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National audience; On 12th July 1892, a sudden drainage of an internal water pocket from the Tete Rousse glacier caused a large outburst flood, destroying a large part of Saint Gervais village and killing 175 people. Many measurements were carried out at the end of the 19th Century in order to understand the origin of this disaster. The origin of this water pocket remains unclear. In 2007, new extensive measurements relative to the thickness of this glacier, ice temperature, and surface mass balance have been performed. These new dataset with the past measurements have been analysed to give new insights into the origin of this outburst flood.

International audience; On 12th July 1892, a sudden drainage of an internal water pocket from the Tete Rousse glacier caused a large outburst flood, destroying a large part of Saint Gervais village and killing 175 people. Many measurements were carried out at the end of the 19th Century in order to understand the origin of this disaster. The origin of this water pocket remains unclear. In 2007, new extensive measurements relative to the thickness of this glacier, ice temperature, and surface mass balance have been performed. These new dataset with the past measurements have been analysed to give new insights into the origin of this outburst flood.

1. The drainage of the Kyagar glacier dammed lake and the Tram Kangri glacier dammed lake at the upper Shaksgam is the main reason for glacier outburst floods in the Yarkant river. The Kyagar glacier dammed lake is characterized by subglacial drainage, while the Tram Kangri glacier dammed lake by mainly lateral drainage and, secondly, by subglacial drainage. 2. The drainage mechanism of the Tram Kangri ice dam determines the main characteristics of flood hydrography of the Kagun station, while the Kyagar glacier dammed lake plays an important role in the formation of floods. 3. Glacier outburst floods in the Yarkant river are characterized mainly by high peak discharge, big rising rate, small total volume and short duration. The floods happen mostly from late summer to early autumn. A period of 6 to 10 years in occurrence of large scale glacier outburst floods exist. The periodicity depends mainly on large scale drainage in the Kyagar ice-dammed lake. 4. Formation and dimensions of glacier dams at the upper Shaksgam were determined by long-term variations of the regional climate, whereas the changes of storage capacity in the lake reflect cold and warm changes of alpine region. Therefore, frequent glacier outburst floods indicate glacier advance and climatic variations.

[1] Lakes impounded by moraines may be considered hazardous in glaciated areas throughout the world because dams can fail suddenly producing destructive floods with peak discharges far in excess of normal flows. Here we present a comprehensive case study in the Zurich, Switzerland, area that reveals several independent lines of evidences for the occurrence of a Late Pleistocene (∼13,760 calibrated years B.P.) moraine breach and subsequent Lake Zurich outburst (discharge volume ∼2.5 km3). We use seismic and core data in order to track and date the geological fingerprint of this event. Data from areas downstream of the lake show coarse-grained massive (>25 m thick) reworked morainic deposits behind four breached zones. In Lake Zurich, sedimentary structures recorded in a paleowater depth of ∼36 m indicate strong outburst-induced currents. Hydrodynamic calculations reconstructing the sediment transport capacity explaining the observed bed forms allow estimating averaged outburst discharge to exceed minimum values of ∼2400 m3s−1. The potential maximal magnitude of the outburst is inferred from calculations considering critical flow conditions through the breaches revealing estimated peak discharge of ∼20,600 m3s−1. We also discuss long-term causes and short-term trigger mechanisms of the dam failure that occurred several thousand years after moraine formation and show that it coincides with a reconstructed strong northern alpine earthquake (magnitude >6.5). Our data thus suggest that catastrophic drainage of Lake Zurich was initiated as a consequence of the moraine dam failure that either was triggered by primary earthquake shaking or by secondary effects, such as overtopping by landslide-generated waves.

[1] Hubbard Glacier, the largest temperate tidewater glacier in the world, has been advancing since 1895 AD and has now twice dammed 60-km-long Russell Fjord, once in 1986 and more recently in 2002. This paper focuses on the 2002 event, when a strong spring advance pushed shallow submarine proglacial sediments against Gilbert Point, closing off Russell Fjord by late June. As a consequence, upstream ice flow decelerated from 5 m d−1 to 1.5 m d−1, with flow diverging to either side of Gilbert Point. Lake height reached 15 m asl before intense rains caused lake water to overtop the moraine dam on 14 August 2002. Three cubic kilometers of water were released within 30 hours, with peak discharge reaching 55,000 m3 s−1 24 hours after the flood began. The discharge records for the 1986 and 2002 outbursts differ significantly and reflect differences in lake height (26 m versus 15 m) and dam types (ice versus moraine). The 2002 outburst proceeded in two stages: (1) relatively slow overtopping of the subaerial moraine with downward erosion rates of 1–2 m h−1 with little lateral expansion, (2) followed by faster downward erosion of the submarine moraine (up to 7 m h−1) with rapid lateral expansion of the channel by ice calving (∼7 m h−1). The annual average terminus position at Gilbert Point has remained constant since 2002, although there are seasonal variations of 100–200 m. The deep channel, strong tidal currents, and seasonally warm ocean water appear to have prevented the advance of this segment of the terminus despite the glacier's continued advance elsewhere along its terminus. Sediments are slowly filling in the channel at a rate of about 4 m yr−1, and their steady accumulation may eventually trigger the next closure.

