scholarly journals Characteristics of Khumbu Glacier, Nepal Himalaya: recent change in the debris-covered area

1999 ◽  
Vol 28 ◽  
pp. 118-122 ◽  
Author(s):  
M. Nakawo ◽  
H. Yabuki ◽  
A. Sakai
Keyword(s):  
General Pattern ◽  
Ablation Rate ◽  
Recent Change ◽  
Longitudinal Distribution ◽  
Nepal Himalaya ◽  
Ablation Area ◽  
Supraglacial Lakes ◽  
Base Camp ◽  
Covered Area ◽  
Glacier Ice

AbstractUsing satellite data, the longitudinal distribution of the ablation rate and flow velocity were estimated for the ablation area, where glacier ice is covered with supraglacial debris. The ablation rate, small around Everest Base Camp (EBC) just below the equilibrium line, increased down-glacier for about 3 km, then decreased gradually toward the apparent terminus, located about 10 km from EBC. The velocity decreased almost linearly from EBC to the terminus. The results allowed estimation of the recent change of ice thickness using the continuity equation. The glacier has thinned recently in the ablation area. The rate of thinning was large near EBC, where the surface is either bare ice or covered with very thin debris cover, but relatively small and rather uniform at lower sites, where the supraglacial debris layer was thick and supraglacial lakes and ice cliffs predominate. The general pattern is compatible with field observations.

scholarly journals Topographic Characteristics in the Ablation Area of the Khumbu Glacier, Nepal Himalaya

1986 ◽  
Vol 8 ◽  
pp. 177-180 ◽  
Author(s):  
O. Watanabe ◽  
S. Iwata ◽  
H. Fushimi
Keyword(s):  
Surface Morphology ◽  
Ablation Rate ◽  
Nepal Himalaya ◽  
Ablation Area ◽  
Morphologic Characteristics ◽  
Glacier Dynamics ◽  
Debris Cover ◽  
Photogrammetric Method ◽  
Topographic Characteristics

Topographic sketch mapping of the whole ablation area of the Khumbu Glacier, East Nepal Himalaya, is performed, using a simple, stereo-photogrammetric method. This map shows that the surface morphology can be classified into 11 morphologic characteristics. Depending on their distribution and combination, the ablation area can be divided into four morphologic areas. Detailed maps, on a scale of 1:1000–2500, of these four areas indicate that the distribution and combination of these 11 morphologic characteristics result from thickness of the debris cover, supraglacial streams and ponds, and glacier dynamics. The irregularity in the ablation area of the Khumbu Glacier can be considered to be a consequence of the mass balance between rate of ice charge from upstream and irregular distribution of ablation rate, depending on debris-cover characteristics in situ.

scholarly journals Surface lowering of the debris-covered area of Kanchenjunga Glacier in the eastern Nepal Himalaya since 1975, as revealed by Hexagon KH-9 and ALOS satellite observations

2017 ◽  
Vol 11 (6) ◽  
pp. 2815-2827 ◽  
Author(s):  
Damodar Lamsal ◽  
Koji Fujita ◽  
Akiko Sakai
Keyword(s):  
Velocity Field ◽  
Mass Balance ◽  
Flow Velocity ◽  
Area Fraction ◽  
Ice Flow ◽  
Nepal Himalaya ◽  
Flow Velocity Field ◽  
Covered Area ◽  
Glacier Ice ◽  
Geodetic Mass Balance

Abstract. This study presents the geodetic mass balance of Kanchenjunga Glacier, one of the largest debris-covered glaciers in the easternmost Nepal Himalaya, which possesses a negative mass balance of −0.18 ± 0.17 m w.e. a−1 for the 1975–2010 study period, estimated using digital elevation models (DEMs) generated from Hexagon KH-9 and ALOS PRISM stereo images. Accurate DEMs, with a relative uncertainty of ±5.5 m, were generated from the intensive and manual editing of triangulated irregular network (TIN) models on a stereo MirrorTM/3D Monitor. The glacier ice-flow velocity field was also calculated using a feature-tracking method that was applied to two ALOS orthoimages taken in 2010. The elevation differences between the two DEMs highlight considerable surface lowering across the debris-covered area, and a slight thickening in the accumulation area of Kanchenjunga Glacier between 1975 and 2010. The magnitude and gradient of surface lowering are similar among the six glacier tributaries, even though they are situated at different elevations, which may reflect variations in the ice-flow velocity field. The pattern of surface lowering correlates well with the ice-flow velocity field over the debris-covered portion of the main tributary, suggesting that the glacier dynamics significantly affect surface lowering by altering the emergence velocity along the glacier, particularly in the compressive ablation area. Surface-lowering patterns partially correspond to the supraglacial pond area fraction of the glacier, with enhanced surface lowering observed in areas that possess a larger pond area fraction. These findings support the hypothesis that supraglacial ponds may intensify ice wastage and play a key role in the heterogeneous surface lowering of debris-covered glaciers. The estimated mass loss of Kanchenjunga Glacier is moderate compared with other debris-covered glaciers in neighboring Himalayan regions, which may be due to the lower pond area fraction of Kanchenjunga Glacier relative to other glaciers.

