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The retreating behavior of glaciers observed in most of the Hindu Kush–Karakoram–Himalaya (HKH) region has given rise to the formation and expansion of numerous glacial lakes in the region. The lakes expansion under changing climate usually poses high risk of glacial lake outburst flood (GLOF) hazard for the downstream communities. In the present study, the risk of glacial lake outburst flood was investigated in the HKH region of Pakistan using LANDSAT-8 OLI (Operational Land Imager) image data of 2013 period coupled with ground information. The results of present study revealed 3044 lakes (surface area about 134.8 km2) in the three HKH ranges, maximum in the Karakoram (1325) and minimum in the Hindu Kush range (722) during 2013. The lakes exhibited an overall increase of about 26% in number and 7% in area in the region during 2001–2013 period. The increase in lake number was 91% within 2500–3500 m, 20% within 3500–4500 m and 31% within 4500–5500 m elevation range. Among total identified lakes during 2013, 36 were characterized as potentially dangerous glacial lakes (PDGLs) that can pose GLOF hazard in the HKH region. A regular monitoring of cryosphere changes and critical glacial lakes is essential to develop sustainable risk management strategies for this region in future.

The Upper Indus Basin (UIB) is prone to Glacial Lake Outburst Floods (GLOFs). Physical monitoring of such a large area on regular basis is a challenging task especially when the temporal and spatial extent of the hazard is highly variable. The study has been conducted in the Shyok sub-basin of UIB, where there are several human settlements which are endangered due to the GLOF hazard. Sudden breaches in the unstable moraine dams adjoining receding glaciers may occur because of rapid and huge accumulation of turbulent water in the glacial lakes. The purpose of this study was to map the two potentially dangerous glacial lakes and simulate the associated hazard in the downward settlements using HEC-RAS in the GIS environment using Landsat 7 remote sensing data. The ASTER Digital Elevation Model (DEM) is utilized to detect flow accumulation of glacial hazard involving slope, elevation, and orientation of the mountain glaciers. The study results have revealed that settlements of the Shyok Basin are threatened by the GLOF hazard. Keeping in view the seasonal growth of the two potentially dangerous glacial lakes of the Shyok Basin, a low discharge of 100 m3/s from both lakes can affect 20%, whereas a moderate discharge of 300 m3/s and a high discharge of 500 m3/s, respectively, can impact 30% and 40% of the Barah village habitat. The results of the study can provide a platform for the establishment of an early warning and monitoring system to minimize the impact of future GLOFs.

This article deals with the 2010 glacial lake outburst flood (GLOF) which happened in the Chucchun Valley in the Cordillera Blanca (Peru). The volume of the ice and rock fall from Mt. Hualcan was estimated to be about 500,000 m3 and the detachment zone was identified between 5,450 and 5,600 m a.s.l. Basic landforms and processes (e.g. stream erosion, accumulation) were characterized by field investigation (2010 and 2011) as well as the rate of deglaciation using remotely sensed data (1948, 1962, 1970 and 2010). Two relatively independent parts of the Chucchun Valley were identified from the point of view of sediment flux: uppermost part of the catchment (4,192–3,575 m a.s.l.), where even fine-grained sediments were laid down, and the lower reaches up to the confluence (3,191–2,640 m a.s.l.), where valley bottom sediments were mobilised by the increased discharge. The comparison of field data and potential for erosion or sedimentation derived from the HEC-RAS model mostly showed conformity and discrepancy occurred in the valley segments where an extreme discharge during the 2010 GLOF laid down sediments after the gradient of the flow diminished. The rate of deglaciation is also described using historical remotely sensed data and unpublished reports and was set as 1,040 m in the last 62 years. We focused our attention also on the uppermost part of the catchment and applied a modified quantitative method for GLOF hazard evaluation—high topographical susceptibility for an icefall into the lake was calculated (0.92).

Natural dam failure may cause disastrous floods in the downstream, especially for dam outbursts in progressive failure mode. Until now researches about the characteristics of progressive failure are still completely unclear. In this paper, a series of flume tests were conducted to investigate the formation mechanism of progressive failure of natural dam, the breaching characteristics and the effect of outburst flood on the channel bed. According to the results, three typical features in the progressive failure process of natural dams were observed: seepage on downstream slope, slide of the downstream slope and overtopping. With phreatic line rising continuously, seepage occurred on the downstream slope, which caused slide of downstream slope of the dam. The breaching discharge hydrographs were asymmetric on both sides of peak discharge, which was similar to the breaching discharge of overtopping. The relationship between breach width and depth was like a shape of “S”, which followed a logistic function. In the breaching process, sediment in the channel bed near the dam was first deposited and then scoured, where the flow velocity was large with strong turbulence; while flow on channel bed far away from the dam showed lower velocity and the flow regime transferred from supercritical flow to subcritical flow. Sediment deposited at first and then scoured gradually on channel bed, but only deposited at a large distance from the dam. The outburst flood eroded the channel bed continuously, the erosion mechanism was from tractive erosion to backward erosion, and returned to tractive erosion finally. In addition, the further away from the dam, the weaker the erosion intensity was. The results of this paper enriched the understanding of the failure mechanism of progressively outburst natural dam, which is helpful to predict breaching parameters in progressive failure mode and to provide some reference about flood prevention.