Considering the high concentration of rock avalanches in the northern part of the Neuquén province of Argentina (36°-38°S and 70°-71°W) and their association with lacustrine basins forming natural dams, their catastrophic collapse seems not to be such a common process as could be expected for these cases. The present work depicts the area immediately affected by the outburst flood corresponding to the Navarrete dam catastrophic collapse (175 × 106 m3), through a sedimentological analysis, generated since the arroyo Colorado was blocked due to a rock avalanche deposit during not well constrained postglacial times. The outburst flood dispersion is initially inferred based on morphological criteria and then determined from a sedimentological analysis of its matrix. Furthermore, the matrix is compared to that of the fluvial terraces, which have been sampled along the arroyo Colorado. This comparison shows that even though differences among them are not so significant through most of the study area, matrix frequency starts to be distinctive from the most distant point of sampling. Fil:Penna, I.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Folguera, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

A 1,050 km long 20” pipeline was constructed to transport natural gas from northern Argentina to the coast of Chile. On the Argentine side, significant portions of the route traverse rugged mountainous terrain subject to landslides, debris flows, flash floods, and earthquakes. On the Chilean side (situated up to 5,000 m above sea level), the pipeline crosses active faults and terminates at locations historically subject to tsunami. The pipeline began operation in 1999. An outburst flood in a steep mountain stream caused the pipeline to rupture in 2001. Reactivation of a large rock slide in 2002 caused a second rupture. It appeared that the original design had underestimated the route’s exposure to geohazards, and efforts were required to improve pipeline safety and reliability. A geohazard risk management program was initiated in April 2002. Geohazards were identified and characterized through airphoto interpretation and field inspection. Sites were initially ranked using semi-quantitative risk estimates. Risk cost-benefit analyses were used to select optimal risk control measures at high ranking geohazard sites. These included monitoring programs, reconstruction of stream crossings, reroutes, and in one instance, landslide avoidance using a horizontal directional drill. Risk control measures were implemented between 2002 and 2006, and additional efforts are ongoing. An updated assessment of geohazard exposure was completed in 2005 with the objective of quantifying the level of risk reduction that had been achieved and prioritizing further risk reduction efforts. This paper describes implementation of the geohazard risk management program using a case history format. It highlights the techniques used to control the range of hazard that were identified in 2002 and to quantify the improvements achieved by 2006. The paper concludes with an overview of additional risk reduction initiatives that are in progress or under consideration.Copyright © 2006 by ASME

Studies performed during the last five years have shown the existence of 74 prehistoric rock-avalanches in the northern Neuquén Andes (36°-38°S). These are mainly related to volcanic grounds of Pliocene to Pleistocene age corresponding to the Hualcupén Formation. In this work we describe their main characteristics and general homogeneous morphology. They are also characterized by a single tectonic control associated with the occurrence of their break-away and mainly postglacial ages, fact revealed by their systematic position into previous glacial valleys and limited radiometric ages. The obstruction produced by these features altered the shape of the valleys giving to local lakes. Eighteen percent of the cases are characterized by landslide dams preserved nowadays while only six percent by ephemeral ones. Two of the dams were actually catastrophically collapsed: the Cerro Pelán and Navarrete rock-avalanches: The former in Barrancas river valley with the consequent formation of the Carrilauquen lake and the later with the generation of Navarrete lake. The Carrilauquen's dam broke during historical times (29/12/1914) forming an outburst-flood that passed from the Barrancas valley to the Colorado river valley destroying their local economy and reaching after 1,500 km the Atlantic coast. The highest computed volumes in the entire region for the deposits related to rock-avalanches correspond to Varva Co Campos avalanche (3 km3). Cosmogenic isotopes have revealed its age and the age of the neighbor deposit of Varvar Co Tapia rock-avalanche, resulting in 30 ka and 60 ka respectively. Further cosmogenic isotope data revealed that the Cerro PeMn avalanche is only 2 ka. A wrong assumption, presently revaluated, was related to the assignment of these deposits to glacial accumulations because of their chaotic structure, their hummocky topography and the induced dams. Finally, several topographic, geomorphological and seismotectonic criteria are exposed to prove a seismic trigger for these avalanches. Graphics and one table are used to display the distribution of their deposits and its dose association with the orogenic front at these latitudes and the crustal seismicity of the region. © 2006 Asociación Geológica Argentina. Fil:Folguera, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

The failure of a lava dam 165,000 yr ago produced the largest known flood on the Colorado River in Grand Canyon. The Hyaloclastite Dam was up to 366 m high, and geochemical evidence linked this structure to outburst-flood deposits that occurred for 32 km downstream. Using the Hyaloclastite outburst-flood deposits as paleostage indicators, we used dam-failure and unsteady flow modeling to estimate a peak discharge and flow hydrograph. Failure of the Hyaloclastite Dam released a maximum 11 × 109 m3 of water in 31 h. Peak discharges, estimated from uncertainty in channel geometry, dam height, and hydraulic characteristics, ranged from 2.3 to 5.3 × 105 m3 s−1 for the Hyaloclastite outburst flood. This discharge is an order of magnitude greater than the largest known discharge on the Colorado River (1.4 × 104 m3 s−1) and the largest peak discharge resulting from failure of a constructed dam in the USA (6.5 × 104 m3 s−1). Moreover, the Hyaloclastite outburst flood is the oldest documented Quaternary flood and one of the largest to have occurred in the continental USA. The peak discharge for this flood ranks in the top 30 floods (>105 m3 s−1) known worldwide and in the top ten largest floods in North America.

