No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Evolution of glacial lakes from the Northern Patagonia Icefield and terrestrial water storage in a sea-level rise context
... While relationships between lake volumes and other morphometric parameters, especially area, are criticized for the inherent autocorrelation, they are useful in practical applications (Huggel et al., 2002;Wang et al., 2012;Loriaux and Casassa, 2013;Cook and Quincey, 2015;Khanal et al., 2015;Wood et al., 2021;Medeu et al., 2022). Results of regression between the bathymetrically derived volumes and other morphometric parameters are shown in Table 3. ...
... The standardized residuals were generally higher for lakes with depth greater than 20 m but the critical threshold was exceeded for seven lakes only. The highest underestimation characterised two large lakes-Nef in North Patagonia (Loriaux and Casassa, 2013) and Lake No Lake in British Columbia (Geertsema and Clague, 2005)-with areas Frontiers in Earth Science frontiersin.org 08 greater than 50x10 5 m 2 and depth of 150 m. ...
... In addition to Lake No Lake, four other large lakes-Nef (770.7x10 6 m 3 ) in Patagonia (Loriaux and Casassa, 2013), Tasman (510.0x10 6 m 3 ) in New Zealand (Robertson et al., 2012), Phantom (500.0x10 6 m 3 ) in Axel Heiberg Island (Maag, 1963), and Rewoco (139.0x10 6 m 3 ) in China (Zhang et al., 2023)-were identified as outliers (with standardized residuals exceeding the threshold of ±2) whose volumes were significantly underestimated ( Figure 7B). The Petrov Lake in the Tien Shan Janský et al. (2009) was an outlier whose volume was overestimated by 61%. ...
Between 2009 and 2020, 74 bathymetric surveys of 57 glacial lakes were conducted in the northern Tien Shan using the ecosounding technique. The surveys provided data on lake depths and other parameters characterising the three-dimensional lake geometry, and bathymetrically derived lake volumes. The sample included 21 glacier-connected lakes, 27 lakes formed on the young moraines without glacier-connected with glacier tongue, eight lakes formed on the older moraines and one rock-dammed lake. The lakes’ volumes ranged between 0.029x10⁵ and 53.89x10⁵ m³ with the largest value of mean depth was 23 m. There is a statistically significant correlation between lake depth and width, length and area, best approximated by the power, linear, and polynomial models, with coefficients of determination ranging between 0.50 and 0.78 for the glacier-connected lakes. The power equations underestimated both depths and volumes of larger lakes but the second-order polynomial model provided a closer approximation in the study region. The obtained data were combined with the bathymetrically derived depth and volume data published in the literature extending the global data set of bathymetries of lakes with natural dams. The area-depth scaling equations derived from the combined data set showed a considerable improvement in correlation between area and depth in comparison with the earlier studies. The measured bathymetries of the glacier-connected lakes were compared with bathymetries of the same lakes simulated using GlabTOP2 model and published simulated ice thickness data. There is generally a good agreement between the measured and simulated bathymetries although GlabTOP2 tends to overestimate lake depths. The data from the bathymetric surveys and GlabTOP2 model are used by the practitioners to reduce and avoid risks associated with glacier lake outburst floods and are important instruments of the regional strategy of adaptation to climate change.
... Proglacial lakes have reportedly grown in number and size across different mountain regions such as the Southern Alps of New Zealand, the Himalayas and Patagonian Andes (e.g., Kirkbride, 1993;Sakai and Fujita, 2010;Carrivick and Tweed, 2013;Loriaux and Casassa, 2013;Iribarren Anacona et al., 2014;Nie et al., 2017;Shukla et al., 2018;Shugar et al., 2020;Zhang et al., 2021). Proglacial lake development can alter ice dynamics by several mechanisms such as flotation of the glacier's terminus, formation of a calving front, and increased ice flow (e.g., Robertson et al., 2012;Tsutaki et al., 2013;Tsutaki et al., 2019). ...
... In 2015 a debris flow entered Chileno Lake, located in Chileno Valley ( Figure 1A), triggering a GLOF that drained an estimated volume of 105 × 10 6 m 3 of water over 7 days (Wilson et al., 2019). In April 2018, the failure of a lateral moraine located in Bayo Glacier, drained Triángulo Lake (0.95 km 2 ) (Loriaux and Casassa, 2013). During the GLOF event, water discharge entered the main trunk of Exploradores Glacier and drained supra-and sub-glacially, damaging a gauging station located downstream. ...
... This is a distinct feature of a glacier in this location, given that most NPI glaciers have experienced a net retreat of the termini from their LIA moraines dated 12th-17th century (Aniya et al., 2007). Recent geomorphological changes in Exploradores Glacier include the development of an ice-dammed lake at the eastern margin (Loriaux and Casassa, 2013;Wilson et al., 2018), an increase in debris cover thickness (Glasser et al., 2016) and supraglacial pond enlargement (Aniya et al., 2007). Moreover, current debris cover disruption by formation of supraglacial ponds and lakes have led previous researchers to hypothesize that the first kilometers (from the glacier front) are disintegrating (Aniya et al., 2007). ...
Proglacial lakes are ubiquitous features formed during deglaciarization and are currently increasing in number in Patagonia and elsewhere. Proglacial lakes can affect glacier dynamics, catchment hydrology and have the potential to cause glacial lake outburst floods. Therefore, monitoring the onset and development of proglacial lake formation is relevant to understand glacial processes and anticipate glacier response to climate change. In this study, we integrate geomorphological and ice-dynamic information to assess proglacial lake development in Exploradores Glacier, Chilean Patagonia. We monitor recent spatial and temporal changes in the lower trunk of Exploradores Glacier (10 km²) to provide a 20-year observation record by combining eight uncrewed aerial vehicles (UAV) surveys between 2019 and 2020, with high-medium resolution satellite imagery (Rapid Eye and Landsat) between 2000 and 2018. We use feature tracking techniques, digital surface elevation model analysis and field data to create a multi-temporal scale (inter-annual and seasonal) and a multi-spatial (cm to km) data set. Our analysis shows that surface velocity overall trend has not changed over the last 20 years and that surface velocity near the terminus is significant (>10 m a⁻¹). Moreover, an exceptional advance over moraine deposits was detected. We also found low downwasting rates (<0.5 m a⁻¹) close to the glacier terminus which are attributed to sufficient ice flux and the insulation effect of the debris-covered surface. However, hundreds of supraglacial ponds were observed and are currently coalescing and expanding by ice-cliff backwasting favoring glacier disintegration. Lastly, it was found that calving losses at the east marginal lake equaled ice-flux input into the lake for the UAV monitored period. This study contributes to a better understanding of glacial lake dynamics during proglacial lake development, and our results may help ice modelling efforts to predict glacier response to future climate scenarios.
... This mass loss is explained in part by regional warming that began in the 1940s and accelerated since the 1960s (Carrasco et al., 2002;Rasmussen et al., 2007;Rosenblüth et al., 1997), followed by increased ice discharge from accelerated tidewater outlet glaciers (Koppes et al., 2009;Melkonian et al., 2013). Twentieth century warming caused many land-terminating glaciers to thin and fragment (Meier et al., 2018;Melkonian et al., 2013), which has promoted the expansion and new formation of proglacial lakes (Izagirre et al., 2018;Loriaux & Casassa, 2013;Wilson et al., 2018). Ice velocity of some tidewater outlet glaciers increased and their fronts retreated significantly (e.g. ...
... Of all the mapped lakes, those that are in direct contact with the CDI and were formed after the end of the LIA, but have lost contact with the ice margin, were considered as glacial lakes. This is because icedammed and moraine-dammed lakes have undergone the greatest changes after the LIA (Loriaux & Casassa, 2013), and are susceptible to further changes due to their interaction with glacier dynamics and newly formed moraines Wilson et al., 2018). For this purpose, the LIA glacier extents mapped by Davies and Glasser (2012) and Meier et al. (2018) were compared with USAF Trimetrogon aerial images from 1944/1945 and posterior aerial and satellite imagery. ...
The Cordillera Darwin Icefield (CDI) has experienced widespread retreat since the Little Ice Age (LIA, ∼1870 AD). Prior to this, information on outlet glacier dynamics is limited as there are few terrestrial observations and little mapped deglacial evidence, limiting our understanding of CDI dynamics on Holocene centennial to millennial timescales. Here we present a glacial geomorphological map of terrestrial landforms and features for the CDI and surrounding areas of the Tierra del Fuego archipelago. We digitized more than 8,000 glacial landforms and features covering an area of ∼13,300 km2 from a combination of digital elevation models (DEMs) and high-resolution satellite and aerial imagery (<3 m), supported by multitemporal field mapping. This work provides a detailed geomorphological assessment for the area, summarized in a single map, that identifies three main glacial landsystem types of the Patagonian–Fuegian landscape: (i) upland glacier, (ii) lowland land-terminating, and (iii) glaciomarine fjord. The resulting map forms the basis for future chronological campaigns.
... Impacts on meltwater storage and delaying (intercepting) sealevel rise By retaining the glacier meltwater flowing into the ocean, the volumetric increase in glacial lakes has the potential to intercept global sea-level rise. Previous assessments have indicated that in specific regions such as the western Greenland Periphery, the Northern Patagonia Icefield, and the Third Pole, this intercepting impact could contribute 1-10% [35][36][37] . Since the 1990s, there has been a net increase in the global glacial lake volume of 117.1 ± 31.5 km 3 (Supplementary Table 3), equivalent to four times that of the glacial lake total volume in the Third Pole in 2020. ...
... However, these automatic or semi-automatic extraction methods require extensive manual post-processing to address the missed glacial lakes and misplaced non-water bodies, as well as correcting impacts from cloud cover, hill shadows, and snow. Currently, the most widely used method of delineating glacial lakes is visual interpretation, which is adaptable to different glacierized regions where the terrain is complex and the spectral characteristics of glacial lakes are highly variable 35 . This method remains the most accurate and cross-comparable mapping approach in alpine regions 58,59,79 . ...
Global glacial lakes have expanded markedly in recent decades, accompanied by many catastrophic glacial lake outburst floods. However, our understanding of glacial lake evolution and connections with global warming and glacier thinning remains insufficient due to fragmented studies and a lack of standardized mapping. Here we evaluated the glacial lake changes and their drivers, taking care to accurately map glacial lakes while excluding non-glacier fed lakes in the same geographic area. In 2020, a total of 71,508 glacial lakes were identified worldwide, covering an area of 21,770.9±544.2 km². The total volume of 1280.6±354.1 km³ is equivalent to a sea-level rise of 3.45 mm. Since the 1990s, glacial lake numbers, areas, and volumes increased by 54%, 11%, and 9%, respectively. The spatial evolution patterns align well with resolved large-scale, decadal glacier mass changes. Glacier-fed lakes extensively expanded due to glacier retreat and melting, while ice-dammed lakes were primarily affected by thinning ice dams, resulting in heterogeneous changes and underestimated outburst potential. Under the sustained glacier degradation scenario, the results of this study have implications for further evaluation of glacial lake water resources and outburst risks on a global scale.
... km 2 to 4,789.7 km 2 ), Central Europe (from 30.9 km 2 to 31.5 km 2 ) and Svalbard (from 110.0 km 2 to 111.0 km 2 ) (Fig. 3a), potentially highlighting the importance of short-term temporal variability; lake area temporarily decreased at the edge of the Northern Patagonian Icefield from 1945 to 1976 (ref. 69) and in Greenland from 1987 to 1992 and from 2005 to 2010 (ref. 16), perhaps contributing to the smaller, yet still positive, long-term trends 16,69 . ...
... 69) and in Greenland from 1987 to 1992 and from 2005 to 2010 (ref. 16), perhaps contributing to the smaller, yet still positive, long-term trends 16,69 . In contrast, much larger changes of >40% dec -1 were observed in Iceland (from 54.8 km 2 to 132.4 km 2 ), Scandinavia (from 258.2 km 2 to 596.9 km 2 ) and the Russian Arctic (from 189.9 km 2 to 478.4 km 2 ) (Fig. 3a). ...
Global glacier mass loss has accelerated, producing more and larger glacial lakes. Many of these glacial lakes are a source of glacial lake outburst floods (GLOFs), which pose threats to people and infrastructure. In this Review, we synthesize global changes in glacial lakes and GLOFs. More than 110,000 glacial lakes currently exist, covering a total area of ~15,000 km2, having increased in area by ~22% dec–1 from 1990 to 2020. More than 10 million people are exposed to the impacts of GLOFs, commonly associated with dam failure or wave overtopping associated with mass movements. Although data limitations are substantial, more than 3,000 GLOFs have been recorded from 850 to 2022, particularly in Alaska (24%), High Mountain Asia (HMA; 18%) and Iceland (19%), the majority (64.8%) being from ice-dammed lakes. Recorded GLOFs have increased in most glaciated mountain regions of the world, with ongoing deglaciation and lake expansion expected to increase GLOF frequency further. In HMA, GLOF hazards are projected to triple by 2100, but changes in other regions will likely be lower given topographic constraints on lake evolution. Future research should prioritize acquiring field data on lake and dam properties, producing globally coordinated multi-temporal lake mapping, and robust and efficient modelling of GLOFs for comprehensive hazard assessment and response planning.
... The peak discharge of the lake in case of total breach was estimated with Froehlich's model using the maximum water volume at the time of outburst and the depth of water above the breach invert at the time of failure (Froehlich 1995). The water volume was estimated considering the lake area, by means of the three empirical relationships proposed by Huggel et al. (2002), Loriaux andCasassa (2013), andIribarren Anacona et al. (2014). The mean water depth was obtained from the width of the lake using the linear relationship proposed by Muñoz et al. (2020). ...
... The peak discharge of the lake in case of total breach was estimated with Froehlich's model using the maximum water volume at the time of outburst and the depth of water above the breach invert at the time of failure (Froehlich 1995). The water volume was estimated considering the lake area, by means of the three empirical relationships proposed by Huggel et al. (2002), Loriaux andCasassa (2013), andIribarren Anacona et al. (2014). The mean water depth was obtained from the width of the lake using the linear relationship proposed by Muñoz et al. (2020). ...
Debris flows cause human losses and material damages in many countries around the world. The associated risk often remains unknown because of uncertainties and the lack of data. This paper presents a semi-quantitative risk assessment of debris flow based on a Risk Matrix Approach to overcome that limitation. Three risk levels were defined through hazard and vulnerability analysis. Hazard scenarios were modeled in Flow path assessment of gravitational hazards at a regional scale (Flow-R). Vulnerability was analyzed and defined according to the physical characteristics of the elements-at-risk. The Huaraco and Huinganco basins, in the north of Patagonia, were selected for detailed analysis based on the frequency and consequences of the debris flows that occurred from the 19th to the 21st centuries, which had recurrence intervals between 30 and 56 years. A detailed study of the 8 February 2013 episode revealed extremely high flow velocities and peak discharges that carried huge boulders and produced extensive damage. The risk assessment determined that under present conditions 38 people might be severely affected by landslides in the high magnitude scenario, with losses up to 5.2 million USD due to the destruction of roads, bridges, and buildings by debris.
... In recent years, numerous glacial lakes expanded or formed as a result of climate variations and related glacier melting (Davies and Glasser, 2012;Dussaillant et al., 2010;Harrison et al., 2006). At the Northern Patagonian Icefield, the total glacial lake area increased by 66 km 2 (65%) from 102 km 2 in 1945 to 168 km 2 in 2011 (Loriaux and Casassa, 2013). Between 1985 and 2011, 65 glacial lakes expanded, and more than 100 new ones formed at the NPI, which resulted in an increase in total glacial lake area by 11.6 km 2 (59%) (Paul and Mölg, 2014). ...
... Compared to the outlines of Alpine glaciers, glacial lake boundaries are levelled and relatively smooth and, hence, easier to edit manually, which-since the lakes can be frozen-is required for most of the glacial lakes in the high elevations of the Andes (Veettil et al., 2017a). The most commonly used automatic method for glacial lake delineation is the normalized difference water index (NDWI=[NIR-SWIR]/[NIR+SWIR]) (Cook et al., 2016;Anacona et al., 2014;UGRH, 2014;Loriaux and Casassa, 2013). Once a glacial lake has been delineated, additional characteristics such as elevation can be calculated with the help of a topographic map or DEM. ...
In this article, we review the current knowledge of the glacial recession and related glacial lake development in the Andes of South America. Since the mid-1980s, hundreds of glacial lakes either expanded or formed, and predictions show that additional hundreds of lakes will form throughout the 21st century. However, studies on glacial lakes in the Andes are still relatively rare. Many glacial lakes pose a potential hazard to local communities, but glacial lake outburst floods (GLOFs) are understudied. We provide an overview on hazards from glacial lakes such as GLOFs and water pollution, and their monitoring approaches. In real-time monitoring, the use of unmanned aerial systems (UASs) and early warning systems (EWSs) is still extremely rare in the Andes, but increasingly authorities plan to install mitigation systems to reduce glacial lake risk and protect local communities. In support, we propose an international remote sensing-based observation initiative following the model of, for example, the Global Land Ice Measurements from Space (GLIMS) one, with the headquarters in one of the Andean nations.
... As observed in regions like Greenland [49] and Alaska [37], the numerous ice-contact lakes of the Patagonia Icefield have expanded significantly in recent decades due to glacier retreat, contributing substantially to the glacial lake volume [36,50]. Consequently, the mechanical and thermal interactions [19,51] between glaciers and these lakes have garnered increasing research interest. ...
