑ kiy Alatau can sharply decrease, but at the same time, a probability of occurrence of the rainfall mudflows can increase in the mountainous zone of the ridge due the increase of areas with melted moraine and slope deposits.Для территории северного склона хр.  Заилийский Алатау (Тянь-Шань) по натурным данным за 100-летний период исследованы изменения климата, характер деградации оледенения и динамика возникновения опасных гляциогидрологических явлений. Указанные явления опосредованно связаны с изменением климата и представляют собой следствие развития моренно-ледниковых комплексов до их опасного состояния при деградации оледенения. Такое состояние моренно-ледниковых комплексов было характерно для периода деградации оледенения в 1960–2000 гг., когда оно сократилось на 55–80% после максимума малого ледникового периода. В  настоящее время опасность гляциальной зоны Заилийского Алатау находится на спаде

Гляциальные сели в Заилийском Алатау за последние 120 лет

Zailiyskiy Alatau is the most mudflow hazardous mountain region of the Republic of Kazakhstan. At the same time, this area is one of the most densely populated and economically developed one, so mudflows here cause the great damage. The paper presents results of our analysis of the glacial mudflow activity for the period from 1900 to 2019. Amount and total volume of glacial mudflows per year were used as indicators of the mudflow activity. 481 mudflows were recorded over 120 years of observations in the Zailiyskiy Alatau, and 24% of them were glacial mudflows. Glacial mudflows are the largest and most destructive. Of the nine mudflows with a volume of more than 1 million m3, seven were glacial mudflows. The chronicle of mudflow disasters is shown. From 1950 to 2019, 87 glacial mudflows were observed in the Zailiyskiy Alatau. Of these, 16 mudflows had volumes exceeding 100 thousand m3. The largest ones occurred in 1977 (6.0 million m3), 1963 (5.8 million m3), 1958 (4.0 million m3), and 1973 (3.8 million m3 ). The causes for formation of glacial mudflows are outbursts of moraine lakes or water from underground reservoirs, as well as collapses of moraines’ slopes. The largest of them occur when a lake is bursting through an open channel. Since 1951, occurrence of glacial mudflows has been increasing and reached its maximum in the 1970s. Since 1978, the number of glacial mudflows has been decreasing, although their volumes remained large until the late 1990s. From 1997 to 2013, mudflow activity was low. During 11 of the 15 years, no mudflow was observed. Every year only one mudflow happened with a volume below 10 thousand m3. Since 2014, there has been a tendency for an increase in mudflow activity. Large glacial mudflows were recorded in 2014 and 2019. To protect against mudflows in the valleys of the Zailiysky Alatau, 14 dams have been built and two more are planned. To prevent outbursts of moraine lakes, they are emptied using pumps and siphons. In 2019, the network of automated monitoring of early warning about mudflows is being organized, which will cover all the valleys of the Northern slope of the Zailiysky Alatau.Проанализированы данные о гляциальных, в том числе катастрофических, селях с 1900 по 2019 г., рассмотрены внутри- и межгодовые колебания селевой активности. С  1951  г. активность гляциальных селей стала расти и достигла максимума в 1970-х годах, с 1978 по 1996 г. активность таких селей снижалась, а с 1997 по 2013 г. была низкой. С 2014 г. наметилась тенденция усиления активности гляциальных селей

Glacial lakes in the Horgos river basin and their outbreak risk assessment

The river Khorgos (in Kazakhstan – Korgas) is a boundary river between Kazakhstan and China. Its basin is located in the central part of southern slope of Dzhungarskiy (Zhetysu) Alatau range. According to agreement between Kazakhstan and China at the boundary transition of Khorgos in the floodplain of the river Khorgos the large Center of Frontier Cooperation is erected. Estimation of safety of the mentioned object including connection with possible glacial lakes outbursts has the importance of political-economical value. Nowadays development of glacial lakes in the overhead part of Khorgos river basin has reached apogee. As a roof we can mention the maximum of total glacial lakes area (1,7 million m² in 41 lakes) and emptied kettles of former glacial lakes. Six lakes reached highly dangerous outburst stage: the volume of lakes reached some million m³, maximum depth up to 30–40 m. Focal ground filtration of the water from lakes takes place. Development of glacial lakes in Khorgos river basin will continue, and these lakes give and will give real danger for the Center of Frontier Cooperation in case of outburst of naturally dammed lake Kazankol with the similar mechanism of Issyk lake outburst, occurred in 1963 in ZailijskiyAlatau (Ile Alatau)

Effects of glaciological and hydro-meteorological conditions on the glacial danger in Zailiyskiy Alatau

