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Terrestrial cosmogenic nuclide (TCN) dating has emerged as one of the most useful techniques in the last two decades for quantifying geomorphological processes and building the chronology of late Quaternary glacial advances/retreats. The chronology based on TCN and optically stimulated luminescence (OSL) dating of glacial landforms from the northwestern (NW) Himalaya suggests that glaciers responded to a complex interaction between temperature and moisture essentially derived from either of the climate systems, the Indian Summer Monsoon (ISM) and the Mid‐latitude Westerlies (MLW). The discrepancies between the TCN ages obtained on moraine boulders/bedrock surfaces, and the OSL ages on the stratigraphically equivalent deposits, highlighted the need for a detailed investigation. The present study attempts to build the chronology of Quaternary glaciation events in the Karakoram and Ladakh Ranges using TCN dating of stratigraphically constrained moraine boulders and striated bedrock surfaces. The TCN ages from glacially eroded surfaces (GES) having prominent striations are narrowly clustered around the Marine Isotopic Stage‐2 (MIS‐2). Agreement between GES TCN ages and OSL ages on the stratigraphically equivalent moraines suggests negligible geological inheritance. The glacial advance during MIS‐2 can be attributed to the combined effect of reduction in north hemispheric insolation and enhanced westerly precipitation. However, relict non‐glacial surfaces and moraine boulders with minimal ice flow modifications yield wide age distributions, most likely suggesting denudational events (interglacials) and/or contribution from tributary valley flanks. Plain Language Summary: Quaternary glacial advances and retreats in the northwestern (NW) Himalaya respond to a complex interaction between climatic parameters, that is, temperature and moisture essentially derived from the two contrasting weather systems viz., the Indian Summer Monsoon (ISM) and the Mid‐latitude Westerlies (MLW). In this study, we employed terrestrial cosmogenic nuclide dating of stratigraphically constrained moraine boulders and striated bedrock surfaces to understand the dynamics of late Quaternary glaciation in the Karakoram and Ladakh ranges. The exposure ages obtained from glacially eroded surfaces (GES) show a narrow cluster around the Marine Isotopic Stage‐2 (MIS‐2), a period when the northern hemispheric insolation was low resulting in a temperature decline. The glacial advance during MIS‐2 is attributed to the combined effect of temperature reduction and enhanced westerly precipitation. Key Points: New insight into the Quaternary glacial history of NW Himalaya based on 40 10Be exposure ages of boulders and bedrock surfacesGlacially eroded surface ages suggest that Marine Isotopic Stage‐2 glacier advances were driven by enhanced westerlies and reduced insolationRelict non‐glacial surface/boulder ages indicate denudational events during the interstadial and/or contribution from tributary valleys [ABSTRACT FROM AUTHOR]

Permafrost degradation increases the likelihood of glacial lake outburst floods on the Tibetan Plateau. Analyses of the freeze–thaw conditions in moraine dams and associated impacts on dam stability contribute toward reducing natural hazard risks. We used the heat transfer module of COMSOL Multiphysics to simulate the soil temperature field in the Longbasaba moraine dam, which is on the northern slope of central Himalaya. There is close agreement between the simulated and observed soil temperature values. Root mean squared errors (the square root of the mean of the square of all of the error) are below 1.30°C and mean bias errors vary from −0.10 to −0.52°C for the different soil layers. Between 1959 and 2020, active layer thickness increased at a mean annual rate of 0.024 m a−1. Under the Coupled Model Intercomparison Project Phase 6 scenarios, the buried ice inside the moraine dam is clearly melting. The maximum‐buried ice thaw depth is currently 3.4 m and at the end of the 21st century is projected to be 9.53, 16.69, and 21.83 m under SSP1‐2.6, SSP2‐4.5, and SSP5‐8.5, which indicates a continuous decrease in moraine dam stability. Plain Language Summary: Glacial Lake Outburst Floods have frequently occurred on the Tibetan Plateau in recent years and have caused many casualties and substantial property damage. Longbasaba lake is located at the end of Longbasaba glacier and is dammed by a terminal moraine complex. We used the heat transfer module of COMSOL Multiphysics simulation software to simulate the freeze–thaw process and melting of buried ice inside the Longbasaba moraine dam between 1959 and 2100 and examined dam stability. The maximum thawing depth of the dam in summer has increased over the past decades and buried ice has been melting since the mid‐1970s. Under future warming scenarios, the depth of melting inside the dam is projected to exceed the depth of freezing and the melting rate of buried ice will accelerate. This indicates that seepage and piping will increase and dam stability will continue to decrease. We must remain alert about the possibility of future dam failure. Key Points: Soil temperatures at different depths of the Longbasaba moraine dam were well simulated by COMSOL Multiphysics softwareBetween 1959 and 2020, annual active layer depth increased at a mean rate of 0.024 m a−1Under Coupled Model Intercomparison Project Phase 6 scenarios, melting of buried ice is projected to accelerate and reduce dam stability [ABSTRACT FROM AUTHOR]

Retreating Glaciers in Himalayas are causing expansion of many glaciers lake, formed behind ice-'dam' or moraine dam and are big risk to the habitation and structures downstream. The unexpected breach in weak moraine lakes discharges huge volume of water and debris flow which are generally known as "Glaciers Lake Outburst Flood" (GLOF). This volume of water and debris can be millions of cubic meter in a short duration, resulting life threatening flooding in the downstream portion. These potentially dangerous lakes are analysed and identified on several factors like spread and condition of these lakes, the condition of dams, location of mother glaciers and some of the topographic feathers associated with lakes, dams, and glaciers. In this research work, the Chenab river basin originating in the Western Himalayan region has been taken to prepare the glacier lake inventory and also to recognize potentially vulnerable lakes. This study demonstrated a standard criterion of identification of vulnerable lakes/glacial lakes in the selected study area i.e. Chenab river basin. Taking lake area, type/location of lake and physical condition etc. as a standard parameter, two lakes have been found as potentially dangerous. [ABSTRACT FROM AUTHOR]

