This contribution aims to reveal patterns of research on natural hazards worldwide, based on the analysis of the Clarivate Analytics Web of Science database. A set of 588,424 research items published ...between 1900 and 2017 is analyzed, covering different types of natural hazards. Two categories of natural hazards are distinguished in this study: (i) geological/geomorphic (earthquakes, slope movements, erosion, volcanic activity, and others); and (ii) climatic/hydro-meteorological (floods, storms, drought, hurricane, and others). General trends, the geographical focus, and the involvement and cooperation between individual countries are revealed, pointing out certain patterns (e.g., hotspots of research) and trends (e.g., changing publishing paradigm). Further, a global overview of research on natural hazards is confronted with disastrous events, fatalities, and losses of MunichRE and SwissRE global databases of natural disasters.
Climate change, glacier retreat and glacial lake outburst floods (GLOFs) are intertwined. The Cordillera Blanca in Peru has one of the world's longest GLOF records and here we assess the evolution of ...glacial lakes in the region between 1948 and 2017 and investigate the links to documented GLOFs. We also model future lake evolution under two climate scenarios to provide an assessment of current and future GLOF triggering potential. Our analysis shows that the number of lakes as well as the total lake area has increased during the historical period. The formation of new lakes is, however, not uniform among different lake types with bedrock-dammed lakes exhibiting the largest increase in recent decades. We argue that moraine-dammed lakes have already formed at the majority of potential locations in the Cordillera Blanca and that the next generation of lakes which are expected to form in response to glacier retreat over topographically suitable areas will be predominantly bedrock-dammed. Based on a regional GLOF inventory, we show that the peak frequency of GLOFs occurred from the late 1930s to early 1950s. While GLOFs originating from moraine-dammed lakes dominated in this period, recent GLOFs have originated from bedrock-dammed lakes. At the same time, the majority of GLOFs originated from lakes in a proglacial phase (i.e. in contact with glacier), even though the share of proglacial lakes did not exceed 12% at any time step during the analysed period. While many moraine-dammed lakes evolved into the glacier-detached evolutionary phase, bedrock-dammed lakes became a major lake dam type among proglacial lakes. Over the remainder of the 21st century, a further increase in lake area of up to 10% is anticipated, with up to 50 new bedrock dammed lakes likely to develop as glaciers retreat. There is little difference in lake development and GLOF triggering potential under climate scenarios driven by RCP 2.6 and 8.5. Based on topographic disposition, recent and future lakes do not individually appear more or less susceptible to landslide impact than lakes that already developed earlier in the 20th century. Synthesizing these findings, we forecast that bedrock-dammed lakes will become the dominant source of GLOFs in the next decades. Because such dams are inherently more stable, we expect overall lower GLOF magnitudes compared to documented GLOFs from moraine-dammed lakes.
An inventory of the lakes within the Cordillera Blanca of Peru was made based on manual analysis of high resolution optical images and was verified during field surveys. In total, 882 lakes were ...detected, classified and described by several qualitative and quantitative characteristics. The majority of the lakes were characterised as moraine-dammed lakes (35.2%), followed by bedrock-dammed lakes (31.3%), while ice-dammed and landslide-dammed lakes were quite rare with 3.5% and 2.6%, respectively. Two thirds of the lakes (66.5%) have a surface area<10,000m2 and are classified as being small, while only 7.3% are classified as large lakes with an area>100,000m2. The majority of the large lakes are characterised as moraine-dammed lakes (48.4%) and the share of landslide-dammed lakes is significantly increased to 12.4% in this class. In the 1950s, most lakes were situated in the elevation range of 4250–4600a.s.l. (Concha, 1951), while 49.4% of the lakes are currently situated above 4600ma.s.l. This elevational shift is considered to be a result of ongoing environmental change and glacier retreat within the Cordillera Blanca. By analysing multi-temporal aerial images covering the period from 1948 to 2013 it was shown that glacial lakes in already deglaciated catchments may persist for long periods of time without any areal change. It was also shown that glacial lake outburst floods (GLOFs) originated from moraine-dammed lakes in the earlier stages of glacier retreat (1940s and 1950s) and from bedrock-dammed lakes in later stages (recently); however, no clear trend was revealed regarding the starting elevation of GLOFs. The susceptibility of all of the large lakes (n=64) to outburst floods was assessed. Monitoring of young proglacial lakes and large moraine-dammed lakes, systematic susceptibility reassessments considering potential future changes, and flood modelling are recommended.
