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The Kangri Karpo Mountain Range on the Qinghai-Tibet Plateau frequently experiences glacial lake outburst floods (GLOFs). This study assessed the risk of outburst floods for Guangxieco Proglacial Lake (GPL) in this Mountain Range as a typical case to reveal the effects of rapid glacial change. The area of Gongzo Glacier behind GPL decreased by 7.39 ± 0.10% from 1987 to 2019, while this glacier advanced by 32.45 m from 5 June to 27 October in 1988. Guangxieco Proglacial Lake decreased from 0.42 ± 0.03 km2 in 1987 to 0.19 ± 0.03 km2 in 1988 and then continuously expanded to 0.43 ± 0.04 km2 in 2019. Heavy precipitation occurred before 15 July 1988, when no supraglacial lake existed. Meanwhile, sustained abnormally high air temperature caused accelerated glacier and snow melting. Since 1988, a larger volume of rainfall and meltwater impounded by the ice wall caused an increase in the basal water pressure in the glacier. A significant increase in winter mass balance has caused a further increase in the downward gravity component of glacier sliding. As a result, the glacier advanced rapidly while reopening previously blocked subglacial drainage systems. The accumulating subglacial water rapidly drained into the Proglacial Lake causing an elevated lake level and a GLOF event. However, the current area of the glacial lake has recovered to the scale present before the outburst in 1988. Therefore, local government agencies and the local community should improve early warning systems and take measures designed to prevent a new GLOF and to minimize the risk of a recurrence of a GPL outburst.

The existence of numerous lakes in the higher reaches of the Himalaya makes it a potential natural hazard as it imposes a risk of glacial lake outburst flood (GLOF), which can cause great loss of life and infrastructure in the downstream regions. Hydrodynamic modeling of a natural earth-dam failure and hydraulic routing of the breach hydrograph allow us to characterize the flow behavior of a potential flood along a given flow channel. In the present study, the flow hydraulics of a potential GLOF generated due to the moraine failure of the Satopanth lake located in the Alaknanda basin is analyzed using one-dimensional and two-dimensional hydrodynamic computations. Field measurements and mapping were carried out at the lake site and along the valley using high-resolution DGPS points. The parameters of Manning’s roughness coefficient and terrain elevation were derived using satellite-based raster, the accuracy of which is verified using field data. The volume of the lake is calculated using area-based scaling method. Unsteady flood routing of the dam-break outflow hydrograph is performed along the flow channel to compute hydraulic parameters of peak discharge, water depth, flow velocity, inundation and stream power at a hydropower dam site located 28 km downstream of the lake. Assuming the potential GLOF event occurs contemporaneously with a 100-year return period flood, unsteady hydraulic routing of the combined flood discharge is performed to evaluate its impact on the hydropower dam. The potential GLOF resulted in a peak discharge of ~ 2600 m3s−1 at the dam site which arrived 38 min after the initiation of the moraine-failure event. The temporal characteristics of the flood wave analyzed using 2D unsteady simulations revealed maximum inundation depth and flow velocity of 7.12 m and 7.6 ms−1, respectively, at the dam site. Assuming that the control gates of the dam remain closed, water depth increases at a rate of 4.5 m per minute and overflows the dam approximately 4 min after the flood wave arrival.

The Bolivian Andes have experienced sustained and widespread glacier mass loss in recent decades. Glacier recession has been accompanied by the development of proglacial lakes, which pose a glacial lake outburst flood (GLOF) risk to downstream communities and infrastructure. Previous research has identified three potentially dangerous glacial lakes in the Bolivian Andes, but no attempt has yet been made to model GLOF inundation downstream from these lakes. We generated 2-m resolution DEMs from stereo and tri-stereo SPOT 6/7 satellite images to drive a hydrodynamic model of GLOF flow (HEC-RAS 5.0.3). The model was tested against field observations of a 2009 GLOF from Keara, in the Cordillera Apolobamba, and was shown to reproduce realistic flood depths and inundation. The model was then used to model GLOFs from Pelechuco lake (Cordillera Apolobamba) and Laguna Arkhata and Laguna Glaciar (Cordillera Real). In total, six villages could be affected by GLOFs if all three lakes burst. For sensitivity analysis, we ran the model for three scenarios (pessimistic, intermediate, optimistic), which give a range of ~ 1100 to ~ 2200 people affected by flooding; between ~ 800 and ~ 2100 people could be exposed to floods with a flow depth ≥ 2 m, which could be life threatening and cause a significant damage to infrastructure. We suggest that Laguna Arkhata and Pelechuco lake represent the greatest risk due to the higher numbers of people who live in the potential flow paths, and hence, these two glacial lakes should be a priority for risk managers.