Analysis of surface energy balance (SEB) at the glacier/snow surface is the most comprehensive way to explain the atmosphere–glacier/snow interactions, but that requires extensive data. In this study, we have analysed an 11-year (2009–2020) record of the meteorological dataset from an automatic weather station installed at 4863 ma.s.l. (above sea level) on a lateral moraine of the Chhota Shigri Glacier, western Himalaya. The study was carried out over the winter months (December to April) to understand SEB drivers and snow loses through sublimation. Furthermore, this study examines the role of cloud cover on SEB and turbulent heat fluxes. The turbulent heat fluxes were calculated using the bulk-aerodynamic method, including stability corrections. The net short-wave radiation was the primary energy source. However, the turbulent heat fluxes dissipated a significant amount of energy. The cloud cover plays an important role in limiting the incoming short-wave radiation by about 70 %. It also restricts the turbulent heat fluxes by more than 60 %, resulting in lower snow sublimation. During winter, turbulent latent heat flux contributed the largest proportion (64 %) in the total SEB, followed by net radiation (25 %) and sensible heat flux (11 %). Sublimation rates were 3 times higher in clear-sky than overcast conditions, indicating a strong role of cloud cover in shaping favourable conditions for turbulent latent heat flux by modulating the near-surface boundary layer conditions. Dry air, along with high snow-surface temperature and wind speed, favours sublimation. Besides, we also observed that strong and cold winds, possibly through mid-latitude western disturbances, impede sublimation by bringing high moisture content to the region and cooling the snow surface. The estimated snow sublimation fraction was 16 %–42 % of the total winter snowfall at the study site. This study substantiates that the snow sublimation is an essential variable to be considered in glaciohydrological modelling at the high-mountain Himalayan glacierised catchments. [ABSTRACT FROM AUTHOR]

Intact rock glaciers are common periglacial landforms that occur in cold alpine mountains and are often considered indicators of alpine permafrost. They can be both active and inactive, but both have ice in them and can be hydrologically significant. Little is known about the distribution of the rock glaciers in the Himalaya at basin-scale and content of water that can be hydrologically significant during the water-stressed months. We have found 967 intact rock glaciers covering an area of 306 km2 in the river basins of Beas, Chenab, Ravi, Sutlej, and Yamuna. Out of these, around 77% are moraine derived and the rest are talus derived. Most of them occur in the elevation between 4000 and 4500 m having a slope of 10° to 30° with a westerly and south-westerly aspect. They start occurring from 3220 to 6206 m, in places with −10°C to 10°C mean monthly temperature and within 50–100 cm of average monthly precipitation. Their alignment suggests that these rock glaciers occur in the area with low to medium incoming solar radiations. These rock glaciers are generally found where the general rock types are low-grade metamorphic rocks and feldspar-rich intrusive granites occurring beyond the Main Central Thrust in the Higher Himalaya. Finally, we calculated about 8.5 billion m3 volume of water (ice water equivalent) stored in them, considering 60% of the volume of rock glaciers is ice. [ABSTRACT FROM AUTHOR]

The dynamic response of large mountain glaciers to climatic forcing operates over timescales of several centuries and therefore understanding how these glaciers change requires observations of their behavior through the Holocene. We used Be‐10 exposure‐age dating and geomorphological mapping to constrain the evolution of glaciers in the Khumbu Valley in the Everest region of Nepal. Khumbu and Lobuche Glaciers are surrounded by high‐relief lateral and terminal moraines from which seven glacial stages were identified and dated to 7.4 ± 0.2, 5.0 ± 0.3, 3.9 ± 0.1, 2.8 ± 0.2, 1.3 ± 0.1, 0.9 ± 0.02, and 0.6 ± 0.16 ka. These stages correlate to each of the seven latest Holocene regional glacial stages identified across the monsoon‐influenced Himalaya, demonstrating that a coherent record of high elevation terrestrial palaeoclimate change can be extracted from dynamic mountain landscapes. The time‐constrained moraine complex represents a catchment‐wide denudation rate of 0.8–1.4 mm a−1 over the last 8 kyr. The geometry of the ablation area of Khumbu Glacier changed around 4 ka from a broad, shallow ice tongue to become narrower and thicker as restricted by the topographic barrier of the terminal moraine complex. Plain Language Summary: Satellite observations indicate that glaciers in the monsoon‐influenced Himalaya are changing rapidly in response to climate change. However, understanding why glaciers are changing requires observing glacier behavior over longer timescales using the glacial geological record. We mapped the geometry and measured the ages of ice‐marginal moraines built by two adjacent glaciers in the Everest region of Nepal. The moraines represent a complete record of glacier expansion during cold periods in the monsoon‐influenced Himalayan region over the last 8,000 years. Moraines formed by the large Khumbu Glacier and the smaller, steeper Lobuche Glacier also reveal differences in how these glaciers have changed since the last Ice Age. The results are useful to understand how monsoon‐influenced Himalayan glaciers respond to climate change, and to improve projections of their future behavior. Key Points: Ice‐marginal moraines in the upper Khumbu Valley represent a complete record of regional glacier change between 7.4 ka and the present dayMoraine building modified the response of Khumbu Glacier to climate change after 8 kaHolocene moraine volume indicates a catchment‐wide denudation rate of 0.8–1.4 mm per year [ABSTRACT FROM AUTHOR]