scholarly journals Topographic Characteristics in the Ablation Area of the Khumbu Glacier, Nepal Himalaya

1986 ◽  
Vol 8 ◽  
pp. 177-180 ◽  
Author(s):  
O. Watanabe ◽  
S. Iwata ◽  
H. Fushimi
Keyword(s):  
Surface Morphology ◽  
Ablation Rate ◽  
Nepal Himalaya ◽  
Ablation Area ◽  
Morphologic Characteristics ◽  
Glacier Dynamics ◽  
Debris Cover ◽  
Photogrammetric Method ◽  
Topographic Characteristics

Topographic sketch mapping of the whole ablation area of the Khumbu Glacier, East Nepal Himalaya, is performed, using a simple, stereo-photogrammetric method. This map shows that the surface morphology can be classified into 11 morphologic characteristics. Depending on their distribution and combination, the ablation area can be divided into four morphologic areas. Detailed maps, on a scale of 1:1000–2500, of these four areas indicate that the distribution and combination of these 11 morphologic characteristics result from thickness of the debris cover, supraglacial streams and ponds, and glacier dynamics. The irregularity in the ablation area of the Khumbu Glacier can be considered to be a consequence of the mass balance between rate of ice charge from upstream and irregular distribution of ablation rate, depending on debris-cover characteristics in situ.

scholarly journals Extreme pregnancy: maternal physical activity at Everest Base Camp

2018 ◽  
Vol 125 (2) ◽  
pp. 580-585 ◽  
Author(s):  
Margie H. Davenport ◽  
Craig D. Steinback ◽  
Kennedy J. Borle ◽  
Brittany A. Matenchuk ◽  
Emily R. Vanden Berg ◽  
...  
Keyword(s):  
Physical Activity ◽  
High Altitude ◽  
Vigorous Physical Activity ◽  
Third Trimester ◽  
Sleep Behavior ◽  
Nepal Himalaya ◽  
Neonatal Complications ◽  
Base Camp ◽  
High Altitude Natives

High-altitude natives employ numerous physiological strategies to survive and reproduce. However, the concomitant influence of altitude and physical activity during pregnancy has not been studied above 3,700 m. We report a case of physical activity, sleep behavior, and physiological measurements on a 28-yr-old third-trimester pregnant native highlander (Sherpa) during ascent from 3,440 m to Everest Base Camp (~5,300 m) over 8 days in the Nepal Himalaya and again ~10 mo postpartum during a similar ascent profile. The participant engaged in 250–300 min of moderate to vigorous physical activity per day during ascent to altitude while pregnant, with similar volumes of moderate to vigorous physical activity while postpartum. There were no apparent maternal, fetal, or neonatal complications related to the superimposition of the large volumes of physical activity at altitude. This report demonstrates a rare description of physical activity and ascent to high altitude during pregnancy and points to novel questions regarding the superimposition of pregnancy, altitude, and physical activity in high-altitude natives.

The expansion mechanism of supraglacial lakes in the Nepal Himalaya

2000 ◽  
Vol 27 (4) ◽  
pp. 2145-2148
Author(s):  
K. Chikita ◽  
S. P. Joshi ◽  
J. Jha ◽  
H. Hasegawa
Keyword(s):  
Nepal Himalaya ◽  
Supraglacial Lakes ◽  
Expansion Mechanism

The debris cover surface of Ponkar glacier: a laboratory for learning

2020 ◽  
Author(s):  
Adina E. Racoviteanu ◽  
Neil F. Glasser ◽  
Smriti Basnett ◽  
Rakesh Kayastha ◽  
Stephan Harrison
Keyword(s):  
Remote Sensing ◽  
Scientific Knowledge ◽  
Interdisciplinary Approach ◽  
Surface Features ◽  
Ice Melt ◽  
Supraglacial Lakes ◽  
High Asia ◽  
Glacier Ice ◽  
Building Activities ◽  
Remote Sensing Methods

<p>Understanding the evolution of debris-covered glaciers, including their evolution over time, the distribution of surface features such as exposed ice walls and supraglacial lakes, and their contributions to glacier ice melt and to glacier-related hazards such as Glacier Lake Outburst Flood (GLOF) events requires an interdisciplinary approach, with a combination of remote sensing methods and collaborative fieldwork.</p><p>Since 2017, the IGCP 672 /UNESCO project led has been focussing on the transfer of scientific knowledge on monitoring debris-covered glaciers to local partner institutions in high Asia through trainings, workshops and field collaborations. Our long-term goal is to disseminate methodologies developed under this project to local institutions in high Asia and to embed scientific knowledge into local communities. Here we report on recent capacity building activities held within the context of this new project involved local participants from universities in Nepal and Sikkim. The training included remote sensing/GIS modules, temperature measurements, sediment logging and drone surveys of the ablation zone, which will allow us to better quantify the surface features and their evolution.</p><p> </p>