The Patagonia Icefield, the largest ice mass in the Southern Hemisphere outside Antarctica, has experienced significant growth and expansion of ice-contact lakes in recent decades, with lake surface water temperature (LSWT) being one of the key influencing factors. LSWT affects glacier melting at the waterline and accelerates glacier mass loss. However, the observations of ice-contact LSWT are often limited to short-term, site-based field measurements, which hinders long-term, whole-lake monitoring. This study examines LSWT for the three largest ice-contact lakes in the Patagonia Icefield—Lake Argentino, Lake Viedma, and Lake O’Higgins, each exceeding 1000 km²—and the three largest nearby non-ice-contact lakes for comparison using MODIS data between 2002 and 2022. In 2022, the mean LSWTs for Lake Argentino, Lake Viedma, and Lake O’Higgins were 7.2, 7.0, and 6.4 °C, respectively. In summer, ice-contact lakes exhibited wider LSWT ranges and more pronounced cooling near glacier termini and warming farther away compared to other seasons, demonstrating glacier melt cooling and its seasonal variability. Over the past 20 years, both Lake Viedma and Lake O’Higgins showed a warming rate of +0.20 °C dec⁻¹, p > 0.1, with slower warming near the glacier, reflecting glacier contact suppression on the LSWT trend. Conversely, Lake Argentino displayed a significant warming rate of +0.43 °C dec⁻¹ (p < 0.05), with faster rates near the glacier terminus, possibly linked to a prolonged and large (>64 km²) iceberg accumulation event from March 2010 to October 2011 in Glacier Upsala’s fjord. Iceberg mapping shows that larger events caused more pronounced short-term (24 days) LSWT cooling in Lake Argentino’s ice-proximal region. This study highlights the role of glacier–lake interactions including calving events in regulating ice-contact lake water temperature.
... Between 2008 and 2012, the glacier stagnated before a slow retreat was again documented until 2015 with 50 m yr − 1 . In front of the Grosse Glacier, a proglacial lake started to appear in c. 1986 and progressively enlarged by coalescing with supraglacial ponds (Aniya, 2017a;Loriaux and Casassa, 2013b); the lake is dammed by a 70-m high frontal moraine, probably from the Little Ice Age (Mardones et al., 2018). ...
Over recent decades, global warming has led to sustained glacier mass reduction and the formation of glacier
lakes dammed by potentially unstable moraines. When such dams break, devastating Glacial Lake Outburst
Floods (GLOFs) can occur in high mountain environments with catastrophic effects on populations and infra
structure. To understand the occurrence of GLOFs in space and time, build frequency-magnitude relationships for
disaster risk reduction or identify regional links between GLOF frequency and climate warming, comprehensive
databases are critically needed. GLOF inventories have thus been compiled at both regional and global scales.
While these accounts offer valuable data for hazard assessment, many GLOF events are omitted because they
occurred before the satellite era or prior to the installation of river gauges, went unreported or were only
mentioned in local media but not documented in the scientific literature. In addition, while geomorphic evidenceof past GLOFs exist, their timing oftentimes remains unknown. These discontinuities preclude the identification
of return periods for the most disastrous events and makes the link between GLOFs and ongoing climate warming
remain inconclusive. To overcome these limitations, long-term records have been developed using a wide variety
of proxies. Here, we explore the potential of coupling dendrogeomorphology and geomorphic analyses to
reconstruct a GLOF event that occurred before the satellite era. The Grosse Glacier outlet, in San Rafael National
Park, Chilean Patagonia, was selected based on satellite imagery, historical photographs and local testimonies
indicating a previous lake drainage. Tree-ring analysis allowed identification of a massive GLOF and five smaller
floods from 105 disturbed Nothofagus and Podocarpus trees. Unmanned aerial vehicle (UAV) imagery and objectbased image analysis (OBIA) were used to identify boulders and to estimate flow direction in the glacio-fluvial
floodplain and point to the occurrence of at least one high-energy flow event. Aerial photo analysis also revealed
the formation of a 200-m-wide breach in the frontal moraine and the disappearance of a lateral lake, estimated to
be 1.8 km2 in size, sometimes after 1944–45. An in-depth interview with an eyewitness pinpointed the date of the
GLOF to October 1957, in line with the estimated date of damage in the tree-ring records and precipitation
records at Puerto Ays´en. When used in conjunction, the different approaches contribute valuable insights into the
timing and consequences of past extreme events, thus aiding in future assessments of GLOF hazards, not only at
the Grosse Glacier but also in other high-mountain environments.
... When considering the ratio of lake area and volume (Figure 10), which can be used as a value to describe the lake shape, all three lakes lie within the range of literature values from surveyed glacial lakes worldwide (Evans, 1986;Huggel et al., 2002;Kapitsa et al., 2017;Loriaux & Casassa, 2013;Muñoz et al., 2020;Wang et al., 2012). ...
As glaciers retreat worldwide, local basal depressions are exposed where new pro‐glacial lakes are forming. Although the formation of such new lakes has been mapped widely, the impact of their interaction with the glacier on sediment dynamics and the thermal state is rarely studied. At the example of Witenwasserengletscher, Switzerland, we use historic aerial imagery and a bathymetric survey to investigate in detail the interaction of glacier retreat, lake formation and sedimentation. Three lakes have emerged since the mid‐1990s with mean depths between 1.25 and 6 m. The deepest lake lost contact to the ice in 2009 with a delta forming from mobilized sub‐glacial sediment. Phases of direct contact of the glacier with the lakes are found to increase terminus retreat and affect the thermal state and sedimentation. In summer, lake water temperatures in these small ice‐contact lakes stay close to 0°C, whereas the disconnected eastern lake shows temperatures consistently over 6°C. Temperature profiles from 2021 show that after losing ice contact, warm sediment‐rich glacial water forms an underflow that is breaking through the summertime stratification with warm water over cold water. In this case, density stratification is dominated by suspended sediment rather than temperature. Sedimentation shows a high multiannual variability and is dependent on a multitude of factors, ultimately on the routing of glacial streams. These tend to migrate towards the centre of the valley as the glacier retreats. Our study shows that during deglaciation lake evolution, sediment redistribution and the thermal state are highly dynamic and pro‐glacial lakes strongly affect the sediment evolution and may thereby impact on the ecosystem in pro‐glacial streams.
... We also calculated the lake volume (m 3 ) and depth (m) for the time periods considered. We used several empirical equations from previous studies to derive a range of volumes for individual time steps (Cook & Quincey, 2015;Emmer & Vilímek, 2014;Evans, 1986;Huggel et al., 2002;Kapitsa et al., 2017;Loriaux & Casassa, 2013;Wang et al., 2012). ...
Glacial lake outburst floods (GLOFs) are sudden, and often hazardous, floods occurring upon the failure of a glacial lake dam or moraine. A GLOF occurred at Sulzenau Lake (Tyrol, Austria) in August 2017 due to a partial moraine and dam failure, damaging nearby infrastructure. Due to the ongoing retreat of Sulzenau Glacier, the areal extent, depth, water volume, and shoreline configuration of Sulzenau Lake fluctuate over both short‐ and long‐term periods. Here, we used remote sensing data to create a detailed geomorphological overview of the valley, analyse the lake's evolution since 2009, and characterize the conditions leading to the 2017 dam failure. Using optical remote sensing imagery, we generated detailed pre‐ and post‐event geomorphological maps of Sulzenau Lake and areas impacted by the GLOF to characterize erosional and depositional zones. We employed the Normalized Difference Water Index (NDWI) and mapped the post‐event boulder distribution. Based on multi‐temporal mapping, we calculated water volumes, analysed changes in lake and glacier surfaces since 1970, and compared them with ERA‐5 meteorological data. Lake growth was primarily due to rising temperatures and glacier retreat. In 2017, both precipitation and air temperatures in the Sulzenau Valley exceeded the 1991–2021 averages, with precipitation 14.8% higher and air temperatures 0.35°C above the 30‐year mean. Ice velocities for Sulzenau Glacier reached 170 m/year during 2015–2022. By modelling flow conditions required for observed boulder movements during the GLOF, we constrained the peak discharge to 150–200 m ³ /s. No significant pre‐2017 GLOF activity or meteorological anomalies were detected. Accordingly, we attribute the GLOF and dam failure to an increased meltwater flux and increased precipitation, possibly augmented by subglacial/englacial lake drainage. The 2017 Sulzenau Valley GLOF is a pertinent example of environmental changes and associated hazards in high‐mountain glacial environments due to global warming.
... Recent inventory studies have shown that these lakes, as dynamically changing landforms, merge at glacier fronts and undergo cyclical or single GLOF events, where, in particular, these single events can lead to the complete drainage of glacial lakes (Urbański 2022. When glacial lakes merge and lose contact with the glaciers that feed them, these water bodies are often stabilised in the landscape (Loriaux, Casassa 2013). The analysis describes glacial lakes as an example of the changes observed during deglaciation of the glaciers feeding them. ...
Contemporary dynamics of glacial lakes: comparison between selected systems developing in northern, central and southern regions in Spitsbergen. AbstrAct: The study investigates glacial lakes in Svalbard, examining examples from the forelands of Gåsbreen, Cram-merbreen, Knivseggbreen, Neppebreen and Ragnarbreen, each representing different classifications of glacial lakes, including ice-dammed, frontal moraine-dammed and medial moraine-dammed. These lakes serve as key indicators of ongoing climate change and the effects of deglaciation processes in polar landscapes. Quantitative analyses reveal notable differences among the selected glacial lakes. For instance, Goësvatnet experienced cyclical glacial lake outburst floods (GLOFs), with a recorded volume of 666,389 m 3 during one event. Conversely, the lake on the Ragnarbreen foreland, while stable, has not encountered any GLOFs, indicating a distinct response to deglaciation compared with other examples. Hydrographic and surface analyses, conducted using digital elevation models (DEMs) and remote sensing data, provide insights into the morphological characteristics and dynamics of the glacial lakes and surrounding landscapes. Longitudinal profiles of glaciers show varied terrains, with Ragnarbreen exhibiting the least variability due to its source zone on the ice cap, while Crammerbreen presents diverse features, including tectonic faults resulting in icefalls with slopes >35°. By including multiple glacial lakes across different locations and classifications, this study offers a comprehensive understanding of the diverse responses of glacial lakes to deglaciation processes in Svalbard, shedding light on the complex interactions between glaciers, lakes and changing environmental conditions in the Arctic region.
... This reduction of c. 25 % of glacierized area (Paul and Mölg, 2014) resulted in the formation of a large number of glacial lakes. Around NPI, for instance, glacial lake area is considered to have increased by c. 66 km 2 between 1945 and 2011 (Loriaux and Casassa, 2013). ...
We present a glacial-related lake inventory for a region spanning 41.5° - 47° S in Patagonian Andes, where information on past glacier lake outburst floods (GLOF's) has hitherto remained significantly underreported. Analyzing remotely sensed images, we obtained data on 702 glacial-related lakes. Through detailed geomorphic assessments and manual supervision, we revised current inventories and added 35 GLOFs triggered from moraine/bedrock dammed lakes failures. The regional GLOF inventory presented contains information on 71 historical failures of moraine/bedrock dammed glacial lakes. From this database we analyzed outburst timing and managed to constrain 37 events occurrences within a period of 1 year. Around 40 % of them have occurred since the early 2000's, most of them originating from lakes probably formed as a delayed response to the glacial retreat imposed by the end of the Little Ice Age. On the other hand, we analyzed meteorological conditions for a sub-set of 10 events constrained within a 10-days period, finding a strong link between atmospheric rivers, cut-off lows impacting the southern Andes, and GLOFs. Only one case is likely to have been triggered by a Mw 4.9 earthquake. Based on topographic potential for avalanching, we estimated GLOF hazard potential, recognizing at least 3 subregions with high hazard, which moreover can be highly susceptible to climate conditions that regionally affect GLOF occurrence.
... Instead, scholars typically utilize single total lake volume data rather than bathymetric distribution in GLOF modeling (Anacona et al., 2015b;Zhang et al., 2021). The lake volume is typically estimated by an empirical equation, e.g., a direct volume-area equation (O'Connor et al., 2001;Huggel et al., 2002;Loriaux and Casassa, 2013) or an indirect area-mean depthmaximum depth-width equation (Wang et al., 2012), which have considerable uncertainty. There is no doubt that the measured and/or interpolated glacial lake bathymetric distributions have great merit that can precisely determine the maximum potential outburst volume of the glacial lake, serving to further simulate the GLOF propagation and evaluate downstream exposures (Frey et al., 2018;Sattar et al., 2021). ...
The formation and expansion of glacial lakes worldwide due to global warming and glacier retreat have been well documented in the past few decades. Thousands of glacial lake outburst floods (GLOFs) originating from moraine-dammed and ice-dammed lakes were reported, causing devastating impacts on downstream lives and properties. Detailed glacial lake bathymetry surveys are essential for accurate GLOF simulation and risk assessment. However, these bathymetry surveys are still scarce as glacial lakes located in remote and high-altitude environments hamper a comprehensive investigation. We developed a conceptual model for glacial lake bathymetric distribution using a semi-automatic simulation procedure. The basic idea is that the statistical glacial lake volume–area curves conform to a power-law relationship indicating that the idealized geometric shape of the glacial lake basin should be hemispheres or cones. First, by reviewing the evolution of various types of glacial lakes, we identified nine standard conceptual models to describe the shapes of lake basins. Second, we defined a general conceptual model to depict the continuum transitions between different standard conceptual models for those specific glacial lakes that lie between two standard conceptual models. Third, we nested the optimal conceptual model in the actual glacial lake basin to construct the water depth contours and interpolate the glacial lake bathymetric distribution. We applied the conceptual model to simulate six typical glacial lakes in the Third Pole with in situ bathymetric surveys to verify the algorithm's applicability. The results show a high consistency in the point-to-point comparisons of the measured and simulated water depths, with a total volume difference of approximately ±10 %. The conceptual model has significant implications for understanding glacial lake evolution and modeling GLOFs in the future.
... There is also increasing awareness of the potential hazards of glacial lake outburst floods (GLOFs). This interest has led to the compilation of glacial lake inventories in many glacierised regions of the world, such as parts of the Himalaya (Ukita and others, 2011;Jain and others, 2012; Govindha Raj and others, 2013; Worni and others, 2013; Zhang and others, 2015; Govindha Raj and Kumar, 2016; Aggarwal and others, 2017; Chen and others, 2017; Prakash and Nagarajan, 2017; Govindha Khadka and others, 2018; Wang and others, 2020; Nie and others, 2017), the Karakoram Range ( Senese and others, 2018; Mal and others, 2020), the Tibetan Plateau ( Luo and others, 2020), the European Alps ( Buckel and others, 2018), Greenland (How and others, 2021; Mallalieu and others, 2021), Alaska (Post and Mayo, 1970; Rick and others, 2022), the Andes ( Loriaux and Casassa, 2013; Wilson and others, 2018) and Scandinavia ( Andreassen and others, 2022). However, changes to glacial lakes in the High Arctic, where Arctic amplification enhances glacier recession ( Rantanen and others, 2022), have received scant attention in contemporary studies owing to the absence of comprehensive lake inventories and the limited impact of GLOFs on settlements and infrastructure. ...
The rapid formation of glacial lakes is one of the most conspicuous landscape changes caused by
atmospheric warming in glacierised regions. However, relatively little is known about the history
and current state of glacial lakes in the High Arctic. This study aims to address this issue by providing the first inventory of glacial lakes in Svalbard, focusing in particular on the post-Little Ice
Age evolution of glacial lakes and their typology. To do so, we used aerial photographs and satellite imagery together with archival topographic data from 1936 to 2020. The inventory comprises the development of 566 glacial lakes (146 km2
) that were still in direct contact with
glaciers during the period 2008–2012. The results show a consistent increase in the total area
of glacial lakes from the 1930s to 2020 and suggest an apparent link between climatic and geological factors, and the formation of specific lake dam types: moraine, ice, or bedrock. We also
detected 134 glacial lake drainage events that have occurred since the 1930s. This study shows
that Svalbard has one of the highest rates of glacial lake development in the world, which is
an indicator of the overall dynamics of landscape change in the archipelago in response to climate
change
... For example, Huggel et al. (2002) proposed an empirical equation for the Swiss Alps, which was widely used in glacial lakes researches (Jain et al., 2012;Sattar et al., 2020). Loriaux and Casassa (2013) proposed an empirical equation for the Northern Patagonia Icefield. In this study, the equation proposed by Zhou et al. (2020) was adopted to calculate the JGL's volume. ...
Glacial lake outburst floods (GLOFs) is one of the main natural disasters in alpine areas, which can cause extreme destruction to downstream settlements and infrastructures. A moraine-dammed lake named JiwenCo glacial lake (JGL) in the southeastern Qinghai-Tibetan Plateau failed on 26 June 2020, destroying many buildings, roads, bridges, and farmlands along the flow path. We reconstructed the process of this GLOF event by the Hydrological Engineering Center’s River Analysis System (HEC-RAS) and examined the JGL’s evolution (area, length, and volume) before its outburst, based on the measured cross sections and hydrological data, videos, and pictures taken by inhabitants, DEM data, and Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper (ETM+)/Operational Land Imager (OLI) images. The result showed that area, length, and volume of the JGL increased by 0.20 ± 0.07 km², 0.66 ± 0.03 km, and 0.03 ± 0.001 km³ from 1988 to 2020 (before the outburst), respectively. Approximately 0.05 km³ of water volume was discharged with the dropped water level of 15.63 m after the outburst. The peak flow was 534.4 m³/s at breach and increased to 1,408.11 m³/s at Zhongyu town. The difference between the simulated and measured peak flows in Zhongyu town was 41.88 m³/s (3.53%), showing the high accuracy of the modeling results. For villages along the river-channel, the highest velocity was found in Yiga village (14.23 m/s) and the lowest was in Gongwa village (1.22 m/s). The maximum depth was gradually increased as the river reached downstream, 8.03 m in Yiga village and 50.96 m in Duiba village. The combination of landslide, high temperature, and extremely heavy precipitation resulted in this GLOF disaster. An integrated disaster prevention and mitigation plan needs to be developed for susceptible areas such as Niduzangbo basin that experienced two GLOFs in recent 10 years.
... The temporal distribution of the GLOFs reported in the literature is not consistent either and changes due to inconsistency of the research practices during different epochs and the growing research interest in glaciers [11]. Although a number of studies reported global [6] and regional (e.g., [16][17][18]) glacial lake expansion, there is only limited evidence for changes in frequency of GLOFs. By compiling a global GLOF database [11] also challenges the opinion that more GLOFs occur under the warming climate. ...