On 7 February 2021, a catastrophic flood destroyed two hydropower plants, killing at least 150 people in the Himalayan Uttarakhand state of India. This flood was reportedly initiated by a high-position landslide. This work explored the capability of using Sentinel-2 images to diagnose the landslide trigger of this event. There were 264 Sentinel-2 images taken before the landslide, 111 of which are clear. In a pre-landslide Sentinel-2 image, tensile cracks are clearly visible on the landslide head. In the post-landslide image acquired on 10 February 2021, a fresh landslide scarp stripped of snow is visible, indicating that a high-position landslide occurred that may have led to the disaster in the downstream areas. The landslide was initiated at an elevation of ~ 5600 m, slid to the valley floor (~ 3800 m elevation) and scooped up an unconsolidated mixture of moraine, ice and water that wreaked havoc on local infrastructure. To derive the slope deformation that occurred before the landslide, we selected 15 Sentinel-2 images to compose 10 image pairs. To filter out background noise, we developed a new method to derive reliable slope deformation results. We found that the slope was consistently moving since 2016, after which it moved at least 25 m. We speculated that the slope instability was caused by the seasonal freeze–thaw process. With the impacts of climate warming, more similar hazard chains are expected in the Himalayan region. The regular monitoring of slope stabilities in the Himalayan Mountains and beyond is urgently needed for regional sustainability. [ABSTRACT FROM AUTHOR]

Robustly-dated glacial landforms provide us a means of examining millennial-scale climate events during the late-glacial period, which could shed new light on the bipolar seesaw hypothesis. Although many moraines are proposed to be late-glacial in age across the Himalayas, the well-determined late-glacial moraine sequences remain extremely rare in the central Himalaya (e.g. the Paiku Gangri area). The paucity of high-precision chronologies limits our ability to fully explore the response of Himalayan glaciers to late-glacial climate reversals. Here, we present a detailed geomorphic map of glaciers in the Laqu River Valley, northwest of Mt. Gang Benchhen and a10Be-based moraine chronology from 24 boulders from the late-glacial period. The dating results indicate that glaciers in the studied catchment reached their maximum late-glacial extent about 16.1 ka ago, prior to the Younger Dryas Stadial (YDS), and that a following glacial culmination occurred at 12.2 ± 0.9 ka, corresponding roughly to the YDS. The emerging pattern of glacial fluctuations is similar at local, regional, and global scales, suggesting a interhemispheric coherency of late-glacial glacier behaviors. The Analysis of dynamic response of Himalayan glaciers to climate change suggests a temperature-sensitive mountain-glacier system, supporting the view that the bipolar seesaw was primarily a northern winter phenomenon during the late-glacial interval. [ABSTRACT FROM AUTHOR]

Indian Himalayas are home to numerous glacial lakes, which can pose serious threat to downstream communities and lead to catastrophic socioeconomic disasters in case of a glacial lake outburst flood (GLOF). This study first identified 329 glacial lakes of size greater than 0.05 km2 in the Indian Himalayas, and then a remote sensing‐based hazard and risk assessment was performed on these lakes. Different factors such as avalanche, rockfall, upstream GLOF, lake expansion, identification of the presence of ice cores, and assessment of the stability of moraine were considered for the hazard modeling. Further, a stochastic inundation model was applied to quantify the potential number of buildings, bridges, and hydropower systems that could be inundated by GLOF in each lake. Finally, the hazard parameters and downstream impact were collectively considered to determine the risk linked with each lake. A total of 23 lakes were identified as very high risk lakes and 50 as high‐risk lakes. The potential flood volumes associated with various triggering mechanisms were also measured and were used to identify the lakes with the most considerable risk, such as Shakho Cho and Khangchung Tso. This study is anticipated to support stakeholders and decision‐makers in identifying critical glacial lakes and make well‐informed decisions related to future modeling efforts, field studies, and risk mitigation measures. Key Points: Avalanche trajectories suggest that 36 out of 329 glacial lakes are susceptible to dynamic failure via an avalanche entering the lakeApplication of stochastic flood model reveals that 67 glacial lakes contain at least one hydropower system along their flow pathIndian Himalayas contain 23 critical glacial lakes, 17 of which are located in the state of Sikkim [ABSTRACT FROM AUTHOR]

Debris-covered glaciers in the Himalaya play an important role in the high-altitude water cycle. The thickness of the debris layer is a key control of the melt rate of those glaciers, yet little is known about the relative importance of the three potential sources of debris supply: the rockwalls, the glacier bed and the lateral moraines. In this study, we hypothesize that mass movement from the lateral moraines is a significant debris supply to debris-covered glaciers, in particular when the glacier is disconnected from the rockwall due to downwasting. To test this hypothesis, eight high-resolution and accurate digital elevation models from the lateral moraines of the debris-covered Lirung Glacier in Nepal are used. These are created using structure from motion (SfM), based on images captured using an unmanned aerial vehicle between May 2013 and April 2018. The analysis shows that mass transport results in an elevation change on the lateral moraines with an average rate of -0.31±0.26 m year -1 during this period, partly related to sub-moraine ice melt. There is a higher elevation change rate observed in the monsoon (-0.39±0.74 m year -1) than in the dry season (-0.23±0.68 m year -1). The lower debris aprons of the lateral moraines decrease in elevation at a faster rate during both seasons, probably due to the melt of ice below. The surface lowering rates of the upper gullied moraine, with no ice core below, translate into an annual increase in debris thickness of 0.08 m year -1 along a narrow margin of the glacier surface, with an observed absolute thickness of approximately 1 m, reducing melt rates of underlying glacier ice. Further research should focus on how large this negative feedback is in controlling melt and how debris is redistributed on the glacier surface. [ABSTRACT FROM AUTHOR]