Kyagar glacier lake outburst floods (GLOFs) have long been a serious nature hazard in Yarkant river basins of the Chinese Karakoram, threatening more than one million people. Between 1810 and 2018, 34 Kyagar GLOF events have been recorded, of which 26 occurred from 1960 onwards and their occurrence frequency reaches at least three times in each decade. An early warning system established in 2011 has successfully predicted the Kyagar GLOF events in 2015, 2016, 2017 and 2018, which provides an important reference for the monitoring and risk pre-evaluation of the GLOFs in Karakoram.

Glacial lake outburst floods (GLOFs) are common where highly dynamic temperate glaciers exist, since seasonal changes in ice-conduit dynamics can start rapid lake drainages. Lakes dammed by cold-based glaciers, however, are less common and GLOFs from these glaciers have been rarely reported. Understanding both the origin and the failure mechanisms of lakes dammed by cold-based glaciers and subsequent flood processes is essential for territorial planning. We study a remarkable GLOF triggered by the failure of a subglacial lake in the Manflas Valley, Arid Andes of Chile, in 1985 providing insights into the lake’s origin, clarifying the failure mechanism and modelling the GLOF event-related dynamics. To identify the factors that contributed to the lake formation and failure, we analysed remotely sensed images, meteorological and topographic data. The GLOF dynamics were reconstructed using empirical (LAHARZ and MSF) and physical models (RAMMS). The obtained results were compared with field data of flow extent, depth and velocity. We show that the failed lake (4 × 106 m3) formed in a low-slope (≤ 10°) area and that extreme (≥ 90th percentile) annual precipitation before the GLOF contributed to the lake filling and probably to the dam collapse. The lake likely drained rapidly after mechanical failure of the ice-dam producing a high energy sediment-laden flow. We show the challenges of modelling large flows over long distances (dozens of kilometres) especially when flows change between Newtonian and Non-Newtonian phases. A GLOF can still endanger the Manflas Valley since a remnant of the lake of about 220.000 m3 exists and economic assets are located along the1985 GLOF path.

Glacial lake outburst floods (GLOFs) are a serious and potentially increasing threat to livelihoods and infrastructure in most high-mountain regions of the world. Here, we integrate modelling approaches that capture both current and future potential for GLOF triggering, quantification of affected downstream areas, and assessment of the underlying societal vulnerability to such climate-related disasters, to implement a first-order assessment of GLOF risk across the Himalayan state of Himachal Pradesh (HP), Northern India. The assessment thereby considers both current glacial lakes and modelled future lakes that are expected to form as glaciers retreat. Current hazard, vulnerability, and exposure indices are combined to reveal several risk ‘hotspots’, illustrating that significant GLOF risk may in some instances occur far downstream from the glaciated headwaters where the threats originate. In particular, trans-national GLOFs originating in the upper Satluj River Basin (China) are a threat to downstream areas of eastern HP. For the future deglaciated scenario, a significant increase in GLOF hazard levels is projected across most administrative units, as lakes expand or form closer towards steep headwalls from which impacts of falling ice and rock may trigger outburst events. For example, in the central area of Kullu, a 7-fold increase in the probability of GLOF triggering and a 3-fold increase in the downstream area affected by potential GLOF paths can be anticipated, leading to an overall increase in the assigned GLOF hazard level from ‘high’ to ‘very high’. In such instances, strengthening resilience and capacities to reduce the current GLOF risk will provide an important first step towards adapting to future challenges.