Glacial lakes are an important and dynamic component of terrestrial meltwater storage, responding to climate change and glacier retreat. Although there is evidence of rapid worldwide growth of glacial lakes, changes in frequency and magnitude of glacier lake outbursts under climatic changes are not yet understood. This study proposes and discusses a method framework for regional-scale mapping of glacial lakes and area change detection using large time-series of optical satellite images and the cloud processing tool Google Earth Engine in a semi-automatic way. The methods are presented for two temporal scales, from the 2-week Landsat revisit period to annual resolution. The proposed methods show how constructing an annual composite of pixel values such as minimum or maximum values can help to overcome typical problems associated with water mapping from optical satellite data such as clouds, or terrain and cloud shadows. For annual-resolution glacial lake mapping, our method set only involves two different band ratios based on multispectral satellite images. The study demonstrates how the proposed method framework can be applied to detect rapid lake area changes and to produce a complete regional-scale glacial lake inventory, using the Greater Caucasus as example.
... Particularly as there is an increasing body of research which highlights the exacerbation of glacier retreat rates where they are in contact with proglacial lakes, through mechanical and thermo-erosional processes (Lliboutry et al. 1977;Kirkbride 1993;Kirkbride and Warren 1997;Warren and Kirkbride 1998;Warren and Kirkbride 2003;Roehl 2006;Komori 2008;Robertson et al. 2012;Trussel et al. 2013;Tsutaki et al. 2013;Wang et al. 2015;Carr et al. 2013;King et al. 2017King et al. , 2018Minowa et al. 2017;Mallalieu et al. 2020;Watson et al. 2020). Proglacial lake distribution and extent has been mapped at the regional scale in the Alps, Greater Himalaya, Peru, Greenland, Norway, and Patagonia through analysis of multispectral satellite imagery (Buchroithner et al. 1982;Huggel et al. 2002;Gardelle et al. 2011;Loriaux and Casassa 2013;Carrivick and Quincey 2014;Hanshaw and Bookhagen 2014;Yao et al. 2018;How et al. 2021;Kumar et al. 2020;Andreassen et al. 2022). Furthermore, Pierre et al. (2019) called for a global proglacial lake inventory as they found that proglacial freshwater may act as a 'globally relevant' sink for atmospheric CO 2 through chemical reactions in turbid meltwater. ...
Proglacial lakes have increased in number and extent in Arctic Sweden since the 1950s/1960s as glaciers have retreated dramatically. Interrogation of Rapid Eye imagery highlights that some lake terminating glaciers had substantial (>100 m) rates of retreat between 2010 and 2018, with one other land terminating glacier also retreating at a similar rate. However, analysis of a regional remote sensing time series suggests that proglacial lake formation in this period across the area has not been uniform. Despite glacier accumulation areas having similar maximum elevations (∼2,000 m) and similar alpine topography, proglacial lakes in the southern area (Sarek) were found to be significantly smaller than proglacial lakes in the northern area (Kebnekaise), which had smaller glaciers within corries and more prominent terminal moraines. Therefore, it cannot be assumed that proglacial lake formation will occur as glaciers retreat in response to elevated air temperature, particularly as only 33% of glaciers had proglacial lakes in their forefield. Thus, whilst it cannot be assumed that proglacial lakes will accommodate water currently held in glaciers, the 108 lakes mapped here present a substantial area (4.767 ± 0.377 km²) of fresh water that has not previously been included in the Global Lakes and Wetlands Database (GLWD). This inventory therefore provides an important dataset that can be used to underpin our understanding of the role of proglacial lakes within the hydrological system in this area of the Arctic.
... One of the consequences of the ongoing shrinkage of Patagonian glaciers (Figures 7-9) is the formation and expansion of lakes in lands recently abandoned by ice. For example, at the NPI, Loriaux and Casassa (2013) detected an increase in glacial lake area of 66 km 2 between 1945 and 2011. At Monte San Lorenzo, south-east of the NPI, Falaschi et al. (2019) measured a three-fold increase in the number of lakes and 5 km 2 of new lake area formed between 1958 and 2018. ...
This chapter addresses the distribution and characteristics of the Patagonian glaciers together with their recent changes and hydrological implications. Recently published national glacier inventories for the Andes between ca. 37 °S and 55 °S indicate that this region contains 24,000 ice masses covering ca. 26,100 km2. This includes the Southern Patagonia Icefield (SPI), the largest ice mass of the Southern Hemisphere outside Antarctica. The region also includes several thousand smaller ice masses, such as mountain glaciers, valley glaciers, rock glaciers, and perennial snowfields, which collectively are crucial water resources to sustain nature contributions to people, socioeconomic activities, and hydropower generation. Recent findings in mass balance and ice dynamics along the Patagonian Andes highlight the processes behind the mass change and differential response of glaciers to climate change. Although most glaciers have experienced considerable thinning and recession in recent decades, they have not responded in the same manner to climate change. Ice-dynamic processes, such as calving, drive mass change of larger Patagonian glaciers. However, ice melt increases, and snowfall depletion have been attributed as the main cause for the shrinkage of the smaller ice masses. It is expected that glacier retreat will continue impacting runoff and glacier-related hazards. Modeling studies suggest strongest impacts due to this recent ice mass loss can be expected, particularly during the dry season. In concordance with the increase in the number and size of proglacial lakes, there has been an increase in the magnitude and frequency of glacial lake outburst floods in the Patagonian Andes.
... Hindered by turbidity, the derivation of reflectance-depth relationships of a lake from satellite sensors has not yet been reliably achieved (Box and Ski, 2007). Consequently, most studies adopted an empirical approach to calculate the volume or depth of a glacial lake (Evans, 1986;O'Connor et al., 2001;Huggel et al., 2002;Yao et al., 2012;Loriaux and Casassa, 2013;Carrivick and Quincey, 2014). In this study, the most widely used relationship proposed by Huggel et al. (2002) was used to estimate the water storage and depth of the Jionglaco. ...
Glacial lake outburst floods (GLOFs) are a serious potential threat to the safety of life and property in downstream areas. In this study, moraine-dammed glacial lakes in the Yi’ong Zangbo River basin were recognized based on Landsat ETM+/TM/OLI images in 2000 and 2019. Also, GLOFs for the Jionglaco, the largest glacial lake in this basin, were simulated using the one-dimensional hydrodynamic model. The results show that the total number and area of moraine-dammed glacial lakes in this basin increased by 10 (10.52%) and 5.49 km² (48.24%) from 2000 to 2019, respectively, in which the area of the Jionglaco increased by 3.22 km². The peak discharge at the breach outlet for five scenarios with different combinations of breach width (80 and 120 m), depth (2.5 and 5 m), and flood time (1.5 and 3 h) are 489 , 1,327.43, 444.32, 617.47, and 1,570.61 m³/s. With the addition of baseflow in the river, the peak discharge at bridge site 15,138.93 km from Jionglaco, is 1,040.89, 1,724.00, 1,024.85, 1,162.25, and 1,990.52 m³/s. The combination of baseflow in river and the GLOF discharge results in an increasing peak discharge in the further downstream region. However, the arrival of peak discharge in downstream areas is delayed, which increases the chances of people escaping.
... For the accuracy of the manual glacier/lake delineation process (δA), we assumed an error of ±1-pixel size (n) (Williams and others, 1997). This delineation error was then multiplied by the perimeter length ( pL) of the glacier/lake feature being mapped (Loriaux and Casassa, 2013;Casassa and others, 2014). (1955), Chile-80 (1983) and GEOTEC (1996) aerial imagery, Structure from Motion (SfM) techniques were applied. ...
Glaciers on Earth along other components of the cryosphere are important for the climate system. However, it is widely known that the vast majority of glaciers are retreating and thinning since the early part of the 20th century. Additionally, future projections have highlighted that at the end of the 21st century, glaciers are going to lose a considerable part of their remaining mass. These glacier changes have several implications for physical, biological and human systems, affecting the water availability for downstream communities and contribute to sea level rise. Unlike other regions, where glaciers are less relevant for the overall hydrology, glaciers in South America constitute a critical resource since minimum flow levels in headwaters of the Andean mountains are usually sustained by ice melt, especially during late summer and droughts, when the contribution from the seasonal snow cover is depleted. In the last decades, the number of studies has increased considerable, however, in the Southern Andes and the surrounding sub-Antarctic islands glaciers still are less studied in comparison with their counterparts in the Northern Hemisphere. The few studies on glacier mass balance in this region suggest a risk of water scarcity for many Andean cities which freshwater supply depends on glacial meltwater. Additionally, glaciers on sub-Antarctic islands have not been completely assessed and their contribution to the sea level rise has been roughly estimated. Hence, the monitoring of glaciers is critical to provide baseline information for regional climate change adaptation policies and facilitate potential hazard assessments. Close and long-range remote sensing techniques offer the potential for repeated measurements of glacier variables (e.g. glacier mass balance, area changes). In the last decades, the number of sensors and methods has increased considerably, allowing time series analysis as well as new and more precise measurements of glacier changes. The main goal of this thesis is to investigate and provide a detailed quantification of glacier elevation and mass changes of the Southern Andes with strong focus on the Central Andes of Chile and South Georgia. Six comprehensive studies were performed to provide a better understanding of the development and current status of glaciers in this region. Overall, the glacier changes were estimated by means of various remote sensing techniques. For the Andes as a whole, the first continent-wide glacier elevation and mass balance was conducted for 85% of the total glacierized area of South America. A detailed estimation of mass changes using the bi-static synthetic aperture radar interferometry (Shuttle Radar Topography Mission -SRTM- and TerraSAR-X add-on for Digital Elevation Measurements -TanDEM-X- DEMs) over the years 2000 to 2011/2015 was computed. A total mass loss rate of 19.43 ± 0.60 Gt a-1 (0.054 ± 0.002 mm a-1 sea level rise contribution) from elevation changes above ground, sea or lake level was calculated, with an extra 3.06 ± 1.24 Gt a-1 derived from subaqueous ice mass loss. The results indicated that about 83% of the total mass loss observed in this study was contributed by the Patagonian icefields (Northern and Southern), which can largely be explained by the dynamic adjustments of large glaciers. For the Central Andes of Chile, four studies were conducted where detailed times series of glacier area, mass and runoff changes were performed on individual glaciers and at a region level (Maipo River basin). Glaciers in the central Andes of Chile are a fundamental natural resources since they provide freshwater for ecosystems and for the densely populated Metropolitan Region of Chile. The first study was conducted in the Maipo River basin to obtain time series of basin-wide glacier mass balance estimates. The estimations were obtained using historical topographic maps, SRTM, TanDEM-X, and airborne Light Detection and Ranging (LiDAR) digital elevation models. The results showed spatially heterogeneous glacier elevation and mass changes between 1955 and 2000, with more negative values between 2000 and 2013. A mean basin-wide glacier mass balance of −0.12 ± 0.06 m w.e. a-1 , with a total mass loss of 2.43 ± 0.26 Gt between 1955–2013 was calculated. For this region, a 20% reduction in glacier ice volume since 1955 was observed with associated consequences for the meltwater contribution to the local river system. Individual glacier studies were performed for the Echaurren Norte and El Morado glaciers. Echaurren Norte Glacier is a reference glacier for the World Glacier Monitoring Service. An ensemble of different data sets was used to derive a complete time series of elevation, mass and area changes. For El Morado Glacier, a continuous thinning and retreat since the 20th century was found. Overall, highly negative elevation and mass changes rates were observed from 2010 onwards. This coincides with the severe drought in Chile in this period. Moreover, the evolution of a proglacial lake was traced. If drained, the water volume poses an important risk to down-valley infrastructure. The glacier mass balance for the Central Andes of Chile has been observed to be highly correlated with precipitation (ENSO). All these changes have provoked a glacier volume reduction of one-fifth between 1955 and 2016 and decrease in the glacier runoff contribution in the Maipo basin. The thesis closes with the first island-wide glacier elevation and mass change study for South Georgia glaciers, one of the largest sub-Antarctic islands. There, glaciers changes were inferred by bi-static synthetic aperture radar interferometry between 2000 and 2013. Frontal area changes were mapped between 2003 and 2016 to roughly estimate the subaqueous mass loss. Special focus was given to Szielasko Glacier where repeated GNSS measurements were available from 2012 and 2017. The results showed an average glacier mass balance of −1.04 ± 0.09 m w.e. a-1 and a mass loss rate of 2.28 ± 0.19 Gt a-1 (equivalent to 0.006 ± 0.001 mm a-1 sea level rise) in the period 2000-2013. An extra 0.77 ± 0.04 Gt a-1 was estimated for subaqueous mass loss. The concurrent area change rate of the marine and lake-terminating glaciers amounts to −6.58 ± 0.33 km2 a-1 (2003–2016). Overall, the highest thinning and retreat rates were observed for the large outlet glaciers located at the north-east coast. Neumayer Glacier showed the highest thinning rates with the disintegration of some tributaries. Our comparison between InSAR data and GNSS measurements showed good agreement, demonstrating consistency in the glacier elevation change rates from two different methods. Our glacier elevation and mass changes assessment provides a baseline for further comparison and calibration of model projection in a sparsely investigated region. Future field measurements, long-term climate reanalysis, and glacier system modelling including ice-dynamic changes are required to understand and identify the key forcing factors of the glacier retreat and thinning.
... This group of glaciers also has the greatest magnitude of change in their average geodetic mass balance between the two time periods (Table 4). Increased retreat for lake-terminating glaciers in the NPI has been attributed to glacial lake development and expansion in other studies (Loriaux and Casassa, 2013;Glasser, 2016). This result also agrees with Falaschi et al. (2019), who found the highest thinning rates among laketerminating glaciers from 2000-2012 on the eastern flanks of the SPI and in mountain ranges directly east of the icefields. ...
Southern Andean glaciers contribute substantially to global sea-level rise. Unfortunately, mass balance estimates prior to 2000 are limited, hindering our understanding of the evolution of glacier mass changes over time. Elevation changes over 1976/1979 to 2000 derived from historical KH-9 Hexagon imagery and NASADEM provide the basis for geodetic mass balance estimates for subsets of the Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI), extending current mass balance observations by ∼20 years. Geodetic mass balances were −0.63 ± 0.03 m w.e. yr⁻¹ for 63% of the NPI and −0.33 ± 0.05 m w.e. yr⁻¹ for 52% of the SPI glacierized areas for this historical period. We also extend previous estimates temporally by 25% using NASADEM and ASTER elevation trends for the period 2000 to 2020, and find geodetic mass balances of −0.86 ± 0.03 m w.e. yr⁻¹ for 100% of the NPI and −1.23 ± 0.04 m w.e. yr⁻¹ for 97% of the SPI glacierized areas. 2000–2020 aggregations for the same areas represented in the 1976/1979 to 2000 estimates are −0.78 ± 0.03 m w.e. yr⁻¹ in the NPI and −0.80 ± 0.04 m w.e. yr⁻¹ on the SPI. The significant difference in SPI geodetic mass balance in the modern period for 100% vs. 52% of the glacierized area suggests subsampling leads to significant biases in regional mass balance estimates. When we compare the same areas in each time period, the results highlight an acceleration of ice loss by a factor of 1.2 on the NPI and 2.4 on the SPI in the 21st century as compared to the 1976/1979 to 2000 period. While lake-terminating glaciers show the most significant increase in mass loss rate from 1976/1979–2000 to 2000–2020, mass balance trends are highly variable within glaciers of all terminus environments, which suggests that individual glacier sensitivity to climate change is dependent on a multitude of morphological and climatological factors.
... Several area-volume empirical relations of glacial lakes were accordingly proposed and applied to derive lake depth by incorporating bathymetrically derived data, which has reduced some amount of fieldwork in inaccessible terrains (Carrivick 180 and Quincey, 2014;Evans, 1986;Huggel et al., 2002;Loriaux and Casassa, 2013;O'connor et al., 2001;Yao et al., 2012b). ...
As the Third Pole of the Earth and the Water Tower of Asia, Tibetan Plateau (TP) nurtures large numbers of glacial lakes, which are sensitive to global climate change. These lakes modulate the freshwater ecosystem in the region, but concurrently pose severe threats to the valley population by means of sudden glacial lake outbursts and consequent floods (GLOFs). Lack of high-resolution multi-temporal inventory of glacial lakes in TP hampers a better understanding and prediction of the future trend and risk of glacial lakes. Here, we created a multi-temporal inventory of glacial lakes in TP using 30 years record of 42833 satellite images (1990-2019), and discussed their characteristics and spatio-temporal evolution over the years. Results showed that their number and area had increased by 3285 and 258.82 km2 in the last 3 decades, respectively. We noticed that different regions of TP exhibited varying change rates in glacial lake size, most regions show a trend of expansion and increase in glacial lakes, while some regions show a trend of decreasing such as the western Pamir and the eastern Hindu Kush. The mapping uncertainty is about 17.5%, lower than other available datasets, thus making our inventory reliable for the spatio-temporal evolution analysis of glacial lakes in TP. Our lake inventory data are freely available at https://doi.org/10.5281/zenodo.5574289 (Dou et al, 2021), it can help to study climate change-glacier-glacial lake-GLOF interactions in the Third Pole and serve input to various hydro-climatic studies.
... This will be caused by the replacement of predictable summer glacier melt by less predictable rainfall events and snowmelt runoff regimes, and these shifts are already visible in the Pyrenees and the Alps (Milner et al., 2017). In the recent decades, retreating glaciers produce lakes at their fronts in many high mountain regions (Gardelle et al., 2011;Loriaux & Casassa, 2013), and lake outbursts are causing floods. Major floods in mountain areas are also generated by rain-on-snow events 24 (Jeong & Sushama, 2018) that are favored by climate change. ...
Mountains and mountain rivers provide a multitude of invaluable goods and services to a profound portion of the planet’s population. As “water towers” of the Earth mountains are sources of the mightiest world rivers and play a pivotal role for global biodiversity, freshwater, and sediment supply. Distinct morphological, climatic, hydrological, hydrochemical, and biological features of mountainous river ecosystems, compared to lowland ones, make them particularly fragile and vulnerable to human interference. Despite a number of remote mountain areas and rivers still remaining intact from direct human pressures, the majority of mountain ecosystems, are being increasingly threatened by adverse local and global changes driven by market economy. To efficiently conserve and sustainably use mountain ecosystems and contribute to the survival of the planet, it is critical to change our standards and life attitudes by realizing and appreciating our immediate connection to the global ecosystem, change attitudes and current consumption patterns, and stimulate the ways our global society functions and interacts with the natural environment.