[1] In glaciated catchments, glacier-generated floods (jokulhlaups) put human activity at risk with large, sporadic jokulhlaups accounting for most flood-related fatalities and damage to infrastructure. In studies of jokulhlaup hydrodynamics the view predominates that floodwater travels within a distinct conduit eroded into the underside of a glacier. However, some jokulhlaups produce subglacial responses wholly inconsistent with the conventional theory of drainage. By focusing on Icelandic jokulhlaups this article reassesses how floodwater flows through glaciers. It is argued that two physically separable classes of jokulhlaup exist and that not all jokulhlaups are an upward extrapolation of processes inherent in events of lesser magnitude and smaller scale. The hydraulic coupling of multiple, nonlinear components to the flood circuit of a glacier can induce extreme responses, including pressure impulses in subglacial drainage. Representing such complexity in mathematical form should be the basis for upcoming research, as future modeling results may help to determine the glaciological processes behind Heinrich events. Moreover, such an approach would lead to more accurate, predictive models of jokulhlaup timing and intensity.

[1] The largest glacier outburst flood (jokulhlaup) ever recorded in Iceland occurred in 1996 and came from subglacial lake Grimsvotn in Vatnajokull ice cap. Among other noteworthy features, this flood was characterized by an unprecedentedly high lake level prior to flood initiation, extremely rapid linear rise in lake discharge, delay between the onset of lake drainage and floodwater arrival at the glacier terminus, formation of short-lived supraglacial fountains, and initially unchannelized outbursts of floodwater at the terminus. Observations suggest that the 1996 flood propagation mechanism was fundamentally different than that of previously observed floods from Grimsvotn. We advance a new model whereby floodwater initially propagates in a turbulent subglacial sheet, which feeds a nascent system of conduits. This model is able to explain key observations made of the 1996 jokulhlaup and may shed light on other outburst floods that do not conform to the standard model.

[1] Hidden Creek Lake (HCL), an ice-marginal lake impounded by Kennicott Glacier, Wrangell Mountains, Alaska, fills annually to ∼20 to 30 × 106 m3 and then drains subglacially within 2 to 3 days. During the 1999 and 2000 jokulhlaups, we carried out a series of planned observations around the lake and in the Kennicott River, which drains the glacier. Approximately 20% of the lake volume was contained within a subglacial water “wedge” beneath the ice dam. The entire volume of the lake drains through the wedge; hydraulic head loss through this constriction may be responsible for the fairly symmetrical shape of the HCL outflow hydrographs, deduced from lake level records, basin hypsometry, and collapse of the ice dam. The flood hydrographs in the Kennicott River are similar in shape to the outflow hydrographs, and within error, lake volume matched the river flood volume in both years. Up to 12 × 106 m3 of water was temporarily stored within the glacier during the 2000 jokulhlaup. During the 2000 jokulhlaup the background flow in the Kennicott River shifted to a dilute chemical composition. As the HCL jokulhlaup progressed, Donoho Falls Lake filled with water whose chemistry was closer to that of the background flow in Kennicott River than to HCL water. Comparison of these chemical signals with typical summer variations in Kennicott River chemistry suggests that the jokulhlaup created high subglacial water pressure that impeded normal drainage of solute-rich water from a distributed drainage system into a conduit system at the glacier bed and even caused flow direction locally to reverse.

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.Key words: glacier lake outburst, hazard potential, remote sensing, empirical parameters.

Coring of Late Quaternary sediments in the Georgia Basin has revealed stratigraphic and micropaleontological evidence of an outburst flood that deposited a clay layer over much of the seafloor of the Strait of Georgia. The flood originated in the Fraser Valley or the British Columbia interior during deglaciation when an ice-dammed lake or lakes drained catastrophically. A reworked pollen assemblage contained within the clay unit has a source in the Fraser Valley or the British Columbia interior. The clay unit contains a characteristic grain-size signature, sedimen- tary structures, and a radiocarbon chronology consistent with a rapidly deposited unit emplaced by a flood event. Diatom assemblages show that a markedly lower salinity of surface waters accompanied deposition. Radiocarbon dating indicates that the flood occurred between 9160 and 9800 radiocarbon years BP. The unit correlates well with a somewhat thicker deposit found at Ocean Drilling Program drilling sites in Saanich Inlet.

On 4 January 2010, a rockslide 1200 meters long, 350 meters wide, and 125 meters high dammed the Hunza River in Attabad, northern Pakistan, and formed Lake Gojal. The initial mass movement of rock killed 20 people and submerged several villages and 22 kilometers of the strategic Karakoram Highway linking Pakistan and China. Tens of thousands of people were displaced or cut off from overland connection with the rest of the country. On 29 May, the lake overflow began to pour through a spillway excavated by Pakistani authorities. On approximately 20 July, the lake attained a maximum depth of 119 meters and a torrent at least 9 meters deep issued over the spillway, according to Pakistan's National Disaster Management Authority (NDMA). To date, the natural dam is holding and eroding slowly. However, the threat of a catastrophic outburst flood remains.