The study reports new progress in the glacial chronology from new sites of the Chandrabhaga basin (CBB), in the transition between the monsoon-dominated Pir-Panjal and westerly-dominated Trans-Himalaya, in Lahaul Himalaya, northern India. In Lahaul, asynchronous timing and extent of late Quaternary glaciation have been reported (Owen et al., 1996, 1997, 2001; Eugster et al., 2016). The established oldest and most extensive Chandra glacial stage remains undated and speculative. We reconstrain the late Quaternary glacial history of the CBB using geomorphological mapping, Infrared Stimulated Luminescence (IRSL), and 10Be Terrestrial Cosmogenic Nuclide (TCN) surface exposure dating. Four local glacial stages, the Chandra, Batal, Dali, and Mayar, are dated to 152 ± 37 ka, 43 ± 3 ka, 21 ± 2 ka, and Little Ice Age (LIA), respectively. The Chandra glacial stage occurred during the late Marine Isotope Stage 6 (MIS 6; 186 ± 30 – 113 ± 10 ka), characterized by thick lacustrine deposits, rock benches, and ice-polished bedrock along the trunk valleys. We provide the first account of the numerical dating for the much-awaited timing of the oldest Chandra glacial stage (Local Last Glacial Maxima; LLGM) in the region (Owen et al., 1996, 1997, 2001). The LLGM in the CBB is much older than previously thought, consistent with some north-western Himalayan glacial records (Owen et al., 2006; Dortch et al., 2010; Hedrick et al., 2011; Orr et al., 2017, 2018). The Batal glacial stage occurred during the early MIS 3 and is dated from 47 ± 2 to 41 ± 2 ka, represented by the thick lacustrine deposits and impressive terraces. The Dali glacial stage occurred during the Global Last Glacial Maxima (GLGM), characterized by a series of latero-frontal recession moraines, and is dated from 33 ± 3 to 13 ± 1 ka. The Mayar advance is characterized by confined tributary valley glaciers, possibly linked to the LIA advance reported in the Kulti valley (Saha et al., 2019). The equilibrium line altitude (ELA) rose by ∼486 m from the Chandra stage to the present day. Reconstructed ELA altitudes and glacial landforms demonstrate that the glaciations have become progressively less extensive through time for this part of the western Himalayas. The change of glaciation pattern during the later part of the Quaternary is like other regions of the orogen, such pattern of glaciation reflects regional climatic forcing. • We present novel 31 k-feldspar IRSL and 12 cosmogenic 10Be ages for Chandrabhaga basin, Lahaul Himalaya, northern India. • We reconstrain the chronology for previously reported glacial stages of Owen et al. (1996, 1997, 2001). • We assign previously reported but undated oldest Chandra glacial stage with absolute dates. • Findings suggest that the Local Last Glacial Maxima in this region is much older than previously thought. • Our findings strongly question the previously reported extensions and rate of deglaciation during Global Last Glacial Maxima by Eugster et al. (2016). • Each glaciation becomes progressively less extensive in the Chandrabhaga basin over time. [ABSTRACT FROM AUTHOR]

Glacier retreat results in the formation and expansion, and sometimes outburst, of moraine-dammed lakes worldwide. Sudden outburst floods from such lakes have caused enormous damage to settlements and infrastructure located downstream. Such lakes located in the Himalayan region are highly prone to outburst floods due to climatic conditions and geotectonic settings. In this study, multi-temporal Landsat images from 2002-2014, digital elevation models (DEMs), geomorphic analysis and modelling were used to assess the changes in glacial lakes and the outburst susceptibility of moraine-dammed lakes in the Chandra-Bhaga basin of the north-western Indian Himalaya. An inventory of lakes was developed using satellite data, thematic maps and ground-based investigations for the Chandra-Bhaga basin. The total area of all glacial lakes (size >5000 m2) increased by 47% from 2002 to 2014, with a pronounced increase of 57% for moraine-dammed lakes. Sixteen moraine-dammed lakes were identified and assessed for outburst susceptibility using the analytic hierarchy process (AHP). Forty-one reported glacial lake outburst flood (GLOF) events from moraine-dammed lakes in Himalayan regions were analysed, culminating in the identification of 11 critical factors for assessing outburst susceptibility using the AHP, including those related to the lake area and change, surrounding terrain characteristics, dam geometry, regional seismicity and rainfall history. The past three GLOF events in the Himalayan region were used to validate the method and to classify moraine-dammed lakes as having very high, high, medium or low outburst susceptibility. Eight lakes classified as very high and high outburst susceptibility should be further investigated in detail. The proposed AHP-based approach is suitable for first-order identification of critical lakes for prioritising future detailed investigation and monitoring of moraine-dammed glacial lakes in the Himalayan region. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Temporal change in Digital Elevation Models observed in 1962 and 1999 were used to determine the elevation change over Parbati and Pin glacier. The results suggest that the average - area thickness decreased over Parbati and Pin glacier with rate of 0.39m /yr and 0.22 m/y. Thickness loss resulted in extreme retreat of snout of Parbati glacier from 4157amsl to 4205 amsl and snout of Pin glacier retreat 4452 amsl to 4582 amsl during 1962 - 2005. The comparative areal coverage of glaciers in 1962 and 2005 suggests the areal shrinkage of 17% and 13% for Parbati and Pin glacier. Thickness losses, areal shrinkage in lower and middle ablation accompanied with rapid snout retreat consequently resulting in the formation of the hummocky type of terminal moraine and fragmentation of the tributary glaciers from main valley glacier in recent times. [ABSTRACT FROM AUTHOR]