... One such relationship developed by Huggel et al. (2002) using various types of lakes situated globally has gained significant attention and has been used by many researchers in several studies to estimate lake volume (Huggel et al. 2004;Bolch et al. 2011;Mergili and Schneider 2011;Jain et al. 2012;Byers et al. 2013;Gruber and Mergili 2013;Wilcox et al. 2013;Che et al. 2014). However, this equation had also been modified for specific locations by Loriaux and Casassa (2013) and Yao et al. (2012c). However, there is still a question on applying these empirical relationships confidently across a range of locations and to various types of lakes (Cook and Quincey 2015). ...
Glacial Lake Outburst Floods (GLOFs) in a deglaciating environment, representing significant threat to downstream people and infrastructure, increasing the necessity of prioritization and assessment of potentially critical glacial lakes (PCGLs). In this current study, a comprehensive updated inventory of glacial lakes for the Indus River basin has been prepared, resulting in 5,335 lakes (≥ 0.0025 ± 0.0006 km²), covering a total area of 173.95 ± 10.13 km². Parameters have been derived using satellite data for two purposes, ‘preliminary screening’ and ‘quantitative assessment’. Using 4 parameters, 367 lakes were preliminary screened-in for further analysis, and 6 quantitative parameters were analysed using Equal Weights (EW) and Unequal Weights methods (UEW). These both methods were applied for two scenarios, scenario-1 which considers 73 lakes (≥ 0.1 km²), and scenario-2 which considers all 367 preliminary screened-in lakes (≥ 0.02 km²). UEW outperformed EW analysis and identified 20 and 48 high potential lakes for scenario-1 and scenario-2 respectively, where all 20 lakes of scenario-1 have been found in common with those of scenario-2, with a difference in their rank. But only 10 of them have storage volume ≥10 MCM and has been flagged as high-risk lakes, of which 6 are end-moraine dammed lakes and have been considered as PCGLs, due to their high bursting potential and self-destructive nature. Rest 4 high risk lakes along with remaining 38 lakes with volume <10 MCM, are considered as critical lakes in case of dynamic mode of failure, caused due to mass movement of avalanche, landslide, heavy precipitation, etc.
... In particular, post-Little Ice Age climatic warming has enhanced ice melt, leading to the development of a large number of glacial lakes behind ice dams, lateral and terminal moraines and within over-deepened de-glaciated valley bottoms (Quincey et al., 2007;Wilson et al., 2018). Glacial lakes are important globally and regionally as (1) they represent a considerable water resource (Loriaux and Casassa, 2013), (2) when in contact with or dammed by glaciers, they can have negative impacts on glacier mass balance (e.g. King et al., 2019), and (3) they are the source of glacial lake outburst floods (GLOFs; Richardson and Reynolds, 2000;Carrivick and Tweed, 2016;Harrison et al., 2018) which are considered to be the largest and most extensive glacial hazard in terms of disaster and damage potential (UNEP, 2007). ...
Glacier recession in response to climate warming has resulted in an increase in the size and number of glacial lakes. Glacial lakes are an important focus for research as they impact water resources, glacier mass balance, and some produce catastrophic glacial lake outburst floods (GLOFs). Glaciers in Peru have retreated and thinned in recent decades, prompting the need for monitoring of ice- and water-bodies across the cordilleras. These monitoring efforts have been greatly facilitated by the availability of satellite imagery. However, knowledge gaps remain, particularly in relation to the formation, temporal evolution, and catastrophic drainage of glacial lakes. In this paper we address this gap by producing the most current and detailed glacial lake inventory in Peru and provide a set of reproducible methods that can be applied consistently for different time periods, and for other mountainous regions.
The new lake inventory presented includes a total of 4557 glacial lakes covering a total area of 328.85 km². In addition to detailing lake distribution and extent, the inventory includes other metrics, such as dam type and volume, which are important for GLOF hazard assessments. Analysis of these metrics showed that the majority of glacial lakes are detached from current glaciers (97%) and are classified as either embedded (i.e. bedrock dammed; ~64% of all lakes) or (moraine) dammed (~28% of all lakes) lakes. We also found that lake size varies with dam type; with dammed lakes tending to have larger areas than embedded lakes. The inventory presented provides an unparalleled view of the current state of glacial lakes in Peru and represents an important first step towards (1) improved understanding of glacial lakes and their topographic and morphological characteristics and (2) assessing risk associated with GLOFs.
... hydropower, tourism, outburst hazards; cf. (Bajracharya and Mool 2009;Haeberli et al. 2016;Loriaux and Casassa 2013;Terrier et al. 2011). ...
... Meltwater can be withdrawn for human use or stored in glacial lakes (Haeberli and Linsbauer, 2013). For example, in Patagonia, terrestrial storage in the lakes of the Northern Patagonian Icefield is as high as 10% of its glacier melt contribution to sea level rise (Loriaux and Casassa, 2013). ...
Glacier ice, including ice sheets and ice caps, covers about 10% of the Earth's surface and stores 69% of freshwater. Over the last millennium, glaciers reached their maximum extent during the Little Ice Age but began to retreat at the end of the 19th century. Glacier wastage has been accelerating worldwide since the second half of the 20th century. Currently, glaciers across most of the polar and mountain regions have negative mass balance dominated by surface melt. This global trend is attributed to the continuing climatic warming. Glaciers in the Karakoram-Kunlun-Pamir region are a notable exception. Recent advancements in satellite data acquisition enabled more reliable assessments of mass balance of ice sheets. Increasing loss of ice from the Greenland and West Antarctic ice sheets and their peripheral glaciers has been observed since the 1990s. The combined glacier and ice sheet contribution is now the dominant source of global mean sea level rise. The Greenland ice sheet makes the largest contribution followed by a combined input from glaciers. Both significantly exceed that of Antarctica. Alaska, the Canadian Arctic, and the Southern Andes account for the largest contribution from glaciers. Glacier wastage is expected to continue in the future, and in many mountain regions glaciers may disappear or retreat to high elevations. Large uncertainty surrounds future evolution of ice sheets but there is a possibility that the Greenland ice sheet may decline to the point of no recovery.
... Chilean Patagonia appears to be particularly vulnerable to GLOFs, which is frequently described in the literature as a consequence of the rise in the number of glacial lakes related to the accelerated glacier recession in the southern Andes . Between 1945 and 2011, it is estimated that the glacial lake volume for the NPI has increased by 4.8 km³, with the largest increase after 1987 (Loriaux and Casassa, 2013). During the last decades, Patagonian glacial lakes, excluding the three largest lakes Argentino, Viedma, and San Martin, have more than doubled in volume (Shugar et al., 2020), and their number increased from 2926 to 4202 (43 %) . ...
Glacial Lake Outburst Floods (GLOFs) constitute one of the most notorious and destructive geohazards worldwide. They have occurred throughout recorded history and form a constant threat for local communities near glacierized regions. Although the recent deglaciation resulted in an increase in glacial lakes, both in size and number, worldwide, little is known about the possible relationship between climate variability and GLOF occurrence. Yet, it is generally assumed that GLOF frequency is currently increasing due to global glacier retreat. This is mainly due to a lack of continuous long-term flood records. Current records of GLOF occurrence, which are based on instrumental and historical data, are intrinsically limited to the last centuries. Consequently, the effect of climate change on GLOF occurrence and the likely evolution of GLOFs under future climate change scenarios remains unclear. However, a comprehensive understanding of the link between climate change, glacier variability, and GLOF occurrence is fundamental for future GLOF predictions and to improve flood hazard assessments. As in many other glacierized regions, GLOFs are a well-known phenomenon in the Patagonian Andes. They are particularly pronounced in the Baker region of Chilean Patagonia (47–48 °S), where repeated GLOFs occurred from the abrupt drainage of ice-dammed Cachet 2 Lake between April 2008 and November 2020. During these events, water from Cachet 2 Lake spills into Colonia River, a tributary of Baker River, and increases both river discharge and sediment suspended concentrations. Colonia GLOFs are able to block the regular Baker River flow and result in the inundation of large areas upstream of the Colonia-Baker confluence, such as the Valle Grande floodplain. Downstream, the Baker River triples in discharge and large amounts of sediment are transported, and ultimately deposited, in fjords. The repeated Baker River GLOFs during the 21st century and the location of the Baker River, which drains most of the eastern side of the Northern Patagonian Icefield (NPI) and therefore integrates meltwater from several lake-river systems, makes the Baker region ideally suited to investigate GLOFs and to study the impact of climate change on GLOF occurrence. To examine how GLOFs are recorded in fjord sediments, this study mapped the bathymetry of the head of Martínez Channel, i.e. the fjord in which the Baker River discharges, using multibeam echosounding. Results show that the subaquatic delta of Baker River is deeply incised by sinuous channels. The presence of sediment waves and coarser sediment within these channels suggest recent channel activity by turbidity currents. The latter is confirmed by sediment records collected at the head of the fjord, which reveal the presence of turbidites intercalated within silty background sediments, particularly on the delta plain in front of the main submarine channel. Although the turbidity currents are most likely generated by elevated river discharge and the associated relatively high suspended sediment loads, most turbidites are not related to GLOFs. Instead, they seem to represent other extreme discharge events, such as extreme precipitation or rain-on-snow events. By comparing geochemical and sedimentological results obtained on the sediment cores to the recent GLOF history of Baker River, we show that the recent 21st century Cachet 2 GLOF deposits can be distinguished from background sediments by their finer grain size and lower organic carbon content, reflecting the increased input of glacial sediments during GLOFs. In addition, the results obtained on the fjord sediment cores demonstrate that the 21st century GLOFs from Cachet 2 Lake, which occurred less than one year apart, are not recorded as individual layers but as units richer in sediment of glacial origin. This suggests that it is not possible to reconstruct GLOF frequency nor magnitude solely based on fjord sediments. Although 21 GLOFs from Cachet 2 Lake occurred between 2008 and 2017, the deposits with the clearest GLOF signature represent the initial events, implying that more glacial sediment was released during those first GLOFs, possibly due to lake-bed erosion. Consequently, it appears that sediment availability plays a more important role than flood magnitude in controlling GLOF deposit properties. Although GLOF frequency and magnitude cannot be accurately reconstructed using fjord sediments, high accumulation rates at the head of Martínez Channel highlight the potential of fjord sediment archives to establish pre-historical GLOF records at high temporal resolution. In addition, the bathymetric imagery and the sediment records obtained at the head of Martínez Channel show that site selection and multi-coring are fundamental to reconstruct the Baker River GLOF history, as fjord heads are dynamic sedimentary environments with rapidly migrating channels. Ideal locations to reconstruct GLOFs are found on the delta slope, away from any submarine channel influence. GLOF deposits are best identified close to the river mouth, as background sediments become progressively finer and less organic, thus more similar to GLOF deposits, with increasing distance from the lip of the Baker River delta. Given the unique context of the Baker River system, where a significant portion of the watershed is vegetated and where the fine and organic-poor signature of GLOF deposits clearly contrasts with the slightly coarser and organic background sediments, our results may only be applicable to fjord sediments from temperate regions. Distinguishing GLOF deposits from background sediments would likely be more challenging in high latitude fjords. Sediments deposited in floodplains constitute another faithful recorder of Baker River GLOFs. In the Valle Grande floodplain, which is located immediately upstream of the Colonia-Baker confluence, GLOFs are registered as organic-poor deposits intercalated within organic-rich background sediments. In contrast to marine archives, the sediments of the Valle Grande floodplain have lower accumulation rates, and can therefore be used to determine changes in GLOF occurrence on longer timescales (late Holocene). Based on four radiocarbon-dated sediment cores collected in the Valle Grande floodplain, our results show that high-magnitude GLOFs occurred intermittently in the upper Baker River watershed over the past 2.75 kyr. Two periods of increased flood activity occurred between approximately 2.57 and 2.17 cal kyr BP, and from 0.75 to 0 cal kyr BP. Comparison with independent proxy records of glacier variability reveals that these two periods of increased flood frequency match with Neoglacial advances. These advances seem to result from lower-than-average temperatures and wetter conditions. Based on these results, we suggest that there is a strong, yet indirect, link between climate variability and GLOF occurrence. We hypothesize that, on multi-millennial timescales, high-magnitude GLOFs from eastern NPI glaciers are more frequent at times when glaciers are larger and thicker, as such glaciers most likely form larger and stronger ice dams, which in turn are able to retain larger lakes. Our results therefore suggest that the probability that high-magnitude GLOFs occur decreases as glaciers thin and retreat. Conversely, the frequency of lower magnitude GLOFs tends to increase during glacier recession because of the rapid growth of glacial lakes and formation of new lakes. Although isolated cases of new lakes formed behind large glaciers could still produce large GLOFs locally, the likelihood of large lake drainage and therefore high-magnitude GLOF occurrence decreases. This study supports the use of sediment-based GLOF records in other GLOF-prone regions for proper flood hazard assessment. A broader knowledge of the impact of climate change on GLOF occurrence can help to prevent further development in flood-prone regions and will reduce the vulnerability of communities to floods. Long-term paleoflood records can be of great importance for integrating spatial planning and planned infrastructure projects, such as hydroelectric dams, particularly since electricity demand is increasing with economic growth.
... GLOFs are of particular contemporary interest due to the role of climate change on the magnitude and frequency of events and therefore societal risk (Carrivick and Tweed, 2016). In a global analysis of GLOFs it was found there was a decrease in flood frequency over recent decades (Carrivick and Tweed, 2016), despite remote sensing studies that show an increase in the number and area of glacial lakes in regions such as Greenland (Carrivick and Quincey, 2014), the Himalaya (Dubey and Goyal, 2020) and Patagonia (Loriaux and Casassa, 2013;Wilson et al., 2018). Focusing only on moraine dam failures, Harrison et al. (2018) note a reduction in floods since the 1970s, but also argue that the greatest frequency of events (1930se1960s) reflect a lagged response to warming at the end of the Little Ice Age (LIA). ...
Glacier outburst floods are a major hazard in glacierized catchments. Global analyses have shown reduced frequency of glacier floods over recent decades but there is limited longer-term data on event magnitude and frequency. Here, we present a Holocene palaeoflood record from the Río Baker (Chilean Patagonia), quantifying the discharge and timing of glacier floods over millennial timescales. A catastrophic flood of 110,000 m³/s (0.11 Sv) occurred at 9.6 ± 0.8 ka, during final stages of the Late Glacial Interglacial Transition, followed by five flood-phases coeval or post-dating Holocene neoglacials. Highest flood frequencies occurred at 4.3–4.4 ka, with 26 floods of minimum discharges of 10,000–11,000 m³/s, and 0.6 ka with 10 floods exceeding 4600–5700 m³/s. The largest modern outburst flood recorded surpassed ∼3810 m³/s. Thus glacier flood magnitude declines from the order of 0.1 to 0.01 Sv over the Early to Mid Holocene, and to 0.001 Sv in the instrumental record.
... Despite the widths of uncertainty bands and prediction intervals of these datasets being high (Froehlich, 1995;Wahl, 2004), they represent useful tools for approximating the range of plausible values. Evans, 1986;O'Connor et al., 2001;Huggel et al., 2002;Wang et al., 2012;Fujita et al., 2013;Loriaux and Casassa, 2013;Emmer and Vilimek, 2014;Cook and Quincey, 2015;Kapitsa et al., 2017;Muñoz et al., 2020 Breach time: tb MacDonald and Langridge- Monopolis, 1984;Costa, 1985;Bureau of Reclamation, 1988;Von Thun and Gillette, 1990;Froehlich, 1995;Wahl, 2004 Peak discharge: Qp Kirkpatrick, 1977;Price et al., 1977;Soil Conservation Service, 1981;Bureau of Reclamation, 1982;Hagen, 1982;MacDonald and Langridge-Monopolis, 1984;Singh and Snorrason, 1984;Costa, 1985;Evans, 1986;Froehlich, 1995;Wahl, 2004 3.5 Process chain simulation with r.avaflow 195 We back-calculate part of the complex GLOF process chain, employing the simulation tool r.avaflow (Mergili et al., 2017;Pudasaini and Mergili, 2019;. r.avaflow is a GIS-based open source simulation framework for multi-phase mass flows, which has the capacity to dynamically compute the interaction between landslides and lakes. ...
We analyze and reconstruct a recent Glacial Lake Outburst Flood (GLOF) process chain on 26 June 2020, involving the moraine-dammed proglacial lake Jinwuco (30.356°N, 93.631°E) in eastern Nyainqentanglha, Tibet, China. Satellite images reveal that from 1965 to 2020, the surface area of Jinwuco has expanded by 0.2 km2 (+56%) to 0.56 km2, and subsequently decreased to 0.26 km2 (-54%) after the GLOF. Estimates based on topographic reconstruction and sets of published empirical relationships indicate that the GLOF had a volume of 10 million m3, an average breach time of 0.62 hours, and an average peak discharge of 5,390 m3/s at the dam. Based on pre-and post-event high-resolution satellite scenes, we identified a large progressive debris landslide originating from western lateral moraine, having occurred 5-17 days before the GLOF. This landslide was most likely triggered by extremely heavy, south Asian monsoon-associated rainfall in June. The time lag between the landslide and the GLOF suggests that pre-weakening of the dam due to landslide-induced outflow pushed the system towards a tipping point, that was finally exceeded following subsequent rainfall, snowmelt, a secondary landslide, or calving of ice into the lake. We back-calculate part of the GLOF process chain, using the GIS-based open source numerical simulation tool r.avaflow. Two scenarios are considered, assuming a debris landslide-induced impact wave with overtopping and resulting retrogressive erosion of the moraine dam (Scenario A), and retrogressive erosion due to pre-weakening of the dam without a major impact wave (Scenario B). Both scenarios yield plausible results which are in line with empirically derived ranges of peak discharge and breach time. The breaching process is characterized by a slower onset and a resulting delay in Scenario B, compared to Scenario A. Evidence, however, points towards Scenario B as a more realistic possibility. There were no casualties from this GLOF but it caused severe destruction of infrastructure (e.g. roads and bridges) and property losses in downstream areas. Given the clear role of continued glacial retreat in destabilizing the adjacent lateral moraine slopes, and directly enabling the landslide to deposit into the expanding lake body, the GLOF process chain under Scenario B can be robustly attributable to anthropogenic climate change, while downstream consequences have been enhanced by the development of infrastructure on exposed flood plains. Such process chains could become more frequent under a warmer and wetter future climate, calling for comprehensive and forward-looking risk reduction planning.
