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Changes of the cryosphere and related geohazards in the high-mountain areas of Tajikistan and Austria: a comparison
Abstract
Mergili, M., Kopf, C., Müllebner, B. and Schneider, J.F., 2012. Changes of the cryosphere and related geohazards in the high-mountain areas of Tajikistan and Austria: a comparison. Geografiska Annaler: Series A, Physical Geography, 93, 79–96. doi:10.1111/j.1468-0459.2011.00450.x
This paper quantifies recent glacier changes and possible future permafrost retreat in the Austrian Alps and the Pamir and Alai Mountains of Tajikistan (Central Asia), two mountainous areas with striking differences in climate and hypsometry, but also in economy and research history. The aim of the comparative study is to improve the understanding of regional differences as a baseline for further research and for a differentiated evaluation of possible socio-economic implications. Besides a review of the available literature, multi-temporal remote sensing of glaciers of selected areas as well as additional helicopter and field surveys were conducted. The Tajik glaciers displayed a differentiated behaviour during the investigation period 1968–2009, with a strong trend to retreat – at least since 2002. More than 100 pro- and supraglacial lakes have been forming or growing in the southwestern Pamir. Destructive outburst floods of such lakes have occurred there in the recent past. Almost all Austrian glaciers are in an advanced stage of retreat, a trend which continues at enhanced rates. Comparatively few glacial lakes exist in the direct forefields of the glaciers. Potential permafrost distribution maps for the present and the future were produced for Tajikistan and Austria by adapting an empirical model developed in Switzerland. In absolute terms, the highest loss was predicted for the Pamir. The expected relative loss in the same area is moderate compared to the rest of Tajikistan and particularly to Austria, where the model predicted the disappearance of more than 90% of the potential permafrost until the end of the twenty-first century.
... In contrast to the above-mentioned studies, negative trends of glacier evolution in and around the Pamir Mountains are documented in the literature, as well: Khromova et al. [16] detected glacier shrinkage east of the Fedchenko glacier system. Mergili et al. [17] found an "accelerated retreat" of glaciers in the Rushan and Shugnan Range of the South-West Pamirs (No. 6 in Figure 1). Glaciers are also retreating in the Wakhan Pamir (No. 7 in Figure 1), north-west of the Karakoram Range [18]. ...
... A retreat of glacier areas in the Gunt River Basin by 14% (96 km 2 ) took place between 1998 and 2011 (Table 1). Glacier retreat rates doubled in comparison to the period 1969-2002 [17]. The "accelerated retreat" reported for parts of the Rushan and Shugnan Pamir (No. 6 in Figure 1; [17]) can be extended to the entire southern Pamirs (No. 13 in Figure 1). ...
... Glacier retreat rates doubled in comparison to the period 1969-2002 [17]. The "accelerated retreat" reported for parts of the Rushan and Shugnan Pamir (No. 6 in Figure 1; [17]) can be extended to the entire southern Pamirs (No. 13 in Figure 1). This region of recent and intense glacier retreat can be classified into a larger scale of glacier retreat documented in the literature, including the Hindu Kush (Nos. ...
With respect to meteorological changes and glacier evolution, the southern Pamir Mountains are a transition zone between the Pamirs, Hindu Kush and Karakoram, which are water towers of Central Asia. In this study, we compare runoff and climate trends in multiple time periods with glacial changes reported in the literature. Recent glacier evolution in the Southern Pamirs and its contribution to river runoff are studied in detail. Uncertainties of estimating glacier retreat contribution to runoff are addressed. Runoff trends in the Pamir-Hindu Kush-Karakoram region appear to be a strong proxy for glacier evolution because they exhibit the same spatial pattern as glacial change. There is an anomaly in the North-West Pamirs and Northern Karakoram, showing decreasing runoff trends. In the opposite way, there is a glacier and hydrological change experienced in the Southern Pamirs and Hindu Kush. The prevailing hypothesis for the Karakoram Anomaly, decreasing summer temperatures along with increasing precipitation rates, seems to be valid for the North-Western Pamirs, as well. In the Southern Pamirs, temperature trends have been rising since 1950. Here, the unique water cycle of exclusively winter precipitation does not protect glaciers from accelerated retreat. Snow cover is preset to melt within the seasonal water cycle, due to much lower precipitation amounts falling on glaciers. Therefore, a probable increase in westerly precipitation in both regions causes glacier mass gain in the Northern Pamirs and rising river flows in the Southern Pamirs.
... A number of studies document the retreat of many glaciers in the study area (e.g. Khromova et al., 2006;Haritashya et al., 2009;Mergili et al., 2012a), favouring the development of lakes in the glacier forefields or in subsiding areas on the glaciers. Mergili et al. (2013b) detected a total number of 652 glacial lakes in the study area. ...
... The identification of areas with melting permafrost builds on the permafrost indication map for Tajikistan presented by Mergili et al. (2012a): a set of rules-of-thumb for the lower boundaries of areas with a potential for sporadic and discontinuous permafrost in Switzerland (Haeberli, 1975) is adapted to the conditions in Tajikistan, based on the difference in the 0 • C isotherm of the MAAT. This set of rules is then combined with the DEM in order to produce a gridded data set indicating the possibility of permafrost occurrence for each raster cell. ...
... more where permafrost is retreating. Here, we only consider areas where retreating permafrost is assumed (see Table 1; Mergili et al., 2012a). Huggel et al. (2004b) noted that, in contrast to ordinary debris flows, parameters such as slope curvature or the proximity to the stream network are hardly significant for the onset of such processes. ...
We present a model framework for the regional-scale analysis of high-mountain
multi-hazard and -risk indicators, implemented with the open-source software
package GRASS GIS. This framework is applied to a 98 300 km2 study
area centred in the Pamir (Tajikistan). It includes (i) rock slides, (ii) ice
avalanches, (iii) periglacial debris flows and (iv) lake outburst floods.
First, a hazard indicator is assigned to each relevant object (steep rock
face, glacier or periglacial slope, lake). This indicator depends on the
susceptibility and on the possible event magnitude. Second, the possible
travel distances, impact areas and, consequently, impact hazard indicators
for all types of processes are computed using empirical relationships. The
impact hazard indicators are finally superimposed with an exposure indicator
derived from the type of land use, resulting in a raster map of risk
indicators finally discretized at the community level. The analysis results
are presented and discussed at different spatial scales. The major outcome of
the study, a set of comprehensive regional-scale hazard and risk indication
maps, shall represent an objective basis for the prioritization of target
communities for further research and risk mitigation measures.
... Consequently, many glaciers are retreating (e.g. Khromova et al., 2006;Hari-10 tashiya et al., 2009;Mergili et al, 2012a), favouring the development of lakes in the glacier forefields or in subsiding areas on the glaciers. Mergili et al. (2013) detected a total number of 652 glacial lakes in the study area. ...
... The identification of areas with melting permafrost builds on the permafrost indication map for Tajikistan presented by Mergili et al. (2012a): a set of rules-of-thumb for the lower boundaries of sporadic and discontinuous permafrost in Switzerland (Haeberli, 1975) is adapted to the conditions in Tajikistan. This set of rules is then combined with the DEM in order to produce a gridded dataset indicating the possibility of per-10 mafrost occurrence for each raster cell. ...
... Such processes may occur in the active layer, but even more where permafrost is retreating. Here, we only consider areas where retreating permafrost is assumed (see Table 1; Mergili et al., 2012a). Figure 8 shows the 15 logical frame work of the periglacial debris flow model r.periflow. ...
We present a model framework for the regional-scale analysis of
high-mountain multi-hazard and -risk, implemented with the Open Source
software package GRASS GIS. This framework is applied to a 98 300
km2 study area centred in the Pamir (Tajikistan). It includes
(i) rock slides, (ii) ice avalanches, (iii) periglacial debris flows,
and (iv) lake outburst floods. First, a hazard indication score is
assigned to each relevant object (steep rock face, glacier or
periglacial slope, lake). This score depends on the susceptibility and
on the expected event magnitude. Second, the possible travel distances,
impact areas and, consequently, impact hazard indication scores for all
types of processes are computed using empirical relationships. These
scores are finally superimposed with an exposure score derived from the
type of land use, resulting in a raster map of risk indication scores
finally discretized at the community level. The analysis results are
presented and discussed at different spatial scales. The major outcome
of the study, a set of comprehensive regional-scale hazard and risk
indication maps, shall represent an objective basis for the
prioritization of target communities for further research and risk
mitigation measures.
... According to the 4th IPCC report (IPCC, 2007), the median of the projected increase of the MAAT from 1980–1999 to 2080–2099 for Tajikistan is 3.7 @BULLET C. A number of studies document the retreat of many glaciers in the study area (e.g. Khromova et al., 2006; Haritashya et al., 2009; Mergili et al., 2012a ), favouring the development of lakes in the glacier forefields or in subsiding areas on the glaciers. Mergili et al. (2013b) detected a total number of 652 glacial lakes in the study area. ...
... Secondary data sets such as elevation with filled depressions, slope and flow direction are generated from the DEM which is further used to generate a gridded data set of the MAAT, making use of temperature data recorded at the stations of the Tajik HydroMet Agency and a vertical temperature gradient of 0.0062 @BULLET C m −1 (Müllebner, 2010; Fig. 3a). The identification of areas with melting permafrost builds on the permafrost indication map for Tajikistan presented by Mergili et al. (2012a): a set of rules-of-thumb for the lower boundaries of areas with a potential for sporadic and discontinuous permafrost in Switzerland (Haeberli, 1975) is adapted to the conditions in Tajikistan, based on the difference in the 0 @BULLET C isotherm of the MAAT. This set of rules is then combined with the DEM in order to produce a gridded data set indicating the possibility of permafrost occurrence for each raster cell. ...
... Such processes may occur in the active layer, but even more where permafrost is retreating. Here, we only consider areas where retreating permafrost is assumed (see Table 1; Mergili et al., 2012a). Huggel et al. (2004b) noted that, in contrast to ordinary debris flows, parameters such as slope curvature or the proximity to the stream network are hardly significant for the onset of such processes. ...
The high-mountain areas of Central Asia are experiencing pronounced
environmental changes, most likely caused by an increase in air
temperature. These changes include both permafrost melting and the
retreat of glaciers. Together with earthquakes, they disturb the dynamic
equilibrium of the fragile high-mountain geomorphic systems, leading to
the increased occurrence of rapid mass relocation processes, sometimes
with a long travel distance and therefore threatening the population in
the valleys. Here we present a scheme for a regional-scale high-mountain
multihazard assessment, implemented with the Open Source software
package GRASS GIS. This scheme is applied to a test area in the Pamir
(Tajikistan). It focuses on low-frequency, high-magnitude processes for
which the preparedness and awareness among the population are limited:
(1) Lake outburst hazards: The sudden drainage of lakes can lead to
major flows of debris, mud and water (in the case of glacial lakes,
Glacial Lake Outburst Floods or GLOFs). 1642 lakes, out of them 652
glacial lakes, were identified from satellite imagery. The relevant
characteristics of each lake (dam type, lake volume, lake development,
topographic situation) were determined or estimated. (2)
Rock-ice-avalanche hazards: glaciers retreating over steep rock cliffs
(hanging glaciers), loosing their abutment, may produce (rock-)ice
avalanches, depending on their slope, thermal condition and possible
triggering factors (e.g., earthquakes). Susceptible glaciers were
identified from remotely sensed data. (3) Rock slide hazards: portions
of steep terrain that may be involved in large rock slides (or rock
avalanches), most commonly triggered by earthquakes, were identified
using a simple topography-based model. First, the susceptibility of each
type of event is determined, depending on an exactly defined scheme, and
a score is assigned to each object (lakes, hanging glaciers) or raster
cell (rock slides). This score is increased for areas with melting
permafrost, which are particularly susceptible to mass relocation
processes: a solar irradiation model is used to determine permafrost
areas under the current conditions and under projected conditions in the
future. Second, empirical relationships are applied to compute the
possible travel distances and impact areas of all types of processes.