Retreating glaciers in the Himalayas have given rise to many glacier lakes. One of such lakes is the Tam Pokhari. It is located in eastern Nepal (86°56'52" E longitude and 27°44'33" N latitude) and breached on 3 September 1998 releasing 17.66 million cubic metres of water. The sediments transported by the outburst flood dammed the Dudh Kosh, River and inundated it up to 2 km upstream The nature of the glacier lake outburst flood, its causes, and downstream impact are presented in this paper.

A great number of the glacial lakes have appeared in many mountain areas of the world during the last half-century due to global warming. Severe floods have been caused by frequent outbursts from the glacial lakes. These glacial lake outburst floods (GLOF) have also occurred in the Himalayan mountains (e.g., Vuichard and Zimmermann 1987, Xu and Feng 1994), including Bhutan Himalaya. The last outburst flood in Bhutan, which originated from Lugge Glacial Lake in October 1994, caused damage to property along the river with the loss of more than 20 lives (Watanabe and Rothacher 1996). Hence, investigation of the glacial lakes is necessary for disaster prevention in Bhutan and the downstream region. Geological Survey of Bhutan (1999) and Mool et al. (2001) made the inventory of the glaciers and glacial lakes in Bhutan. Ageta et al. (2000) and Komori et al. (2003) obtained the expansion records of the lakes in Bhutan. However, much remains to be established about the spatial and temporal variation of glacial lakes not only in Bhutan but also the other Himalayan mountains. The present study revealed the current condition of glacial lakes and its secular variations during the last 45 years.

Coarse-grained deposits produced by a rare, extreme flood in the Mt. Everest region of Nepal and fine-grained deposits produced by frequent, moderate floods along the Colorado River in and near the Grand Canyon, U.S.A. illustrate a wide range of depositional patterns, processes, and mechanics along resistant-boundary channels. Deposition processes in each of these case studies were strongly influenced by sediment supply. The availability of sediment was an important factor in both case studies in determining the occurrence, location, stability, and sedimentologic characteristics of deposits produced by their respective floods. A glacial-lake outburst flood in the Mt. Everest region of Nepal eroded, transported, and deposited large quantities of boulders, cobbles, pebbles, and sand along the outburst-flood route. Depositional macroforms produced by this flood include: (1) expansion bars at abrupt expansions immediately downstream of constricted reaches, (2) longitudinal bars at local flow expansions along valley margins, (3) point bars along the inner margins of valley bends, (4) pendant bars immediately downstream of obstructions, and (5) imbricate clusters of cobbles and boulders immediately upstream of obstructions. Along the upper 16 km of the outburst-flood route, deposition is more extensive and deposits are thicker, are more poorly sorted, have more finely-skewed distributions, and have a higher percentage of fine-grained sediment than deposits below 16 km. Additionally, deposits along the upper 16 km of the flood route are reverse graded and coarsen in the downstream direction, whereas deposits below 16 km lack grading or are normally graded. These deposit characteristics suggest that the flood waters along the upper 16 km had higher sediment concentrations and were closer to their transport capacity than the flood waters below 16 km. Most resistant-boundary channels are supply limited with respect to entrainment and transport of cobble- and boulder-sized particles during frequent, low to moderate flows. However, superimposed on this supply limited coarse-grained system is a dynamic fine-grained system in which eddy bars along the channel margins are eroded and redeposited during the rising limb of a given flood. Eddy sand bar deposits along the Colorado River in and near the Grand Canyon are an excellent example of this dynamic erosional and depositional cycle that occurs during frequent, moderate floods. The erosional and depositional cycle of eddy bars during a given flood is strongly controlled by sediment delivered to the plunge pool adjacent to the eddy bar. Sediment delivered to the plunge pool on the rising limb of the flood alters the flow patterns and hydraulics in the pool and causes the eddy bar to scour. As discharge increases, plunge pools are scoured and deposition resumes in the recirculating eddies. If fine-grained sediment supply is reduced along a river because of flow regulation structures, this dynamic cycle of erosion and deposition associated with pools and eddy sand bars no longer occurs and the eddy bars become stable.

Climatic wanning during the last 100 to 150 years has caused many alpine glaciers to thin and retreat (Grove, 1990; O’Connor and Costa, 1993; Evans and Clague, 1994). This glacial downwasting has disturbed geomorphic systems in mountainous environments, increasing the risk of geologic and hydrologic hazards such as glacial-lake outburst floods, landslides, and glacier avalanches (O’Connor and Costa, 1993; Evans and Clague, 1994). Glacial-lake outbursts are perhaps the most devastating of these processes because they can travel tens to hundreds of kilometers downstream dramatically modifying channel morphology and, in some cases, causing loss of human life and destruction of property. The devastating effects of glacial-lake outburst floods have been documented in the Andes (Lliboutry et al., 1977), Himalayas (Hewitt, 1982; Fushimi et al., 1985; Ives, 1986; Vuichard and Zimmermann, 1986, 1987), Canadian Rockies (Clarke, 1982; Blown and Church, 1985; Desloges and Church, 1992; Evans and Clague, 1994), Swiss Alps (Haeberli, 1983; Haeberli et al., 1989), and Cascades (O’Connor et al., in press).