Glacial lakes are characteristic landforms within many terrestrial proglacial landscapes. In addition to being very important reservoirs of glacial meltwater, glacial lakes are often reservoirs of glacial sediments in paraglacial sediment cascades and a potential source of geohazards such as glacial lake outburst floods (GLOFs). This PhD dissertation presents the first inventory of glacial lakes for the warming Svalbard archipelago. A total of 566 glacial lakes were identified, most of which were classified as moraine-dammed lakes (n=290), followed by ice-dammed lakes (n=157) and bedrock-dammed lakes (n=113). In general, the moraine-dammed lakes were located in the western and southern parts of the main island Spitsbergen, where the bedrock consists of sedimentary rocks and unconsolidated sediments (including till, glaciofluvial outwash plains, and uplifted marine terraces). Ice-dammed lakes were mainly found in central and north-eastern Spitsbergen, where the bedrock is metamorphic, whereas glacial bedrock-dammed lakes dominated the island Nordauslandet. From the 1930s to 2020, the total area of glacial lakes on Svalbard more than doubled from 40.5 km² to 112.14 km². This development was attributed to progressive deglaciation, which has resulted in the merging of many glacial lakes in the proglacial zone, with a simultaneous decrease in the total number of lakes over the study period. The increase in total area was offset by 134 incidents of total lake drainage or significant reduction in area. In most cases, this was likely due to GLOF events. Most of these events occurred between 0 and 150 metres above sea level.
The compiled inventory allowed for selection of case studies distinguished by dynamic changes since the end of the Little Ice Age. For example, Svalbard's largest glacial lake, Trebrevatnet, is characterised by significant seasonal water fluctuations, reflecting the peak of Svalbard's ablation season (late July/early August) when snowmelt, ice melt, and precipitation peak. Seasonal sediment fluxes from this and other glacial lakes, such as Goësvatnet, were also observed to assess the importance of glacial lakes in shaping the sediment cascade in paraglacial processes. An important finding was that accumulated sediment was transported mainly during GLOF events as exemplified by Goësvatnet in 1991, where the amount of runoff (water) was estimated to be over 7 million m3.
A comparative analysis of selected glacial lakes clearly demonstrated that glacial lakes closer to the coast were more susceptible to GLOF events due to their exposure to the maritime climate. Coastal catchments receive warmer air masses and more precipitation, which both influence glacier melt and accumulation of large volumes of water within glacial lakes. This, in turn, affects the stability of natural dams. As deglaciation progresses and air temperature continues to rise, it is inevitable that many glacial lakes will lose contact to the glaciers that feed them, reducing the risk of future GLOFs.
Glacier retreat is projected to increase with future climate warming, elevating the risk of mass movement-triggered glacial lake outburst floods (GLOFs). These events are an emerging yet understudied hazard in Iceland, including at Fjallsjökull, an outlet glacier of the Vatnajökull ice cap in southeast Iceland. A multibeam sonar scanner survey revealed that the proglacial Fjallsárlón lake significantly expanded from 1945 to 2021. If recent glacier terminus retreat rates continue, Fjallsárlón will reach its maximum extent around 2110, more than doubling in surface area and tripling in volume. The lake will occupy two overdeepened basins with a maximum depth of ~210 m, which will likely increase terminus melting and calving rates—and thus glacier retreat—as well as potentially float the glacier tongue. Three zones on the valley walls above Fjallsjökull have high topographic potential of sourcing rock falls or avalanches that could enter Fjallsárlón and generate displacement waves or GLOFs, significantly impacting visitors and infrastructure at this tourism site. This study provides input data for risk assessments and mitigation strategies at Fjallsjökull; a template for investigating this hazard at other proglacial lakes in Iceland; and field data to advance understanding of overdeepenings and lake–terminus interactions in proglacial lakes worldwide.
We present a new model called Bayesian Estimated Glacial Lake Volume (BE‐GLAV) to estimate the volume of proglacial lakes. Presuming the lake cross‐section as trapezoidal, BE‐GLAV uses a Bayesian calibration approach to adjust the cross‐sectional geometry to match modeled and observed lake surface widths. We validated our model using bathymetric measurements from lakes spread across High Mountain Asia (specifically, the Himalaya and Tien‐Shan), with aerial extents ranging from 0.01 to 5.5 km². The modeled lake volumes agreed with the measured lake volume with a root‐mean‐square absolute uncertainty of ∼14%. With minimum and maximum errors of ∼0.3% and ∼61.2%, BE‐GLAV performed well compared to 10 other models in a model inter‐comparison experiment. Using the measured set of volumes, our model can constrain both the root mean square (RMS) error and the maximum percentage error in modeled lake volume, unlike other models, some of which can compute just the RMS uncertainty.
Glacial lake outburst floods (GLOFs) are a severe threat to communities in the Himalayas; however, GLOF mitigation strategies have been implemented for only a few lakes, and future changes in hazard are rarely considered. Here, we present a comprehensive assessment of current and future GLOF hazard for Gepang Gath Lake, Western Himalaya, considering rock and/or ice avalanches cascading into the lake. We consider ground surface temperature and topography to define avalanche source zones located in areas of potentially degrading permafrost. GLOF process chains in current and future scenarios, also considering engineered lake lowering of 10 and 30 m, were evaluated. Here, varied avalanche impact waves, erosion patterns, debris flow hydraulics, and GLOF impacts at Sissu village, under 18 different scenarios were assessed. Authors demonstrated that a larger future lake does not necessarily produce larger GLOF events in Sissu, depending, among other factors, on the location from where the triggering avalanche initiates and strikes the lake. For the largest scenarios, 10 m of lowering reduces the high‐intensity zone by 54% and 63% for the current and future scenarios, respectively, but has little effect on the medium‐intensity flood zone. Even with 30 m of lake lowering, the Sissu helipad falls in the high‐intensity zone under all moderate‐to‐large scenarios, with severe implications for evacuations and other emergency response actions. The approach can be extended to other glacial lakes to demonstrate the efficiency of lake lowering as an option for GLOF mitigation and enable a robust GLOF hazard and risk assessment.
Recent studies indicate that - due to climate change - the Earth is undergoing rapid changes in all cryospheric components, including polar sea ice shrinkage, mountain glacier recession, thawing permafrost, and diminishing snow cover. This book provides a comprehensive summary of all components of the Earth's cryosphere, reviewing their history, physical and chemical characteristics, geographical distributions, and projected future states. This new edition has been completely updated throughout, and provides state-of-the-art data from GlobSnow-2 CRYOSAT, ICESAT, and GRACE. It includes a comprehensive summary of cryospheric changes in land ice, permafrost, freshwater ice, sea ice, and ice sheets. It discusses the models developed to understand cryosphere processes and predict future changes, including those based on remote sensing, field campaigns, and long-term ground observations. Boasting an extensive bibliography, over 120 figures, and end-of-chapter review questions, it is an ideal resource for students and researchers of the cryosphere.
Glacial lake outburst floods (GLOFs) – sudden releases of water retained in glacial lakes – are among the consequences of retreating glaciers. In high mountain regions across the globe, glaciers have receded from their Little Ice Age (LIA) positions, leading to the formation and evolution of different types of glacial lakes. By integrating the analysis of remotely sensed imageries, documentary data sources, field data as well as other data and approaches, this study aims at revealing the relationship between evolution of different generations (and sub-types) of glacial lakes and the occurrence of GLOFs, and characterizing past events for better anticipation of future ones. The primary geographical focus of this work is on the Peruvian Andes with special attention given to the most glacierized part of it – the Cordillera Blanca, certain chapters and section also focus on High Asia (parts of Indian and Nepal Himalaya) and Austrian Alps (Tyrol and Salzburg provinces). This habilitation is designed as a collection of published studies of the author and the core of this work is a set of 23 peer-reviewed lake- and GLOF- oriented papers and one book chapter, published between 2015 and 2021.
Inventories of high mountain lakes prepared in this work provide insights into the characteristics and dynamics of evolution of glacial lakes in different parts of the world. Unlike most of the existing lake inventories, insights into qualitative lake characteristics (e.g. dam type, lake evolution phase) are derived and analyzed. Several thousands of lakes are inventoried in the three study regions (Peruvian Andes, Sikkim Himalaya, Austrian Alps), revealing general patterns suggesting that: (i) moraine-dammed lakes are dominant lake type forming and evolving in earlier stages of the post-LIA glacier retreat; (ii) the formation and evolution of bedrock-dammed lakes and lakes with combined dams dominate in later stages; (iii) relatively narrow elevational band hosts currently forming (proglacial) lakes. As a result of climate change-driven glacier retreat, this ‘active’ band of proglacial lakes evolution is documented to be shifting upwards and in combination with topographical setting control the formation and evolution of new glacial lakes.
This study presents unprecedently detailed GLOF inventory for the Peruvian Andes, which provides novel insights into the GLOF triggering and characterization and in combination with the lake inventory generate apparent utilizations for GLOF hazard identification and assessment efforts. It was shown that most of the high magnitude GLOFs originated from failures of moraine dams of lakes in the proglacial stage of their evolution, highlighting the monitoring priority. Trigger-wise, rapid mass movements into the lake dominated, while other triggers were documented rather marginally. Strikingly, Peruvian Andes are among the few regions of the world where there is an evidence of earthquake triggering of GLOFs – a specific process chain. By combining GLOF inventory with the lake inventory, it is shown that GLOFs occur in temporal clusters (peak frequencies) which are associated with specific stages of glacier retreat, lake formation and evolution (e.g. an increased number of proglacial moraine-dammed lakes) or extreme triggering events (e.g. a strong earthquake). Importantly lagged response of glaciers, lakes and GLOFs to initial forcings are desired to be considered in the anticipation of future GLOFs.
A substantial part of this habilitation focuses on characterization and reconstruction of past GLOF events. Several recent (e.g. the 2020 Lake Salkantaycocha GLOF in Peru; the 2020 Lake Jinwuco GLOF in Tibet) as well as historic lake outbursts (e.g. the 1941 Lake Palcacocha GLOF) are analyzed and modelled in order to: (i) understand drivers and processes involved in GLOF preconditioning, triggering, propagation and attenuation; (ii) derive a set of plausible parameters for the modelling of potential future events. In addition, the evolution of future lakes and potential future GLOFs are modelled at selected study sites in Peruvian Andes and Indian Himalaya, with obvious implications for GLOF hazard and risk management.
Last but not least, observations and findings from study sites in South America, Asia and Europe are put into the context of GLOF research and sustainable development efforts in mountain regions across the globe.
Patagonia is one of the regions of the world with the highest spatial contrast in terms of water availability. The rain shadow effect on the leeward side of the Andes mountain range induces a strong negative gradient of rainfall in a narrow 60 km strip. Therefore, two highly differentiated hydroclimatic-ecological regions can be identified:
1.
The Andean Patagonia, which is a water-producing area, containing glaciers, seasonal snow, valleys with large drainage networks of torrential courses, big lakes, and wetlands, wherein the forest is the dominant vegetation
2.
The Extra Andean Patagonia, which extends to the east of the Andes through the windy and arid/semiarid plateau, wherein water productivity is very low and steppe vegetation dominates
This chapter focuses on the main hydrologic systems of these regions and presents an overview of the state of knowledge regarding the main surface water bodies, river basin features, main water uses, and the conflicts linked to the pressure on water resources by human activities in a context of increasing development and climate change.KeywordsPatagonian riversAndean hydrologyWater usesWater managementPatagonia
Lake volume is a critical parameter in the prediction of potential flood volume and peak discharge in the risk assessment of glacial lake outburst flood (GLOF). As existing volume–area scaling relationships often blur the complexity of lake geometry, we presented a new volume-scaling law specific to moraine-dammed lakes, derived from a large lake bathymetry dataset. The relationship was based on the premise that lake geometry parameters (i.e., area, volume, width/length ratio) scale predictably. We then critically evaluated the performance of the new approach and compared it with 19 existing empirical relationships by examining a database of glacial lake bathymetry obtained without repeated measurements. Overall, the new volume-scaling relationship showed a more robust performance than other published formulas. In addition, an intriguing result was that regional differences were not always controlled by the predictability of lake volumes, that is, there were no regional restrictions on the use of the new method, at least not in the Himalayas. Finally, using the new approach and high-resolution Landsat imagery, our results of sequential mapping of all lakes in the Poiqu basin indicated that the total lake volume has increased by 148% from 1974 to 2020. Compared with other formulas, the lake volume estimation approach proposed in this paper provides an approximate mean value, which provides a key input parameter for flood simulation and a new alternative for estimating lake volume.
Monitoring and inventorying proglacial lakes in the Maritime Antarctica region is essential for understanding the effects of climate change on these environments. This study uses Landsat images to create a map of lakes in ice-free areas of the South Shetlands Islands (SSI) for 1986/89, 2000/03 and 2020, and verification of patterns of change in lake areas and numbers. Normalized water difference index (NDWI) products, image segmentation, field records, and cartographic products from other studies were used to validate the results. Results show a 60% increase in the number of lakes from 1986/89 to 2000/03; and a 55% increase from 2000/03 to 2020. There was a 52% increase in lake areas from 1986/89 to 2000/03; a 79% increase from 2000/03 to 2020; and a 173% increase from 1986 to 2020. From 1986 to 2020, the most significant changes were a decrease in the average elevation and distance from glaciers and an increase in distance from the sea. In 2020, SSI lakes were predominantly coastal and ice-marginal, with an E and S orientations, flat surfaces, and a low declivity.
Rapid changes of glacial lakes are among the most visible indicators of global warming in glacierized areas around the world. The general trend is that the area and number of glacial lakes increase significantly in high mountain areas and polar latitudes. However, there is a lack of knowledge about the current state of glacial lakes in the High Arctic. This study aims to address this issue by providing the first glacial lake inventory from Svalbard, with focus on the genesis and evolution of glacial lakes since the end of the Little Ice Age. We use aerial photographs and topographic data from 1936 to 2012 and satellite imagery from 2013 to 2020. The inventory includes the development of 566 glacial lakes (total area of 145.91 km2) that were in direct contact with glaciers in 2008–2012. From the 1990s to the end of the 2000s, the total glacial lake area increased by nearly a factor of six. A decrease in the number of lakes between 2012 and 2020 is related to two main processes: the drainage of 197 lakes and the merger of smaller reservoirs into larger ones. The changes of glacial lakes show how climate change in the High Arctic affect proglacial geomorphology by enhanced formation of glacial lakes, leading to higher risks associated with glacier lake outburst floods in Svalbard.
Glacial lake outburst floods (GLOFs) are a serious potential threat to the safety of life and property in downstream areas. In this study, moraine-dammed glacial lakes in the Yi’ong Zangbo River basin were recognized based on Landsat ETM+/TM/OLI images in 2000 and 2019. And the GLOFs for the Jionglaco, the largest glacial lake in this basin, was simulated using the one-dimensional hydrodynamic model. The results show that the total number and area of moraine-dammed glacial lakes in this basin increased by 10 (10.52%) and 5.49 km ² (48.24%) from 2000 to 2019, in which the area of the Jionglaco increased by 3.22 km ² . The peak discharge at the breach outlet for five scenarios with different combinations of breach width (80 m and 120 m), depth (2.5 m and 5 m) and flood time (1.5 h and 3 h) are 489 m ³ /s, 1327.43 m ³ /s, 444.32 m ³ /s, 617.47 m ³ /s and 1570.61 m ³ /s. With the addition of baseflow in river, the peak discharge at bridge site 15 138.93 km from Jionglaco are 1040.89 m ³ /s, 1724.00 m ³ /s, 1024.85 m ³ /s, 1162.25 m ³ /s and 1990.52 m ³ /s. The combination of baseflow in river and the GLOFs discharge results in the increasing peak discharge in the further downstream region. However, the arrival of peak discharge in downstream areas is delayed, which increases the chances of people escaping. This study aims to provide some references for the prevention of GLOFs in this region.
We analyze and reconstruct a recent glacial lake outburst flood (GLOF) process chain on 26 June 2020, involving the moraine-dammed proglacial lake – Jinwuco (30.356∘ N, 93.631∘ E) in eastern Nyainqentanglha, Tibet, China. Satellite images reveal that from 1965 to 2020, the surface area of Jinwuco has expanded by 0.2 km2 (+56 %) to 0.56 km2 and subsequently decreased to 0.26 km2 (-54 %) after the GLOF. Estimates based on topographic reconstruction and sets of published empirical relationships indicate that the GLOF had a volume of 10 million cubic meters, an average breach time of 0.62 h, and an average peak discharge of 5602 m3/s at the dam. Based on pre- and post-event high-resolution satellite scenes, we identified a large debris landslide originating from western lateral moraine that was most likely triggered by extremely heavy, south-Asian-monsoon-associated rainfall in June 2020. We back-calculate part of the GLOF process chain, using the GIS-based open-source numerical simulation tool r.avaflow. Two scenarios are considered, assuming a debris-landslide-induced impact wave with overtopping and resulting retrogressive erosion of the moraine dam (Scenario A), as well as retrogressive erosion without a major impact wave (Scenario B). Both scenarios are in line with empirically derived ranges of peak discharge and breach time. The breaching process is characterized by a slower onset and a resulting delay in Scenario B compared to Scenario A. Comparison of the simulation results with field evidence points towards Scenario B, with a peak discharge of 4600 m3/s. There were no casualties from this GLOF, but it caused severe destruction of infrastructure (e.g., roads and bridges) and property losses in downstream areas. Given the clear role of continued glacial retreat in destabilizing the adjacent lateral moraine slopes and directly enabling the landslide to deposit into the expanding lake body, the GLOF process chain can be plausibly linked to anthropogenic climate change, while downstream consequences have been enhanced by the development of infrastructure on exposed flood plains. Such process chains could become more frequent under a warmer and wetter future climate, calling for comprehensive and forward-looking risk reduction planning.