Inaccuracies of the relationships are accounted for by applying multiple
random walks with the key parameters varied within the confidence
interval. The results for all processes are overlaid, so that a
multihazard impact susceptibility score is assigned to each raster cell.
The impact susceptibility score is then superimposed with a layer of
settlements, farmland and infrastructures, in order to derive a raster
cell-based risk indication map. The risk indication scores are
summarized by village. The results shall represent an objective base for
(1) the prioritization of areas requiring mitigation measures and (2)
the identification of safe places.
... Many glacier tongues in the study area are covered by debris, making it hard to delineate their extent from satellite imagery or superficial field surveys. Even though a general retreat of the areas of exposed ice was identified for several mountain ranges within the study area (e.g., Khromova et al., 2006;Haritashya et al., 2009;Mergili et al., 2012), melting of ice within decaying debris-covered glacier tongues may contribute a significant share of the total loss of ice volume on the one hand and favours the development of lakes in the subsiding areas on the other hand. ...
... No detailed and up-to-date permafrost investigations are available for the study area, but national or even global datasets of the potential permafrost distribution become increasingly available (e.g., Gruber, 2012). Here, a map of the potential present and future distribution of discontinuous and sporadic permafrost in Tajikistan (Mergili et al., 2012) is used. It was derived by adapting the scheme developed by Haeberli (1975) for Switzerland to the conditions in Tajikistan. ...
... The lake only slightly increased in area until it drained suddenly on August 7, 2002 (Fig. 9). The resulting GLOF caused major damage and dozens of fatalities in the village of Dasht 11 km downstream Mergili et al., 2012). Only a small pond remained in the former lake bed which did not fill up again. ...
The sources of the Amu Darya, one of the major Central Asian rivers draining to the Aral Sea, are located in the glacierized high-mountain areas of Tajikistan, Kyrgyzstan and Afghanistan. There, climate change and the resulting retreat of glaciers have led to the formation of numerous new glacial lakes. Other lakes in the area are embedded in older glacial landscapes (erosion lakes) or retained by block or debris dams (e.g., Lake Sarez). A multi-temporal lake inventory is prepared and analysed, based on remotely sensed data. Corona images from 1968 are used as well as more up-to-date ASTER and Landsat 7 scenes. 1642 lakes are mapped in total, 652 out of them are glacial lakes. 73% of all lakes are located above 4000 m a.s.l. Glacial lakes, abundant in those areas where glacier tongues retreat over flat or moderately steep terrain, have experienced a significant growth, even though changes are often superimposed by short-term fluctuations. The analysis results also indicate a shifting of the growth of glacial lakes from the south western Pamir to the central and northern Pamir during the observation period. This trend is most likely associated with more elevated contribution areas in the central and northern Pamir. The lakes of the other types have remained constant in size in general. The lake development reflects changes in the state of the water resources in the study area on the one hand and determines the level of lake outburst hazards on the other hand.
... The 'supply index' partly associated with glacier volume and water yield in the Amu Darya basin is higher than most major river basins 26 . Because more than half of the land area of Tajikistan is above 3000 m, 44% of the country has been identi ed as potential permafrost area 27 . Most of this permafrost is concentrated in the high-elevation Badakhshan region of the southern and eastern Pamir in Tajikistan and northern Afghanistan. ...
... A few studies have noted the major challenge of quantifying the connectivity of various high mountain runoff sources to streams and rivers 15,27 . Additionally, understanding how much runoff from the Pamir recharges groundwater in alluvial valleys and plains is poorly understood 13 . ...
Changes in water delivery from the Pamir Water Towers to streams affect poor regions of Central Asia. We used a 20-yr remotely sensed climate record to assess water source dynamics in the sparsely monitored region. Varying spatial and temporal patterns of rain and snowfall occurred throughout the region. Temperatures increased across the east-central Panj and eastern Vakhsh basins. Warmer temperatures in central Panj and Wakhan corridor coupled with minor declines in snow water will induce water stress during dry years. In contrast, stable temperatures at lower elevations together with increasing precipitation, especially in spring, will benefit agriculture and community water supplies. Seasonal temperature increases, particularly in December, occurred in glaciated areas; however, December temperatures were <-20°C. In the Fedchenko and lower Panj glacier sectors, increasing spring snowfall offsets temperature increases causing little glacier mass change. The Wakhan corridor is at highest risk of glacier mass loss due to declining snow in early spring and increasing temperature in late winter and early spring. Interannual snowfall variability poses the largest uncertainty for water supplies. Permafrost thaw may contribute a small, but timely, source of runoff. Because of high interannual and spatial variability of precipitation, regional climate change scenarios cannot inform adaptation measures for mountain communities, thus, more granular-scale data are needed.
... Furthermore, the disintegration of surging (and non-surging) glaciers which did not lead to ice-rock avalanches have also been reported (e.g. Milana, 2007;Wang et al., 2021). Finally, another non-frequent behaviour of surge-type glaciers is extreme surface bulging that has been observed as a consequence of a polythermal ice structure (Clarke and Blake, 1991) (cf. ...
... All over the range, signs of large debris flows, rock avalanches, or ice-rock avalanches are visible in highresolution satellite images (Maxar, CNES/Airbus, Planet; Leinss et al., 2020). The Pamirs are known to be very geomorphologically active, with a number of associated hazards (Mergili et al., 2012;Gruber and Mergili, 2013;Strom and Abdrakhmatov, 2018) and a cluster of surge-type glaciers (Kotlyakov et al., 2008(Kotlyakov et al., , 2010aGardelle et al., 2013;Lv et al., 2019;Goerlich et al., 2020). A number of glaciers in the Peter the Great Range were surging at the time of writing or have done so in the recent past (Fig. 5). ...
The detachment of large parts of low-angle mountain glaciers resulting in massive ice–rock avalanches have so far been believed to be a unique type of event, made known to the global scientific community first for the 2002 Kolka Glacier detachment, Caucasus Mountains, and then for the 2016 collapses of two glaciers in the Aru range, Tibet. Since 2016, several so-far unrecognized low-angle glacier detachments have been recognized and described, and new ones have occurred. In the current contribution, we compile, compare, and discuss 20 actual or suspected large-volume detachments of low-angle mountain glaciers at 10 different sites in the Caucasus, the Pamirs, Tibet, Altai, the North American Cordillera, and the Southern Andes. Many of the detachments reached volumes in the order of 10–100 million m3. The similarities and differences between the presented cases indicate that glacier detachments often involve a coincidental combination of factors related to the lowering of basal friction, high or increasing driving stresses, concentration of shear stress, or low resistance to exceed stability thresholds. Particularly soft glacier beds seem to be a common condition among the observed events as they offer smooth contact areas between the glacier and the underlying substrate and are prone to till-strength weakening and eventually basal failure under high pore-water pressure. Partially or fully thawed glacier bed conditions and the presence of liquid water could thus play an important role in the detachments. Surface slopes of the detached glaciers range between around 10∘ and 20∘. This may be low enough to enable the development of thick and thus large-volume glaciers while also being steep enough to allow critical driving stresses to build up. We construct a simple slab model to estimate ranges of glacier slope and width above which a glacier may be able to detach when extensively losing basal resistance. From this model we estimate that all the detachments described in this study occurred due to a basal shear stress reduction of more than 50 %. Most of the ice–rock avalanches resulting from the detachments in this study have a particularly low angle of reach, down to around 5∘, likely due to their high ice content and connected liquefaction potential, the availability of soft basal slurries, and large amounts of basal water, as well as the smooth topographic setting typical for glacial valleys. Low-angle glacier detachments combine elements and likely also physical processes of glacier surges and ice break-offs from steep glaciers. The surge-like temporal evolution ahead of several detachments and their geographic proximity to other surge-type glaciers indicate the glacier detachments investigated can be interpreted as endmembers of the continuum of surge-like glacier instabilities. Though rare, glacier detachments appear to be more frequent than commonly thought and disclose, despite local differences in conditions and precursory evolutions, the fundamental and critical potential of low-angle soft glacier beds to fail catastrophically.
... Cryospheric changes directly affect the frequency, extent, and spatial and temporal scales of the impact of glacier and permafrost hazards, including glacier lake outburst floods, glacial debris flow, wind-blown snow, avalanches, blizzards, freezing rain, freeze-thaw hazards, and river and sea-ice disasters. The study of cryosphere hazards is focused on formation processes and mechanisms, and the interaction between the environment and the hazard [83,86]. With climate change and rapid economic development, the degree of disaster exposure is higher, thus these hazards are occurring with higher frequency. ...
... Overall, the cryosphere has both positive and negative effects on natural and societal systems. Positive influences mainly derive from the benefits provided by the cryosphere [86], such as the key roles of the cryosphere in maintaining ecosystems and regulating water resources. The cryosphere is also an important tourism resource [88,89]. ...
Cryospheric changes and their impacts have received increasing concern, extending the research to include the interactions between earth spheres and the impacts of and social adaptation to cryospheric changes. As a result, Cryospheric Science is rapidly developing. However, the research framework of Cryospheric Science has not completely been set up, and the intension and extension of Cryospheric Science are unclear. Following a literature review, the research framework for Cryospheric Science and the discipline components are analysed in this paper. We consider that Cryospheric Science is an inevitable product of international research on the earth and environmental changes as well as on human sustainable development. It will not only strengthen the linkage between the cryosphere and other earth spheres by deepening traditional research areas, but will also bring more focus on the critical roles of the cryosphere in interactions between earth spheres, and will enhance the relationship between cryospheric change and climate, ecology, hydrology, surface environment and sustainable development. The disciplinary tree of Cryospheric Science is developed following the mainstream of change-impacts adaptation. The disciplines of Cryospheric Science were teased out against characteristics of traditional branches and the developing interdisciplinary branches of cryosphere elements, which will provide reference to Cryospheric Science as it systematically grows to maturity. © The Author(s) 2017. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd. All rights reserved.
... In a similar event on 7 August 2002 in the Shahdara Valley, Pamir, Tajikistan, a 320 000 m 3 drainage from a small lake caused a mudflow that buried the Dasht village on the alluvial fan and killed 25 people (Mergili et al., 2012). In the northern Tien Shan, a drainage occurred from the western Zyndan glacial lake in the Teskey Range on 24 July 2008 (Narama et al., 2010a). ...