A need to estimate a hazard of a mudflow stream appearance in the glacial-nival zone of the Northern slope of Zailiyskiy Alatau (Kasakhstan) is now one of the really urgent problems. The objective of this study was to inves‑ tigate influence of glacial and hydrometeorological factors on the condition of snow-glacial zone of Zailiyskiy Alatau and find out a mudflow-forming role of the mudflow centers arising due to climate warming and degra‑ dation of glaciation: periglacial lakes, intramoraine channels and reservoirs, and also talik massifs of morainic deposits. We analyzed glacial processes in the Zailiysky Alatau over a long period using meteorological data of the Almaty weather station and its close correlations with data from weather stations in the mountains. The area of glaciations was found out to be reduced after the maximum of the Little Ice Age. A combined diagram of occurrence of the mudflow manifestations and factors causing them had been constructed on the basis of sta‑ tistical data on the landslide phenomena. Glacial mudflows were the most frequent in 1960–1990, and later on activity of them became weaker. We believe, that in the next 10–20 years, the glacial mudflow hazard in Zailiys‑ kiy Alatau can sharply decrease, but at the same time, a probability of occurrence of the rainfall mudflows can increase in the mountainous zone of the ridge due the increase of areas with melted moraine and slope deposits

Glacial debris flows in Zailiysky Alatau over the past 120 years

Zailiyskiy Alatau is the most mudflow hazardous mountain region of the Republic of Kazakhstan. At the same time, this area is one of the most densely populated and economically developed one, so mudflows here cause the great damage. The paper presents results of our analysis of the glacial mudflow activity for the period from 1900 to 2019. Amount and total volume of glacial mudflows per year were used as indicators of the mudflow activity. 481 mudflows were recorded over 120 years of observations in the Zailiyskiy Alatau, and 24% of them were glacial mudflows. Glacial mudflows are the largest and most destructive. Of the nine mudflows with a volume of more than 1 million m3, seven were glacial mudflows. The chronicle of mudflow disasters is shown. From 1950 to 2019, 87 glacial mudflows were observed in the Zailiyskiy Alatau. Of these, 16 mudflows had volumes exceeding 100 thousand m3. The largest ones occurred in 1977 (6.0 million m3), 1963 (5.8 million m3), 1958 (4.0 million m3), and 1973 (3.8 million m3 ). The causes for formation of glacial mudflows are outbursts of moraine lakes or water from underground reservoirs, as well as collapses of moraines’ slopes. The largest of them occur when a lake is bursting through an open channel. Since 1951, occurrence of glacial mudflows has been increasing and reached its maximum in the 1970s. Since 1978, the number of glacial mudflows has been decreasing, although their volumes remained large until the late 1990s. From 1997 to 2013, mudflow activity was low. During 11 of the 15 years, no mudflow was observed. Every year only one mudflow happened with a volume below 10 thousand m3. Since 2014, there has been a tendency for an increase in mudflow activity. Large glacial mudflows were recorded in 2014 and 2019. To protect against mudflows in the valleys of the Zailiysky Alatau, 14 dams have been built and two more are planned. To prevent outbursts of moraine lakes, they are emptied using pumps and siphons. In 2019, the network of automated monitoring of early warning about mudflows is being organized, which will cover all the valleys of the Northern slope of the Zailiysky Alatau

Гляциальные озёра бассейна реки Хоргос и оценка опасности их прорывов

The river Khorgos (in Kazakhstan – Korgas) is a boundary river between Kazakhstan and China. Its basin is located in the central part of southern slope of Dzhungarskiy (Zhetysu) Alatau range. According to agreement between Kazakhstan and China at the boundary transition of Khorgos in the floodplain of the river Khorgos the large Center of Frontier Cooperation is erected. Estimation of safety of the mentioned object including connection with possible glacial lakes outbursts has the importance of political-economical value. Nowadays development of glacial lakes in the overhead part of Khorgos river basin has reached apogee. As a roof we can mention the maximum of total glacial lakes area (1,7 million m² in 41 lakes) and emptied kettles of former glacial lakes. Six lakes reached highly dangerous outburst stage: the volume of lakes reached some million m³, maximum depth up to 30–40 m. Focal ground filtration of the water from lakes takes place. Development of glacial lakes in Khorgos river basin will continue, and these lakes give and will give real danger for the Center of Frontier Cooperation in case of outburst of naturally dammed lake Kazankol with the similar mechanism of Issyk lake outburst, occurred in 1963 in ZailijskiyAlatau (Ile Alatau).Река Хоргос (в Казахстане – Коргас) – пограничная между Казахстаном и КНР. Её бассейн расположен в центральной части южного склона хр. Джунгарский (в Казахстане – Жетысу) Алатау. По соглашению между Казахстаном и КНР на пограничном переходе Хоргос, в пойме р. Хоргос, создаётся крупный Центр приграничного сотрудничества. Оценка безопасности данного объекта, в том числе и в связи с возможными прорывами гляциальных озёр, имеет важное политическое и экономическое значение. В настоящее время состояние гляциальных озёр в верхней части бассейна р. Хоргос достигло апогея. Это подтверждаетcя наличием огромной суммарной площади гляциальных озёр (1,7 млн м2 в 41 озере) и «отработанных» чаш бывших гляциальных озёр. Шесть озёр достигли особо опасной прорывной стадии – их объёмы составляют несколько миллионов кубических метров, а максимальные глубины – 30–40 м. Развитие гляциальных озёр в бассейне р. Хоргос, вероятно, ещё будет продолжаться, поэтому и сейчас, и в дальнейшем они представляют собой реальную угрозу для Центра приграничного сотрудничества в случае «наведённого» прорыва завального оз. Казанколь по механизму, аналогичному прорыву завального оз. Иссык, про­изошедшему в 1963 г. в Заилийском (Иле) Алатау.