•An inventory of the lakes within the Cordillera Blanca of Peru was made.•882 lakes were detected, classified and described by several characteristics.•Number and characteristics of lakes reflect ongoing environmental change.•The susceptibility of all large lakes to outburst floods was assessed.
Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first ...global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste. GLOFs can have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the rapid drainage of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and regularity – rather unexpectedly – have declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From an assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine-dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.
Outburst floods originating in moraine-dammed lakes represent a significant geomorphological process as well as a specific type of threat for local communities in the Cordillera Blanca, Peru ...(8.5°–10° S; 77°–78° W). An exceptional concentration of catastrophic floods has been reported from the Cordillera Blanca in the first half of 20th Century (1930s–1950s), leading to thousands of fatalities. The main objective of this paper is to provide a revised and comprehensive overview of geomorphologically effective floods in the area of interest, using various documentary data sources, verified by analysis of remotely sensed images (1948–2013) and enhanced by original field data. Verified events (n = 28; 4 not mentioned before) are analysed from the perspective of spatiotemporal distribution, pre-flood conditions, causes, mechanisms and geomorphological impacts as well as socioeconomical consequences, revealing certain patterns and similar features. GLOFs are further classified according to their magnitude: 5 extreme events, 8 major events and 15 minor events are distinguished, referring to the quantified geomorphological and socioeconomical impacts. Selected moraine dams and flood deposits are dated using lichenometric dating. Special attention is given to moraine dam breaches - the most frequent type of water release with the most significant consequences. Selected major events and their consequences are studied in detail in a separate section. Finally, a general schematic model of lake formation, growth and post-flood evolution reflecting initial topographical setting and glacier retreat is introduced and the utilization of the obtained results is outlined.
•Documentary data, remotely sensed images and field data are successfully employed.•28 GLOFs from moraine-dammed lakes (4 not mentioned before) are identified and analysed.•5 extreme, 8 major and 15 minor events are distinguished, according to the geomorphological and societal impacts.•Transition of GLOF causes and types of water release in time is observed, revealing a relation to (geo)environmental change.•A general schematic model of lake evolution reflecting initial topographical setting and glacier retreat is introduced.
Glacial lakes represent a threat for the populations of the Andes and numerous disastrous glacial lake outburst floods (GLOFs) occurred as a result of sudden dam failures or dam overtoppings ...triggered by landslides such as rock/ice avalanches into the lake. This paper investigates a landslide-triggered GLOF process chain that occurred on February 23, 2020, in the Cordillera Vilcabamba in the Peruvian Andes. An initial slide at the SW slope of Nevado Salkantay evolved into a rock/ice avalanche. The frontal part of this avalanche impacted the moraine-dammed Lake Salkantaycocha, triggering a displacement wave which overtopped and surficially eroded the dam. Dam overtopping resulted in a far-reaching GLOF causing fatalities and people missing in the valley downstream. We analyze the situations before and after the event as well as the dynamics of the upper portion of the GLOF process chain, based on field investigations, remotely sensed data, meteorological data and a computer simulation with a two-phase flow model. Comparison of pre- and post-event field photographs helped us to estimate the initial landslide volume of 1–2 million m
3
. Meteorological data suggest rainfall and/or melting/thawing processes as possible causes of the landslide. The simulation reveals that the landslide into the lake created a displacement wave of 27 m height. The GLOF peak discharge at the dam reached almost 10,000 m
3
/s. However, due to the high freeboard, less than 10% of the lake volume drained, and the lake level increased by 10–15 m, since the volume of landslide material deposited in the lake (roughly 1.3 million m
3
) was much larger than the volume of released water (57,000 m
3
, according to the simulation). The model results show a good fit with the observations, including the travel time to the uppermost village. The findings of this study serve as a contribution to the understanding of landslide-triggered GLOFs in changing high-mountain regions.