... In Shahimardan village, where a flood killed more than 100 residents (UNEP, 2007), many lived along the river. In the Dasht village, where a flood killed 25 people (Mergili et al., 2012), the debris flow covered the village on the alluvial fan. ...
Four large drainages from glacial lakes occurred during 2006–2014 in the western Teskey Range, Kyrgyzstan. These floods caused extensive damage, killing people and livestock as well as destroying property and crops. Using satellite data analysis and field surveys of this area, we find that the water volume that drained at Kashkasuu glacial lake in 2006 was 194 000 m3, at western Zyndan lake in 2008 was 437 000 m3, at Jeruy lake in 2013 was 182 000 m3, and at Karateke lake in 2014 was 123 000 m3. Due to their subsurface outlet, we refer to these short-lived glacial lakes as the “tunnel-type”, a type that drastically grows and drains over a few months. From spring to early summer, these lakes either appear, or in some cases, significantly expand from an existing lake (but non-stationary), and then drain during summer. Our field surveys show that the short-lived lakes form when an ice tunnel through a debris landform gets blocked. The blocking is caused either by the freezing of stored water inside the tunnel during winter or by the collapse of ice and debris around the ice tunnel. The draining then occurs through an opened ice tunnel during summer. The growth–drain cycle can repeat when the ice-tunnel closure behaves like that of typical supraglacial lakes on debris-covered glaciers. We argue here that the geomorphological characteristics under which such short-lived glacial lakes appear are (i) a debris landform containing ice (ice-cored moraine complex), (ii) a depression with water supply on a debris landform as a potential lake basin, and (iii) no visible surface outflow channel from the depression, indicating the existence of an ice tunnel. Applying these characteristics, we examine 60 depressions (> 0.01 km2) in the study region and identify here 53 of them that may become short-lived glacial lakes, with 34 of these having a potential drainage exceeding 10 m3 s-1 at peak discharge.
... • lake area A L in m 2 , x and y coordinates in m and elevation z L in m asl; • lake type: the entire set of lakes was organized into a system of seven classes (Table 1); the visual interpretation of the imagery was validated by detailed field surveys (reconnaissance) at selected lakes realized in summer and autumn 2014; • direct contact with glacier (yes or no); glaciers within catchment: also this attribute has a boolean format (yes or no); • type of drainage: here, we distinguished between surface and subsurface drainage; and • influence of permafrost: for the estimation of the location within the zone of possible and probable permafrost, the map of potential permafrost areas presented by Mergili et al. (2012) was used. ...
... Further, medium-sized falls or slides of rock or debris are possible in the catchments of all studied lakes. These movements might increase in frequency and/or magnitude as a result of permafrost warming and thaw Mergili et al., 2012;Haeberli, 2013;Stoffel et al., 2014). Nevertheless, detailed field surveys including long-term monitoring of the permafrost conditions would be needed to better understand the possible role of such processes as potential triggers of GLOFs (Krainer et al., 2012;Deline et al., 2015). ...
Climate-induced environmental changes are triggering the dynamic evolution of high-mountain lakesworldwide, a phenomenon that has to be monitored in terms of lake outburst hazards.We analyzed the spatial distribution and recent temporal development of high-mountain lakes in a study area of 6139 km2, covering the central European Alps over most of the province of Tyrol and part of the province of Salzburg in western Austria. We identified 1024 natural lakes.While eight lakes are ice-dammed, one-third of all lakes are located in the immediate vicinity of recent glacier tongues, half of them impounded by moraines, half by bedrock. Two-thirds of all lakes are apparently related to LIA or earlier glaciations. One landslide-dammed lake was identified in the study area.
The evolution of nine selected (pro)glacial lakeswas analyzed in detail, using multitemporal remotely sensed images and field reconnaissance. Considerable glacier retreat led to significant lake growth at four localities, two lakes experienced stagnant or slightly negative areal trends, one lake experienced a more significant negative areal trend, and two lakes drained completely during the investigation period. We further (i) analyzed the susceptibility of selected lakes to glacial lake outburst floods (GLOFs), using two different methods; (ii) identified potential triggers and mechanisms of GLOFs; (iii) calculated possible flood magnitudes for predefined flood scenarios for a subset of the lakes; and (iv) delineated potentially impacted areas.
We distinguished three phases of development of bedrock-dammed lakes: (a) a proglacial, (b) a glacierdetached, and (c) a nonglacial phase. The dynamics — and also the susceptibility of a lake to GLOFs — decrease substantially from (a) to (c). Lakes in the stages (a) and (b) are less prominent in our study area, compared to
other glacierized high-mountain regions, leading us to the conclusion that (i) the current threat to the population by GLOFs is lower but (ii) the future development of emerging lakes has to be monitored carefully.
... Glacial lakes dominate in the zone of recent glaciers and fresh moraines above 4500 m a.s.l., with the highest lake identified above 5100 m a.s.l. It is estimated that 95.6 % of all glacial lakes are located in the areas with at least sporadic permafrost ( Mergili et al. 2012). As such, glacial lakes can be viewed as early indicators of climate warming, reflecting the state of glaciers and permafrost as their sources of water. ...
... During the study period, the number of growing glacial lakes in the southwestern part of Pamir has decreased, whereas in the central and northern parts of Pamir it has increased, reflecting trends in glacier dynamics. It is hypothesized that the process of glacier retreat has started earlier in the southwestern part of Pamir than in its central and northern parts, which are more humid and therefore, more favorable for glacier accumulation processes ( Mergili et al. 2012). A parallel situation was described for the Hindu Kush Himalaya range by Gardelle et al. (2011). ...
Pamir is a highland region in Central Asia (the highest ranges exceeding 7,000 a.s.l.), characterized by extreme climatic conditions (cold desert biome), isolation and exceptionally short growing season. Therefore, a unique landscape and nature characteristics developed in this region. Moreover, it is an important area of mountain glaciers with their total surface estimated at 8,000 km2. However, with increasing temperatures, glaciers recede, profoundly changing hydrological conditions in Pamir. Furthermore, current land and water resources management practices, are threatening the long‑term preservation of this unique area as a space both for human use and wilderness.
... The important point to note is that The 172 glacial lakes are mostly located at 4,400-4,700 m a.s.l. (Mergili et al., 2012). This altitudinal zone is significantly higher than the altitudes ranging from 3,810-4,000 m a.s.l., which are calculated as the lower boundary of the discontinuous permafrost (permafrost probable) by Müllebner (2010). ...
... Glacial lakesSystematic investigations to clarify the distribution, types, and development of glacial lakes have been conducted only in the southwestern Tajik Pamir (the Gunt and Shakhdara valleys;Fig. 1) byMergili et al. (2012). These studies were performed for 1968-2009 using multitemporal satellite images (Corona, Landsat ETM+, ASTER), and define the proximal lake, which is either directly embedded in the exposed ice, or dammed by debris-covered glacier tongues, rock glaciers or fresh moraines, as the glacial lake. ...
This paper reviews contemporary glacial features, characteristics of documented glacial hazards, and the status of hazard assessment studies in the Pamirs of Tajikistan (hereafter the Tajik Pamir). The review found detachment of a hanging glacier, glacier-surging, and outburst discharge of a glacial lake to be major potential causes of glacial hazards in the Tajik Pamir, especially in the western area (west from approx. 73° E). Guerrilla glacial lakes, which are characterised as glacial lakes on the ice-core moraine that " appear repeatedly, " " enlarge rapidly (within less than one year), " " disappear within less than two years, " " are superficially closed, " and " are of relatively small size (approx. < 10 6 m 2) " should hereafter be paid special attentions. Preparation of appropriate hazard-mitigation activities should re-quire early detection of not only the large crack in the hanging-glacier terminus, surge behaviour, and the glacial lake and guerrilla glacial lake, but also regular monitoring of these hazard factors. One of the most suitable monitoring techniques is to use earth observation satellite images with a relatively short repetitive cycle (ideally once every few days) and a high spatial resolution (ideally several meters). These criteria may be satisfied in the near future by using images captured by many sets of microsatel-lites, such as the 50-kg class microsatellite SPRITE-SAT (RISING).
... So far, glacial lakes are mainly mapped and monitored using interpretation and manual mapping based on optical data, both air-photos and optical satellite data (Haeberli et al., 2001;Huggel et al., 2002;Kääb et al., 2005b;Quincey et al., 2005;Kääb, 2008;Bolch et al., 2008Bolch et al., , 2011Mergili et al., , 2012Ukita et al., 2011). The accuracy and level of detail of such glacial lake maps mainly depends on the data source and acquisition conditions (including areas in shadow), the temporary or permanent charateristics of the glacial lake (e.g. ...
... Costs and processing effort of satellite SAR data are similar to that of satellite optical data, although interpretation, as explained before, might need more training. Thus, we envisage that the provided service is mature and complements well the more established optical remote sensing technology (Schneider, 2004;Kääb et al., 2005a;Quincey et al., 2005;Ukita et al., 2011;Mergili et al., 2012). The users involved in our study are developing more capacity in radar remote sensing analysis as part of ongoing and future risk management interventions in Tajikistan and the Himalayas. ...
Floods resulting from the outbursts of glacial lakes are among the most
far-reaching disasters in high mountain regions. Glacial lakes are
typically located in remote areas and space-borne remote sensing data
are an important source of information about the occurrence and
development of such lakes. Here we show that very high resolution
satellite Synthetic Aperture Radar (SAR) data can be employed for
reliably mapping glacial lakes. Results in the Alps, Pamir and Himalaya
using TerraSAR-X and Radarsat-2 data are discussed in comparison to
in-situ information, and high-resolution satellite optical and radar
imagery. The performance of the satellite SAR data is best during the
snow- and ice-free season. In the broader perspective of hazard
management, the detection of glacial lakes and the monitoring of their
changes from very high-resolution satellite SAR intensity images
contributes to the initial assessment of hazards related to glacial
lakes, but a more integrated, multi-level approach needs also to include
other relevant information such as glacier outlines and outline changes
or the identification of unstable slopes above the lake and the
surrounding area, information types to which SAR analysis techniques can
also contribute.
... Moreover, understanding climate factors, including increased rainfall, glacial melt, steep terrain, and loose soil, is essential for comprehending the origins and actual reasons of mudflows in Tajikistan. The combination of high elevations and prevalent glaciers, along with intensified rainfall and accelerated ice melting due to climate change, significantly accelerates the risk of mudflows (Mergili et al. 2012;Mustaeva et al. 2015). ...
In recent years, mudflows have emerged as a significant threat to infrastructure and lives, exhibiting increased frequency and severity. This study collectively addresses the rising threat of natural hazards, specifically mudflows in mountain-foothill zones in Tajikistan, utilizing UAV and remote sensing technologies to monitor their impact. From 2020 to 2023, we employed a QC-2 Micro UAV and a DJI Phantom 4 quadcopter to capture high-resolution aerial imagery across multiple affected districts, supplemented by pre- and post-event Sentinel-2 images analyzed using the Normalized Difference Water Index (NDWI) and Normalized Difference Vegetation Index (NDVI). Our analysis revealed that 49 districts and cities experienced significant mudflow events, resulting in estimated damages and economic losses of 30.2 million USD, with particularly severe impacts noted in the Khuroson, Tojikobod, Vakhsh, Panjakent, Lakhsh, and Varzob. The composition of mudflows in the six studied areas predominantly consisted of clay, with some regions featuring mudstone and a few exhibiting a mixture of both materials. Our findings indicate the predominance of rain-induced mudflows in foothill areas, contrasting with rain-snow, glacial, and lake-outburst-induced mudflows in mountainous regions. This underscores the urgent need for effective disaster risk management strategies in vulnerable locations. Integrating UAV and remote sensing technologies provides crucial information for analyzing damages, identifying vulnerable areas, and advising emergency response efforts, thereby enhancing disaster risk management in Tajikistan.