Kedarnath (3,533 m, 30°44′05″N, 79°04′02″E) is situated within a kilometre of the termini of the Chorabari and Companion glaciers in the Indian Himalaya. An outburst flood from a lake (3,845 m) formed by right lateral moraine of the former caused severe damage to the village on 17 June 2013. We determined various physical parameters of the lake from three digital elevation datasets (CartoDEM, SRTM and ASTER) and selected the SRTM-derived data as they appeared to portray the region more accurately. The obtained parameters were used in predictive equations suggested by different authors to estimate peak discharge of the flood. We also compared high-resolution images of 10 December 1965 (Corona), June 2011 (Bing) and 25 June 2013 (Catrosat-1 Pan + LISS-4mx) to assess the damage caused to the village besides other geomorphic changes. The results showed that at least 149 mm of rainfall in its 291-ha catchment was required to fill up the lake, without considering the presence of antecedent water and loss from seepage and evaporation. At the point of breaching, the lake released 0.43 × 106 m3 of water with a peak discharge of 1,352 cumecs. The north-western section of Kedarnath village was on the direct path of the debris flow triggered by the flood and was almost completely destroyed. The southern and south-eastern sections were least affected. Out of 37,299 m2 of pre-event roof area of Kedarnath (259 structures), 44.2 % were obliterated and 26.7 % were partly damaged, representing 138 and 56 structures, respectively. Only one-quarter of the structures of the village emerged intact or slightly affected after the event.

Glacial lake outburst flood (GLOF) is a powerful natural phenomenon that is very active in the Karakoram and Himalayas. This paper presents a case study from Gupis Tehsil in northern areas of Pakistan that is exposed to GLOFs from nine different glacial lakes in its upper catchment areas. Khukush Lake being the largest of all the glacial lakes has been studied and a flood attenuation model has been created for the whole Gupis Tehsil. This lake covers almost 2.2 km2 of surface area, and its calculated volume is 2.6 × 104 m3. In case of its outburst, the peak flow discharge is calculated to be 7,642 m3/s. The catchment area which contributes water and debris to the lake is 170 km2. This lake is dammed by a glacial moraine, which is not strong enough to sustain the pressure for a longer period of time. Other factors that are reducing the reliability of the dam are the secondary hazards which are in direct contact with the lake, and in case of their reactivation, they can put severe impacts on the dam. There are eight potential sites of the snow avalanche activity where debris along with snow may fall directly into the lake producing a strong wave. This strong wave of water will increase the pressure on the dam and ultimately will increase the probability for its outburst. The presense of water springs towards the downstream side of the natural dam also indicate the presence of hidden channels passing through the dam which may weaken the shear strength of the dam. Almost 24 villages settled along either sides of the Gupis River are critically studied for the expected flood from Khukush Lake. With few exceptions, almost 20–25 % area of all the villages will be affected from this flood.

In April 2010, an ice/rockfall into Lake 513 triggered a glacial lake outburst flood (GLOF) along the Chucchun River in the Cordillera Blanca of Peru. This paper reconstructs the hydrological characteristics of this as yet undocumented event using a 1D flood model prepared with HEC-RAS. The principle model inputs were obtained during detailed field surveys of surface characteristics and topography within the river and across the adjacent floodplain; a total of 120 cross-sections were surveyed. These inputs were refined further by eyewitness accounts and additional geomorphological observations. The flood modelling has enabled us to constrain the extent of the water surface and its elevation at each cross-section in addition to defining the peak discharge (580 m3 s−1). These modelling results show good agreement with other information about the flood including: flood marks and minimum flood levels; the lake displacement wave height; the extent of the flooded area; and the travel time from Lake 513 to the confluence with the Santa River. This demonstrates that the model offers a reliable reconstruction of the basic hydrological characteristics of the GLOF. It provides important information about the flood intensity and significantly improves our ability to model future flood scenarios along both the studied river and within neighbouring catchments. The flood hazard, defined by the flood depth during peak discharge, shows that the majority of the damaged infrastructure (houses, bridges, and a drinking water treatment plant) was only subjected to low or medium flood intensities (defined by a maximum water depth of less than 2 m). These low flood intensities help to explain why the flooding caused comparatively minor damage despite the significant public attention it attracted.

