scholarly journals Distribution and recent variations of supraglacial lakes on dendritic-type glaciers in the Khan Tengri-Tomur Mountains, Central Asia

2013 ◽  
Vol 7 (5) ◽  
pp. 4545-4584 ◽  
Author(s):  
Q. Liu ◽  
C. Mayer ◽  
S. Liu
Keyword(s):  
Central Asia ◽  
Air Temperature ◽  
Lake Area ◽  
Ice Melting ◽  
Glacial Lakes ◽  
Study Region ◽  
Supraglacial Lakes ◽  
The Mean ◽  
Area Limit ◽  
Upper Boundary

Abstract. Supraglacial lakes are widely distributed on glaciers in the Tomur-Khan Tengri Tianshan Mountains, Central Asia. The existence and development of supraglacial lakes play an important role in the ice melting processes and also in the storage and release of glacial melt water. Here we mapped the supraglacial lakes of eight typical debris-covered dendritic-type glaciers around the Tomur-Khan Tengri peaks based on 9 Landsat TM/ETM+ images acquired in the summers of 1990 until 2011. With a lower area limit of 3600 m2 for a conservative identification of glacial lakes, we mapped 775 supraglacial lakes and 38 marginal glacial lakes in total. Our results indicate that supraglacial lakes (area > 3600 m2) in the study region never develop beyond an elevation of about 3850 m a.s.l., 800 m lower than the maximum upper boundary of debris cover (4650 m a.s.l.). The area-elevation distribution shows that lakes are predominantly occured close to the altitude of 3250 m a.s.l., where the clean ice simultaneously disappears. The majority of the supraglacial lakes are found on the Tomur Glacier and the South Inylchek Glacier, two strongly debris-covered dendritic-type glaciers in the region. As for the multi-year variation of lake area, the summer total and mean areas of supraglacial lakes show some variability from 1990 and 2005 but increased noticeably between 2005 and 2011. The mean area of the mapped lakes reached a maximum in 2010. We found that the area of supraglacial lakes is positively correlated to the total precipitation in summer (July to September) but negatively correlated to the mean spring air temperature (April to June). Pre-summer air temperature fluctuations likely have a stronger impact on the different evolution processes of glacial drainage, evolving from unconnected to connected systems, which may lead to the drainage of larger supraglacial lakes and results in shrinkage of the total and mean lake area during the summer.

scholarly journals Spatially and Temporally Resolved Monitoring of Glacial Lake Changes in Alps During the Recent Two Decades

2021 ◽  
Vol 9 ◽  
Author(s):  
Jingsong Ma ◽  
Chunqiao Song ◽  
Yanjun Wang
Keyword(s):  
Glacial Lake ◽  
Water Volume ◽  
High Mountain ◽  
Lake Area ◽  
Glacial Lakes ◽  
Holistic View ◽  
Supraglacial Lakes ◽  
Different Types ◽  
The Alps ◽  
The Mean

Climate warming is intensifying the melting of glaciers and the growth of glacial lakes in the Alps, which has a profound impact on the management of water resources and high-mountain hydropower in this region. However, the research on the spatial distribution and temporal evolution of the Alps glacial lakes of various types still lacks a holistic view. In this study, we developed an inventory of Alps glacial lakes of different types and then obtained the annual areas of these lakes from 2000 to 2019 using JRC Global Surface Water and Global Land Analysis and Discovery data at a resolution of 30 m. A total of 498 glacial lakes (>0.01 km2) with the net area of 33.77 ± 6.94 km2 were identified in the Alps in 2019 and are mainly distributed in the western and central Alps. These Alps glacial lakes, with the area ranging 0.01–1.59 km2, are generally dominated by small-sized ones. The comparison of lakes of different types indicated that ice-uncontacted lakes are dominant in number and area, accounting for 59.4 and 58.4%, respectively. In terms of the elevation distribution, almost half of the lakes are concentrated at the altitude of 2,250–2,750 m (a.s.l.). Meanwhile, the mean altitude of small glacial lakes is higher than that of large lakes. The distribution of ice-contacted lakes and supraglacial lakes were more concentrated, and the mean altitude was higher. During the study period, the number, area, and water volume of glacial lakes were increasing, but the expansion varied between different periods. The changing trends of the glacial lake area and volume were consistent and presents in three stages, as the glacial lake expanded rapidly in the first 5 years and in the last 7 years and remained relatively stable between 2005 and 2012. The number and area of glacier-fed lakes increased rapidly, while the non-glacier-fed lakes were relatively stable. The area change rate of supraglacial lakes was the largest (+47%). This study provides a spatially-complete and temporally-consecutive picture of glacial lake changes in the Alps and can be greatly helpful for future research on climate-glacier-lake interactions, glacial lake outburst floods, and freshwater resources in this region.