... Higher elevations also exhibit increased share of lakes located close to glaciers and the band > 3,000 m asl is characterized by an increased share of ice-dammed lakes (11.1%; i.e., 87.5% of all icedammed lakes are located in this elevation band). Considering possible and probable permafrost areas defined by Mergili et al. (2012), about one sixth of inventoried lakes (n=179; 17.5%) are located in areas with possible or probable permafrost while one tenth (n=102; 10.0%) are located in areas with probable permafrost occurrence. ...
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.
... During our field expedition in 2015, we confirmed the presence of the ground ice at a depth of > 1 m in the Rangkul-Shorkul catchment (Mętrak et al., 2019 and own unpublished data). Simultaneously, in both Yashilkul and Rangkul-Shorkul catchments permafrost at the depth of several meters was reported in Russian literature (3-5 m according to Baranov and Klunnikov, 1936) and confirmed by modern modelling (Brown et al., 2001;Mergili et al., 2012). Due to the occurrence of ground ice and the potential presence of permafrost, we expect that lakeside and riverine areas in the Eastern Pamir have specific climatic profiles, comprising higher air and soil moisture and lower air and soil temperatures, described as cold-air ponding/pooling (e.g. ...
High-altitude wetlands in the Eastern Pamir are habitat islands located in an arid landscape. They play several important roles, including that of water sources and forage grounds for people and their livestock. Considering high variation in micro-relief and complexity of water supplies observed in these wetlands, we assessed their potential to play a role of refugia for species whose present ranges may be limited by climate changes projected for Central Asia. Such species currently occur typically in less moist habitats, often located at lower elevations (e.g. steppe and meadow species). To perform this assessment, we analyzed current spatial structure and species diversity of vegetation accompanying selected water bodies in the studied catchments, identified present changes in temperature and precipitation in these catchments and analyzed alterations in area of lakes and small water bodies located in the vegetation mosaic. Presently, the biodiversity of the studied wetlands comprises 110 species of vascular plants from 26 families, forming ten distinct vegetation types, over 40 recorded species are typical for steppes and various types of alpine meadows. Both meteorological data and satellite data on open water area indicated that with growing temperatures, areas of the studied lakes and small water bodies in the vegetation mosaic increase. This effect is probably caused by thawing of ground ice and permafrost, whose occurrence helps mitigate the effects of the ongoing warming and lessening precipitation. Thus, the wetlands may temporarily maintain their cold, wet and mesic characteristics under the changing climatic conditions and, as such, potentially become refugia for steppe and meadow species. However, after the period of intense thawing, lowering of groundwater level and huge surface water fluctuations may occur, potentially resulting in a decrease in the total vegetated area on lacustrine and riverine terraces in the Eastern Pamir.
... Tajikistan is characterized by an extremely complex rough terrain, with approximately 44% of its territory potentially hosting permafrost, which is rapidly thawing [32]. Thick soils with a relatively high erodibility index [33] characterize the area. ...
Mapping existing landslides is a fundamental prerequisite to build any reliable susceptibility model. From a series of landslide presence/absence conditions and associated landscape characteristics, a binary classifier learns how to distinguish potentially stable and unstable slopes. In data rich areas where landslide inventories are available, addressing the collection of these can already be a challenging task. However, in data scarce contexts, where geoscientists do not get access to pre-existing inventories, the only solution is to map landslides from scratch. This operation can be extremely time-consuming if manually performed or prone to type I errors if done automatically. This is even more exacerbated if done over large geographic regions. In this manuscript we examine the issue of mapping requirements for west Tajikistan where no complete landslide inventory is available. The key question is: How many landslides should be required to develop reliable landslide susceptibility models based on statistical modeling? In fact, for such a wide and extremely complex territory, the collection of an inventory that is sufficiently detailed requires a large investment in time and human resources. However, at which point of the mapping procedure, would the resulting susceptibility model produce significantly better results as compared to a model built with less information? We addressed this question by implementing a binomial Generalized Additive Model trained and validated with different landslide proportions and measured the induced variability in the resulting susceptibility model. The results of this study are very site-specific but we proposed a very functional protocol to investigate a problem which is underestimated in the literature.
... Most short-lived glacial lakes fill periodically and within 1 year, though some may develop for 2-3 years before draining. The latter type is also dangerous; for example, in the Tajik Pamirs, drainage from a short-lived glacial lake that formed within 2 years resulted in 25 casualties (Mergili et al., 2012). In northern Tien Shan, short-lived glacial lakes can be a severe hazard for local residents because they appear suddenly yet can cause large debris flows. ...
In the Teskey Range of the Tien Shan (Kyrgyz Republic), five outburst flood disasters from short-lived glacial lakes in 2006, 2008, 2013, 2014, and 2019 caused severe damages in the downstream part. Short-lived glacial lakes in the Teskey Range grow rapidly and drain within a few months, due to closure and opening of an outlet ice tunnel in an ice-cored moraine complex at the glacier front. In addition to these factors, summer meltwater from the glacier can cause rapid growth. Outburst floods of this lake type are a major hazard in this region and differ from the moraine-dam failures common to the eastern Himalaya. To clarify how short-lived glacial lakes store and drain water over short periods, we use results from a field survey and satellite data to analyze the water level, area, volume, and discharge of Korumdu lake (2017–2019) as well as satellite data to monitor the appearance of 160 other short-lived lakes (2013–2018). Except in 2016, Korumdu lake appeared and drained within about 1 month during all the summers. Water level data recorded by a data logger and time-lapse camera images show that the lake appeared and expanded suddenly from July to August in 2017–2019. The timing of lake appearance indicates that the lake formed when an outlet ice tunnel (subsurface channel) drainage was blocked by depositions of an ice–debris mixture due to ice melting and not by freezing of stored water. For 2017, we used uncrewed aerial vehicle (UAV)-derived digital surface models (DSMs) and water levels, finding that the lake's volume reached 234 000 m3 within 29 d, and then the water discharged for 17 d at a maximum rate of 0.66 m3/s. This discharge rate is more than 20 times smaller than those found earlier (2006–2014) for four short-lived lakes of tunnel type in this region. We argue that this large variation in discharge rates is due to variation in the dimensions of the outlet ice tunnels. For the 160 other short-lived glacial lakes, we found that 117 formed during the ice-melt period from July to September. This timing and our findings for Korumdu lake show that these 117 lakes likely formed primarily because deposition of an ice–debris mixture blocked the outlet tunnel, though increased glacial melt would also have contributed. In the Teskey Range, the appearance of short-lived glacial lakes on the moraine complexes at glacier fronts is inevitable in summer when the melting rate is high. Similar behavior of short-lived lakes may occur in other mountain regions of Central Asia, such as the Tien Shan and Pamir Mountains, wherever ice-cored moraine complexes exist within mountain permafrost zone. Moreover, increasing temperatures may increase both tunnel size and lake-basin size (lake volume), leading to increased hazard potential from such lakes in the future.
... Such short-lived glacial lakes grow rapidly and drain within a few months (Narama et al., 2010(Narama et al., , 2018Daiyrov et al., 2018). In the Tajik Pamir, drainage from a short-lived lake that formed within 2 years resulted in 25 casualties (Mergili et al., 2012). Such lakes drain through an outlet ice-tunnel (subsurface channel) within an ice-cored moraine complex (Popov, 1987), and are also called nonstationary lakes (Erokhin et al., 2017), though this term also includes lakes with a long lifetime. ...
In the Teskey Range of the Tien Shan (Kyrgyz Republic), four outburst flood disasters from short-lived glacial lakes caused severe damages in the downstream part in 2006, 2008, 2013, and 2014. The short-lived lake grows rapidly and drain within a few months, due to closure and opening of an outlet ice-tunnel in moraine complex at glacier front. The outburst flood of this lake type is a major hazard in this region, it differs from many cases of moraine-dam failure in the eastern Himalaya. To clarify how short-lived lakes store and drain water for short period, we examined its recent changes in water level, area, volume, and discharge with a field survey and satellite data analysis. Korumdu lake appeared and drained within about one month during all summers during 2014–2019 except that in 2016. Water-level data recorded by a data logger and time-lapse camera images show that the lake appeared and expanded suddenly from July to August in 2017–2019. The timing indicates that the lake formed when an outlet ice-tunnel (subsurface channel) drain was blocked by deposition of debris and ice due to ice melting, not by freezing of stored water. Based on calculation of UAV DSMs and water level in 2017, the lake's water volume reached 234,000 m3 within 29 days, and then the water discharged for 17 days at a maximum rate of 0.66 m3/s. The small discharge indicates that the diameter of the outlet ice-tunnel was much smaller than those of four short-lived lakes in the same range that caused large drainages (12–27 m3/s) in 2006, 2008, 2013, and 2014. As the results, the dimensions of the outlet ice-tunnel of short-lived glacial lakes presently are related to the flooding scale. Recent warming temperatures may increase both the size of the tunnels and the basin volumes leading to greater hazard from such lakes in the future. In addition, we investigated the timing of appearance of 160 short-lived glacial lakes in this region using Landsat-7/8, Sentinel-2, and PlanetScope satellite images (2013–2018). We conclude that tunnel closure of 117 lakes was due to deposition of debris and ice during summer. The appearance of a short-lived glacial lake is inevitable in summer when the melting rate is high. The characteristics of this lake type might be shown in another Asian mountain permafrost regions.
... Together with other ranges of Central Asia, the Pamir Mountains belong to the largest reservoirs of glaciers in the world outside the polar regions (Gorbunov, 1978;Kayumov, 2010). Modern modelling estimates the glacial cover in the Pamir Mountains at approximately 8000-12,000 km 2 (Aizen, 2011;Mölg et al., 2018) and the permafrost area at ca. 54,000 km 2 , mostly in a discontinuous form (Mergili et al., 2012). The distribution of glaciers roughly reflects the present precipitation gradient. ...