Quaternary climate change in eastern Himalaya is evidenced by a variety of glacial and fluvial landforms. In eastern Himalaya, the Teesta Khangtse glacier region located in the North District, Sikkim, has preserved many glacial and glacio-fluvial geomorphic features. The Optically stimulated luminescence (OSL) geochronology of lateral, recessional and ground moraines has provided proper evidence of episodic deglaciation and corresponding landform evolution of the region. The field disposition ground moraines exhibit the existence of a vast glacier system before 52 ka and successive different stages of its recession in the Late Quaternary time. The thinning of the glacier system laid down a thick cover of the ground moraine. Data show that the major recession of the Teesta glacier system took place in the Upper Pleistocene at around 52 ± 3 ka. This was followed by many episodic deglaciations between 11.4 and 1.4 ka. The recessional phase, close to the beginning of the Meghalayan stages of Holocene at 3.4 ± 0.2 ka, has been marked by fluvial and aeolian activities. [ABSTRACT FROM AUTHOR]

Quantifying the timing and extent of Quaternary mountain glaciations can help us in understanding the cause of ice-age cycles. As such, impressive achievements have been made in glacial dynamics across many mountain ranges around the world, such as the Himalayas. Yet, the Marine Isotope Stage 6 (MIS 6) glacial histories have not been well determined across the Himalayan regions due to a lack of adequate chronological controls. Here, we present a 10Be surface-exposure chronology northwest of Mt. Gang Benchhen, Paiku Gangri. Twelve 10Be exposure-ages show that the outermost hummocky moraine outside of the Laqu Valley was formed around ∼165.7 ka, reflecting the MIS 6 glacial maximum in the central Himalaya. The minimum age constraint is consistent with the low atmospheric CO 2 levels as well as low summer solar insolation intensity at northern high-latitude, which indicate that glaciers in the Laqu Valley culminated during cold climate condition. Also, we identified a potential correlation between the MIS 6 glacial advance in the central Himalaya and Heinrich-like event. We thus hypothesize that there seems to be a response of Himalayan glaciers to the combined forcing of the boreal summer solar insolation intensities, atmospheric CO 2 concentrations, and North Atlantic climate oscillations during the MIS 6 glaciation. • Tightly-clustered 10Be ages constrain the MIS 6 glacial advance to ∼165.7 ka. • The MIS-6 glacial maximum pre-dates the Penultimate Glacial Maximum. • Atmospheric CO 2 levels are the key to the maximum extent of MIS 6 glaciation. [ABSTRACT FROM AUTHOR]

Monitoring of lakes in glaciated terrain in the Himalayan region has been recognized as one of the priority areas especially after the Kedarnath disaster. Among all types of glacial lakes, moraine dammed lakes (MDLs) are the most important from disaster point of view. Remote sensing plays a significant role in view of availability of unbiased repeated data on the expansion or contraction of MDLs located in rugged terrains of the Himalaya. Monitoring of two MDLs, associated with Katkar and Gepang-gath glaciers in Zanskar and Chandra sub-basins respectively was done using satellite images of 1965, 1976, 1989, 2001, 2006-07, 2012 and 2014. Survey of India (SOI) topographical maps of 1962 were also referred to monitor the respective glaciers lakes. SOI maps show the presence of only one lake associated with Gepang-gath glacier. Areal extent of the MDLs had increased from 21 to 57 ha between 1965 and 2014, and from 27 to 80 ha between 1962 and 2014 for the Katkar and Gepang-gath glaciers respectively. Increase in peak discharge of the two lakes was also estimated using different empirical models in case of outbursts of these lakes. The lake outburst probability for both these lakes was found to be very low (less than 1%), however, possibility of outburst of lakes due to natural calamity like cloud burst, landslide or earthquake cannot be ignored. The rate of retreat of these two glaciers was observed to be high due to the presence of MDLs in comparison to surrounding glaciers in the valley. [ABSTRACT FROM AUTHOR]

Global climate change during the twentieth century had a significant impact on the glaciers that resulted in creation of new lakes and expansion of existing ones, and ultimately an increase in the number of glacial lake outburst floods (GLOFs) in the Himalayan region. This study reports variation of the end-moraine dammed lakes in the high altitude Hindukush-Karakoram-Himalaya (HKH) region of Pakistan to evaluate future floods hazard under changing climate in this region. An integrated temporal remote sensing and Geographic information system (GIS) based approach using satellite images of Landsat-7 and 8 was adopted to detect 482 endmoraine dammed lakes out of which 339 lakes (>0.02 km) were selected for temporal change analysis during the 2001-2013 period. The findings of the study revealed a net expansion in the end-moraine dammed lakes area in the Karakoram (about 7.7%) and in the Himalayas (4.6%), while there was a net shrinkage of about 1.5% in the lakes area in the Hindukush range during this period. The percentage increase in the lakes' area was highest above 4500 m asl in the Hindukush, within 3500-4000 m asl in the Himalayas and below 3500 m asl in the Karakoram range. The overall positive change in the lakes' area appears to prevail in various altitudinal ranges of the region. The heterogeneous areal changes in the endmoraine dammed lakes might be attributed to different climate regimes and glacial hydrodynamics in the three HKH ranges. A periodic monitoring of the glacial lakes and their associated glaciers is essential for developing effective hazard assessment and risk reduction strategies for this high altitude Himalayan region. [ABSTRACT FROM AUTHOR]