Glacial hazards relate to hazards associated with glaciers and glacial lakes in high mountain areas and their impacts downstream. The climatic change/variability in recent decades has made considerable impacts on the glacier life cycle in the Himalayan region. As a result, many big glaciers melted, forming a large number of glacial lakes. Due to an increase in the rate at which ice and snow melted, the accumulation of water in these lakes started increasing. Sudden discharge of large volumes of water with debris from these lakes potentially causes glacial lake outburst floods (GLOFs) in valleys downstream. Outbursts from glacier lakes have repeatedly caused the loss of human lives as well as severe damage to local infrastructure. Monitoring of the glacial lakes and extent of GLOF impact along the downstream can be made quickly and precisely using remote sensing technique. A number of hydroelectric projects in India are being planned in the Himalayan regions. It has become necessary for the project planners and designers to account for the GLOF also along with the design flood for deciding the spillway capacity of projects. The present study deals with the estimation of GLOF for a river basin located in the Garwhal Himalaya, India. IRS LISSIII data of the years 2004, 2006 and 2008 have been used for glacial lake mapping, and a total of 91 lakes have been found in the year 2008, and out of these, 45 lakes are having area more than 0.01 km2. All the lakes have been investigated for vulnerability for potential bursting, and it was found that no lake is vulnerable from GLOF point of view. The area of biggest lake is 0.193, 0.199 and 0.203 km2 in the years 2004, 2006 and 2008, respectively. Although no lake is potentially hazardous, GLOF study has been carried out for the biggest lake using MIKE 11 software. A flood of 100-year return period has been considered in addition to GLOF. The flood peak at catchment outlet comes out to be 993.74, 1,184.0 and 1,295.58 cumec due to GLOF; 3,274.74, 3,465.0 and 3,576.58 cumec due to GLOF; and 100-year return flood together considering breach width of 40, 60 and 80 m, respectively.

Existing methods of evaluating the hazard posed by moraine-dammed lakes are unsystematic, subjective, and depend on the expertise and biases of the geoscientist. In this paper, we provide a framework for making objective preliminary assessments of outburst flood hazard in southwestern British Columbia. Our procedure relies on remote sensing methods and requires only limited knowledge of glacial processes so that evaluations of outburst flood hazard can be incorporated into routine hazard assessments of glaciated regions. We describe objective approaches, which incorporate existing empirical relations applicable to the study region, for estimating outburst peak discharge, maximum volume, maximum travel distance, maximum area of inundation, and probability. Outburst flood hazard is greatest for moderately large lakes that are impounded by large, narrow, ice-free moraine dams composed of sedimentary rock debris and drain into steep, sediment-filled gullies above major river valleys. We demonstrate the application of the procedure using three case studies and show that flood hazard varies, especially with major changes in lake level. Our assessment scheme yields reproducible results and enables engineers and geoscientists to prioritize potentially hazardous lakes for more detailed field investigation.

Landslide Lake Outburst Floods (LLOFs) are common in the Himalayan river basins. These are caused by breaching of lakes created by landslides. The active and palaeo-landslide mapping along the Satluj and Spiti Rivers indicate that these rivers were blocked and breached at many places during the Quaternary period. In the present article, we document LLOFs during 2000 and 2005 caused by the breaching of landslide lakes created in the Trans-Himalayan region along the Satluj River and Paree Chu (stream), respectively, both in the Tibetan region of China and its impact on the channel and infrastructure in the Kinnaur district of Himachal Pradesh, India. It has been observed that the loss of life and property due to these LLOFs is directly related to the disposition of the Quaternary materials and the different morphological zones observed in the area.

A good understanding of seismic giant landslides could provide favourable guidance for seismic stability evaluation of nearby slopes. Here, an excellent example of a catastrophic seismic landslide named the Mogangling giant landslide (MGL), located upstream along the Dadu River and triggered by the 1786 Moxi M 7.75 earthquake, is analysed for its deposit characteristics, failure mechanism and dammed lake. The MGL, with a volume of approximately 4500 × 104 m3, 450 m long and 1000 m wide, blocked the Dadu River completely and caused over 100 000 deaths when the landslide dam broke. The MGL occurred on the upper part of a narrow granite ridge; a potentially unstable wedge-shaped rock mass was separated from the remaining massif by unloading fissures and an active fault (Detuo fault) that just crossed the slope foot. The Moxi earthquake coupled with strong site amplification triggered the MGL, which blocked the Dadu River; the elevation of the dam crest was approximately 130 m higher than the present river level. The dammed lake had a volume of approximately 9.504 × 108 m3, an area of 19.91 km2 and a length of approximately 31 km; the peak flow of the outburst flood was larger than 7100 m3/s. After hundreds of years of concave bank erosion, the deposit is divided into the right bank deposit (main deposit) and left bank deposit (residual deposit).