Rapid growth of proglacial lakes in the current warming climate can pose significant outburst flood hazards, increase rates of ice mass loss, and alter the dynamic state of glaciers. We studied the nature and rate of proglacial lake evolution at Pasterze Glacier (Austria) in the period 1998–2019 using different remote-sensing (photogrammetry, laser scanning) and fieldwork-based (global navigation satellite system – GNSS, time-lapse photography, geoelectrical resistivity tomography – ERT, and bathymetry) data. Glacier thinning below the spillway level and glacier recession caused flooding of the glacier, initially forming a glacier-lateral to supraglacial lake with subaerial and subaquatic debris-covered dead-ice bodies. The observed lake size increase in 1998–2019 followed an exponential curve (1998 – 1900 m2, 2019 – 304 000 m2). ERT data from 2015 to 2019 revealed widespread existence of massive dead-ice bodies exceeding 25 m in thickness near the lake shore. Several large-scale and rapidly occurring buoyant calving events were detected in the 48 m deep basin by time-lapse photography, indicating that buoyant calving is a crucial process for the fast lake expansion. Estimations of the ice volume losses by buoyant calving and by subaerial ablation at a 0.35 km2 large lake-proximal section of the glacier reveal comparable values for both processes (ca. 1×106 m3) for the period August 2018 to August 2019. We identified a sequence of processes: glacier recession into a basin and glacier thinning below the spillway level; glacio-fluvial sedimentation in the glacial–proglacial transition zone covering dead ice; initial formation and accelerating enlargement of a glacier-lateral to supraglacial lake by ablation of glacier ice and debris-covered dead ice forming thermokarst features; increase in hydrostatic disequilibrium leading to destabilization of ice at the lake bottom or at the near-shore causing fracturing, tilting, disintegration, or emergence of new icebergs due to buoyant calving; and gradual melting of icebergs along with iceberg capsizing events. We conclude that buoyant calving, previously not reported from the European Alps, might play an important role at alpine glaciers in the future as many glaciers are expected to recede into valley or cirque overdeepenings.
Ice marginal lakes are a dynamic component of terrestrial meltwater storage at the margin of the Greenland Ice Sheet. Despite their significance to the sea level budget, local flood hazards and bigeochemical fluxes, there is a lack of Greenland-wide research into ice marginal lakes. Here, a detailed multi-sensor inventory of Greenland’s ice marginal lakes is presented based on three well-established detection methods to form a unified remote sensing approach. The inventory consists of 3347 (±8%) ice marginal lakes (>0.05km2) detected for the year 2017. The greatest proportion of lakes lie around Greenland’s ice caps and mountain glaciers, and the southwest margin of the ice sheet. Through comparison to previous studies, a ∼75% increase in lake frequency is evident over the west margin of the ice sheet since 1985. This suggests it is becoming increasingly important to include ice marginal lakes in future sea level projections, where these lakes will form a dynamic storage of meltwater that can influence outlet glacier dynamics. Comparison to existing global glacial lake inventories demonstrate that up to 56% of ice marginal lakes could be unaccounted for in global estimates of ice marginal lake change, likely due to the reliance on a single lake detection method.
The response of glaciers to atmospheric warming has become a key issue in scientific as well as public and even political discussions about human impacts on the climate system. The predominant tendency of continued worldwide glacier shrinkage indeed constitutes one of the clearest indications in nature of rapid climate change at a global scale. The observed trend of increasingly negative mass balances is consistent with an accelerated trend in global warming and correspondingly enhanced energy flux toward the earth surface. Mountain ranges at lower latitudes have lost large percentages of their glacier areas and volumes since the end of the Little Ice Age. Many of them may become mostly or even completely de-glaciated during the coming decades. Such changes have the potential to profoundly affect environmental conditions far beyond cold mountain chains. Sea-level rise, shifting seasonality in water supply, and local formation of new lakes reflect changes in the water cycle at global, continental, and regional-to-local scales. They are accompanied by rather marked changes in cold-mountain landscape appearance, slope stability, erosion/sedimentation, and hazard conditions. Worldwide monitoring of glaciers today involves process-oriented field measurements, high-resolution geodetic information from space and new terrestrial technologies, but also faces difficult challenges of vanishing glaciers with long-term mass-balance observations. Combining rich observational data with spatio-temporal modeling increasingly helps to prepare integrated analyses of observed phenomena and with anticipating likely future developments as a basis for the planning and realization of climate adaptation strategies. This article examines the monitoring and inventory of glaciers worldwide, observed and forecasted changes, and impacts of deglaciation on geomorphic and water resources systems.
Glacier lake outburst floods (GLOF) at Laguna de los Témpanos, a glacier-dammed side lake of Glaciar Steffen, Hielo Patagónico Norte, were documented for a period between December 1974 and February 2020. With manual interpretation of 150 remote sensing images of aerial surveys, vertical aerial photographs, Landsat MSS, TM, ETM and OLI, ALOS, and ASTER images, 19 GLOFs were captured/inferred by focusing on icebergs and water levels, except two periods in the 1980s and the 1990s for which no image was available. This translates to the occurrence of the GLOF on average once ca. every 14 months. Many GLOFs occurred in late summer to early fall, with a few in late spring: but one GLOF was inferred to have occurred in wintertime. The causes of GLOFs were supposed to be heavy rainfalls, probably accompanied with rapid snow/ice melting by warm air temperatures, judging from the general weather condition over the laguna area. The latest two GLOFs (2016 & 2017) were very large, enough to have completely exposed the lake floor in the middle section. The GLOF of 2017 (Mar. 31) was registered in a hydrograph set up at Lower Río Huemules. After this GLOF, the water level has become stable with a more or less continuous outlet stream along the glacier sidewall and there has been no GLOF to date. So probably the prospect of another GLOF has considerably diminished by now. As Glaciar Steffen receded about 6km during this study period, the glacier has thinned accordingly, to which the water level adjusted with three distinctive relatively stable states while fluctuating frequently.
Glacier retreat is accompanied by formation of lakes within glacier moraines. The lakes may produce outburst floods which can transform into destructive debris flows. In the Central Caucasus this hazard has not been sufficiently studied, and the location and size of glacial lakes is not shown on the topographical maps. We have combined field and remote sensing research to study glacial lakes and debris flow initiation zones in periglacial areas. Two case studies are presented. Bashkara lakes in the upper Adyl-Su River valley have been subject to detailed monitoring since 1999. In 2005 their total area reached 93,000 m 2, and the total volume exceeded 900,000 m 3. Buildings, bridges and camping sites are in areas endangered by potential debris flows. A second group of 13 glacier lakes was identified in 2005 on the northeastern slopes of Mt. Elbrus. In July 2006 the area of the largest lake reached 89,000 m 2, and its volume was 550,000 m 3. On August 11, 2006 the lake produced an outburst flood releasing about 400,000 m 3 of water which later transformed into a debris flow that entrained up to 350,000 m 3 of solid material. A downstream mineral water resort was damaged. We have identified 71 glacial lakes in the Central Caucasus. These include post-disaster lakes, e.g. in the Genaldon River valley where 13 new lakes formed after a glacier disaster in 2002, which at one point reached 437,000 m 2 in area and 5,000,000 m 3 in volume. In the future we hope to develop detailed recommendations for risk management of glacier and debris flow hazards in the Central Caucasus.
A revised glacier inventory comprising glacier changes between 1986 and 2000 have been compiled for the Southern Patagonia Icefield (SPI) based on Landsat TM and Landsat ETM+ imagery acquired on January 14, 1986 and October 27, 2000, respectively. Elevation data from the Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) were used to interpret ice divides. The 1986 ice area of the 48 major SPI glaciers is 11,022 ± 412 km2, which represents 85 % of the total SPI area of 13,003 ± 282 km2. Our results agree in general with Aniya et al. (1996), although there are large differences in the basin limits for a few glaciers. Area loss of 489 ± 377 km2 is obtained for the period 1986–2000 for the whole SPI, of which 68 % corresponds to the 48 major glaciers (333 ± 106 km2). Major (> 5 km2) area loss is detected in 20 glaciers (268 ± 87 km2), which accounts for 80 % of the total area loss of the major glaciers between 1986 and 2000. Smaller (< 5 km2) but significant area losses have occurred within 17 other glaciers, all of which have retreated more than 100 m. While our new results confirm the general retreat of the SPI reported earlier (Aniya et al. 1997; Rignot et al. 2003), we show that 9 glaciers within the latitudes of 49°48′–50°25′S had relatively stable frontal positions between 1986 and 2000, 8 of which were previously retreating over the period 1944/1986. Independent evaluation of ice thickness changes within the SPI (Rignot et al. 2003) show that significant thinning exists for only 2 of the 9 glaciers with stable fronts (excluding Moreno Glacier which we regard as stable). The stable frontal positions of the 13 glaciers might be due to the recent increase of precipitation in the central–south sector of the SPI. Although enhanced precipitation has not yet been detected by observations, it is to be expected based on the intensification of the westerly circulation, as has already been observed in the Southern Hemisphere since the mid-1960s (Marshall, 2003).
A Landsat TM mosaic of the Southern Patagonia Icefield (SPI), South America, was utilized as an image base map to inventory its outlet glaciers. The spI is South America's larg-est ice mass with an area of approximately 13,000 km2. The icefield does not have complete topographic map coverage. With the aid of stereoscopic interpretation of aerial photo-graphs and digital enhancement of the Landsat TM image, glacier divides were located and glacier drainage basins were delineated, giving a total of 48 outlet glaciers. Employing a supervised classification using Landsat TM bands 1, 4, and 5, glacier drainage basins were further divided into accumula-tion and ablation areas, thereby determining the position of the transient snow line (TSL). After comparing with existing data, it was found that the TSL could be taken, for practical purposes, as the equilibrium line (EL). The position of the TSL was then compared with topographic maps, where available, to determine the equilibrium line altitude (ELA). Altogether, 11 parameters relating primarily to glacier morphology were inventoried. Pio XI Glacier (1265 kmz) is found to be the largest outlet glacier in South America, a i d m a y also be its longest. The average accumulation area ratio of 0.75 is larger than those of the Northern Patagonia Icefield and European glaciers. All but two outlet glaciers calve into fjords or pro-glacial lakes.
Glacier lakes are a common phenomenon in high mountain areas. Outbursts from glacier lakes have repeatedly caused the loss of human lives as well as severe damage to local infrastructure. In several high mountain ranges around the world, a grave uncertainty about the hazard potential of glacier lakes still exists, especially with respect to the effects of accelerating rates of glacier retreat as a consequence of atmospheric warming. Area-wide detection and modeling of glacier lake hazard potentials is, therefore, a major challenge. In this study, an approach integrating three scale levels allows for the progressive focus on critical glacier lakes. Remote sensing methods for application in glacier lake hazard assessment are presented, and include channel indexing, data fusion, and change detection. Each method matches the requirements of a certain scale level. For estimating potential disaster amplitudes, assessments must be made of maximum discharge and runout distance of outbursts floods and debris flows. Existing empirical relations are evaluated and complementary ones as derived from available data are proposed. Tests with observations from a recent outburst event from a moraine-dammed lake in the Swiss Alps show the basic applicability of the proposed techniques and the usefulness of empirical relations for first hazard assessments. In particular, the observed runout distance of the debris flow resulting from the outburst does not exceed the empirically estimated maximum runout distance. A list of decision criteria and related remote sensing techniques are discussed in conclusion. Such a list is an essential tool for evaluating the hazard potential of a lake. A systematic application of remote sensing based methods for glacier lake hazard assessment is recommended.
Summit Lake, which is impounded by Salmon Glacier, is the largest self-draining, ice-dammed lake in Canada. Until 1961, it contained few icebergs and was stable, overflowing to the north into the Bowser River valley. The first jokulhlaup occurred in December 1961, after a lengthy period of thinning and retreat of Salmon Glacier, when a subglacial tunnel developed in the weakened ice dam, allowing the lake to drain suddenly. This flood and two others in 1965 and 1967 caused major damage to the road system in the Salmon River valley south of the lake. Since 1965, with three exceptions, Summit Lake has drained annually; minor floods along Salmon River in 1966, 1969, and 1973 may record partial drainings of the lake, although other explanations are possible. Jokulhlaups in recent years have been smaller and have occurred earlier in the year than most of the early floods. Rapid water-level fluctuations associated with the annual emptying and refilling of Summit Lake have generated large numbers of icebergs, derived from the Salmon Glacier dam; these icebergs presently choke the surface of the lake. The present jokulhlaup cycle is likely to continue either until the glacier readvances or until it retreats to the point that it no longer forms an effective seal.
Mass balance variations of Glaciar San Rafael, the northernmost tidewater glacier in the Southern Hemisphere, are reconstructed over the period 1950-2005 using NCEP-NCAR reanalysis climate data together with sparse, local historical observations of air temperature, precipitation, accumulation, ablation, thinning, calving, and glacier retreat. The combined observations over the past 50 yr indicate that Glaciar San Rafael has thinned and retreated since 1959, with a total mass loss of ~22 km3 of ice eq. Over that period, except for a short period of cooling from 1998-2003, the climate has become progressively warmer and drier, which has resulted primarily in pervasive thinning of the glacier surface and a decrease in calving rates, with only minor acceleration in retreat of the terminus. A comparison of calving fluxes derived from the mass balance variations and from theoretical calving and sliding laws suggests that calving rates are inversely correlated with retreat rates, and that terminus geometry is more important than balance fluxes to the terminus in driving calving dynamics. For Glaciar San Rafael, regional climate warming has not yet resulted in the significant changes in glacier length seen in other calving glaciers in the region, emphasizing the complex dynamics between climate inputs, topographic constraints and glacier response in calving glacier systems.
Ice elevation changes of the Northern Patagonia Icefield (NPI) were analyzed by comparing three Digital Elevation Models (DEM) corresponding to 1975 (constructed based on topographic maps), the SRTM DEM of 2000 yr and a SPOT 5 DEM of 2005. In addition, the glacier length fluctuations and the surface area evolution between 2001 and 2011 of 25 glaciers of the NPI were studied: the information extracted from the Landsat ETM+ satellite image of 11 March 2001 was compared to the measurements performed based on the Landsat ETM+ satellite image of 19 February 2011. From a global point of view, the majority of the studied glaciers thinned, retreated and lost surface between 2001 and 2011, only few glaciers (Leones, Nef, Pared Sur and Soler) located on the eastern side of the NPI have been stable. Glaciers located on the western side of the NPI suffered a stronger wasting compared to the glaciers located on the eastern side.
Overall, over the ablation areas of the NPI (below 1150 m a.s.l.) a more rapid thinning of 2.6 m yr−1 occurred between 2000 and 2005 yr compared to the period 1975–2000, in which a mean thinning of 1.7 m yr−1 was measured for the same zones of the NPI. For the whole period (1975–2005) the most important thinning of the ablation areas has been estimated for HPN-1 Glacier (4.4 m yr−1) followed by Benito (3.4 m yr−1), Fraenkel (2.4 m yr−1), Gualas (2.1 m yr−1) and Acodado glaciers, all of them located on the western side of the NPI.
Between 2001 and 2011, a noteworthy retreat of 1.9 km was experienced by Gualas Glacier and by Reichert Glacier with 1.6 km, both located on the north-western side of the NPI. On the south-western side of the NPI, during the same decennia, Steffen Glacier experienced a remarkable retreat of 1.6 km as well. During the 2001–2011 period, Steffen Glacier more than doubled its rate of retreat (compared to the 1979–2001 period) and experienced the disintegration of its main front as well as a lateral tongue that retreated 3.1 km. The most significant retreat observed on the eastern side was experienced by Colonia Glacier (1 km).
Area loss was also relevant during the period 2001–2011. Overall, the icefield experienced a reduction of 50.6 km2 which represents a 1.3 % relative to the surface area calculated for 2001 yr. The most remarkable surface reduction was observed for HPN-1 Glacier that lost 3.2 % of its surface estimated in 2001, followed by Steffen Glacier (2.8 %).
We suggest that the glacier shrinking observed in the NPI is controlled firstly by atmospheric warming, as it has been reported in this area. Nevertheless, updated climatic studies are needed in order to confirm this suggestion. If the detected past climate trends persist, in the future, glaciers of the NPI will continuous or even increase their rate of shrinking generating important consequences for this region like the production of Glacier Lake Outburst Flood events or the decrease of the melt-water runoff in the long-term future.
The melting of mountain glaciers and ice caps is expected to contribute significantly to sea-level rise in the twenty-first century, although the magnitude of this contribution is not fully constrained. Glaciers in the Patagonian Icefields of South America are thought to have contributed about 10% of the total sea-level rise attributable to mountain glaciers in the past 50 years. However, it is unclear whether recent rates of glacier recession in Patagonia are unusual relative to the past few centuries. Here we reconstruct the recession of these glaciers using remote sensing and field determinations of trimline and terminal moraine location. We estimate that the North Patagonian Icefield has lost 103+/-20.7km3 of ice since its late Holocene peak extent in AD 1870 and that the South Patagonian Icefield has lost 503+/-101.1km3 since its peak in AD 1650. This equates to a sea-level contribution of 0.0018+/-0.0004mmyr-1 since 1870 from the north and 0.0034+/-0.0007mmyr-1 since 1650 from the south. The centennial rates of sea-level contribution we derive are one order of magnitude lower than estimates of melting over the past 50 years, even when we account for possible thinning above the trimline. We conclude that the melt rate and sea-level contribution of the Patagonian Icefields increased markedly in the twentieth century.
A combination of remotely sensed data, field mapping, bathymetric survey and geophysical soundings is used to describe the recent changes in the terminal area of Petrov glacier, the largest glacier in the Akshiirak massif, central Tien Shan. According to our results, three periods of accelerated glacier retreat (1977–80, 1990–95 and 2008–09) can be distinguished since 1977. The largest recession occurred in 1990–95 when the glacier retreated by 54 AE 8 m a –1 . Accelerated glacier retreat affected the enlargement rate of Petrov lake, which increased by 0.04–0.1 km 2 a –1 and by 1.3–2.2 Â 10 6 m 3 a –1 in the last three decades. Since 1995, the mean annual retreat rate of the lake-calving northern glacier section has been up to three times higher than the retreat rate of the land-terminating southern section. The calving flux ranged from 2.5 to 4.6 Â 10 6 m 3 a –1 in 2003–09, resulting in a total glacier mass loss of (17.7 AE 0.4) Â 10 6 m 3 . The calving terminus of Petrov glacier was >65 m thick in 2009 according to ground-penetrating radar measurements.