About 8200 years ago, the climate of much of the Northern Hemisphere cooled abruptly for a period of about 200 years. In their Perspective, Clarke et al . examine the most likely culprit for this cooling: an outburst of fresh water from a vast, ice-dammed glacial lake in North America. The superlake had formed when the kilometers-thick ice sheet covering much of North America disintegrated. When the ice dam became unstable, fresh water flooded from the lake into the North Atlantic. It remains unclear how this fresh water affected ocean circulation or whether the outburst occurred in more than one stage, but the timing points strongly to the outburst flood as the trigger of the 8200-year climate event.

International audience; During the 2004 outburst flood of Gornersee, Switzerland, we observed surface microseismic activity (so‐called icequakes) near the glacier‐dammed lake on Gornergletscher. Using surface waves, we located near‐surface tensile fracturing events by inverting time delays using a quasi‐Newton scheme. We located 8520 near‐surface events with uncertainties of less than 10 m. Seismic activity increased during the lake drainage, and the icequake epicenters migrated downglacier. Furthermore, we identified events whose fault plane orientations are nearly perpendicular to the local pattern of surface crevassing. These observations can be explained by the rotation of principal strains at the glacier surface deduced from local ice flow measurement which occurred during the flotation of the ice dam at the onset of the lake drainage. In general, we suggest that our technique is a useful tool to locate large data sets of microseismic events and can be used to monitor the temporal evolution of fracture processes and their dependence on glacier flow and glacier hydrology.

It is known that the Kingdom of Bhutan is subject to dangerous glacial lake outburst floods (GLOFs). Gansser (1966, 1970), for example, described the GLOFs in northern Bhutan, and proposed to take measures to minimize the risks (Gansser, 1970, 1978). However, unfortunately, little effort has been made and a catastrophic outburst of two glacial lakes in the Lunana area, northern Bhutan on 6 October 1994 resulted in the deaths of 21 persons. In spite of the damage, including the loss of lives, the details of the 1994 incident in Bhutan are not available, partly because of the political background and partly because of the geographical situation. The second author, who lived in Bhutan from 1990 until 1994, obtained a video tape showing the flooding and observed the area along the lower Pho Chhu after the incident, and the first author collected information about the incident through several sources. The authors, therefore, have not conducted scientific research, and their information concerning the flood is rather limited. Nevertheless, it is hoped that this report of the damage caused by the 1994 outburst flood in northern Bhutan and the review of the

Debris flows have blocked rail and highway routes in the upper Kicking Horse River valley, British Columbia, a number of times during this century. The origins of debris flows from the most troublesome tributary basin were investigated following the debris flows and floods of September 6, 1978. A jökulhlaup (catastrophic glacial outburst flood) origin was determined for the debris flows and flood of this event. An investigation of weather records prior to debris flows of 1962, 1946, and 1925 indicates a similar origin for the 1946 and 1925 events.

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 in 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. Landslide dams can be classified into six categories based on their relation with the valley floor. Type I dams (11% of 184 landslide dams from around the world that we were able to classify) do not reach from one valley side to the other. Type II dams (44%) span the entire valley floor, in some cases depositing material high on opposite valley sides. Type III dams (41%) move considerable distances both upstream and downstream from the landslide failure. Type IV dams (

The first known occurrence of outburst flooding at Ape Lake, British Columbia, was in October 1984 following the formation of a subglacial tunnel in an ice dam created by Fyles Glacier. Following tunnel closure, the lake refilled in 150 d and then a second outburst flood occurred in August 1986. During both events, 55% of the Apc Lake volume or 46 × 106 m3 was released in less than 24 h into the 50 km long, ungauged Noeick River, producing an average discharge of 540 m3 s−1. Channel and flood-plain erosion, damage to access roads, bridges, a logging camp, and an airstrip were related to the peak or maximum instantaneous discharge. In the absence of direct measurements, and to facilitate planning for future flood events, several independent methods were employed to estimate peak discharge. A modified version of the Clague-Mathews formula and the slope-area method yield consistent estimates which approach 1600 m3 s−1 near the ice-dam outlet. Attenuation of the flood peak in Noeick River is as high as 25% in the upper 12 km due to channel and flood-plain storage. Results using Clarke’s (1982) physical-based model suggest lower discharges and may be related to the irregular morphology of Ape Lake. Since Fyles Glacier is in continuous retreat, drainage around the margin of the ice dam which began in the summer of 1987 is expected to continue and no further outburst floods are anticipated.