The assumed Jargalant rockslide is located in Khentey Upland of Mongolia, an area undergoing active tectonic deformation and seismogenic activity but where geomorphic research that connects rock slope failure and long-term paleoseismic events has yet to be conducted. We present the first reconnaissance study on this topic, which demonstrates the possibility of cosmogenic 10Be dating of landslide-induced bouldery deposits to date the timing of the assumed seismic events. We performed integrated geomorphic analysis (geomorphic mapping, topographic profile analysis, and surface trenching) and 10Be surface exposure dating (boulder and bedrock scar) to document the recurrence interval of the assumed paleoseismic events by determining the recurrence of rock slope failures in Jargalant River valley. We identified four geomorphic surfaces and units identified based on their morphology, the distribution of quartzite boulders, and their ages. The geomorphic units are as follows: (1) outburst flood fan (S1), (2) remnant landslide-dam deposit (S2), (3) surviving rockslide body (S3), and landslide scar (S4). Bedrock quartzite outcrops only in the assumed headscarp, while most of the upland is composed of schist. The average 10Be age of quartzite boulders of S1 to S3 is 283.4, 138.8, and 48.4 ka, respectively, and that of the landslide scar (inner and outer edge) are 44.5 and 193.5 ka. Based on the morphology, depositional characteristics, quartzite provenance, and separated and clustered 10Be exposure age, we hypothesize that at least three catastrophic rock slope failures could occur at 283 ka, 138 ka, and 48 ka, likely being triggered by earthquakes associated with active Kherlen fault.

Future trends in the occurrence of heat waves (HW) over Pakistan have been presented using three regional climate models (RCMs), forced by three different global climate models (GCMs) runs under RCP8.5 scenarios. The results of RCMs are obtained from CORDEX (Coordinated Regional climate Downscaling EXperiment) database. Two different approaches for the assessment of HWs are defined, namely Fixed and Relative approaches. Fixed approach is defined for a life-threatening extreme event in which the temperature can reach more than 45 °C for a continuous stretch of several days; however, Relative approach events may not be directly life-threatening, but may cause snow/ice melt flooding and impact on food security of the country in summer and winter seasons, respectively. The results indicate a consistent increase in the occurrence of HWs for both approaches. For the Fixed approach, the increase is evident in the eastern areas of Pakistan, particularly plains of Punjab and Sindh provinces which host many big cities of the country. It is argued that the effect of HWs may also be exacerbated in future due to urban heat island effect. Moreover, summer time HWs for Relative approach is most likely to increase over northern areas of the country which hosts reservoirs of snow and glacier, which may result in events like glacial lake outburst flood and snow/ice melt flooding. Furthermore, the increase in winter time HWs for Relative approach may affect negatively on the wheat production, which in turn can distress the overall food productivity and livelihoods of the country. It is concluded that this study may be a useful document for future planning in order to better adapt to these threats due to climate change.

Glaciers are retreating and thinning in the high altitude of the Himalayas due to global warming, causing into formation of numerous glacial lakes. It is necessary to monitor these glacial lakes consistently to save properties and lives downstream from probable disastrous glacial lake outburst flood. In this study, image processing software ArcGIS and ERDAS Imagine have been used to analyse multispectral image obtained by Earth resource satellite Landsat for delineating the glacial lakes with the help of image enhancement technique like NDWI. Landsat data since 1972 through 2013 have been used and maximum seven glacial lakes (L1–L7) have been detected and delineated in Dhauliganga catchment, they are situated above 4000 masl. The Glacial Lake L2 (Lat 30°26′45″E and Long 80°23′16″N) is the largest whose surface area was 132,300 m2 in Sept 2009, and L6 (Lat 30°23′27″E and Long 80°31′52″N) is highly unstable with variation rate −55 to +145 % with increasing trend. Additionally, glacial lakes L2 (Lat 30°26′45″E and Long 80°23′16″N) and L6 (Lat 30°23′27″E and Long 80°31′52″N) have been identified as potentially hazardous. These lakes may probably burst; as a result, huge reserve of water and debris may be released all on a sudden. This may transform into hazardous flash flood in downstream causing loss of lives, as well as the destruction of houses, bridges, fields, forests, hydropower stations, roads, etc. It is to note that Dhauliganga river considered in this study is a tributary of Kaliganga river, and should not be confused with its namesake the Dhauliganga river, which is a tributary of Alaknanda river.