Melting glaciers release new ground surfaces, which may be either a source of greenhouse gas emissions or a sink for carbon dioxide. Studies carried out in subpolar and alpine ecosystems confirm the relatively rapid soil development and increase of carbon and nitrogen pools. However, observations from high-mountain glacier forelands in cold and dry climate are very scarce. This study analyses the impact of major environmental factors related to climate, topography, and vegetation, over a time-scale, on soil development and spatial soil differentiation in the foreland of Uisu Glacier, East Pamir Mountains. Moreover, the usefulness of the World Reference Base (WRB) and Soil Taxonomy in the classification of poorly developed soils in the ultracontinental climate was assessed. Geomorphological, pedological, and botanical surveys covered a sequence of terraces, alluvial fans, and end-moraines. Typical characteristics of the soils in the glacier foreland were: very high stoniness, coarse texture, high content of calcium carbonate, alkaline reaction, and low salinity. Soil development has extremely low intensity and was manifested in (a) soil organic carbon pools being among the lowest reported in the world (up to 1.4 kg m⁻² in the layer 0–50 cm), and (b) the presence of cambic/calcic horizons only on landforms older than of Mid-Holocene age (estimated). It was concluded that both the extremely cold and extremely dry climate conditions in the Uisu Glacier foreland limit the water flux and availability, suppress vegetation density and variability, and slow down the rate of soil development. Both WRB and Soil Taxonomy were able to reflect the advances in soil development and spatial soil differentiation (Calcaric Hyperskeletic Leptosols – Calcaric Cambisols – Cambic Calcisols, and Gelifluvents – Haplocambids - Haplocalcids, respectively); however, highlighting different features developed under an extremely cold and dry climate conditions of the East Pamir Mountains.
... This elevation was interpreted as the approximate lower boundary (without considering surface offsets) for permafrost in Tajikistan. That constitutes approximately 44.3 percent of the total area of Tajikistan as potential permafrost area and up to 84.1 percent of the eastern Pamir (Gruber and Mergili 2013;Mergili et al. 2012). ...
... This elevation was interpreted as the approximate lower boundary (without considering surface o sets) for permafrost in Tajikistan. That constitutes approximately 44.3 per cent of the total area of Tajikistan as potential permafrost area and up to 84.1 per cent of the eastern Pamir (Gruber and Mergili 2013;Mergili et al. 2012). ...
open access via:
https://www.routledge.com/The-Aral-Sea-Basin-Water-for-Sustainable-Development-in-Central-Asia/Xenarios-Schmidt-Vogt-Qadir-Janusz-Pawletta-Abdullaev/p/book/9781138348882#sup
... In case of the Pamir Mountains both former Russian data and modern modelling confirm presence of permafrost and estimate its area at 54,000 km 2 (Baranov and Klunnikov, 1936;Mergili et al., 2012). According to Brown et al. (1998), our sampling sites are located in the region of discontinuous permafrost. ...
Nutrient cycling in alpine permafrost-affected wetlands remains insufficiently studied, as it is influenced by a complex network of interrelated climatic and environmental factors, at both regional and local scale. Therefore, we applied mathematical models to examine relationship between environmental factors and plant functional traits reflecting N availability in wetland communities developed under locally variable conditions in a geographic and climatic gradient of high-altitude habitats. Moreover, we assessed impact of local differences in soil chemistry on plant fractionation of N isotopes as a response to N availability. Based on environmental data and chemistry of biomass from 192 study sites from the Pamir Mountains (Tajikistan) and Khangai and Khentei Mountains (Mongolia), a matrix of rank correlations was prepared for regional and local factors and community level plant functional traits. For the traits that were highly correlated either with regional or with local drivers (that is plant N:P ratio and plant δ¹⁵N), linear models were built, with a limited set of predictors selected according to the Risk Inflation Criterion and the SOS algorithm. The models were fitted for each of the studied regions. Presented regional models indicated significant influence of soil NH4⁺ and/or PO4³⁻ content on plant N:P ratio, which showed increase with altitude and lowering precipitation. Thus, its values clearly distinguished between the Pamir Mountains (high N:P) and the Mongolian ranges (low N:P). Models for plant δ¹⁵N showed its strong positive correlations with soil δ¹⁵N and soil salinity. Average values of plant δ¹⁵N were comparable for both study areas. The studied plant functional traits showed different response to regional and local drivers. Plant N:P ratio was controlled by regional drivers via their influence on soil NH4⁺ content. Contrastingly, plant δ¹⁵N was significantly affected by local factors, namely soil δ¹⁵N and soil salinity expressed as Na:EC.
... This elevation was interpreted as the approximate lower boundary (without considering surface offsets) for permafrost in Tajikistan. That constitutes approximately 44.3 percent of the total area of Tajikistan as potential permafrost area and up to 84.1 percent of the eastern Pamir (Gruber and Mergili 2013;Mergili et al. 2012). ...
This book offers the first multidisciplinary overview of water resources issues and management in the Aral Sea Basin, covering both the Amu Darya and Syr Darya River Basins. The two main rivers of Amu Darya and Syr Darya and their tributaries comprise the Aral Sea Basin area and are the lifeline for about 70 million inhabitants in Central Asia. Written by regional and international experts, this book critically examines the current state, trends and future of water resources management and development in this major part of the Central Asia region. It brings together insights on the history of water management in the region, surface and groundwater assessment, issues of transboundary water management and environmental degradation and restoration, and an overview of the importance of water for the key economic sectors and overall socioeconomic development of Central Asian countries, as well as of hydro politics in the region. The book also focusses on the future of water sector development in the Basin, including a review of local and international actors, as well as an analysis of the current status and progress towards the Sustainable Development Goals by Basin countries. The book will be essential reading for those interested in sea basin management, environmental policy in Central Asia and water resource management more widely. It will also act as a reference source for decision-makers in state agencies, as well as a background source of information for NGOs. Large river basins are dynamic and complex entities. Defined by hydrological boundaries, they are nearly always shared by more than one country. Encompassing a diverse range of landscapes with often huge temporal and spatial variability of resources, they are put to different and often conflicting uses, and managed by a range of institutions and organisations. While an intrinsic part of Nature, many have been extensively engineered and used by people, often with adverse consequences. Each major river basin has its own development trajectory and often fascinating history. Bringing together multidisciplinary teams of experts, this series explores these complex issues, identifies knowledge gaps and examines potential development pathways towards greater sustainability.
... This elevation was interpreted as the approximate lower boundary (without considering surface offsets) for permafrost in Tajikistan. That constitutes approximately 44.3 per cent of the total area of Tajikistan as potential permafrost area and up to 84.1 per cent of the eastern Pamir (Gruber and Mergili 2013;Mergili et al. 2012). ...
... This elevation was interpreted as the approximate lower boundary (without considering surface offsets) for permafrost in Tajikistan. That constitutes approximately 44.3 per cent of the total area of Tajikistan as potential permafrost area and up to 84.1 per cent of the eastern Pamir (Gruber and Mergili 2013;Mergili et al. 2012). ...
... The responses of the environmental systems to the retreat of glacier tongues are complex and with contributions from different biotic and abiotic features. The newly exposed areas are fast changing sites (Staines et al., 2015) where paraglacial and periglacial processes have implications for environmental hazard and risk conditions (Mergili, Kopf, & Muellebner, 2012). These latter are mainly due to the unconsolidated sediment present at the glacier forelands (in some cases also containing heterogenic ground ice) and susceptible of rapid modifications in relation to climate warming thus influencing both geomorphic processes and sediment supply to the processes acting down valley (Bosson et al., 2015); furthermore melting water as well as ground water may affect depositional landforms in areas of glacier retreat (Levy, Robinson, Krause, Waller, & Weatherill, 2015) and proglacial lakes and water ponds develop and undergo to spatial and temporal variations (Geilhausen, Morche, Otto, & Schrott, 2012;Salerno et al., 2014) with also biological consequences (Sommaruga, 2015). ...
We analysed the recent involution of glaciers in the Bernina group (Italy), which are shrinking thus permitting a rapid enlargement of the forelands. We delimited glacier outlines upon aerial photographs (1954 and 1981 stereo pairs analysed through an optical system) and orthophotos (2003 and 2007 digital imagines directly managed via GIS software). All the obtained data were overlapped and compared. The estimated glacier area change during 1954–2007 was −36.5 ± 2.4% (−16.2 ± 0.4 km²). The changes sped up more recently; in fact, during 1981–1954 (27 years) the variation was −0.206 km²/y, against −0.387 km²/y during 1981–2003 (22 years), and −0.535 km²/y during 2007–2003 (4 years). In the 1954–2007 period, the forelands experienced a continuous increase (+14.7 km²). Moreover, the analysis of the colour orthophotos allowed observations of: (i) changes affecting shape and geometry of glaciers (growing rock outcrops, tongue separations, increasing supraglacial debris and collapse structures) and (ii) main features of glacier forelands (bare rock exposures, debris and sediments and, in the latter case, occurrence of vegetation colonizing such pristine areas). Glacier forelands resulted also subjected to the action of melting water, debris transport, and periglacial processes, with consequences on landscape and geoheritage.
... Low air temperatures, combined with relatively low precipitation typical for the Eastern Pamir, are conducive to the occurrence of permafrost (Haeberli, 1978). Its presence has been confirmed both by old Russian data and modern modeling (estimated area of 54,000 km 2 ) (Baranov and Klunnikov, 1936;Loskutov, 1968;Mergili et al., 2012). ...
This study was aimed at collecting and examining a sediment core from Lake Rangkul (Eastern Pamir, Tajikistan) to better understand the lake’s development and to assess past variations in climatic conditions in this particular area in comparison with data available from other lakes from the neighboring locations. For the purposes of this study, we performed detailed geochemical and palynological analyses on the sediment core taken from Lake Rangkul in 2014. Moreover, we obtained historical satellite and meteorological data and performed field tests for ground ice presence to identify trends in recent lake development. We distinguished 5 distinct stages over the past 2000 years of the lake’s history that differ in geochemical and palynological characteristics. Despite the fact that Lake Rangkul is shallow and sensitive to various disturbances in sedimentation, the recorded stages are in accordance with general climatic trends observed for the Northern Hemisphere in the Late Holocene. Satellite data from the past 45 years shows a noticeable increase in the lake’s area, which coincides with rising air temperatures. As the lake is located in the permafrost region with ground ice present immediately below the soil surface, its functioning is influenced by permafrost thawing, which will lead to future changes in the lake area and the distribution of surrounding wet meadows, used as pastures by local inhabitants.
... Natural hazards related to glaciers' degradation in high mountain terrains can have severe downstream consequences. GLOFs and glacier related debris flows have significant social and economic consequences in lower-elevation valleys and even in adjacent lowlands [6][7][8][9]. These phenomena have been described in all large mountain ranges around the world: in Central Asia [10,11], in the Swiss Alps [12,13], the Himalayas [14][15][16], and the Andes [17,18]. ...
Debris flows caused by glacial lake outburst floods (GLOFs) are common hazards in mountain environments. The risk posed by glacial lake outburst hazards is particularly evaluated where the lower reaches of catchments are populated. A potentially dangerous lake has been identified adjacent to the Uchitel Glacier in Northern Tien Shan. This lake formed between 1988 and 1994 on the site of a retreated glacier in the upper part of the Aksay Valley. In this study we consider the possibility of an outburst of this pro-glacial lake in the future. The study involved bathymetry mapping of the lake, detailed profile sections of the valley, flow rate measurements on the Aksay river, and monitoring of the lake development using satellite images. Modelling of secondary debris flow inundation heights and hazard footprints has been undertaken. The outburst of this lake could cause powerful debris flows posing a threat to permanent residents living downstream, in the Ala-Archa Valley. Monitoring of the lake over the past ten years suggests certain changes in the runoff to the subsurface, and an increase in lake depth is observed. Glacial lakes with subsurface drainage are considered to be the most hazardous type as the knowledge of drainage channels functioning is still very limited and, thus, the timing of an outburst is hard to predict. Development of monitoring approaches to support forecasting of these hazards is of paramount importance to safety in mountain territories globally.