scholarly journals Recent Lake Area Changes in Central Asia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Haijun Liu ◽  
Yaning Chen ◽  
Zhaoxia Ye ◽  
Yupeng Li ◽  
Qifei Zhang
Keyword(s):  
Central Asia ◽  
Least Squares Method ◽  
Alpine Lakes ◽  
Lake Area ◽  
Interannual Variations ◽  
Study Region ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Global Water

Abstract Using Moderate Resolution Imaging Spectroradiometer (MODIS) 500 m spatial resolution global water product data, Least Squares Method (LSM) was applied to analyze changes in the area of 14 lakes in Central Asia from 2001 to 2016. Interannual changes in lake area, along with seasonal change trends and influencing factors, were studied for the months of April, July and September. The results showed that the total lakes area differed according to interannual variations and was largest in April and smallest in September, measuring −684.9 km2/a, −870.6 km2/a and −827.5 km2/a for April, July and September, respectively. The change rates for the total area of alpine lakes during the same three months were 31.1 km2/a, 29.8 km2/a and 30.6 km2/a, respectively, while for lakes situated on plains, the change rates were −716.1 km2/a, −900.5 km2/a, and −858 km2/a, respectively. Overall, plains lakes showed a declining trend and alpine lakes showed an expanding trend, the latter likely due to the warmer and wetter climate. Furthermore, there was a high correlation (r = 0.92) between area changes rate of all alpine lakes and the lakes basin supply coefficient, although there was low correlation (r = 0.43) between area changes rate of all alpine lakes area and glacier area/lake area. This indicates that lakes recharge via precipitation may be greater than lakes recharge via glacier meltwater. The shrinking of area changes for all plains lakes in the study region was attributable to climate change and human activities.

scholarly journals Glacial lake evolution and glacier–lake interactions in the Poiqu River basin, central Himalaya, 1964–2017

2019 ◽  
Vol 65 (251) ◽  
pp. 347-365 ◽  
Author(s):  
GUOQING ZHANG ◽  
TOBIAS BOLCH ◽  
SIMON ALLEN ◽  
ANDREAS LINSBAUER ◽  
WENFENG CHEN ◽  
...  
Keyword(s):  
River Basin ◽  
Glacial Lake ◽  
Lake Area ◽  
Central Himalaya ◽  
Glacial Lakes ◽  
Elevation Change ◽  
Ice Flow ◽  
Entire Study ◽  
Lake Development ◽  
The Mean

ABSTRACTDespite previous studies, glacier–lake interactions and future lake development in the Poiqu River basin, central Himalaya, are still not well understood. We mapped glacial lakes, glaciers, their frontal positions and ice flow from optical remote sensing data, and calculated glacier surface elevation change from digital terrain models. During 1964–2017, the total glacial-lake area increased by ~110%. Glaciers retreated with an average rate of ~1.4 km2 a−1 between 1975 and 2015. Based on rapid area expansion (>150%), and information from previous studies, eight lakes were considered to be potentially dangerous glacial lakes. Corresponding lake-terminating glaciers showed an overall retreat of 6.0 ± 1.4 to 26.6 ± 1.1 m a−1 and accompanying lake expansion. The regional mean glacier elevation change was −0.39 ± 0.13 m a−1 while the glaciers associated with the eight potentially dangerous lakes lowered by −0.71 ± 0.05 m a−1 from 1974 to 2017. The mean ice flow speed of these glaciers was ~10 m a−1 from 2013 to 2017; about double the mean for the entire study area. Analysis of these data along with climate observations suggests that ice melting and calving processes play the dominant role in driving lake enlargement. Modelling of future lake development shows where new lakes might emerge and existing lakes could expand with projected glacial recession.