This study presents the one-dimensional hydrodynamic modeling for the Glacier Lake Outburst Flood (GLOF) simulation for the six hydroelectric (HE) power projects in Dhauliganga River of Alaknanda Basin. ArcGIS and HEC-GeoRAS extension is used for the whole river GIS database creation. Elevation values and cross-sections were taken from digital elevation models. The initial flow hydrographs were used as upstream boundary condition in MIKE11. The land use/land cover map and Manning’s N values for roughness were prepared using LANDSAT TM and CARTOSAT-1 and verified by the field observation. Cross-sections were also modified after identifying the actual cross-sections width and depth. Subsequently, simulation has been carried out by using MIKE11 HD model at different sections of the river stretch. Calibration is done for the period of June 1, 2001, to May 31, 2002, and validated for the year of 2005 with about 95 % accuracy of observed data. In this study, results have been carried out by 100-year flood ordinates and considering the redistribution of lateral flow from five catchments of Alaknanda Basin. The GLOF peaks for the breach parameters are 1394.28, 1552.04 and 1898.04 m3/s for breach width 40, 60 and 80 m, respectively, just the downstream of the lake site. It is inferred from the study that the GLOF for 80 m breach width gives the peak flood of 1575 m3/s at the project site 1 for first scenario and 3500 m3/s at the site 6 for second scenario. The maximum simulated water levels and depth for the Central Water Commission gauging site at Joshimath are 1381.49 and 4.329 m, respectively, for 100-year-plus GLOF event. This information is critical for the project design discharge calculations.

Knowledge of Himalayan cryosphere seems to be an outstanding requirement for assessment of glacier storage, water balance analysis, planning of water resources and flood hazard monitoring. A stepwise approach through mapping glaciers and glacial lakes using satellite remote sensing data and investigating potential glacial lake outburst flood (GLOF) hazards was adopted for the three Hindukush, Karakoram and Himalayan (HKH) ranges of Pakistan. The findings of the study revealed 5,218 glaciers in the cryosphere of HKH ranges. The cumulative glacial cover of over 15,000 km2 contains ice reserves of about 2,738 km3. About 46 % of the Karakoram glaciers are contributing 77 % to the total glacial cover and 87 % to the cumulative ice reserves of the country. The 33 % Himalayan glaciers and 21 % Hindukush glaciers contribute only 3 and 10 % ice reserves, respectively. Among 2,420 glacial lakes identified in the three HKH ranges, 52 were classified as critical lakes that can pose GLOF hazard for the downstream communities. Most of the potential hazardous lakes lie in the Karakoram and Himalayan ranges, the monitoring of which is crucial to reduce high risk of future floods hazard in this fragile mountain ecosystem of the Himalayan region.

In recent decades, many of the larger glaciers in the Himalaya and Andes that have experienced increased melting have become glacial lakes. Some of these lakes present a risk of glacial lake outburst floods that can unleash stored lake water and eroded debris, often causing enormous devastation downstream. Many of these new glacial lakes have formed in the Mt. Everest and Makalu Barun National Parks of Nepal, nine of which in the remote Hinku and Hongu valleys have been designated as “potentially dangerous” based on remote sensing analyses. Until recently, however, relatively little ground-based information was available for these lakes, including their physical characteristics, danger level, prospective downstream impacts in the event of an outburst, and mitigation methods appropriate and applicable to remote regions within the Nepal Himalaya. This paper describes three separate, interdisciplinary expeditions to the Hinku and Hongu valleys between 2009 and 2012 that were designed to close these information gaps. Each expedition combined remote sensing with field-based analyses, repeat photography, interviews with local people, bathymetric surveys, ground penetrating radar, and flood modeling. Eight of the “potentially dangerous” lakes surveyed were found to be stable, and one that had escaped mention in previous studies (L464) was found to contain a high risk of an outburst flood. In the data-deficient high mountain world, we suggest that the combined use of sophisticated remote sensing and modeling technologies with traditional, field-based methods can provide the most thorough understanding of glacial lakes possible at this time, including the actual risks that they pose as well as the most appropriate and community-based risk reduction strategies.