The recent evolution and outburst risk of two typical moraine-dammed lakes, Galong and Gangxi, central Chinese Himalaya, are analyzed using topographic maps from 1974 and Landsat satellite imagery acquired in 1988, 2000 and 2014. The datasets show the areas of Galong and Gangxi lakes increasing at rates of 0.45 and 0.34 km/year during the period 1974-2014, an expansion of 501% and 107%, respectively, in the past 41 years, while the areas of the parent glaciers, Reqiang and Jipucong decreased by 44.22% and 37.76%, respectively. The accelerating retreat of the glaciers not only reflects their generally negative mass balance but is consistent with the rapid expansion of the moraine-dammed lakes. When acted upon by external forces such as earthquakes, heavy rainfall, rapid melting of glaciers and dead ice, and snow/ice/rock avalanches, these lakes can become extremely dangerous, easily forming outburst mudslides, which can potentially spread to the Poiqu river basin and develop into cross-border (China and Nepal) GLOF disasters. Therefore, there is an urgent need to strengthen integrated risk management of glacial lake outburst disasters with multiple objectives and modes. [ABSTRACT FROM AUTHOR]

To better understand the risk of disasters due to glacial lake outburst floods (GLOFs), we synthetically analyze the spatial distribution and evolution of moraine-dammed lakes and potentially dangerous glacial lakes (PDGLs) in the Chinese Himalaya. Our county-based assessment of GLOF disaster risk combines PDGL outburst hazard, regional exposure, vulnerability of exposed elements and adaptation capability (risk management) using the analytic hierarchy process. We synthetically analyze the disaster risk using the weighted comprehensive method. Remote-sensing data show there are 329 moraine-dammed lakes (>0.02km2; total area 125.43km2) in the Chinese Himalaya, of which 116 (total area 49.49 km2) are identified as PDGLs. The zones at highest risk of GLOF disaster are mainly located in Nyalam, Tingri, Dinggyê, Lhozhag, Kangmar and Zhongba, in the mid-eastern Himalaya. Lowest-risk zones are located in the eastern Himalaya. On the county scale, Lhozhag and Lhunze have the highest hazard degrees and exposure, while Zhongba and Zando have the highest degree of vulnerability and lowest adaptation capacity. Our regionalization results for GLOF disaster risk are consistent with the distribution of historical disaster sites across the Chinese Himalaya. [ABSTRACT FROM AUTHOR]

The glacial history of the Tons River Valley reveals significant changes in the glacier extent during the late Quaternary driven by regional and global climatic changes. The successions of moraines in glaciated valley of the upper Tons River, Garhwal Himalaya, provide evidence of at least five glacial advances during the late Quaternary Period. This study discusses about the synchronicity of Himalayan glaciers and comparison between results of Optically Stimulated Luminescence (OSL) and Cosmogenic Radio Nuclide (CRN 10Be) dates. The OSL dates of moraine sediments deposited by glacier in the upper Tons valley show parallelism with the ages deduced from the CRN of 10Be by Scherler et al. in the same area. The five episodes of glacier advances are dated at 20 ± 3, 16 ± 2, 8 ± 1.2, 6 ± 0.7 and 3 ± 0.6 kyr (between Marine Isotope Stages (MISs) I and II). Two of the more extensive phases of glaciation were during the early and later parts of MIS II, which attributed to the lower temperature and enhanced the mid-latitude westerlies. During the periods between 20 ± 3 kyr and present day, the glacier lost ~47 km2 (33%) area, 0.88 × 1010 m3 water equivalent (w.e.) volume with the rate of 0.44 × 106 m3 w.e./yr, which is close to the current melting rates of Central Himalayan glaciers. The estimation of equilibrium line altitude (ELA) using these dates and geomorphic data suggests a vertical shift of ~451 m for Jaundhar Glacier and ~598 m for Bandarpunch Glacier since 20 kyr. The results from Tons valley glaciation show synchronicity with the records of glacial advancements from the other Himalayan glacier valleys. These data allow testing of two widely used dating techniques and importance of global climate change and monsoon influence on glaciation in the Himalaya. [ABSTRACT FROM AUTHOR]

To make first-order estimates of the probability of moraine-dammed lake outburst flood (MDLOF) and prioritize the probabilities of breaching posed by potentially dangerous moraine-dammed lakes (PDMDLs) in the Chinese Himalayas, an objective approach is presented. We first select five indicators to identify PDMDLs according to four predesigned criteria. The climatic background was regarded as the climatic precondition of the moraine-dam failure, and under different climatic preconditions, we distinguish the trigger mechanisms of MDLOFs and subdivide them into 17 possible breach modes, with each mode having three or four components; we combined the precondition, modes and components to construct a decision-making tree of moraine-dam failure. Conversion guidelines were established so as to quantify the probabilities of components of a breach mode employing the historic performance method combined with expert knowledge and experience. The region of the Chinese Himalayas was chosen as a study area where there have been frequent MDLOFs in recent decades. The results show that the breaching probabilities (P) of 142 PDMDLs range from 0.037 to 0.345, and they can be further categorized as 43 lakes with very high breach probabilities (P ≥ 0.24), 47 lakes with high breach probabilities (0.18 ≤ P <0.24), 24 lakes with mid-level breach probabilities (0.12 ≤ P <0.18), 24 lakes with low breach probabilities (0.06 ≤ P <0.12), and four lakes with very low breach probabilities (p <0.06). [ABSTRACT FROM AUTHOR]

The article presents a survey which estimates the depth of Longbasaba lake with the use of SyQwest Hydrobox high-resolution echo sounder in Himalaya. The morphology of the lake basin was modeled by building a triangulated irregular network and the lake was discovered to have a storage capacity of 0.064 ± 0.002 kilometer (km)3. The results show that the area and length of the lake have increased for the past 32 years, from 1977 to 2009, with a drastic expansion happening since year 2000.