Glacier lakes are common phenomena in the Himalaya region of Nepal. Glacier lake outburst floods have repeatedly caused the death tolls and severe damage to downstream infrastructures. In Himalayas, a vital uncertainty about the glacier lake hazard potential still exists, thereby the effects of accelerating rates of glacier retreat and expansion of Glacier Lake could be the wake of recent global warming and resulting climatic changes. The paper, first describes the general different-level approach upon which the study is based. Then, in the methodological part, applicable remote sensing techniques, geographic information system (GIS) and statistical methods are presented. Observed data of lake area, volume, and depth having similar lake characteristics reported in the different literature are used to develop empirical equations by using statistical methods. The values of r 2 (coefficient of determination) - obtained are very high (r 2 =0.939 for depth – area relationship and r 2 = 0.990 for volume – area relationship). The comparison of the empirical expression clearly indicated that there is more than 90% variation in the dependent variable, lake volume,as explained by the linear regressions in both cases. Area of Imja glacier lake for different years are determined from the available satellite imagery and volume of the Imja glacier lake are estimated using the expression: V = 0.094 A 1.453 .developed from linear regression analysis of the observed data. Similarly, mean depth can be estimated by using the expression: D = 0.94 A 0.452 . After the preparation of maps and data, a scheme of decision criteria for the evaluation of hazard potential of Imja glacier lake is established. A list of decision criteria is a documented set of factors that are used to examine and compare for evaluating the hazard potential of a glacier lake. The empirical scores are given in terms of hazard magnitude for hazard rating. Analysis of Imja glacier lake based on the empirical scoring system clearly indicated that GLOF risk of the possible outburst from Imja glacier lake is MODERATE . A systematic application of remote sensing based methods for glacier lake outburst flood risk assessment is applicable and thus recommended. Keywords: Glacier lake outburst; remote sensing; risk assessment; hazard potential; empirical parameters; climate change DOI: http://dx.doi.org/10.3126/jhm.v7i1.5618 JHM 2010; 7(1): 75-91

More than 2000 of mountain lakes covering more than 0.1ha exist in a territory of Kyrgyzstan. Nearly 20% of them are dangerous because of instability of lake dams, frequent overflows and melting of buried ice inside the moraine dams. According to the Kyrgyz lake inventory, 328 lakes are at risk of outburst and 12 lakes are considered as actually dangerous. Since 1952 more than 70 disastrous cases of lake outbursts have occurred. The majority of the endangered lakes belong to one of the three genetic types: morainic-glacier, supraglacial and lake dammed by landslides and debris flows. Petrov, Adygine and Koltor lakes were selected and studied in the Tien-Shan Mountains as case studies of the most frequent genetic types of hazardous lakes. Observations were focused on the morphology of the lake basin and the surrounding relief, outflow pattern and processes controlling the development of lake. For the hazard assessment, evolution of glaciers and lakes was reconstructed using historical reports, aerial photographs and satellite images.

INTRODUCTION Glaciers in Alaska cover an area of about 73,800 square kilometers (28,500 square miles). They are most highly concentrated along the Pacific Coast and in the south-central part of the State. Many of these glaciers, as elsewhere in the world, flow across the mouths of adjoining valleys and cause lakes to form behind the ice streams. These glacier ice dams are subject to repeated failure. Because most Alaskan communities and transportation routes are situated along rivers which flow from glaciers the hazards presented by glacier dammed lakes are serious. The damage by floods from these lakes will increase if people encroach into areas where flooding occurs. Glacier dammed lakes in south-central and southeastern Alaska and in adjacent Canada which drain into rivers entering Alaska are included in this study. Such lakes are numerous in this area; 750 glacier dammed lakes have been plotted on the maps on sheets 1 and 2. The number and size of individual lakes vary enormously during the seasons and from year to year; the total number of lakes plotted provides an indication of their abundance. Not included in this report are the few, very small lakes dammed by glaciers that are widely scattered in the Brooks Range, Alaska Peninsula, Kodiak Island, and Aleutian Islands. The major hazard presented by glacier dammed lakes is catastrophic flooding which occurs when the ice dams fail. In many places flooding occurs annually; there are many exceptions and the situations change rapidly from one year to the next. It should be noted that large quantities of water can also be stored in or under glaciers and may create serious floods even though no surface lake is visible. Such catastrophic floods have occurred in Iceland so frequently (Thorarinsson, 1953) that the Icelandic term "jokulhlaup" is now used internationally to describe them. In the State of Washington floods of this nature have been observed from at least four glaciers (Richardson, 1968). Thus, glaciers with no visible lakes may present unusual flood hazards. However, one cannot identify from aerial photographs or maps those glaciers which are likely to produce large jokulhlaups except to note a common association of glacier outburst floods with glacier-clad volcanoes. Any glacier may produce an outburst flood, but only visible glacier dammed lakes and glaciers on volcanoes are shown in this report. The largest glacier outburst floods in Alaska are from the release of glacier dammed lakes. The purpose of this report is to present an up-to-date assessment of the hazardous glacier outburst floods in Alaska by mapping the present extent of glaciers, the location of glacier dammed lakes and glacier-clad volcanoes, presenting the recent history of several prominent glacier dammed lakes, and delineating areas where outburst flooding may be expected. Avoiding particularly hazardous situations is advised and recommendations are made for monitoring a few lakes which cause very large or potentially damaging floods.