A shallow-focus damaging earthquake of magnitude 6.9 Mw struck the Sikkim Himalaya, north-east India, on 18 September 2011 at 12:40:48 UTC (06:10:48PM IST). The epicentre was located north-west of Chungthang on Indo-Nepal border of Sikkim Himalaya. The earthquake was widely felt in northern India and caused widespread damage to poorly built and framed structures in Sikkim region, northern Bihar, eastern Nepal, southern Bhutan and part of Tibet adjoining Sikkim Himalaya. A lot of secondary effects in the form of landslides, rockfalls and landslide lake outburst flood were caused due to strong shaking effect of the earthquake. Maximum intensity IX according to the European Macroseismic Scale-98 was observed in the meizoseismal zone surrounding Chungthang village. Asymmetrical distribution and heterogeneous damage pattern demonstrate intensity attenuation characteristics of the region. Although the regional tectonic framework of Sikkim region indicates compressional thrust tectonics regime, according to CMT fault-plane solution this earthquake involved predominantly strike-slip motion on a steep fault. Unlike Nepal and north-west Himalaya where microseismicity and large earthquakes indicate thrust mechanism, this Sikkim earthquake suggests that strike-slip principal component may imply transcurrent deformation.

Natural dams are caused by the blockage of streams as a result of the sudden arrival of detritus material during a glacial surge advance or fast slope collapse threatening downstream populations. Nevertheless, origin, morphological characteristics and stability of dammed lakes are frequently ignored. Six impounded palaeo-lakes were geomorphologically studied in the Benjamin Matienzo gully (32°14′ S–70°02′ W), denominated, from north to south: Goyete, Negro, Casa de Piedra, Lagunita, Susanita and Matienzo. We determined the origin, morphometric parameters, stability index and rate of streamflow rupture for these dammed ancient lakes in order to shed light on the potential outburst flood hazard in this Andean mountain region. According to our findings, we concluded that palaeo-lakes would have had a short life as they turned out to be unstable, except for the Goyete Lake, matching with the lack of fine lacustrine sediments in all river blockages. We also estimated the maximum peak discharge of a probable outburst flow generated during a drastic collapse of these dams. Obtained values range between 22 and 151 m3/s being notably higher than the average annual streamflow of Las Cuevas River (6.6 m3/s), but similar to the instantaneous streamflow of this river (157 m3/s, 2-year recurrence time).

The moraine dam of the Tam Pokhari glacial lake breached on 3 September 1998 and caused a catastrophic flood in the downstream areas. To learn from the event, a field survey was conducted. The survey team found that a landslide, which is considered to be responsible for the outburst flood, occurred in the northeast-facing slope of the moraine dam. The dam internal structure played a crucial role in forming a landslide that triggered the excess overflow and finally the breach of the dam. The internal structure of the dam was made of alternating layers of finer and coarser sediments inclining at 30° downstream and layers are truncated in the upslope direction by a huge pile of unconsolidated and structureless moraine materials. Since the upstream slope angle of the dam i.e., 40° is larger than the angle of repose i.e. 35° of sediments, the increased pore water pressure in the dam triggered a landslide. The rainfall and seismological activities of that particular day, which hit the record high, were crucial in triggering the failure. It is estimated that the dam’s north and northeast-facing slopes completely slid involving about 30,000 m3 of sediment mass of unconsolidated moraine materials above the shear plane. A slope stability analysis was also performed. The calculated safety factor was 0.85, and the calculated slip circle agreed with the shear plane marked in the dam. About 18 million cubic metres of water was swiftly released due to the sudden breach of the moraine dam.