Melting glaciers have a direct contribution to sea level rise, runoff and glacier lake outburst flood disasters. Therefore, accurate estimations of glacier mass balances with high spatial (large region) and temporal (annual, seasonal) resolutions are very important. However, the estimation of glacial mass balances in mountainous regions is usually hampered by remoteness and the lack of high-precision topographic data for most mountain ranges. This study presents a novel method for estimating mass changes in mountain glaciers using InSAR data. We utilised observations of glacier surface deformation to derive changes in thickness, and then calculated the mass change. This method can accurately estimate short-term mass changes. We apply this method to the Koxkar glacier in the Tien Shan Mountain Range in China and successfully estimate the seasonal mass change. Using theoretical error and statistical error analysis, we determined that the accuracy of this method is much better than other geodetic methods. We analyse the spatial characteristics of the mass changes in the ablation zone for the first time. The results show considerable spatial and seasonal variability, which were mainly from ablation in the summer, with the greatest amount of glacial ablation reaching up to − 3872 mm water equivalent (w.e.), and from accumulation in the winter.

Mountain glacier is one of the extremely sensitive indicators for climate change, and its surface motion distribution and corresponding variation are valuable information for understanding ice mass exchange and glacier dynamics. This paper presents the long-term ice velocity distributions of Inylchek Glacier in the Tianshan region by pixel-tracking algorithm with time-series Landsat imagery acquired during 2006–2016. Then the monitored ice motion fields of Inylchek Glacier were carefully analyzed and revealed a generally similar spatial distribution characteristic. Most of the ice of the North Inylchek Glacier remains in a stagnant state except for the upstream part, but a relatively high velocity of 20–40 cm/day with an RMSE of 3 cm/day was observed on most part of the South Inylchek Glacier, except for the slow-moving glacier terminus. We also state the glacier dynamics around Lake Merzbacher and their possible effect on its glacier lake outburst flood (GLOF) risk. Besides, the surface velocity distribution on South Inylchek Glacier surface during the ablation period from 2014 to 2016 was also established and also compared with annual velocity. The corresponding difference yields that there is a positive relation between ice motion and temperature variation. Therefore, the time-series ice surface motion yielded by the Landsat imagery thus could provide us an efficient and low-cost way to analyze the current state and changes in glaciers, thanks to the continuous and regular spaceborne observations provided by the Landsat satellites.

This study assessed the changes in the area, snout and proglacial lake formation for Drang Drung glacier located in Zanskar region of Jammu and Kashmir using earth observation data of 46 years from 1971 to 2017. In addition, ice thickness and formation of potential future lakes were modelled using a distributed model—GlabTop. Our analysis indicated that Drang Drung glacier shrunk by 13.84% from 1971 to 2017. Meteorological projections of temperature and precipitation over region were used to understand climatic changes over Drang Drung region. The snout of the glacier has retreated by 925 m since 1971 at the rate of 21.11 ma−1. However, the snout retreat radically accelerated since 2014 at 60 ma−1. Analysis of available satellite data suggested that the proglacial lake formed around 2014. The lake has expanded to 16.62 ha in 2017 amassing a water volume of 2.69 mi m3 with a potential peak discharge of 2667 m3 s−1. Based on GlabTop simulation, the mean thickness of the glacier is 155 m with the highest thickness of 311 m. Climate projections indicate that the temperatures would rise by over 4 °C by the end of this century with insignificant increase in precipitation. GlabTop simulations indicate formation of two huge lakes with areas of 97 and 47 ha in the lower ablation part of the glacier which could pose a risk to the incidence of glacial lake outburst flood in the near future.

Glaciers on the Tibetan Plateau are undergoing an accelerating retreat under climatic warming, with the immediate result of glacial lake outburst floods (GLOFs) becoming increasingly frequent. Glacial lakes in the southeast of the Tibetan Plateau are densely distributed. Due to the difficulties associated with field investigations of glacial lakes, including remote locations and harsh weather conditions, methods which combine remote sensing, geographic information systems and hydrodynamic modeling (HEC-RAS) with field investigation were developed to assess regional glacial lake variation and hazard. The methods can be divided into three levels. At the first level, multi-temporal satellite images were used to (1) study the variation of glacial lakes for the whole region during recent decades, as well as (2) qualitatively identify potentially dangerous glacial lakes (PDGLs). The second level is an in-depth evaluation of the degree of danger for selected PDGLs by ground-based surveys, and then verification of the first-level results. At the third level, the one-dimensional (1D) hydrodynamic model HEC-RAS was used to simulate the inundation characteristics of hypothetical outburst of PDGLs. The three levels downscale from the whole study area to individual PDGLs, and thus assess the hazard of glacial lakes progressively. The methods were then applied to a region of southeastern Tibet—the Boshula mountain range—to analyze the variation of glacial lakes and assess potential hazards posed by GLOFs. Since these methods employ easily accessible data and instruments, the application in other regions is promising.