Trends in occurrence of glacial lake outburst floods (GLOFs) in space and time as well as frequency-magnitude relationships are typically derived from inventories of past GLOFs. Searching for ...geomorphic evidence (GLOF diagnostic features) in remote sensing images is a commonly used method for building GLOF inventories. In this study, I examine the longevity of geomorphic GLOF diagnostic features and thus the reliability of GLOF inventories that build on them. A set of 160 GLOFs documented from the Tropical Andes of Peru and Bolivia is analyzed, focusing on four GLOF diagnostic features: (i) breached dams; (ii) pre-GLOF water levels; (iii) outwash fans; (iv) impact areas. A total of 359 GLOF diagnostic features are identified and their evolution is analyzed from multi-decade remote sensing images, with special focus on GLOF diagnostic features that vanished in time. Building on these data, the expected longevity of GLOF diagnostic features is outlined, revealing long persistence of breached dams (>102 years), long persistence of pre-GLOF water levels (up to 102 years) and comparably more intense degradation and vanishing of outwash fans and impact areas. The main degradation processes of GLOF diagnostic features are identified, including the succession of vegetation, geomorphic reworking and anthropogenic activities. Further, the implications for building GLOF inventories are discussed, highlighting that vanishing geomorphic evidence of GLOF diagnostic features may lead to: (i) underestimated spatial extent of GLOF impact areas; and (ii) underestimated total numbers of GLOFs in GLOF inventories. Considering the number of major GLOFs as predictors of the number of minor GLOFs, an example of the Tropical Andes shows that the total number of GLOFs in the post-LIA period may be underestimated by up to 40 % (reference period 2011–2020).
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•The longevity (persistence) of geomorphic imprints associated with GLOFs is analyzed.•Four types of GLOF diagnostic features are studied (breached dams, outwash fans, pre-GLOF water levels and impact areas).•GLOF diagnostic features vanished as a result of geomorphic reworking, succession of vegetation and anthropogenic activities.•GLOF counts in GLOF inventories might be underestimated because of vanishing evidence.
Infilled lakes are a prevalent geomorphic feature in the intricate high mountain landscape of the Cordillera Blanca, Peru. Despite their apparent geomorphic, hydrological, and ecological importance, ...a systematic inventory of these areas has been lacking. This study presents an inventory of infilled lakes in the Cordillera Blanca. A total of 962 infilled lake polygons have been manually mapped, covering an area of nearly 90 km2 (the area of individual mapped polygons ranges from 0.001 km2 to 1.760 km2), more than double the area of existing lakes (40 km2) and the majority of flat areas (62% of areas with slope ≤5°). The study reveals that infilled bedrock-dammed lakes are the most common type (42%), while moraine-dammed lakes account for the majority of the infilled lake area (52%) and sediment volume (52% to 57%). Considering high uncertainty of infilled basins’ morphology, the estimated sediment volume of infilled lakes ranges between 0.9 km3 and 2.3 km3 (compared to 0.79 km3 to 1.15 km3 of water stored in existing lakes). The case study of Lake Aguascocha catchment reveals a mean sediment yield of 0.64 to 1.63∙106 m3∙km−2 during the past 10.7 ± 0.3 ka, that is, a mean annual sediment yield of 58.5 to 156.4 m3∙km−2∙yr−1. Furthermore, 65 locations where preserved geomorphic evidence indicates possible outburst floods in the past are identified. These areas are particularly important for understanding patterns of lake outburst occurrence on longer timescales than traditionally considered in lake outburst flood hazard studies. The dataset presented in this study is intended to serve as a basis for identifying sites suitable for further site-specific paleo-geographical, sedimentological, geochronological as well as broader mountain landscape evolution studies.