Glacier lakes pose threat to downstream settlements and infrastructure. In recent decades the number and area of lakes have been growing at an accelerating rate due to worldwide glacier shrinkage. In the Russian Caucasus this process is understudied. We present results obtained during a 12-year (1999–2010) continuous field monitoring of the Bashkara proglacial lakes group, which we identified as the place with the highest GLOF risk in the region. Recession of the parent Bashkara Glacier was the main driver of the rapid expansion of the lower Lake Lapa. The upper Lake Bashkara has not been enlarging, but its water level has shown significant inter- and intra-annual fluctuations. The lake outburst probability has increased in recent years, and in 2008 we observed surface overflow over the moraine dam. Taking into account that in the late 1950s lake outbursts at this site led to large-scale glacial debris flows, we have simulated a potential outburst using River and FLO-2D software and carried out hazard zonation. An early warning system has been designed and established at Lake Bashkara, and measures to mitigate risk have been proposed. Rapid change of proglacial lakes requires regular monitoring in ‘hot spot’ areas where the GLOF hazard is high and is dynamically changing.

Like in many other parts of the world, the glaciers in northern Tien Shan are receding, and the permafrost is thawing. Concomitantly, glacial lakes are developing. Historically, outbursts of these glacial lakes have resulted in severe hazards for infrastructures and livelihood. Multi-temporal space imageries are an ideal means to study and monitor glaciers and glacial lakes over large areas. Geomorphometric analysis and modelling allows to estimate the potential danger for glacial lake outburst floods (GLOFs). This paper presents a comprehensive approach by coupling of remote sensing, geomorphometric analyses aided with GIS modelling for the identification of potentially dangerous glacial lakes. We suggest a classification scheme based on an additive ratio scale in order to prioritise sites for detailed investigations. The identification and monitoring of glacial lakes was carried out semi-automatically using band ratioing and the normalised difference water index (NDWI) based on multi-temporal space imagery from the years 1971 to 2008 using Corona, ASTER and Landsat data. The results were manually edited when required. The probability of the growth of a glacial lake was estimated by analysing glacier changes, glacier motion and slope analysis. A permafrost model was developed based on geomorphometric parameters, solar radiation and regionalised temperature conditions which permitted to assess the influence of potential permafrost thawing. Finally, a GIS-based model was applied to simulate the possibly affected area of lake outbursts. The findings of this study indicate an increasing number and area of glacial lakes in the northern Tien Shan region. We identified several lakes with a medium to high potential for an outburst after a classification according to their outburst probability and their downstream impact. These lakes should be investigated more in detail.

Five similar glacial-lake outburst floods (GLOFs) occurred in April, October, December 2008, March and September 2009 in the Northern Patagonia Icefield. On each occasion, Cachet 2 Lake, dammed by the Colonia Glacier, released circa 200-million m3 water into the Colonia River. Refilling has occurred rapidly, such that further outbreak floods can be expected. Pipeflow calculations of the subglacial tunnel drainage and 1D hydraulic models of the river flood give consistent results, with an estimated peak discharge surpassing 3,000 m3 s−1. These floods were larger in magnitude than any flood on record, according to gauged data since 1963. However, geomorphological analysis of the Colonia valley shows physical evidence of former catastrophic outburst floods from a larger glacial-lake, with flood discharges possibly as high as 16,000 m3 s−1. Due to potential impacts of climate change on glacier dynamics in the area, jökulhlaups may increase future flood risks for infrastructure and population. This is particularly relevant in view of the current development of hydropower projects in Chilean Patagonia.

Scientific risk assessment of dammed lakes is vitally important for emergency response planning. In this study, based on the evolution process of the disaster chain, the logic topology structure of dammed lake risk was developed. Then, a quantitative risk assessment model of dammed lake employing Bayesian network is developed, which includes the three modules of dammed lake hazard evaluation, outburst flood routing simulation, and loss assessment. In the proposed model, the network nodes of each module were quantified through statistical data, empirical model, logical inference, and Monte Carlo method. The failure probability of a dammed lake, and the losses of life and property because of its breaching were calculated. This can be multiplied to assess the risk a dammed lake imposes after the uniformization of each loss type. Based on the socio-economic development and longevity statistics of dammed lakes, a risk level classification method for dammed lakes is proposed. The Baige dammed lake, which emerged in China in 2018, was chosen for a case study and risk assessment was conducted. The calculated results showed that the comprehensive risk value of Baige dammed lake is 0.7339 under the condition without manual intervention, identifying it as the extra-high level according to the classification. These results are in accordance with the actual condition, which corroborates the reasonability of the proposed model. This model can quickly and quantitatively evaluate the overall risk of a dammed lake and provide a reference for decision-making in a rapid emergency response scenario.