scholarly journals Decoupling of water and air temperature in winter causes warm season bias of lacustrine brGDGTs temperature estimates

2020 ◽  
Author(s):  
Jiantao Cao ◽  
Zhiguo Rao ◽  
Fuxi Shi ◽  
Guodong Jia
Keyword(s):  
Air Temperature ◽  
Lake Water ◽  
North China ◽  
Physical Phenomenon ◽  
Warm Season ◽  
High Latitudes ◽  
Study Region ◽  
Suspended Particulate ◽  
Local Mean ◽  
The Mean

Abstract. It has been frequently found that lacustrine brGDGTs-derived temperatures are warm season biased relative to measured annual mean air temperature (AT) in the mid to high latitudes, the mechanism of which, however, is not very clear. Here, we investigated the brGDGTs from catchment soils, and suspended particulate matter (SPM) and surface sediments in the Gonghai Lake in north China to explore this question. Our results showed that the brGDGTs distribution in sediments resembled that in the SPM but differed from the surrounding soils, suggesting a substantial aquatic origin of the brGDGTs in the lake. Therefore, established lake-specific calibrations were applied to estimate local mean annual AT. As usual, the estimates were significantly higher than the measured mean annual AT. However, they were similar to, and thus actually reflected, the mean annual lake water temperature (LWT). Interestingly, the mean annual LWT is close to the measured mean warm season AT, hence suggesting that the apparent warm season bias of lacustrine brGDGTs-derived temperatures could be caused by the discrepancy between AT and LWT. In our study region, ice forms at the lake surface during winter, leading to isolation of the underlying lake water from air and hence higher LWT than AT, while LWT follows AT during warm seasons when ice disappears. Therefore, we believe what lacustrine brGDGTs actually reflected is the mean annual LWT, which is higher than the mean annual AT in our study location. Since the decoupling between LWT and AT in winter due to ice formation is a universal physical phenomenon in the mid to high latitudes, we propose this phenomenon could be also the reason for the widely observed warm season bias of brGDGTs-derived temperatures in other lakes, especially the shallow lakes.

scholarly journals Large drainages from short-lived glacial lakes in the Teskey Range, Tien Shan Mountains, Central Asia

2018 ◽  
Vol 18 (4) ◽  
pp. 983-995 ◽  
Author(s):  
Chiyuki Narama ◽  
Mirlan Daiyrov ◽  
Murataly Duishonakunov ◽  
Takeo Tadono ◽  
Hayato Sato ◽  
...  
Keyword(s):  
Early Summer ◽  
Tien Shan ◽  
Water Volume ◽  
Lake Basin ◽  
Glacial Lakes ◽  
Study Region ◽  
Field Surveys ◽  
Supraglacial Lakes ◽  
Outflow Channel ◽  
Tien Shan Mountains

Abstract. Four large drainages from glacial lakes occurred during 2006–2014 in the western Teskey Range, Kyrgyzstan. These floods caused extensive damage, killing people and livestock as well as destroying property and crops. Using satellite data analysis and field surveys of this area, we find that the water volume that drained at Kashkasuu glacial lake in 2006 was 194 000  m3, at western Zyndan lake in 2008 was 437 000 m3, at Jeruy lake in 2013 was 182 000 m3, and at Karateke lake in 2014 was 123 000 m3. Due to their subsurface outlet, we refer to these short-lived glacial lakes as the “tunnel-type”, a type that drastically grows and drains over a few months. From spring to early summer, these lakes either appear, or in some cases, significantly expand from an existing lake (but non-stationary), and then drain during summer. Our field surveys show that the short-lived lakes form when an ice tunnel through a debris landform gets blocked. The blocking is caused either by the freezing of stored water inside the tunnel during winter or by the collapse of ice and debris around the ice tunnel. The draining then occurs through an opened ice tunnel during summer. The growth–drain cycle can repeat when the ice-tunnel closure behaves like that of typical supraglacial lakes on debris-covered glaciers. We argue here that the geomorphological characteristics under which such short-lived glacial lakes appear are (i) a debris landform containing ice (ice-cored moraine complex), (ii) a depression with water supply on a debris landform as a potential lake basin, and (iii) no visible surface outflow channel from the depression, indicating the existence of an ice tunnel. Applying these characteristics, we examine 60 depressions (> 0.01 km2) in the study region and identify here 53 of them that may become short-lived glacial lakes, with 34 of these having a potential drainage exceeding 10 m3 s−1 at peak discharge.