... Although glacial lakes in this region are smaller than the more often-studied proglacial lakes in the eastern Himalayas [1][2][3], the resulting floods cause serious damage [4]. In the Central Asian mountains, large drainage events have occurred in three regions: northern Tien Shan in 1952-2014 [4][5][6][7][8][9][10], Gissar-Alay in 1977 and 1998 [11,12], and Pamirs in 2002 [13][14][15]. According to Popov [16], the glacial lakes here drained either through a dam incision [6,7,[17][18][19][20] or through an underground ice channel inside a debris landform containing ice [4,10,17,21]. ...
To assess the current state of glacial lakes, we examine the seasonal lake-area changes of 339 glacial lakes in the Teskey and Kungoy Ranges of the Issyk-Kul Basin, Kyrgyzstan, during 2013–2016 based on optical satellite images (Landsat7/ETM+ and 8/OLI). The glacial lakes are classified into six types based on their seasonal variations in area: stable, increasing, decreasing, appearing, vanishing, and short-lived. We then track the number of each type in a given year and examine how each number changes from one year to the next. We find that many appearing, vanishing, and short-lived types occurred in both mountain ranges, having a large variability in number that is not directly related to the local short-term summer temperature anomaly, nor to precipitation or glacier recession. However, those in the Teskey Range vary significantly more than those in the Kungoy Range. To determine if the changing number and distribution of the various lake types may be due to changes in ground ice, we apply differential interferometric synthetic aperture radar (DInSAR) analysis using ALOS-2/PALSAR-2 for the debris landforms behind which glacial lakes appear. In the Teskey Range, ground ice occurs in 416 out of a total of 557 debris landforms, whereas in the Kungoy Range, ground ice occurs in 71 out of 131. In zones with predominant glacier-retreat during 1971–2010 (from Corona KH-4B and ALOS/PRISM), the Teskey Range had 180 new lake depressions as potential lake-basins, whereas the Kungoy Range had just 22. Existing depressions also expanded when melting ice produced subsidence. Such subsidence, together with debris landforms containing ground ice and ice tunnels, appear to cause the observed large number variability. In particular, the deposition of ice and debris by tunnel collapse or the freezing of storage water in a debris landform may close-off an ice tunnel, causing a lake to appear. Subsequent re-opening via melting of such blockage would produce either a vanishing or a short-lived type. In this way, the large variability in the number of each lake type and the distribution of types over this four-year period arises from regional geomorphological conditions and not directly from the local short-term summer temperature anomaly and precipitation or glacier recession.
... Glacier-related hazards can have severe downstream consequences (Evans et al. 2009;Mergili et al. 2012;Westoby et al. 2014), particularly if the outburst of glacial lakes leads to debris flows and floods. Glacial lake outburst floods (GLOFs) are generally known for their potential to cause some of the largest floods known in mountain environments (Costa and Schuster 1988;Clague and Evans 2000;O'Connor and Costa 2004;Borga et al. 2014;Worni et al. 2014;Schwanghart et al. 2016). ...
One of the most far-reaching glacier-related hazards in the Tian Shan Mountains of Kyrgyzstan is glacial lake outburst floods (GLOFs) and related debris flows. An improved understanding of the formation and evolution of glacial lakes and debris flow susceptibility is therefore essential to assess and mitigate potential hazards and risks. Non-stationary glacier lakes may fill periodically and quickly; the potential for them to outburst increases as water volume may change dramatically over very short periods of time. After the outburst or drainage of a lake, the entire process may start again, and thus these non-stationary lakes are of particular importance in the region. In this work, the Teztor lake complex, located in Northern Kyrgyzstan, was selected for the analysis of outburst mechanisms of non-stationary glacial lakes, their formation, as well as the triggering of flows and development of debris flows and floods downstream of the lakes. The different Teztor lakes are filled with water periodically, and according to field observations, they tend to outburst every 9–10 years on average. The most important event in the area dates back to 1953, and another important event occurred on July 31, 2012. Other smaller outbursts have been recorded as well. Our study shows that the recent GLOF in 2012 was caused by a combination of intense precipitation during the days preceding the event and a rapid rise in air temperatures. Analyses of features in the entrainment and depositional zones point to a total debris flow volume of about 200,000 m3, with discharge ranging from 145 to 340 m3 s−1 and flow velocities between 5 and 7 m s−1. Results of this study are key for a better design of sound river corridor planning and for the assessment and mitigation of potential GLOF hazards and risks in the region.
... The Pamir Mountains, as a high altitude area, are especially sensitive to climate changes, that manifest themselves in temperature increases, changes in precipitation patterns, enhanced permafrost and glacial melt and the intensification of extreme events, such as floods or landslides [27][28][29][31][32][33]. As advancing climate change and growing human impact influence the functioning of wetland ecosystems in the Eastern Pamir, we should expect profound structural and functional transformations of wetland vegetation, mostly due to changes in water supply and soil moisture. ...
The eastern part of the Pamir Mountains, located in Central Asia, is characterized by great climatic continentality and aridity. Wetlands developed in this hostile region are restricted to spring areas, terraces of shallow lakes or floodplains along rivers, and provide diversified ecosystem services e.g. as water reservoirs, refugia for rare species and pastures for domestic cattle. These ecosystems are particularly susceptible to climate changes, that in the Pamir Mountains result in increased temperatures, intense permafrost/glacial melt and alterations of precipitation patterns. Climatic changes affect pasture management in the mountains, causing overutilization of sites located at lower elevations. Thus, both climate and man-induced disturbances may violate the existing ecological equilibrium in high-mountain wetlands of the Eastern Pamir, posing a serious risk to their biodiversity and to food security of the local population. In this context, we sought to assess how environmental drivers (with special focus on soil features and potential water sources) shape the distribution and diversity of halophytic plant communities developed in valleys in the Eastern Pamir. This task was completed by means of a vegetation survey and comprehensive analyses of habitat conditions. The lake terraces and floodplains studied were covered by a repetitive mosaic of plant communities determined by differences in soil moisture and salinity. On lower, wetter sites, this patchwork was formed by Blysmus rufus dominated salt marshes, saline small sedge meadows and saline meadows with Kobresia royleana and Primula pamirica; and on drier, elevated sites, by endemic grasslands with Hordeum brevisubulatum and Puccinellia species and patches of xerohalophytic vegetation. Continuous instability of water sources and summer droughts occurring in the Pamir Mountains may lead to significant structural and functional transformations of described wetland ecosystems. Species more tolerant to decreased soil moisture and/or increased soil salinity will expand, leading to alterations of ecosystem services provided by the Pamirs’ wetlands. The described research will help to assess the current state of the wetlands and to predict directions of their future changes.
... Regardless of the hydrological components addressed in the present study, the apparent positive temperature trend exerts the danger of more frequent natural hazards. Mergili et al. [2012] has outlined the large areas that will be affected by a change in the permafrost boundary. The forming of periglacial lakes increases the chance of GLOFs, and thawing permafrost as well as higher portions of rainfall over snowfall increases the chance of landslides and mudflows [Gruber and Mergili , 2013]. of the spatiotemporal precipitation patterns of the HAR data set, and exemplifies the strong potential of GRACE for validating precipitation data sets in snowfall-dominated catchments even at regional scale. ...
Newly developed approaches based on satellite altimetry and gravity measurements provide promising results on glacier dynamics in the Pamir-Himalaya but cannot resolve short-term natural variability at regional and finer scale. We contribute to the ongoing debate by upscaling a hydrological model that we calibrated for the central Pamir. The model resolves the spatiotemporal variability in runoff over the entire catchment domain with high efficiency. We provide relevant information about individual components of the hydrological cycle and quantify short term hydrological variability. For validation we compare the modelled total water storages (TWS) with GRACE (Gravity Recovery and Climate Experiment) data with a very good agreement where GRACE uncertainties are low. The approach exemplifies the potential of GRACE for validating even regional scale hydrological applications in remote and hard to access mountain regions. We use modelled time-series of individual hydrological components to characterise the effect of climate variability on the hydrological cycle. We demonstrate that glaciers play a two-fold role by providing roughly 35% of the annual runoff of the Panj River basin and by effectively buffering runoff both during very wet and very dry years. The modelled glacier mass balance (GMB) of -0.52 m w.e. yr−1 (2002 to 2013) for the entire catchment suggests significant reduction of most Pamiri glaciers by the end of this century. The loss of glaciers and their buffer functionality in wet and dry years could not only result in reduced water availability and increase the regional instability, but also increase flood and drought hazards. This article is protected by copyright. All rights reserved.
... It has been estimated that N80% of the volume of alpine glaciers has disappeared since the Little Ice Age around 1850 and losses of 70% of the remaining volume are expected in the next century (Frezzotti and Orombelli, 2014). Although it is less well measured, permafrost is also degrading, and is expected to continue to degrade in the next century (Haeberli and Beniston, 1998;Harris et al., 2009;Mergili et al., 2012). ...
Climate change over the last century, expressed as temperature increase, is substantially stronger in the European Alps than the average for the northern Hemisphere. This leads to fast glacial retreat and permafrost degradation, and hence to increased rates and risks of mass wasting, more extreme floods in spring and lower base flow in summer. We do not know enough about the interplay between increased proglacial mass wasting and geomorphic activity on the one hand, and soil development on proglacial areas on the other hand. Both processes affect the attenuation of storm flow, provision of base flow and the future geo-, pedo- and biodiversity of Alpine valleys. However, despite the known importance of soil-landscape interactions, soils and landscapes have so far only been studied in isolation. Our objective was to assess whether soil development (the silent play) in a geomorphically active proglacial area (the loud theatre) was nonetheless dominantly a function of time since glacial retreat – as often observed in geomorphically inactive proglacial areas. We used conditional Latin Hypercube sampling to select 97 locations in the Gepatsch glacier proglacial area in the west of Austria that best cover variation in soil age and topographic position. Standard soil observations were done in all locations. Soil development indicators were then related to time since glacial retreat and a range of geomorphic variables. Results indicate that time since glacial retreat indeed remains an important explanatory variable, and that soil development in the Gepatsch glacier proglacial area roughly equals that in some other well-studied valleys. Geomorphic variables were found to be significant co-determinants of soil development, with a strong scale-dependency. Variation in soil properties increased over time, and the storage of organic matter in the proglacial area is currently in the order of 330 kg per year.
... Likewise, interrupted streamflow is assumed for other high-elevation tributaries in winter and the entire catchment area east of Lake Yashilkul. The eastern part of the catchment is in a zone of potential permafrost (altitudes above 3800 m a.s.l.; Mergili et al., 2012 ). Hence, water release from permafrost or from sporadically frozen soils is assumed to play a role in the hydrological cycle. ...