Structure and englacial debris content of a Himalayan debris-covered glacier revealed by an optical televiewer

2020 ◽  
Author(s):  
Katie Miles ◽  
Bryn Hubbard ◽  
Duncan Quincey ◽  
Evan Miles ◽  
Ann Rowan
Keyword(s):  
Horizontal Resolution ◽  
Hot Water ◽  
Flow Paths ◽  
Validation Data ◽  
Nepal Himalaya ◽  
Discharge Water ◽  
Colour Image ◽  
Covered Area ◽  
Historical Flow ◽  
Unique Surface

<p>Himalayan debris-covered glaciers contribute to the discharge of some of Earth’s largest river systems, shaping the seasonal water supply to millions of people. The supraglacial debris layer heavily influences the pattern of surface melt, producing a range of unique surface features that make it challenging to collect any data, particularly from the interior of such glaciers. Models of debris-covered glaciers therefore lack calibration and validation data, which are needed for accurate predictions of future glacier geometric change and contributions to river discharge, water resources and ultimately sea level. In 2017 and 2018, we logged four boreholes drilled using pressurised hot water into the debris-covered Khumbu Glacier, Nepal Himalaya, with a high-resolution optical televiewer. The boreholes were located at four sites across the lower glacier’s debris-covered area, down-flow of the Khumbu Icefall. The resulting logs, ranging in length from 22–150 m, produced a 360° geometrically-accurate full-colour image of each borehole at ~1 mm vertical and ~0.22 mm (1,440 pixel) horizontal resolution. The logs reveal three material facies: i) steeply-dipping ice layers, some including debris; ii) steeply-dipping sediment-rich layers; and iii) clusters of sediment and debris dispersed through the ice. On the basis of these facies, we present reconstructions of the glacier’s structure and historical flow paths and the first measurements of the englacial debris concentration of a Himalayan debris-covered glacier. From the latter, we additionally infer both the sources of this englacial debris and of the supraglacial debris layer present across much of the lower ablation area of Khumbu Glacier.</p>

scholarly journals Onset of calving at supraglacial lakes on debris-covered glaciers of the Nepal Himalaya

2009 ◽  
Vol 55 (193) ◽  
pp. 909-917 ◽  
Author(s):  
A. Sakai ◽  
K. Nishimura ◽  
T. Kadota ◽  
N. Takeuchi
Keyword(s):  
Water Temperature ◽  
Water Surface ◽  
Glacial Lakes ◽  
Valley Wind ◽  
Nepal Himalaya ◽  
Field Surveys ◽  
Water Currents ◽  
Ice Melt ◽  
Supraglacial Lakes

AbstractField surveys of supraglacial ponds on debris-covered glaciers in the Nepal Himalaya clarify that ice-cliff calving occurs when the fetch exceeds ∼80 m. Thermal undercutting is important for calving processes in glacial lakes, and subaqueous ice melt rates during the melt and freeze seasons are therefore estimated under simple geomorphologic conditions. In particular, we focus on the differences between valley wind-driven water currents in various fetches during the melt season. Our results demonstrate that the subaqueous ice melt rate exceeds the ice-cliff melt rate when the fetch is >20 m and water temperature is 2–4°C. Calculations suggest the onset of calving due to thermal undercutting is controlled by water currents driven by winds at the surface of the lake, which develop with expanding water surface.

scholarly journals Influence of debris-rich basal ice on flow of a polar glacier

2014 ◽  
Vol 60 (223) ◽  
pp. 989-1006 ◽  
Author(s):  
Erin C. Pettit ◽  
Erin N. Whorton ◽  
Edwin D. Waddington ◽  
Ronald S. Sletten
Keyword(s):  
Low Temperatures ◽  
Ablation Rate ◽  
Surface Velocity ◽  
Inverse Theory ◽  
Limited Data ◽  
Outlet Glacier ◽  
Basal Ice ◽  
Glacier Ice ◽  
Glacier Flow ◽  
Taylor Glacier

AbstractAt Taylor Glacier, a cold-based outlet glacier of the East Antarctic ice sheet, observed surface speeds in the terminus region are 20 times greater than those predicted using Glen’s flow law for cold (–17°C), thin (100 m) ice. Rheological properties of the clean meteoric glacier ice and the underlying deformable debris-rich basal ice can be inferred from surface-velocity and ablation-rate profiles using inverse theory. Here, with limited data, we use a two-layer flowband model to examine two end-member assumptions about the basal-ice properties: (1) uniform softness with spatially variable thickness and (2) uniform thickness with spatially variable softness. We find that the basal ice contributes 85–98% to the observed surface velocity in the terminus region. We also find that the basal-ice layer must be 10–15 m thick and 20–40 times softer than clean Holocene-age glacier ice in order to match the observations. Because significant deformation occurs in the basal ice, our inverse problem is not sensitive to variations in the softness of the meteoric ice. Our results suggest that despite low temperatures, highly deformable basal ice may dominate flow of cold-based glaciers and rheologically distinct layers should be incorporated in models of polar-glacier flow.

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