Abstract: Moraine-dammed glacial lakes are becoming increasingly common in the Himalaya as a result of glacier mass loss, causing concern about glacier lake outburst flood risk. In addition to extant lakes, the potential exists for many more to form, as more glaciers ablate down to the level of potential moraine dams. In this paper, we document the recent rapid growth of, a moraine-dammed lake on Ngozumpa Glacier, Nepal. Using a combination of ground-based mapping and sonar surveys, aerial photographs (<1m resolution), and ASTER imagery (15m resolution), processes and rates of lake expansion have been determined. The lake first formed between 1984 and 1992 when collapse of an englacial conduit allowed water to accumulate at the level of a gap in the lateral moraine, ~km from the glacier terminus. Lake growth was initially slow, but since 2001 it has undergone exponential growth at an average rate of 10%y−1. In 2009, the lake area was 300,000m2, and its volume was at least 2.2million m3. Calving, subaqueous melting, and melting of subaerial ice faces all contribute to the expansion of the lake; but large-scale, full-height slab calving is now the dominant contributor to growth. Comparison with other lakes in the region indicate that lake growth will likely continue unchecked whilst the spillway remains at its current level and may attain a volume of hundreds of millions of cubic metres within the next few decades. [Copyright &y& Elsevier]

Abstract: To help delineate the transition in pattern and timing of glaciation between two contrasting regions, Lahul to the south and Ladakh to the north, moraines in the Puga and Karzok valleys of Sanskrit in the Transhimalaya of northern India were mapped and dated using cosmogenic 10Be. In Lahul, Late Quaternary glaciation was extensive with total valley glacial systems being >100 km in extent, whereas glaciation in Ladakh has been comparatively restricted, with glaciers advancing only ∼15 km from the contemporary glaciers during the last 200 ka. In the Puga valley, glaciers advanced >15 km at ∼129 ka and ∼10 km at ∼46 ka, ∼4.2 ka, and ∼0.6 ka. In the Karzok valley, glaciers advanced ∼1 km at ∼3.6 ka. Boulder exposure ages from a large moraine complex in Karzok indicate a glacial advance at ∼80 ka of ∼4 km from the present ice margin. The oldest moraine in Karzok is ∼311 ka, indicating that glaciers advanced >10 km from the present ice margin during or before marine isotope stage 9. The glacial chronology of the two valleys shows a lack of early Holocene glaciation and generally asynchronous glaciation between them. Moraines in the Puga and Karzok valleys broadly correlate with previous studies in the Zanskar Range but the paucity of data for many of the glacial stages across the Zanskar region makes the correlations tentative. The lack of early Holocene glaciation in the Puga and Karzok valleys is in stark contrast to many regions of the Himalaya, including Lahul, and the restricted glacial extent in Zanskar is more similar to the style of glaciation in Ladakh. The similarity between the glacial records in the Puga and Karzok study areas suggests that the transition to Lahul style glaciation is to the south of the Karzok valley, showing that this geographical transition is abrupt. [Copyright &y& Elsevier]

The climate change of the 20th century has had a pronounced effect on glacier environments of the Himalayas. The formation of moraine dammed glacial lakes and outburst floods from such lakes are a major concern in countries such as Bhutan, Tibet (China), India, Nepal and Pakistan. The hazardous lakes, however, are situated in remote areas and are very difficult to monitor through ground surveys due to the rugged terrain and extreme climatic conditions. This paper depicts the growth of a glacial lake in Reru Valley, Zanskar Himalaya based on the observations made from temporal satellite data. The change detection studies show the glacier retreating at an average rate of 12 m per year, causing lateral growth of the lake. Peak discharge from the lake is estimated using empirical formulas and varies from 1.7 m3 s-1 to 196 m3 s-1. [ABSTRACT FROM AUTHOR]

Abstract: Equilibrium-line altitude (ELA) of a glacier can be an adequate indicator for glaciation and local climate. This study addresses the present ELA in eastern Nepal, in comparison with that of the Last Glacial Maximum (LGM). The present ELA of each glacier was identified by its surface topography using the latest aerial photograph interpretations. ELAs during the LGM were mostly estimated by the maximum elevation of lateral moraines (MELMs). The distinguished higher altitudes of the MELM were selected to estimate the ELAs during the LGM. Latitudinal profiles of the present equilibrium-line show southward gradients, interpreted as a product of the reduction in precipitation from monsoon humid wind blowing into the High Himalayas. Latitudinal ELA profiles of the LGM show the same southward inclination, suggesting that monsoon precipitation is likely to be a ruling resource on glacier nourishment. The eastern Nepal Himalayas, hence, was under summer monsoon environment during the LGM same as present, even if the SW monsoons were weaker. [Copyright &y& Elsevier]