Abstarct
To investigate the impact of proglacial lake formation on the dynamics and evolution of glaciers, we measured the ice motion of the terminal part of Rhonegletscher, Switzerland, where a lake formed in 2005. In 2009, the flow velocity near the terminus was >20 m a ⁻¹ . One of the survey stakes tripled its velocity between 2006 and 2007. Since the lake water pressure was consistently close to the ice overburden pressure, it is likely that the high subglacial water pressure enhanced the basal ice motion. The estimated flow velocity due to ice shearing was negligibly small; almost 100% of the horizontal velocity near the terminus was caused by basal sliding. The longitudinal strain rate was large, 0.064 a –1 , indicating that much of the glacier thinning was due to ice dynamics. The region of ice flotation adjacent to the lake expanded between 2008 and 2009 as a result of glacier thinning. Accordingly, a huge uplift of the surface was observed in 2009. It is clear from the vertical ice motion as well as visual observations that the marginal part of the glacier began to float. The ice-thinning rate in the studied area from 2008 to 2009 was 3.4 ma –1 , larger than previous estimates.
Glaciar Nef, a 164 km2eastern outlet of Hielo Patagónico Norte (the northern Patagonia icefield), terminates in a proglacial lake that has formed in conjunction with 20th-century glacier retreat. The terminus is inferred to be transiently afloat. A hinge-calving mechanism is proposed in which buoyant forces impose a torque on the glacier tongue, resulting in the release of coherent sections of the glacier tongue as "tabular" ice-bergs. A simple model shows how torque and tensile stress reach a maximum at the up-glacier limit of the buoyant zone, and that glacier thinning causes this point to migrate up-glacier. Empirical evidence supporting this model includes elevated thermo-erosional notches ≤6.5 m above lake level, and the ubiquitous presence since 1975 of "tabular" ice- bergs with surface areas ≤0.3 km2. Flow speeds of 1.2−1.3 m d−1 were measured near the terminus in February 1998. Extrapolations from these short-term data yield a calvingrate of 785−835 m a−1 and a calvingflux of 232 × 106 m3 a−1 or 0.2 km3 a−1. The calculated mean water depth at the terminus is 190 m. This calvingrate is higher than at grounded temperate glaciers calving in fresh water, but is nevertheless almost an order of magnitude less than calvingrates at both grounded and floatingtidewater glaciers.
Changes in the area and bathymetry of Imja Glacial Lake and in the elevation of its damming moraine, Khumbu region, Nepal Himalaya are investigated. Previously reported changes in the lake area have been updated by multi-temporal ASTER images, which revealed a decreased expansion rate after 2000. A provisional expansion of the lake observed in 2004, from which some studies concluded an accelerated lake expansion due to global warming, has, from 2005, subsided to the glacier surface. Bathymetric changes for the period 1992–2002 that were first obtained for Himalayan glacial lakes suggest that the melting of debris-covered ice beneath the lake is insignificant in terms of the increase in lake volume, and that the retreat of a glacier in contact with the lake by calving is essential for the lake's expansion. Changes in the height of a damming moraine for the period 2001–2007 suggest a continuous surface lowering near the lake, though the lowering rates are smaller than those for the period 1989–1994.
The dominant spatial and temporal patterns of a network of 23 homogenous instrumental rainfall records of Southern South America were analysed and used to define four regional annual precipitation series: (1) Northwestern Patagonia (1950–2000) with nine stations from both side of the Andes between 41 and 44°S; (2) Central Patagonia (1950–2000) with five Chilean stations between 45 and 47°S; (3) Patagonian plains–Atlantic (1961–2000) with five Argentinean stations spread between 43 and 50°S and from the eastern foothills of the Andes to the Atlantic coast and (4) Southern Patagonia (1950–2000) with four stations east of the Andes, near the Strait of Magellan between 51 and 53°S. Unique patterns were also identified for two of the southernmost stations in Ushuaia and Evangelistas (EVA). Time series analysis of these regional patterns shows marked decadal variability for Northwestern and Central Patagonia, 3–7 years oscillations for the Patagonian plains–Atlantic region and a strong biannual oscillation mode for Southern Patagonia. Regional annual rainfall appears to be strongly influenced by Antarctic circulation modes (Antarctic Oscillation Index), whereas the El Niño-Southern Oscillation (ENSO) influence on rainfall variability is less evident. Highly significant correlation of precipitation on the west coast of Patagonia with the pressure gradient between the subtropical eastern Pacific and the high-latitude south eastern Pacific is confirmed. Copyright © 2008 Royal Meteorological Society
Recent climate changes have had a significant impact on the high-mountain glacial environment. Rapid melting of glaciers has resulted in the formation and expansion of moraine-dammed lakes, creating a potential danger from glacial lake outburst floods (GLOFs). Most lakes have formed during the second half of the 20th century. Glaciers in the Mount Everest (Sagamartha) region, Nepal, are retreating at an average rate of 10–59 m a –1 . From 1976 to 2000, Lumding and Imja Glaciers retreated 42 and 34 m a –1 , respectively, a rate that increased to 74 m a –1 for both glaciers from 2000 to 2007. During the past decade, Himalayan glaciers have generally been shrinking and retreating faster while moraine-dammed lakes have been proliferating. Although the number of lakes above 3500 m a.s.l. has decreased, the overall area of moraine-dammed lakes is increasing. Understanding the behaviour of glaciers and glacial lakes is a vital aspect of GLOF disaster management.
The purpose of the present work was to investigate variations in the surface areas of lakes in the north-east sector of Sagarmatha National Park (Nepal) at the end of the 20 th century, through comparison of the Mount Everest maps based on a survey done in the early 1980s, and the official Map of Nepal based on a survey done at the beginning of the 1990s. The analysis of the changes occurring between the 1980s and the 1990s in the surface areas and distribution of lakes in the north-east sector of SNP reveals that lake areas substantially increased, by 15.4 (-5.5; +5.7)% (median 12.5%), within hydrographic basins that included a certain amount of glacial cover. In fact, 96% of the lakes whose surface area increased are located in glacial basins. Conversely, the majority of the lakes without glacial cover in their catchment showed a reduction in surface area, and in many cases disappeared (83% of the lakes that disappeared were situated in basins without glaciers). This different behaviour of these two types of lakes, though observed over a short time span, would appear to be consistent with the consequences of temperature increases recorded from the beginning of 1980s on a global and local scale. The digital tool produced (Limnological Information System, LIS) as part of this work is intended to provide a useful platform for extending the analysis to entire area of SNP, as well as for subsequent comparisons based on earlier maps or more recent satellite images.
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-millionm3 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 3,000m3s−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 16,000m3s−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.
KeywordsJökulhlaup-Outburst flood-Patagonia-Glacial-lake-Climate change
An interdisciplinary study of glacier-related hazards in the Petrov lake region (Ak-Shiirak Range, the Inner Tien-Shan, Kyrgyzstan) has been undertaken to identify potential dangers to the area. A cooperative effort from experts in the fields of hydrology, glaciology, geomorphology and geophysics has been employed in this study. For the hazard assessment, evolution of the Petrov glacier and lake was reconstructed using historical reports, aerial photographs and satellite images. Geomorphological mapping and geophysical soundings was applied to the lake territory and the moraine dam. This has identified potentially hazardous areas of the dam including subsurface drainage zones and cracks that could cause a sudden extremely high discharge. In the
past three decades, the Petrov lake has doubled in size, while in recent years, its area has been increasing by more than 92,000 square metres per year. Although there is no evidence for an imminent outburst, the dramatic increase in the lake’s size emphasizes the importance of this study.
Glaciar León is a temperate, grounded outlet of the eastern North Patagonian Icefield (NPI). It terminates at an active calving margin in Lago Leones, a 10 km long proglacial lake. We take a multidisciplinary approach to its description and use ASTER imagery and clast sedimentology to describe the geomorphology of the glacier and its associated moraines. We date periods of glacier retreat over the last 2500 years using a combination of lichenometric, dendrochronological, cosmogenic and optically stimulated luminescence techniques and show that the glacier receded from a large terminal moraine complex some 2500 years ago and underwent further significant recession from nineteenth-century moraine limits. The moraine dates indicate varying retreat rates, in conjunction with significant downwasting. The bathymetry of Lago Leones is characterized by distinct ridges interpreted as moraine ridges that dissect the lake into several basins, with water depths reaching 360 m. The fluctuations of Glaciar León appear to have been controlled by the interplay between climatic forcing and calving dynamics. NERC; University of St Andrews; American Alpine Club; British Geomorphological Research Group; Dudley Stamp Memorial Trust; Royal Scottish Geographical Society; Quaternary Research Association; Carnegie Trust for the Universities of Scotland
BGRに掲載された論文の著作権は原則として社団法人日本雪氷学会に帰属する。 （日本雪氷学会著作権規程） The major results of the Glaciological Research Project in Patagonia (GRPP) ,2003-2005, whichtargeted Glaciar Exploradores of the Hielo Patagonico Norte (HPN) and Glaciar Perito Moreno of theHielo Patagonico Sur (HPS), were reported. Studies at Glaciar Exploradores include recent glacialchronology, glacier flow measurements with D-GPS, meteorological measurements with an AWS andhydrological measurements at the outlet stream. Three moraine systems were recognized, and mostrecent two of them were formed sometime between the 12th and 17th century and the early to mid-19thcentury. The annual glacier flows in the area within 5km from the terminus ranged 48 to 138m in 2003-2004. Strong emergence velocity was observed near the terminus. The annual precipitation near theterminus was close to 3000mm,the mean annual air temperature was 7.5C and the annual specific runoffwas about 6200mm in 2005. Also the variations of 21 outlet glaciers of the HPN from 1944/45 to 2004/05were presented with their notable characteristics. The area loss due to recession in 60 years amountedto ca. 100km2, of which close to 30% was accounted by Glaciar San Quintin, the largest glacier of the HPN.At Glaciar Perito Moreno, observations and measurements were carried out for flow, strain gridand meteorological measurements, and calving activities. Flow velocity per day in December 2004ranged 3.95 to 0.53m, with the average of 1.66m at the calving front. At the middle reach, the averagedaily flow velocity was 1.5m, and the profile survey revealed that the inner zone maintained thickerconditions, but with no significant trend of additional thickening. The annual mean temperaturenear the EL (ca. 1350m) was 1.0C, while that at near the terminus was 6.3C in 2005.
Failures of glacial lake dams can cause outburst floods and represents a serious hazard. The potential danger of outburst floods depends on various factors like the lake's area and volume, glacier change, morphometry of the glacier and its surrounding moraines and valley, and glacier velocity. Remote sensing offers an efficient tool for displacement calculations and risk assessment of the identification of potentially dangerous glacial lakes (PDGLs) and is especially helpful for remote mountainous areas. Not all important parameters can, however, be obtained using spaceborne imagery. Additional interpretation by an expert is required. ASTER data has a suitable accuracy to calculate surface velocity. Ikonos data offers more detail but requires more effort for rectification. All investigated debris-covered glacier tongues show areas with no or very slow movement rates. From 1962 to 2003 the number and area of glacial lakes increased, dominated by the occurrence and almost linear areal expansion of the moraine-dammed lakes, like the Imja Lake. Although the Imja Lake will probably still grow in the near future, the risk of an outburst flood (GLOF) is considered not higher than for other glacial lakes in the area. Potentially dangerous lakes and areas of lake development are identified. There is a high probability of further lake development at Khumbu Glacier, but a low one at Lhotse Glacier.
Lake Arsine, a pro-glacial lake in the French Alps, first appeared 30 years ago and has since been growing steadily. In 1985, it reached an area of 5.9 ha, a maximum depth of 39 m, and a volume of 0.8 × 106 m3. This lake is dammed partially by a glacial moraine and partially by a tongue of dead ice covered by a moraine 1–2 m thick. The glacier calves into the lake, which collects all the melt water from the surrounding glacial area of 250 ha. No open outlet exists and seepage reaches a value of 5 × 106 m3 year−1. A 1 year water balance shows that seepage increases rapidly with water level, from less than 0.03 m3 s−1to more than 0.75 m3 s−l for a rise in water level of 10 m. The seasonal lake-volume fluctuations of 0.5 × 106 m3 are small compared with the inflow volume of 5 × 106 m3.
Progressive clogging of the bottom by glacial flour has led to a gradual rise of 8 m in 16 years in the summer level, while at the same time the height of the dam has decreased by 10 m due to the melting of dead ice. Consequently, by the end of July 1985 the freeboard was only 2 m and overflow on to the dead ice was thought likely to occur in the very near future. To eliminate this flood hazard, a 250 m long channel was dug in an ice-free zone which had been profiled by geophysical prospecting. This work was carried out between 14 April and 13 June 1986, in order to benefit from the low winter water level.
Geotechnical studies of the moraine have shown that no large landslide is to be feared. A crude model of the waves created by calving shows that the new water level is safe and the channel is capable of handling the maximum likely discharge of 15 m3 s−1 resulting from the highest possible wave of 3.5 m.
Vatnajökull, Iceland, is the Earth’s most studied ice cap and represents a classical glaciological field site on the basis of S. Pálsson’s seminal glaciological field research in the late 18th century. Since the 19th century, Vatnajökull has been the focus of an array of glaciological studies by scientists from many nations, including many remote-sensing investigations since 1951. Landsat-derived positions of the termini of 11 outlet glaciers of Vatnajökull were compared with frontal positions of six of these 11 outlet glaciers determined by field observations during the period 1973–92. The largest changes during the 19 year period (1973–92) occurred in the large lobate, surge-type outlet glaciers along the southwestern, western, and northern margins of Vatnajökull. Tungnaárjökull receded −1413 ± 112 m (−1380 ± 1 m from ground observations), and Brúarjökull receded −1975 ± 191 m (−2096 ± 5 m from extrapolated ground observations) between 1973 and 1992. Satellite images can be used to delineate glacier margin changes on a time-lapse basis, if the glacier margin can be spectrally discriminated from terminal moraines and sandur deposits and if the advance/recession is larger than maximum image pixel size. “Local knowledge” of glaciers is critically important, however, in the accurate delineation of glacier margins on Landsat images.
The retreat of glaciers since 1927 in Cordillera Blanca has produced dangerous lakes at the front of many glaciers. All the known data, most of them unpublished, are reviewed. The known aluviones are listed, and those of Chavin, Quebrada Los Cedros and Artesoncocha described in full. In these three cases a breach in the front moraine came from big ice falls into the lake. The protective devices made on the outlets are described, as well as the effects of the big earthquake on 31 May 1970. In the case of Laguna Parón, which keeps its level thanks to infiltrations, the fluctuations of the discharge of the springs as related to the level of the lake from 1955 to 1969 are reported. The projects for lowering the level of Laguna Parón and for emptying Safuna Alta are described. The latter partially emptied in fact by piping after the earthquake, allowing a final solution.
In western Canada, existing and former lakes dammed by landslides, moraines, and glaciers have drained suddenly to produce floods, orders of magnitude larger than normal streamflows. Landslide dams consisting of failed bedrock generally are stable, whereas those comprising Quaternary sediments or volcanic debris fail soon after they form, typically by overtopping and incision. Moraine dams are susceptible to failure because they are steep-sided and consist of loose, poorly sorted sediment. Irreversible rapid incision of a moraine dam may result from a large overflow associated with a severe rainstorm, avalanche, or rockfall. Some glacier-dammed lakes drain suddenly through englacial and subglacial tunnels to produce large floods. -from Authors
Describes research into the lake situated at the end of the Petrov glacier on the north-western slope of the Ak-Shiyrak massif in Tien-Shan. The lake was not formed until about 1870 and cannot be more than about 110 years old. At the present time it is increasing in size at approximately the same rate as the glacier is retreating.-translated by P.Cooke
An approach for semi-automatic lake detection based on multispectral optical remote sensing data and digital elevation models (DEM) is presented in this contribution. After preprocessing of the satellite images, all data are processed in a Geographic Information System (GIS). Preliminary hazard assessment of the detected lakes in a test region was performed: Potential ice avalanches and debris fl ows originating in glacier lake outbursts are modeled by means of hydrological fl ow-routing models. The strength of the presented methods is the ability to quickly create an overview of the glacier lake situation and related hazard potentials over large regions. With few adjustment works, the presented approach can be applied to mountain regions all over the world.
Area variations of outlet glaciers of the Hielos Patagonicos (Patagonia icefields), South America, since 1944/45, are summarized, and the volume of ice loss due to recession and thinning estimated, in order to derive the contribution of the Patagonian glaciers to sea-level change. For the Hielo Patagonico Norte (HPN), variations of 22 outlet glaciers were studied for the period between 1944/45 and 1995/96. Until 1990, most glaciers retreated at increasing rates; however, since then, the retreat has slowed down. The total area loss of the HPN due to frontal recession is about 64 km(2). From the estimated ice thickness and thinning rates, a total ice loss of 152-310 km(3) was obtained for the 51 yr. In the Hielo Patagonico Sur (HPS), 48 outlet glaciers were studied for the period between 1944/45 and 1985/86. Most glaciers have been retreating, with a few remaining almost stagnant, but two glaciers, Pio XI and Perito Moreno, showed a net advance. The total area loss of the HPS due to recession was about 200 km(2). From the estimated ice thickness and thinning rates, a total ice loss was 285-670 km(3) for the period of 1945-1986. With a simple linear extrapolation to the period of 1945-1996, figures of 355-833 km(3) were obtained. The total volume reduction of the HPN and HPS is therefore roughly 825 +/- 320 km(3) for the 51-yr period. This amount roughly translates into a world-wide sea-level rise of 1.93 +/- 0.75 mm, or 0.038 mm yr(-1) since 1944/45, which accounts for 3.6% of the total sea-level change. Analyses of climatic data at several Chilean and Argentinean meteorological stations located around the icefield revealed a slight increase in air temperature and a decrease in precipitation over the last 40 to 50 yr. Other factors affecting the variation include calving status, the ratio of the accumulation area to the total area (AAR), the gradient of the glacier surface near the equilibrium line (EL), and subglacial topography.
Lake Arsine, a pro-glacial lake in the French Alps, first appeared 30 years ago and has since been growing steadily. In 1985, it reached an area of 5.9 ha, a maximum depth of 39 m, and a volume of 0.8 × 10 ⁶ m ³ . This lake is dammed partially by a glacial moraine and partially by a tongue of dead ice covered by a moraine 1–2 m thick. The glacier calves into the lake, which collects all the melt water from the surrounding glacial area of 250 ha. No open outlet exists and seepage reaches a value of 5 × 10 ⁶ m ³ year ⁻¹ . A 1 year water balance shows that seepage increases rapidly with water level, from less than 0.03 m ³ s ⁻¹ to more than 0.75 m ³ s −l for a rise in water level of 10 m. The seasonal lake-volume fluctuations of 0.5 × 10 ⁶ m ³ are small compared with the inflow volume of 5 × 10 ⁶ m ³ .