scholarly journals Assessment of Ecological Vulnerability on Northern Sand Prevention Belt of China Based on the Ecological Pressure–Sensibility–Resilience Model

2021 ◽  
Vol 13 (11) ◽  
pp. 6078
Author(s):  
Xiufen Li ◽  
Lining Song ◽  
Zunbo Xie ◽  
Tian Gao ◽  
Tingting Wang ◽  
...  
Keyword(s):  
Environmental Protection ◽  
Ecological Status ◽  
Vulnerability Index ◽  
Mean Value ◽  
Vegetation Coverage ◽  
Study Region ◽  
Ecological Protection ◽  
Ecological Vulnerability ◽  
The Mean ◽  
Ecological Pressure

Quantitative assessment of ecological vulnerability is of great significance for ecological protection and restoration in ecologically vulnerable regions. Here, the ecological vulnerability of the northern sand prevention belt (NSPB) of China was assessed using an ecological pressure–sensibility–resilience model from 2000 to 2015. Results showed that the ecological vulnerability index (EVI) displayed low values in the eastern part and high values in the western part of the study region. The EVI ranged from 0.29 to 1.32 in 2000, with the mean value of 0.88, whereas it averaged 0.78 in 2015, ranging from 0.21 to 1.26. Decreasing EVI from 2000 to 2015 indicated that the ecological status has been improved. Moreover, the area proportion of moderately, heavily, and extremely ecological vulnerability levels occupied approximately 87% in both 2000 and 2015, indicating a high ecological vulnerability level. Furthermore, the change in area proportion of different ecological vulnerability levels were associated with the change in the spatial distribution of vegetation coverage, indicating that eco-environmental protection projects were indeed effective. These findings indicated that differential strategies in different restoration zones should be adopted, especially in the western parts of the study region, and eco-environmental protection projects should be reinforced to improve the ecological restoration.

scholarly journals Glacial lake change risk and management on the Chinese Nyainqentanglha in the past 40 years

2016 ◽  
Author(s):  
Wang Shijin
Keyword(s):  
Lake Area ◽  
Glacial Lakes ◽  
Analytic Hierarchy ◽  
Adaptation Capacity ◽  
Comprehensive Method ◽  
Outburst Floods ◽  
Integrated Risk ◽  
Lake Change ◽  
Hierarchy Process ◽  
County Scale

Abstract. The paper analyzed synthetically spatial distribution and evolution status of moraine-dammed lakes in the Nyainqentanglha Mountain, revealed risk degree of county-based potential dangerous glacial lakes (PDGLs) outburst floods disaster by combining PDGLs outburst hazard, regional exposure, vulnerability of exposed elements and adaptation capability and using the Analytic Hierarchy Process and Weighted Comprehensive Method. The results indicate that 132 moraine-dammed lakes (> 0.02 km2) with a total area of 38.235 km2 were detected in the Nyainqentanglha in the 2010s, the lake number decreased only by 5 %, whereas total lake area expanded by 22.72 %, in which 54 lakes with a total area of 17.53 km2 are identified as PDGLs and total area increased by 144.31 %, higher significantly than 4.06 % of non-PDGLs. The zones at very high and high integrated risk of glacial lakes outburst floods (GLOFs) disaster are concentrated in the eastern Nyainqentanglha, whereas low and very low integrated risk zones are located mainly in the western Nyainqentanglha. On the county scale, Nagque and Nyingchi have the lowest hazard risk, Banbar has the highest hazard and vulnerability risk, Sog and Lhorong have the highest exposure risk. In contrast, Biru and Jiali have the highest vulnerability risk, while Gongbo'gyamda and Damxung have lowest adaptation capacity. The regionalization results for GLOF disaster risk in the study are consistent with the distribution of historical disaster sites across the Nyainqentanglha.