Glacial lake outburst floods (GLOFs) from moraine-dammed lake failures represent a significant threat to inhabitants of high mountain areas across the globe. The first part of this paper summarises ...the causes and mechanisms of moraine-dammed lake failures through a review of the scientific literature and unpublished reports. There are eight main causes, of which five are characterised as dynamic and three as long-term, and these are associated with around twenty failure mechanisms. The dynamic causes are slope movements into the lake, earthquakes, flood waves from a lake situated upstream, blocking of underground outflow channels, and intensive rainfall or snowmelt. The long-term causes are the melting of buried ice, the impact of hydrostatic pressure, and the effect of time. These causes (triggers) and the consequent mechanisms of dam failure are described in detail. The second part compares the historical moraine-dammed lake failures within three regions between 1900 and 2009: the Cordillera Blanca of Peru, the North American Cordillera, and the Himalayas. It has been found that dynamic causes are around four times more common than long-term causes although significant regional differences have been observed. The most frequent causes in these regions were found to be slope movements in which the displaced material was dominated by solid-state water (ice falls, ice avalanches, and snow avalanches). The other causes tended to show distinct regional patterns while the temporal distribution of events also differs according to region. In the North American Cordillera and Himalayas moraine dam failures occur exclusively during the summer season while in the Cordillera Blanca they are more evenly distributed with the exception of the dry season. This reflects the general climatic setting of each of the study regions. Analýza příčin a mechanismů destrukcí hrází jezer hrazených morénami v pohořích Cordillera Blanca (Peru), Severoamerická Kordillera a Himaláj Přispěvek je členěn do dvou časti. Prvni čast ma rešeršni charakter a shrnuje rozlične přičiny a mechanismy destrukci (protrženi) hrazi jezer hrazenych morenami. Pět dymanickych přičin (různe typy svahovych pohybů, zemětřeseni, povodňova vlna z vyše položeneho jezera, intenzivni dešťove sražky / tani sněhu, ucpani podzemnich odtokovych kanalů) a tři dlouhodobe přičiny (odtavani pohřbeneho ledu, působeni hydrostatickeho tlaku a dlouhodoba degradace tělesa hraze v čase) jsou popsany spolu s mechanismy vedoucimi k destrukcim morenovych hrazi, a to včetně konkretnich přikladů ze zajmovych oblasti. Ve druhe časti přispěvku je provedena srovnavaci analyza těchto udalosti mezi oblastmi pohoři Cordillera Blanca (Peru), Severoamericka Kordillera a pohoři Himalaj. Na zakladě vytvořene databaze protrženych morenovych hrazi mezi lety 1900 a 2009 je zhodnoceno jednak zastoupeni různych přičin, jednak časova distribuce těchto udalosti. Nejfrekventovanějši přičinou ve všech studovanych oblastech byl dynamicky svahovy pohyb do jezera. Zastoupeni a vyskyt dalšich přičin se však mezi jednotlivymi oblastmi vyrazně liši. Časova distribuce udalosti vyrazně odlišuje oblast Cordillera Blanca od zbyvajicich dvou, což do určite miry odraži ročni chod klimatu a na něj vazanych přičin destrukci morenovych hrazi.
As the world’s glaciers recede in response to a warming atmosphere, a change in the magnitude and frequency of related hazards is expected. Among the most destructive hazards are glacier lake ...outburst floods (GLOFs), and their future evolution is concerning for local populations and sustainable development policy. Central to this is a better understanding of triggers. There is a long‐standing assumption that earthquakes are a major GLOF trigger, and seismic activity is consistently included as a key hazard assessment criterion. Here, we provide the first empirical evidence that this assumption is largely incorrect. Focusing on the Tropical Andes, we show that, of 59 earthquakes (1900–2021) the effects of which intersect with known glacier lakes, only one has triggered GLOFs. We argue that, to help develop climate resilient protocols, the focus for future assessments should be on understanding other key GLOF drivers, such as thawing permafrost and underlying structural geology.
Plain Language Summary
Climate change is increasing glacier melt in high mountains and increasing the size and number of glacial lakes. Over time, these lakes may drain catastrophically to generate glacier lake outburst floods (GLOFs), which can devastate downstream communities and destroy valuable infrastructure such as roads, bridges, and hydroelectric power facilities. As a result, many risk assessments have been carried out to understand what the triggers of GLOFs might be, in order to better predict their occurrence. One of the main triggers has been assumed to be earthquakes, but this association has not been properly tested. In this paper, we use earthquake and GLOF data from the Peruvian and Bolivian Andes to test this and find that there is little association between earthquakes and GLOFs. We conclude by arguing that focus needs to be on other GLOF triggers, and earthquake activity should be used as a secondary – not primary – indicator in GLOF susceptibility studies.
Key Points
Glacier lake outburst floods (GLOFs) are a major risk concern, with earthquakes being commonly considered effective triggers in hazard assessments
Of 59 earthquakes (1900–2021), the effects of which intersect lakes in the Tropical Andes, only one triggered GLOFs
We suggest that earthquake activity should be used as a secondary – not primary – susceptibility indicator for GLOFs
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