Progressive clogging of the bottom by glacial flour has led to a gradual rise of 8 m in 16 years in the summer level, while at the same time the height of the dam has decreased by 10 m due to the melting of dead ice. Consequently, by the end of July 1985 the freeboard was only 2 m and overflow on to the dead ice was thought likely to occur in the very near future. To eliminate this flood hazard, a 250 m long channel was dug in an ice-free zone which had been profiled by geophysical prospecting. This work was carried out between 14 April and 13 June 1986, in order to benefit from the low winter water level.
Geotechnical studies of the moraine have shown that no large landslide is to be feared. A crude model of the waves created by calving shows that the new water level is safe and the channel is capable of handling the maximum likely discharge of 15 m ³ s ⁻¹ resulting from the highest possible wave of 3.5 m.
Glaciers in Patagonia are temperate and many of them are receding at an accelerated rate, with a consequent enlargement of glacial lakes. We will review the occurrence of Glacial Lake Outburst Floods (GLOFs) recorded during the last century in Patagonia (Northern and Southern Patagonia icefields), and analyse them in view of the general warming of 0.5°C affecting the region during the last 40 years. Special attention will be devoted to Lake Cachet 2 (47°12' S, 73°15' W, 422 m a.s.l.) which has experienced 6 GLOF events during the last 2 years: April 6-7 2008, October 7-8 2008, 21-22 December 2008, 5 March 2009, 16 September 2009 and 5-6 January 2010. Lake Cachet 2 has an area of 4 km2, located on the eastern margin of the Northern Patagonia Icefield, being dammed on its southern margin by Colonia Glacier. Prior to the April 2008 event there had been no historical record of catastrophic flooding of this lake. Each event resulted in a flood wave of which travelled down Colonia River to the confluence with Baker River in a period of less than 48 hours, where it reached peak flows of approximately 2,000 m3/s. Here we present airborne and ground explorations carried out in the period 2008-2009 which confirm that the Lake Cachet 2 floods drain through an englacial tunnel under Colonia Glacier for a distance of 8 km, emerging at the front of the glacier. We propose that the lake started draining in 2008 as a result of the weakening of the ice dam produced by long-term thinning of Colonia Glacier. Measurements of the empty lake bed were performed with the CECS airborne laser scanner onboard a helicopter, which show that the maximum water volume of the lake is 200 x 106 m3. Modelling of the flood events has been carried out based on the subglacial flood model of Clarke (2003), showing that a semi-circular subglacial tunnel attaining a maximum dimension of 15 m can evacuate Lake Cachet 2 in approximately 48 hours, with peak flows on the order of 4000 m3/s. Preliminary results of morphological changes will be shown from lapse-rate photography of cameras installed in the summer season 2009/2010 at the Lake Cachet 2/Colonia Glacier outlet and at the Colonia Glacier front. We use our field data, airborne data, satellite imagery and hydrologic data collected by automatic sensors from Dirección General de Aguas (Chilean Water Cadastre) to describe the flood events and attempt to predict them.
Vatnajökull, Iceland, is the Earth's most studied ice cap and represents a classical glaciological field site on the basis of S. Pálsson's seminal glaciological field research in the late 18th century. Since the 19th century, Vatnajökull has been the focus of an array of glaciological studies by scientists from many nations, including many remotesensing investigations since 1951. Landsat-derived positions of the termini of 11 outlet glaciers of Vatnajökull were compared with frontal positions of six of these 11 outlet glaciers determined by field observations during the period 1973-92. The largest changes during the 19 year period (1973-92) occurred in the large lobate, surge-type outlet glaciers along the southwestern, western, and northern margins of Vatnajökull. Tungnaárjökull receded - 1413 ± 112 m (-1380 ± l m from ground observations), and Brúarjökull receded -1975 ± 191 m (-2096 ± 5 m from extrapolated ground observations) between 1973 and 1992. Satellite images can be used to delineate glacier margin changes on a time-lapse basis, if the glacier margin can be spectrally discriminated from terminal moraines and sandur deposits and if the advance/recession is larger than maximum image pixel size. "Local knowledge" of glaciers is critically important, however, in the accurate delineation of glacier margins on Landsat images.
The retreat of glaciers since 1927 in Cordillera Blanca has produced dangerous lakes at the front of many glaciers. All the known data, most of them unpublished, are reviewed. The known aluviones are listed, and those of Chavin, Quebrada Los Cedros and Artesoncocha described in full. In these three cases a breach in the front moraine came from big ice falls into the lake. The protective devices made on the outlets are described, as well as the effects of the big earthquake on 31 May 1970. In the case of Laguna Parón, which keeps its level thanks to infiltrations, the fluctuations of the discharge of the springs as related to the level of the lake from 1955 to 1969 are reported. The projects for lowering the level of Laguna Parón and for emptying Safuna Alta are described. The latter partially emptied in fact by piping after the earthquake, allowing a final solution.
The Northern Patagonia Icefield (NPI), covering 3953 km(2), is the second largest temperate ice body in South America. Despite its importance as a climate change indicator because of its location and size, data oil ground-based mass balance and meteorological records for the analysis of glacier (Snout) variations are still lacking. The use of multitemporal satellite images to estimate equilibrium line altitude variations could be a Surrogate for such analyses. Since late-summer snowlines of temperate glaciers coincide with the equilibrium line, we analyzed Five Landsat images spanning 1979-2003 and an ASTER-derived digital elevation model to reveal oscillations in the equilibrium line altitude (Delta Z(ELA)). The average ELAs range between 870 in and 1529 (+/- 29 m), with lower altitudes on the west side. Winter snow cover accumulation indicates higher elevations (relative to the glacier snout) of the transient snowlines in the west. Thus, one of the reasons for the higher retreating rates observed on the west side is that the lower part of the ablation area is likely exposed to year-round ablation. Glacier sensitivity to Delta Z(ELA) oscillations Would depend upon the topographic condition of the accumulation area (gentle or steep). In Outlet glaciers with gentle accumulation areas such as San Rafael and San Quintin, Delta Z(ELA) of up to 65 and 70 in at the central flow part and bare ice area variations > 5 km(2) and > 13 (+/- 0.6 km(2)) were observed, respectively.
Glaciar León, a temperate, grounded outlet of the North Patagonian Icefield, terminates at an active but stable calving margin in Lago Leones. Glaciological and limnological data gathered during 2001 and 2002 are used to examine the relative contributions of calving and melting to mass loss at the terminus, and the interplay between glacier and lake processes. The calving rate of 880 m/a in a mean water depth of 65 m is high for lake-calving glaciers. Subaerial melt rates at the terminus are small compared with calving rates, but melting at the waterline facilitates calving by undercutting the subaerial calving cliff. Ice-proximal surface water temperatures of 6-7°C allow waterline melt notches to grow at rates of c. 0.8 m/day, suggesting that melt-driven calving accounts for c. 23% of ice loss at the terminus. The significance of melting at calving termini decreases with increasing calving speeds, but is greater than simple calculations of melt losses suggest because of the process-linkage with calving.
Of the numerous kinds of dams that form by natural processes, dams formed from landslides, glacial ice, and late-neoglacial moraines present the greatest threat to people and property. Landslide dams form a wide range of physiographic settings. The most common types of mass movements that form landslide dams are rock and debris avalanches; rock and soil slumps and slides; and mud, debris, and earth flows. The most common initiation mechanisms for dam-forming landslides are excessive rainfall and snowmelt and earthquakes. Natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam. Although data are few, for the same potential energy at the dam site, downstream flood peaks from the failure of glacier-ice dams are smaller than those from landslide, moraine, and constructed earth-fill and rock-fill dam failures.
Upper-air conditions archived in the NCEP-NCAR Reanalysis have been used to investigate changes in precipitation and snowfall over the Patagonia icefields during 1960 99. Apparently, whereas total precipitation has not changed, warming has caused a decrease in the amount falling as snow. Precipitation at a site is taken to be proportional to the product of the relative humidity and the component of the wind in a particular critical direction, both at 850 hPa (˜ 1400 m) at a point over the ocean to the west of the icefields; whether it falls as rain or snow is assumed to depend on whether the temperature at the elevation of the site is above or below + 2 °C. The critical direction is assumed to be 270°, which is perpendicular to the north south trending Andes and is also the prevailing wind direction in this zone of strong westerlies. Because of the scarcity of precipitation records on or near the icefields, the constant of proportionality cannot be determined, so the investigation is limited to examining relative changes in those upper air variables. Warming at 850 hPa has been ˜ 0.5 °C over the 40 years, both winter and summer, with the effects that it has: (1) shifted from snow to rain ˜ 5% of the precipitation, the total of which has changed little, and (2) increased annual melt in the ablation areas by ˜ 0.5 m w.e. The icefields have been losing mass since at least 1870, so this 40-year trend represents only an acceleration of the longer-term trend of adjusting to climate change since the Little Ice Age.
Glacier lake dams consisting of unconsolidate d material are prone to failure and may cause disastrous surges of water heavily charged with debris. Consideration of potential glacier lake outburst floods (GLOF) is, therefore, of essential importance for the design of river engineering structures located downstream of hazardous glacier lakes. As an example, a flood study carried out for a hydropower project on the Arun River in Nepal is taken. The results indicate, that, in addition to the "classical" flood flow analysis, GLOF analysis should be considered for derivation of design floods of projects located in glacier dominated watersheds.
Three distinct phenomena related to sudden lake drainage, which occurred in a restricted area within the southern Coast Mountains of British Columbia, are described: (i) moraine breaching by solitary wave action following an icefall into a lake; (ii) failure of a glacier ice dam by flotation and melting to produce a ‘glacier outburst’ flood or ‘jökulhlaup;’ (iii) debris torrent following a moraine breach. The possibility for a fourth failure phenomenon: moraine failure by piping, is discussed. A first attempt to develop practical hazard evaluation methods before the event, which relies on simple scale relations or index relations developed from experience of events elsewhere, is presented. Key words: dam break, debris flow, hazard evaluation, jökulhlaup, lakes, lake drainage.
We use a satellite-based survey of glacier surface elevation changes, speeds and surface melt conditions between 2000 and 2011 to quantify mass loss from the Northern Patagonian Icefield (NPI), Chile. A history of ice elevation change is found by differencing ASTER Digital Elevation Models (DEMs) relative to a void-filled version of the DEM collected by the Shuttle Radar Topography Mission (SRTM) in February 2000. Thinning rates have accelerated at lower elevations, while above the Equilibrium Line Altitude (ELA) recent thinning rates are not significantly different from those observed in previous studies. A volumetric change of − 4.06 ± 0.11 km³/yr is found by summing surface elevation changes over all glaciers in the NPI. This is regarded as a lower bound because volume loss due to frontal retreat and sub-aqueous melting is not included. This volume change is converted to a mass loss of 3.40 ± 0.07 Gt/yr, taking into account density differences above and below the equilibrium line. We find that the NPI is providing at least 0.009 ± 0.0002 mm/yr to ongoing sea level change, in agreement with previous estimates.
We demonstrate an application of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images to detect and monitor supraglacial lakes on glaciers in the Mount Everest region in Tibet (Xizang) and Nepal. ASTER offers powerful capabilities to monitor supraglacial lakes in terms of (1) surface area, growth and disappearance (spatial resolution =15 m), (2) turbidity (15 m resolution), and (3) temperature (90 m resolution). Preliminary results show an overall similarity of supraglacial lakes on three glaciers. Lakes have widely varying turbidity as indicated by color in visible/near-infrared bands 1-3, the largest lakes being bright blue (highly turbid), cold (near 0°C) and hydraulically connected with other lakes and supraglacial streams, while small lakes are mostly dark blue (relatively clear water),warmer (>4°C), and appear hydraulically isolated. High levels of turbidity in supraglacial lakes indicate high rates of meltwater input from streams or erosion of ice cliffs, and thus are an indirect measure relating to the activity and hydraulic integration of the lake with respect to other lakes and streams in the glacier.
Mendenhall Glacier is a lake-calving glacier in southeastern Alaska, USA, that is experiencing substantial thinning and increasingly rapid recession. Long-term mass wastage linked to climatic trends is responsible for thinning of the lower glacier and leaving the terminus vulnerable to buoyancy-driven calving and accelerated retreat. Bedrock topography has played a major role in stabilizing the terminus between periods of rapid calving and retreat. Lake-terminating glaciers form a population distinct from both tidewater glaciers and polar ice tongues, with some similarities to both groups. Lacustrine termini experience fewer perturbations (e.g. tidal flexure, high subaqueous melt rates) and are therefore inherently more stable than tidewater termini. At Mendenhall, rapid thinning and simultaneous retreat into a deeper basin led to flotation conditions along approximately 50% of the calving front. This unstable terminus geometry lasted for approximately 2 years and culminated in large-scale calving and terminus collapse during summer 2004. Buoyancy-driven calving events and terminus break-up can result from small, rapidly applied perturbations in lake level.
Current conditions and secular changes in ice-contact lakes in the Bhutan–China border region were investigated using satellite imagery. More than 50 moraine dammed ice-contact or ice-proximal lakes were identified, of which 14 were evidently growing. In debris-covered areas of valley glaciers, lake growth is characterised by the initial appearance of supraglacial lakes and subsequent upstream expansion by a coalesced lake. In small debris-free or partially debris-covered glaciers, lake growth begins from a single lake. Lake growth has continued over a period ranging from 20 to 70 years, with a growth rate of <70 m/year in length and <0.04 km2/year in area. These values observed at the northern side of the main Himalayan range are smaller than those observed at the southern side. The initial appearance year, estimated from the expansion rate of most of the lakes in the southern and northern sides, ranges from the 1950s to the 1970s and before the 1950s, respectively.
In this study, we present a first regional assessment of glacial lake distribution and evolution in the Hindu Kush Himalaya (HKH). Seven sites have been selected between Bhutan and Afghanistan, to capture the climatic variability along the 2000-km long mountain range. For each site, glacial lakes have been mapped with LANDSAT satellite imagery acquired in 1990, 2000 and 2009, using an automatic classification. In the East (India, Nepal and Bhutan), glacial lakes are bigger and more numerous than in the West (Pakistan, Afghanistan), and have grown continuously between 1990 and 2009 by 20% to 65%. On the other hand, during the same period, the glacial lake coverage has shrunk in the Hindu Kush (−50%) and the Karakorum (−30%). This east/west pattern of lake changes seems in agreement with sparse glaciological measurements that suggest less (or even no) ice loss in the western part of the HKH.
High thinning rates (up to − 4.0 ± 0.97 m a− 1) have been measured at Campo de Hielo Patagónico Norte (CHN) or Northern Patagonia Icefield, Chile between 1975 and 2001. Results have been obtained by comparing a Digital Elevation Model (DEM) derived from regular cartography compiled by Instituto Geográfico Militar of Chile (IGM) based upon 1974/1975 aerial photographs and a DEM generated from Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) satellite images acquired in September 2001. A complete cloud-free Landsat ETM+ satellite image mosaic acquired in March 2001 was used to update the available glacier inventory of the CHN, including all glaciers larger than 0.5 km2 (48 new glaciers). A new delineation of ice divides was also performed over the accumulation areas of glaciers sharing the high plateau where the existing regular cartography exhibits poor coverage of topographic information. This updated glacier inventory produced a total ice area for 2001 of 3953 km2, which represents a decrease of 3.4 ± 1.5% (140 ± 61 km2 of ice) with respect to the total ice area of the CHN in 1979 calculated from a Landsat MSS satellite image. Almost 62% of the total area change between 1979 and 2001 took place in glaciers located at the western margin of the CHN, where the maximum area loss was experienced by Glaciar San Quintín with 33 km2. At the southern margin, Glaciar Steffen underwent the largest ice-area loss (12 km2 or 2.6% of the 1979 area), whilst at the eastern margin the greatest area loss took place in Glaciares Nef (7.9 km2, 5.7% of the 1979 area) and Colonia (9.1 km2, 2.7% of the 1979 area). At the northern margin of the CHN the lower debris-covered ablation area of Glaciar Grosse collapsed into a new freshwater lake formed during the late 1990s. The areal changes measured at the CHN are much larger than previously estimated due to the inclusion of changes experienced in the accumulation areas. The CHN as a whole is contributing melt water to global sea level rise at rates ∼ 25% higher than previous estimates.
Calving glaciers constitute a great majority of all glaciers in Patagonia and Tierra del Fuego, and are dynamically important elements of the southern South American icefields. Large numbers of tidewater glaciers calve into the Chilean fjords, and many outlet glaciers terminate in proglacial lakes. Most probably, all are temperate and grounded, with steep mass balance gradients. A majority of these glaciers remained largely unknown to science until very recently. This paper reviews recent research in the region in the context of glaciological and Quaternary debates, and discusses current understanding and uncertainties. During the 20th century most glaciers have retreated, but the particular dynamics of calving glaciers have produced some striking exceptions to this regional trend, producing sustained advances (e.g., Glaciar Pio XI, Glaciar Perito Moreno), accelerated retreats (e.g., Glaciar O'Higgins, Glaciar Marinelli), and long-maintained stillstands of glaciers with very high accumulation area ratios (e.g., Glaciar Calvo). The relative importance of climatic, topographic, and glaciodynamic controls on regional patterns of glacier fluctuation remain an enigma, especially in the Cordillera Darwin, but space-borne radar imagery is now yielding much information. Key research themes in recent years include: (1) glacier inventory work using remotely-sensed data; (2) calving rates and calving dynamics, particularly the contrast between calving rates in tidewater and freshwater; (3) glacier/climate relationships, both in historic and longer timeframes; and (4) geographic contrasts in glacier behaviour, especially the relative significance of precipitation and temperature for glacier mass balance in this region of steep climatic gradients. Many intriguing and important questions cannot presently be resolved due to the paucity of mass balance and climatic data, but current research is yielding data that have regional, interhemispheric and theoretical significance.
Diss. Nr. 11716 Naturwiss. ETH Zürich. Literaturverz.