Constraining the timing and extent of past glaciations can help understand how glaciers respond to climate change as well as study past changes in atmospheric circulation patterns, precipitation and temperature. Southern Tibet, thanks to its numerous, well-preserved, glacial deposits, is an ideal place to conduct such study, as it receives occasional winter precipitation from the mid-latitude Westerlies and abundant summer precipitation (snowfall at high elevation) from the Indian and East Asian monsoons. The fact that amounts of precipitation varied in space and time over the plateau, greatly influenced past glaciations, now recorded as successive moraine deposits. Here, we study two large moraines from the southern Yadong rift (China-Bhutan border) and determined (using 19 new 10Be cosmogenic samples) that at Jichu, which is located at the base of high summits (~7000 m), glacial deposits were abandoned during Marine oxygen Isotope Stage (MIS)-3 (~29–57 ka), and that at Qudui, located at the base of lower summits (~6000 m), the moraine was deposited during the Last Glacial Maximum (LGM, 19–26.5 ka). Both moraines directly rest on top of presumably MIS-6 (~130–191 ka) remnant surfaces. We suggest that while abundant MIS-3 precipitation allowed MIS-3 moraines to be deposited at the base of the highest summits (such as at Jichu) despite warmer temperature than during the LGM, smaller amounts of precipitation occurred during colder MIS-2, blocked by high summits, preventing deposition of large LGM moraines. By contrast, where restricted LGM precipitation can easily reach across lower summits, large MIS-2 moraines exist at their base (such as at Qudui). In addition, we compiled published ages from 22 most extensive moraines (≤MIS-6) from the northern Himalaya to central Tibet (211 samples) along three N-S transects (~50–400 km-long). We found that the relative extent of LGM and MIS-3 moraines varies between different regions, that we infer is due to spatial variations in precipitation: in general, MIS-3 (or maybe MIS-4 at places) moraines are more extensive than MIS-2 moraines, except in the Yadong rift, where LGM monsoon was able to reach, thanks to low topographic barrier and proximity to the monsoonal front. This thus allows to draw the limit of monsoonal precipitation during the LGM. [Display omitted] • We dated one MIS-3 moraine at the base of >7000 m-high peaks in the Yadong rift. • We dated one LGM moraine at the base of ~6000 m peaks with abundant LGM precipitation. • We compiled ages from three N-S transects from northern Himalaya to central Tibet. • LGM moraines >MIS-3 moraines only where LGM precipitation are strongest. • We show new LGM monsoon limit from relative moraine extents. [ABSTRACT FROM AUTHOR]

The article focuses on the findings of a study on the composition of plant species found in Garwahal Himalaya Mountains. It mentions about the rapidly rising snowline of the Himalayas due to climatic change leading to the formation of moraines and informs that the study aimed to examine the extension of plants due to reduced mass of the glacier, together with vegetational composition. The study discussed various plant species in the geomorphic units, glacio-fluvial and glacial zones.

In Nepal, rockfall related studies are rarely conducted and are limited to the landslide study along with few case studies on rockfall events. Rockfall problems in Nepal are more frequent in the Higher Himalayan region than Midland and Lesser Himalayan regions. In the glaciated valley and glacial lakes, rockfall and associated tsunami like huge wave are a recently initiated research. In this context, a glacial lake of the Himalaya, named as Imja Glacial Lake situated in eastern Nepal has been selected to understand the rockfall problems and their possible consequences. The lake was formed at the end part of the Imja glacier. The northern valley slope of Imja Glacier Lake, i.e. southern slope of the Island Peak has serious problem of rockfall into the lake. Rockfall simulation was performed during this research with field data. Three different Plots were defined for simulation of rockfall. Among them, Plot III seems to be the most hazardous since the detached boulders on the higher elevation can enter into the lake with the maximum velocity of 40 m/s with pre-impact energy more than 3500 kJ. This can develop a surge in the lake water that can break moraine dam. This leads to a serious threat to the downstream communities. Moreover, this research confirms that the rockfall hazard in the higher mountain region of Nepal is critical to creating flash floods due to tsunamis like surge in the lake water and breaching of the dam. [ABSTRACT FROM AUTHOR]

The Himalayan Arc accommodates ~ 2 cm/yr of shortening from the India-Eurasia collision, mostly along the Main Himalayan Thust. Perpendicularly to the main structures, regional cross structures formed by en échelon grabens and half-grabens mark Quaternary extension from central Tibet to the Himalayas. The Yadong-Gulu Rift system is the most striking one with a total length of ~ 500 km. Its southernmost segment -the ~100-km-long Yadong half-graben- entrenches through the Himalayas and forms a 500-to-1500-m-deep asymmetric basin. The average basin surface elevation of ~ 4500 m contrasts with high reliefs of the Jomolhari range that reach 7326 m. They are separated by the N15-trending Yadong normal fault (also called Jomolhari Fault System, JFS) that forms spectacular triangular facets and affects glacial landforms.Though observed as early as the 1980s, offset moraines were never studied in detail in terms of measured displacement or age determination. Recent efforts from paleoclimate studies yielded a high-resolution framework to identify the various stages of Holocene glacial advances and associated moraine formation. These landforms display specific geomorphometric features recognized regionally (ELA, rugosity, crest freshness) that allow correlating across the various glacial valleys within the Yadong Rift and across similar settings in western Bhutan and eastern Nepal. This serves as a robust basis to place the moraine sequence within the Holocene paleoclimatic record and propose formation ages.By combining satellite images from Sentinel-2 (10 m, visible and NIR), Pléiades (0.5 m, visible) and a Pléiades-derived tri-stereo photogrammetric DEM (1 m), we map the fault trace and affected landforms in details and measure co-seismic and cumulative vertical offsets. Paleoclimatic age constraints yield age-vs-displacement measurements along the whole 100-km-long JFS and define a chronology of Holocene deformation events. Within the limits of our observations, we conclude that the last surface-rupturing earthquake likely occurred between 3 and 8 ka BP and produced an average surface displacement of ~2 m. According to scaling relationships, the associated earthquake would have reached Mw 7.2. In addition, cumulative deformation suggests an average vertical slip rate of ~1 mm/yr for the Holocene. [ABSTRACT FROM AUTHOR]