A clear understanding of the hydrology is required to capture surface processes and potential inherent hazards in orogens. Complex climatic interactions control hydrological processes in high mountains that in their turn regulate the erosive forces shaping the relief. To unravel the hydrological cycle of a glaciated watershed (Gunt River) considered representative of the Pamir Mountains' hydrologic regime, we developed a remote-sensing-based approach. At the boundary between two distinct climatic zones dominated by the Westerlies and Indian summer monsoon, the Pamir Mountains are poorly instrumented and only a few in situ meteorological and hydrological data are available. We adapted a suitable conceptual distributed hydrological model (J2000g). Interpolations of the few available in situ data are inadequate due to strong, relief-induced, spatial heterogeneities. Instead of these we use raster data, preferably from remote sensing sources depending on availability and validation. We evaluate remote-sensing-based precipitation and temperature products. MODIS MOD11 surface temperatures show good agreement with in situ data, perform better than other products, and represent a good proxy for air temperatures. For precipitation we tested remote sensing products as well as the HAR10 climate model data and the interpolation-based APHRODITE data set. All products show substantial differences both in intensity and seasonal distribution with in situ data. Despite low resolutions, the data sets are able to sustain high model efficiencies (NSE ≥ 0.85). In contrast to neighbouring regions in the Himalayas or the Hindu Kush, discharge is dominantly the product of snow and glacier melt, and thus temperature is the essential controlling factor. Eighty percent of annual precipitation is provided as snow in winter and spring contrasting peak discharges during summer. Hence, precipitation and discharge are negatively correlated and display complex hysteresis effects that allow for the effect of interannual climatic variability on river flow to be inferred. We infer the existence of two subsurface reservoirs. The groundwater reservoir (providing 40 % of annual discharge) recharges in spring and summer and releases slowly during autumn and winter, when it provides the only source for river discharge. A not fully constrained shallow reservoir with very rapid retention times buffers meltwaters during spring and summer. The negative glacier mass balance (−0.6 m w.e. yr
... These semi-arid characteristics are accompanied by a typical alpine hydrology with steep slopes, permafrost, snowmelt and glaciation. Almost 84% of the catchment area is classified as potential permafrost area while 94 % out of that area is permafrost probable (Mergili et al. 2012). ...
... These semi-arid characteristics are accompanied by a typical alpine hydrology with steep slopes, permafrost, snowmelt and glaciation. Almost 84% of the catchment area is classified as potential permafrost area while 94 % out of that area is permafrost probable (Mergili et al. 2012). ...
Under arid conditions of the Eastern Pamir Mountains, the high-altitude lake-wetland systems perform important ecological functions, including water storage, resting and feeding sites for wild animals, and supplying fodder for yaks, sheep, and goats bred in the area. However, their functioning and ecological roles are being modified by ongoing climate changes, especially the rising temperature and alterations in precipitation patterns observed lately for this region. This chapter presents the biodiversity of microorganisms, plants, and animals recorded in the Rangkul and Shorkul Lakes and their surroundings, including the habitats of wetland, grassland, cold desert, and rocky screes. As a biodiversity hotspot, this area was declared a Ramsar site (1085), a Key Biodiversity Area (KBA), and an Important Bird Area (TJ013). Yet, no systematic biodiversity monitoring is performed there, and grazing pressure is growing. Hence, there is a need for the elaboration of sustainable use and conservation practices for this area.
Global climate change gives rise to changing spatial patterns of snow and ice, especially over mountain blocks where orographic and synoptic circulation effects play significant roles in creating patterns of precipitation and glacier development. The presence of snow and ice results in heat balance changes and other land surface feedbacks that have implications for patterns of mountain glacier retreat and the dynamics of mountain geomorphic systems. This study considers the sensitivity of the mountain cryosphere (snow, ice, permafrost) to global climate change, and the implications of this sensitivity analysis for evaluating mountain surface stability, geomorphic change, and the generation of mountain geohazards. Consideration of these issues is informed by evidence from case studies reported in the literature and by field observations of mountain system dynamics worldwide. Results show that ‘sensitivity’ to climate forcing has been interpreted and defined in different ways in mountain snow, ice, and permafrost systems, with respect to properties such as albedo, mass balance or rapidity of system change. There are also significant spatial differences in sensitivity between different mountain blocks for snow, ice and permafrost, and these regions are therefore likely to follow different trajectories of geomorphic change in response to climate forcing, related to their physiographic properties and the extent of cryospheric coverage. Within glaciated mountains in particular, the relative timing of different geomorphic events, and the interplay between slope, glacier front, and proglacial sediment sources and environments, may vary depending on glacier size, geomorphic setting, and microclimate. By contrast, responses to permafrost warming (increased surface instability and mass movements) and changes in snow patterns (avalanche risk, floods) may have quite different spatial and temporal patterns and influenced by different environmental controls. An integrated evolutionary model for mountain system development under a changing cryosphere is proposed, highlighting the critical role of energy balance as a forcing factor that then triggers downstream mountain system responses. This suggests that different elements of mountain systems exhibit different sensitivities, and furthermore that these sensitivities change over time and space through the period of anthropogenic global warming and paraglacial relaxation.
The origin and evolution of Iskanderkul Lake are studied in relation to geomorphic hazards within a broader area of interest. It is shown that the giant Kchazormech rockslide with its volume of masses of approximately 1 km3 entirely blocked the Iskanderdarja river valley, likely in the Middle Holocene, impounding thus the palaeolake of Iskanderkul. Geomorphological evidence indicated that the palaeolake suddenly decreased its volume by 83% and its areal extent by 65% and released 0.84 ± 0.1 km3 of water. The present-day Iskanderkul Lake is therefore considered as a remnant of a much larger palaeolake of Iskanderkul. Recent slope movements, incision and backward erosion of rockslide accumulation leading to the formation of a bypass gorge are documented. Current geomorphic hazards are outlined and the near-future evolution of Iskanderkul Lake is discussed with respect to the ongoing climate change suggesting a relatively low longevity of lakes in the Tien Shan.
Pamir
is a highland region in Central Asia, located on the orogenic uplift known as the Pamir Knot which joins several Asian mountain ranges. The name Pamir may derive from the ancient Iranian pai-mir, “foot of Mithra,” god of the sun or from the word pamers, which means the flat and wide high valleys with typical mountain meadows in altitudes around 3500–4000 m above sea level (a.s.l.) High mountain topography (the highest ranges exceed 7000 m a.s.l.) is a characteristic feature of this region and acts as a barrier isolating it from the rest of the world.
Glacier shrinkage in the Alps has been clearly manifest since the middle of the 19th century and could continue beyond the limits of holocene variability in the near future. Changes in Alpine permafrost are less well documented but are likely to take place at various time and depth scales. This development leads to a variety of slope stability problems in bedrock and non-consolidated sediments (moraines and scree slope). A brief overview, with references to recent literature, is given with regard to characteristic situations and interactions as illustrated by recent events observed in the Alps. The achievement of progress in recognizing and mitigating risks from such slope stability problems in high mountain areas requires improved process understanding from field observations and computer modelling, systematic investigation of natural archives reflecting former slope instability processes and adequate monitoring of potentially critical situations.
Glacial lake outburst floods (GLOFs) are potentially highly dangerous events and have contributed to numerous disasters in history. Today, computer models are standard tools to estimate the magnitude of hazardous events in the future and to support risk mitigation. The present paper explores the potentials and limitations of modelling for predicting the motion of potential future GLOF events, based on examples from the Pamir (Tajikistan). Since the flow behaviour of GLOFs is in between debris flows and floods, different model approaches come into consideration, though none of them is perfectly suitable for GLOFs. RAMMS as a mass movement model and FLO-2D as a river hydraulics model were employed comparatively for the same areas. The friction parameters for RAMMS and rheologic parameters for FLO-2D were first calibrated by back calculation with the well-documented Dasht event from summer 2002, and then applied to other areas. However, the applicability of such parameters to GLOFs of different volume and over a different topography remains questionable. The results may nevertheless be a valuable input for risk mitigation efforts, but due to the complex nature of GLOFs and the connected uncertainties, particular care is required when interpreting the model results. The critical points and potential approaches to deal with the limitations are discussed in the paper.
The main objective of the study is the investigation of the link between glacier retreat and discharge in selected catchments in Central Asia and the comparison of these results with conditions in the Alps. For this purpose, the conceptual runoff model HBV-ETH has been applied in three glacierized basins in Kazakhstan, Kyrgyztan and China, which represent regions of different continentality. Operating only with air temperature and precipitation data, the model calculates discharge and other water balance components in a daily timestep. To evaluate the reaction of the simulated hydrograph to climate change, the meteorological model input has been modified, according to the results of regional climate modeling under the assumption of doubling of atmospheric CO2. These runoff scenarios were made for three different stages of deglacierization. The first results show a similar pattern as observed in the Alps in previous studies: under a present-day glacier extent the water yield rises drastically during the melting period, after a reduction of the glacierized area by 50 % the flood peaks are reduced to presently observed values, and after a complete disappearance of the glaciers the calculated runoff indicates a strong reduction of runoff during summer months, which would have a significant effect on the availability of water resources in these dry regions of Asia.
This paper presents an analysis of the hazards emanating from the sudden drainage of alpine lakes in South-Western Tajik Pamir. In the last 40 yr, several new lakes have formed in the front of retreating glacier tongues, and existing lakes have grown. Other lakes are dammed by landslide deposits or older moraines. In 2002, sudden drainage of a glacial lake in the area triggered a catastrophic debris flow. Building on existing approaches, a rating scheme was devised allowing quick, regional-scale identification of potentially hazardous lakes and possible impact areas. This approach relies on GIS, remote sensing and empirical modelling, largely based on medium-resolution international datasets. Out of the 428 lakes mapped in the area, 6 were rated very hazardous and 34 hazardous. This classification was used for the selection of lakes requiring in-depth investigation. Selected cases are presented and discussed in order to understand the potentials and limitations of the approach used. Such an understanding is essential for the appropriate application of the methodology for risk mitigation purposes.
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.
Glacial hazards such as ice avalanches, glacial lake outburst floods, and debris flows have caused severe damage,in populated,mountain,regions such as the Swiss Alps. Assessment,of such hazards must consider basic glaciological, geomorphological, and hydraulic principles together with experience gained from previous events. An ap- proach is presented here to assess the maximum,event magnitude,and probability of occurrence,of glacial hazards. Analysis of magnitude,is based on empirical relationships derived from published case histories from the Swiss Alps and other mountain,regions. Probability of occurrence,is difficult to estimate because of rapid changes in the nature of glacial systems, the low frequency of events, and the high complexity of the involved processes. Here, the probability is specified in qualitative and systematic terms based on indicators such as dam type, geometry, and freeboard height (for glacial lakes) and tendency of avalanche repetition, precursor events, and increased water supply to the glacier bed (for ice avalanche,events). The assessment,procedures are applied to a recent lake outburst with subsequent,debris flow and to an ice avalanche,in the Swiss Alps. The results yield reasonable event maxima,that were not exceeded,by actual events. The methods,provide first-order assessments,and may,be applied in dynamic,mountain,environments,where population and infrastructure growth,require continuous,evaluation of hazards. Key words: glacial hazards, lake outburst, debris flow, ice avalanche, hazard assessment procedure, probability of occur-
Satellite data are used to measure the shrinkage of the tongue of the Pasterze Glacier, a valley glacier located in the Austrian Alps. Summer Landsat satellite data from the following years have been analyzed: 1976, 1984, 1986, 1988, 1990, 1992, 2000 and 2001. Ikonos satellite data from 2000 are also shown. Between 1984 and 2000, Landsat-derived measurements show a recession of the glacier terminus of 303 m, with a measurement error of 40 m, while ground data from the same period show a recession of 290 m. When the glacier position was measured using Landsat data acquired only two years apart, the measurement error was often close to or greater than the terminus recession, however, when images were spaced more than ten years apart, the terminus recession was far greater than the measurement error. In addition, earlier positions of the terminus of the Pasterze Glacier were determined from topographic maps from the 1940s to 1985, and are compared with each other and with the satellite measurements. The Pasterze Glacier has experienced a continuous loss of ice at its terminus since 1851.