Glacier Lake Outburst Floods (GLOFs) depict an environmental risk with an increasing damage potential in many regions of the world. GLOFs are often caused by glacier margin lakes, which suddenly find a drainage path underneath the bottom of a glacier, which is destabilized and retreating as a consequence of local or global climate changes. In a typical GLOF event, a glacier margin lake may drain completely in 24 hours, causing a large flood wave in the area downstream the glacier. The paper documents some recent GLOF events in the Northern Patagonian Icefield (Chile) and presents a terrestrial photogrammetric glacier margin lake monitoring system. The system is based on a camera taking images at regular time intervals. In these images, variations of the water level can be detected by tracking the water-land interface at pre-defined image spots. Due to the drainage mechanism, which is characterized by progressive erosion and melting at the bottom of the glacier, GLOFs are indicated by a progressive water level drop in the lake. Water level changes may be detected with subpixel accuracy by image sequence processing methods. If a 3D model of the lake bottom topography (or at least one height profile through the lake) exists, water level changes in monoscopic image sequences may be transformed into volume loss. The basic idea herein is the intersection of a terrain profile with a water level detected in the image and projected into object space. The camera orientation is determined through a GPS-supported photogrammetric network. Camera orientation changes, which may for instance be induced by wind, can be compensated by tracking some fiducial marks in the image. The system has been used in a pilot study at two glacier margin lakes in the Northern Patagonian Icefield. These lakes have a depth of about 80 - 100 meters. The larger one has a length of 5 km and a maximum volume of about 200,000,000 cubic meters. During the pilot study, several GLOF events could be recorded and processed. Water level changes can be determined at decimeter level precision. The results prove the feasibility of the concept, which has to be completed by a data telemetry and alarm system.

The terrestrial margins of the Middle Pleistocene ice sheets in northern central Europe were characterised by the formation of extensive ice-dammed lakes, which were controlled by the blockage of spillways by the ice margin. The largest ice-dammed lake had a volume of ∼224 km³ and formed in a late stage of the first Saalian ice advance (MIS 6) in central Germany. The failure of the ice dam in the bedrock-outlet channel triggered a major glacial lake-outburst flood. Flood-related erosional and depositional features include large-scale scours, trench-like channels, streamlined hills, giant bars and run-up deposits, indicating a wide spreading of the outburst flood in an early stage and the incision of trench-like valleys in a later stage. The incision of large valleys in the proximal flood pathway strongly impacted the regional drainage system by providing an efficient drainage network. The trench-like channels initiated by the lake-outburst flood became a crucial part of the ice-marginal drainage and subsequent fluvial system. The reconstructed outlet hydrographs imply peak discharges of 465,000–673,000 m³s−1. The numerical simulation indicates flow depths of up to 87 m, flow velocities of up to 7 ms−1, peaks of the bed-shear stress of 2500 Nm−2 and the inundation of large parts of northwestern Germany and the northern Netherlands. The numerical simulation of the outburst flood was conducted on both the modern digital elevation model and on palaeotopographic models, representing the palaeotopography prior to the outburst flood and during maximum flood-related incision, respectively. Distally, the outburst flood probably followed an east-west trending route through northwestern Germany and the central Netherlands into the ice-dammed lake in the southern North Sea Basin. The added water volume might have led to the overspill and drainage of the proglacial lakes in the central Netherlands and the North Sea Lake in a chain reaction, eventually opening an east-west trending meltwater-drainage pathway along the southwestern margin of the decaying ice sheet.

Episodes of ice-sheet disintegration and meltwater release over glacial–interglacial cycles are recorded by discrete layers of detrital sediment in the Labrador Sea1, 2. The most prominent layers reflect the release of iceberg armadas associated with cold Heinrich events3, but the detrital sediment carried by glacial outburst floods from the melting Laurentide Ice Sheet is also preserved4. Here we report an extensive layer of red detrital material in the Labrador Sea that was deposited during the early last interglacial period. We trace the layer through sediment cores collected along the Labrador and Greenland margins of the Labrador Sea. Biomarker data, Ca/Sr ratios and δ18O measurements link the carbonate contained in the red layer to the Palaeozoic bedrock of the Hudson Bay. We conclude that the debris was carried to the Labrador Sea during a glacial outburst flood through the Hudson Strait, analogous to the final Lake Agassiz outburst flood about 8,400 years ago, probably around the time of a last interglacial cold event in the North Atlantic5. We suggest that outburst floods associated with the final collapse of the Laurentide Ice Sheet may have been pervasive features during the early stages of Late Quaternary interglacial periods.

The glacier-dammed Lac des Faverges, located on Glacier de la Plaine Morte (Swiss Alps), has drained annually as a glacier lake outburst flood since 2011. In 2018, the lake volume reached more than 2 × 106 m3, and the resulting flood caused damage to the infrastructure downstream. In 2019, a supraglacial channel was dug to artificially initiate a surface lake drainage, thus limiting the lake water volume and the corresponding hazard. The peak in lake discharge was successfully reduced by over 90 % compared to 2018. We conducted extensive field measurements of the lake-channel system during the 48 d drainage event of 2019 to characterize its hydraulics and thermodynamics. The derived Darcy–Weisbach friction factor, which characterizes the water flow resistance in the channel, ranges from 0.17 to 0.48. This broad range emphasizes the factor's variability and questions the choice of a constant friction factor in glacio-hydrological models. For the Nusselt number, which relates the channel-wall melt to the water temperature, we show that the classic, empirical Dittus–Boelter equation with the standard coefficients does not adequately represent our measurements, and we propose a suitable pair of coefficients to fit our observations. This hints at the need to continue research into how heat transfer at the ice–water interface is described in the context of glacial hydraulics.