Application of the vertical model of the seasonally thawed layer for the Tulik Lake area (Alaska)

2021 ◽  
pp. 4-15
Author(s):  
Виктор Михайлович Белолипецкий ◽  
Светлана Николаевна Генова
Keyword(s):  
Air Temperature ◽  
Stefan Problem ◽  
Soil Layer ◽  
Vertical Direction ◽  
Soil Surface ◽  
Dirichlet Condition ◽  
Transfer Model ◽  
Problem Solution ◽  
Computational Domain ◽  
Lake Area

Практический интерес в районах вечной мерзлоты представляет глубина сезонного оттаивания. Построена одномерная (в вертикальном направлении) упрощенная полуэмпирическая модель динамики вечной мерзлоты в “приближении медленных движений границ фазового перехода”, основанная на задаче Стефана и эмпирических соотношениях. Калибровочные параметры модели выбираются для исследуемого района с использованием натурных измерений глубины оттаивания и температуры воздуха. Проверка работоспособности численной модели проведена для района оз. Тулик (Аляска). Получено согласие рассчитанных значений глубины талого слоя и температуры поверхности почвы с результатами измерений Due to the change in global air temperature, the assessment of permafrost reactions to climate change is of interest. As the climate warms, both the thickness of the thawed soil layer and the period for existence of the talik are increased. The present paper proposes a small-size numerical model of vertical temperature distributions in the thawed and frozen layers when a frozen layer on the soil surface is absent. In the vertical direction, thawed and frozen soils are separated. The theoretical description of the temperature field in soils when they freeze or melt is carried out using the solution of the Stefan problem. The mathematical model is based on thermal conductivity equations for the frozen and melted zones. At the interfacial boundary, the Dirichlet condition for temperature and the Stefan condition are set. The numerical methods for solving of Stefan problems are divided into two classes, namely, methods with explicit division of fronts and methods of end-to-end counting. In the present work, the method with the selection of fronts is implemented. In the one-dimensional Stefan problem, when transformed to new variables, the computational domain in the spatial variable is mapped onto the interval [0 , 1]. In the presented equations, the convective terms characterize the rate of temperature transfer (model 1). A simplified version of the Stefan problem solution is considered without taking into account this rate (“approximation of slow movements of the boundaries of the phase transition”, model 2). The model is tuned to a specific object of research. Model parameter values can vary significantly in different geographic regions. This paper simulates the dynamics of permafrost in the area of Lake Tulik (Alaska) in summer. Test calculations based on the proposed simplified model show its adequacy and consistency with field measurements. The developed model can be used for qualitative studies of the long-term dynamics of permafrost using data of the air temperature, relative air humidity and precipitation

scholarly journals Direct Calculation of Thermodynamic Wet-Bulb Temperature as a Function of Pressure and Elevation

2013 ◽  
Vol 30 (8) ◽  
pp. 1757-1765 ◽  
Author(s):  
Sayed-Hossein Sadeghi ◽  
Troy R. Peters ◽  
Douglas R. Cobos ◽  
Henry W. Loescher ◽  
Colin S. Campbell
Keyword(s):  
Air Temperature ◽  
Mean Absolute Error ◽  
Direct Calculation ◽  
Ambient Air ◽  
Absolute Error ◽  
Mean Square ◽  
Air Temperatures ◽  
Order Polynomial ◽  
The Mean ◽  
Very High

Abstract A simple analytical method was developed for directly calculating the thermodynamic wet-bulb temperature from air temperature and the vapor pressure (or relative humidity) at elevations up to 4500 m above MSL was developed. This methodology was based on the fact that the wet-bulb temperature can be closely approximated by a second-order polynomial in both the positive and negative ranges in ambient air temperature. The method in this study builds upon this understanding and provides results for the negative range of air temperatures (−17° to 0°C), so that the maximum observed error in this area is equal to or smaller than −0.17°C. For temperatures ≥0°C, wet-bulb temperature accuracy was ±0.65°C, and larger errors corresponded to very high temperatures (Ta ≥ 39°C) and/or very high or low relative humidities (5% < RH < 10% or RH > 98%). The mean absolute error and the root-mean-square error were 0.15° and 0.2°C, respectively.

Sign in / Sign up

Export Citation Format

Share Document