An oxygen isotope record of biogenic carbonate from paleolake Riwasa in northwestern (NW) India provides a history of the Indian Summer Monsoon (ISM) from ∼11 to 6 kyr B.P. The lake was dry throughout the Late Glacial period when aeolian sands were deposited. Lacustrine sedimentation commenced in the early Holocene and the lake deepened significantly at ∼9.4 kyr B.P., indicating a strengthening of the ISM in response to summer insolation forcing. This high lake stand was interrupted by an abrupt desiccation, which is marked by a 12-cm limestone hardground that formed during a period of sub-aerial exposure after ∼8.3 kyr B.P. The base of the hardground surface coincides with the beginning of the ‘8.2-kyr B.P. cooling event’ in the North Atlantic that has been associated with a glacial outburst flood and slowdown of Atlantic meridional overturning circulation. The hardground provides robust evidence of a weakening of the ISM on the Indian subcontinent at ∼8.2 kyr B.P., and supports previous results of a strong teleconnection between monsoon Asia and North Atlantic climate. Lacustrine sedimentation resumed at ∼7.9 kyr B.P. suggesting the 8.2-kyr desiccation of paleolake Riwasa represented an abrupt response of the ISM to forcing from the North Atlantic.

Gornersee, Switzerland, is an ice-marginal lake, which drains almost every year, subglacially, within a few days. We present an analysis of the lake outburst events between 1950 and 2005, as well as results of detailed field investigations related to the lake drainage in 2004 and 2005. The latter include measurements of lake geometry, water pressure in nearby boreholes and glacier surface motion. A distributed temperature-index melt model coupled to a linear-reservoir runoff model is used to calculate hourly discharge from the catchment of Gornergletscher in order to distinguish between the melt/precipitation component and the outburst component of the discharge hydrograph. In this way, drainage volume and timing are determined. From 1950 there is a clear trend for the outburst flood to occur earlier in the melt season, but there is no trend in lake discharge volumes. Peak discharges from the lake lie significantly below the values obtained using the empirical relation proposed by Clague and Mathews (1973). The shapes of the 2004 and 2005 lake outflow hydrographs differ substantially, suggesting different drainage mechanisms. From water balance considerations we infer a leakage of the glacier-dammed lake in 2005, starting 1 week prior to the lake outburst. During the drainage events, up to half of the lake water is temporarily stored in the glacial system, causing substantial uplift of the glacier surface.

Filiacion institucional de autor: Alejo Cochachin Rapre / Autoridad Nacional del Agua - Unidad de Glaciologia y Recursos Hidricos (ANA-UGRH), Huaraz, Peru

Filiación institucional de autor: Alejo Cochachín Rapre /Autoridad Nacional del Agua - Unidad de Glaciología y Recursos Hídricos (ANA-UGRH), Huaraz, Peru Original abstract: Recent warming has had enormous impacts on glaciers and high-mountain environments. Hazards have changed or new ones have emerged, including those from glacier lakes that form as glaciers retreat. The Andes of Peru have repeatedly been severely impacted by glacier lake outburst floods in the past. An important recent event occurred in the Cordillera Blanca in 2010 when an ice avalanche impacted a glacier lake and triggered an outburst flood that affected the downstream communities and city of Carhuaz. In this study we evaluate how such complex cascades of mass movement processes can be simulated coupling different physically-based numerical models. We furthermore develop an approach that allows us to elaborate corresponding hazard maps according to existing guidelines for debris flows and based on modelling results and field work. Artículo en acceso abierto Manifiesta que el calentamiento global ha tenido enormes impactos en los glaciares y en los entornos de alta montaña, en este contexto los peligros han cambiado o han surgido otros nuevos, incluidos los de los lagos glaciares que se forman cuando los glaciares retroceden. En el pasado, los Andes del Perú se han visto gravemente afectados por las inundaciones en el lago glaciar. Un evento reciente importante ocurrió en la Cordillera Blanca en 2010 cuando una avalancha de hielo impactó en un lago glaciar y provocó una inundación de estallido que afectó a las comunidades río abajo y a la ciudad de Carhuaz. Este estudio evalúa cómo pueden simularse tales complejas cascadas de procesos de movimiento de masas acoplando diferentes modelos numéricos basados ¿¿en la física. Además, desarroll un enfoque que permite elaborar los mapas de peligro correspondientes de acuerdo con las directrices existentes para flujos de escombros y en base a los resultados de la modelización y el trabajo de campo.

Heavy precipitation fell over the eastern Queen Elizabeth Islands on July 21-23, 1973; 54.6 mm fell at Vendom Fiord, south central Ellesmere Island. The rainfall at Vendom Fiord was associated with a depression which had moved over the rest of the archipelago without producing unusual precipitation. None of the official weather stations in the region reported exceptional amounts, yet there is evidence that the record from Vendom Fiord was representative of a much larger area. The storm was responsible for inundation of flood plains, reworking of coarse alluvium, and rapid mass movements on slopes in the locality of Vendom Fiord, and it is possible that it was the catalyst for a glacier outburst flood (jokulhlaup) which issued from an ice-dammed lake 10 days later. Depressions which impinge upon the mountains of the eastern High Arctic merit further climatological attention.