Air temperature decrease with altitude was estimated by simple linear regression for several regions around northern Italy for minimum, maximum, and mean monthly temperatures. The comparison of the gradients with previous works revealed the absence of a lapse rate seasonal pattern in most earlier studies. Such inconsistencies in other analyses were demonstrated to be largely due to insufficient climatic stations in each area, and incomplete temporal coverage. These problems were solved here by using 269 stations in northern Italy, 205 in the Tyrol area, and 166 in the Trentin-Upper Adige region, covering a wide range of elevations and based on at least 30-yr means. Yearly lapse rates ranging from 0.54° to 0.58°C (100 m)1 were obtained. As hypothesized, a seasonal pattern in monthly gradient variations was observed, regardless of location, and with higher lapse rates during summer. Weather stations on valley bottoms were distinguished from those located on slopes, the former group being heavily influenced by a cold-air drainage process. Both differences in temperatures at sea level and lower lapse rates on valley bottoms explained minimum temperature variation with exposure, mainly due to temperature inversions. On the other hand, maximum temperature changes with topography mostly imply differences among the lapse rates themselves, attributed to a stronger sun warming of slopes. Since lapse rates may be used for monthly temperature spatial interpolation, an analysis of cross-validated interpolation errors was performed, to assess the method accuracy. The highest interpolation reliability was founded for maximum temperature, especially for summer values, and even when topographic information was not available (with an accuracy about 1°C in most cases). The degree to which topographic differences influence the lapse rate determination was also quantified. The addition of topographic information appeared to significantly increase the temperature interpolation reliability, especially for slope sites, and was required for both minimum and winter temperature reconstruction. Thus, the interpolation error of January minimum temperature in slope stations was reduced from 2.8° to 1.1°C by using such a technique. Finally, the lapse rate's spatial variability was shown to be a potential source of error, especially when the region exceeds a 1° width latitude area, whereas longitude role was shown to be less crucial.
Beginning in 1996, aerial photographs were taken for a new Austrian glacier inventory, resulting in digital elevation models (DEMs) and digital orthoimages. An earlier inventory of the Austrian glaciers containing the original aerial photographs and glacier maps and a manual evaluation of various glacier parameters as of 1969 has been re-evaluated at the present state of the art. The two inventories provide the basis for the comparison of glacier reactions over a period of 29 years. In general a reduction of glacier area is observed for almost all Austrian glaciers between 1969 and 1998. The overall reduction in ice-covered area is 17%. The glacier volume change calculated from the DEMs amounts to about 5 km3. This is almost 22% of the ice volume in Austria in 1969, estimated from a volume-area relation. Changes of individual glaciers, however, show a wide variability, depending on their size and physiographic setting.
Experience with man‐induced permafrost problems in periglacial mountains has increased during recent years. Such problems can be local, as in the case of building foundations on ice‐bearing ground, or can affect larger areas, as in the case of ski‐run preparation on perennially and seasonally frozen ground. The most severe natural hazard concerns the destabilization, erosion and displacement by debris flows of loose, non‐frozen material or weak bedrock on steep slopes. Such flows often take place as a consequence of glacier retreat or permafrost degradation and relate to atmospheric warming, which may continue or even accelerate in the future.
The greatest drawback in man's behaviour with respect to these problems remains the ignorance of mountain permafrost. This probably originates from the fact that permafrost is not directly visible and, hence, is often not considered in the planning stage. The most important progress with respect to construction technology, environment protection and hazard mitigation in periglacial mountain belts can be achieved by improving communication and sharing of experience among scientists and technicians.
Large areas of the glacier tongues at Mt. Everest are heavily covered by supraglacial debris. This hampers the automated mapping of the actual ice snout by means of spaceborne imagery due to the similar spectral signal of the surrounding debris. The most significant features which differentiate the glaciers are the typical surface characteristics like a rough surface or "cryokarst" and a number of ablation ponds. At a first glance the outline of these debris-covered glaciers seems to be stable. Looking in detail at these glaciers using multitemporal space imagery it is obvious that recent glacier shrinkage results in an increasing debris coverage and an increasing number and, hence, area of supra-glacial lakes. In addition, the surface, especially at the very distal part of the glacier, looks smoother and shows no significant indications for movement. Hence, presently ASTER stereo-images represent an ideal tool to develop an automated way of outlining the ice extents of the active and inactive glacier. Combining ASTER's thermal information with various shape parameters derived from stereo-models, both the actual glacier beds and the marginal moraines could be outlined. Mainly due to the resolution of the ASTER DEM (30 m) this concept is only promising for large glaciers such as the Khumbu Glacier. In future, when high resolution DEMs will be available, the accuracy will be sufficient for a fully automated glacier monitoring, including smaller glaciers.
We present a review of the changing state of European permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of Svalbard and the discontinuous high altitude mountain permafrost of Iceland, Fennoscandia and the Alps. The paper focuses on methodological developments and data collection over the last decade or so, including research associated with the continent-scale network of instrumented permafrost boreholes established between 1998 and 2001 under the European Union PACE project. Data indicate recent warming trends, with greatest warming at higher latitudes. Equally important are the impacts of shorter-term extreme climatic events, most immediately reflected in changes in active layer thickness. A large number of complex variables, including altitude, topography, insolation and snow distribution, determine permafrost temperatures. The development of regionally calibrated empiricalstatistical
models, and physically based process-oriented models, is described, and it is shown that, though more complex and data dependent, process-oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography. Mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed. We report on recent research into ground ice formation, including ice segregation within bedrock and vein ice formation within ice wedge systems. The potential impacts of climate change on rock weathering, permafrost creep, landslides, rock falls, debris flows and slow mass movements are also discussed. Recent engineering responses to the potentially damaging effects of climate warming are outlined, and risk assessment strategies to minimise geological hazards are described. We conclude that forecasting changes in hazard occurrence, magnitude and frequency is likely to depend on process-based modelling, demanding improved understanding of geomorphological process-response systems and their impacts on
human activity.
The effects of socioecological transformations such as climate change, the collapse of the Soviet empire, and civil war are
examined for 14 villages in the valleys of the Pamir Mountains in the historical Badakhshan region, now divided between Afghanistan
and Tajikistan. Preliminary findings indicate concern for food sovereignty, evidence of biocultural impacts of climate change,
an increasing burden on women, debilitating opium addiction, the ecological importance of sacred sites, and other priorities
related to sustainable livelihoods, such as energy needs (for fuel and lighting) and physical and social infrastructure in
the form of roads and schools. In the complex setting of the Pamir Mountains, characterized by both cultural and ecological
diversity and marked by artificial political boundaries, the creative and pragmatic interaction between indigenous and scientific
knowledge sustains the best hope for survival. Applied research must combine communities of inquirers (research institutions) with communities of social practitioners (farmers, pastoralists, and civil society institutions) to facilitate indigenous participation in generating context-specific
knowledge. The goal of such research is practical outcomes that will meet the urgent priorities of village communities. This
paper establishes a baseline from which undertake applied human ecological research related to livelihood security.
The Digital Elevation Model that has been derived from the February 2000 Shuttle Radar Topography Mission (SRTM) has been one of the most important publicly available new spatial data sets in recent years. However, the 'finished' grade version of the data (also referred to as Version 2) still contains data voids (some 836,000 km 2)—and other anomalies—that prevent immediate use in many applications. These voids can be filled using a range of interpolation algorithms in conjunction with other sources of elevation data, but there is little guidance on the most appropriate void-filling method. This paper describes: (i) a method to fill voids using a variety of interpolators, (ii) a method to determine the most appropriate void-filling algorithms using a classification of the voids based on their size and a typology of their surrounding terrain; and (iii) the classification of the most appropriate algorithm for each of the 3,339,913 voids in the SRTM data. Based on a sample of 1304 artificial but realistic voids across six terrain types and eight void size classes, we found that the choice of void-filling algorithm is dependent on both the size and terrain type of the void. Contrary to some previous findings, the best methods can be generalised as: kriging or inverse distance weighting interpolation for small and medium size voids in relatively flat low-lying areas; spline interpolation for small and medium-sized voids in high-altitude and dissected terrain; triangular irregular network or inverse distance weighting interpolation for large voids in very flat areas, and an advanced spline method (ANUDEM) for large voids in other terrains.
Automated glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces. Supraglacial debris exhibits the same spectral properties as lateral and terminal moraines, fluvioglacial deposits, and bedrock outside the glacier margin, and is thus not detectable by means of multispectral classification alone. Based on the observation of low slope angles for debris-covered glacier tongues, we developed a multisource method for mapping supraglacial debris. The method combines the advantages of automated multispectral classification for clean glacier ice and vegetation with slope information derived from a digital elevation model (DEM). Neighbourhood analysis and change detection is applied for further improvement of the resulting glacier/debris map. A significant percentage of the processing can be done automatically. In order to test the sensitivity of our method against different DEM qualities, it was also applied to a DEM obtained from ASTER stereo data. Additionally, we compared our multisource approach to an artificial neural network (ANN) classification of debris, using only multispectral data. While the combination with an ASTER-derived DEM revealed promising results, the ANN classification without DEM data does not.
At Galena Creek, the ice/debris system has alternated between rock glacier and debris-covered glacier modes due to changes in the size of the accumulation area. In the rock glacier mode, coarse debris is concentrated at the base of couloirs along the lower edge of a small, steep accumulation area where it becomes part of the surface debris mantle of the rock glacier. In the debris-covered glacier mode, debris is primarily incorporated englacially within an expanded accumulation area. Englacial debris originating on the sides of the cirque is concentrated at the margins of the glacier; debris originating from the cirque head-wall is concentrated where it emerges in the ablation area and forms a debris cover. As the equilibrium line rises during warm periods,the debris-covered glacier is transformed into a rock glacier. The marginal englacial debris is exposed progressively up-glacier resulting in ice-cored debris ridges which extend into the cirque and are analogous to the ice-cored lateral moraines of many subpolar alpine glaciers. The debris-covered terminus continues to flow as a rock glacier lobe. The debris ridges/lateral moraines record previous positions of a debris-covered glacier margin and can be used to map past accumulation areas and to infer the position of the associated glacier terminus. At least three of these features are cross-cut by the rock glacier. Age estimates for three glacial advances are made using reasonable surface velocities and the distance between a rock glacier lobe and the inferred position of its associated glacier terminus. The estimated ages correlate with regional alpine glacier chronologies. These observations, which are not unique to the Absaroka Range, have general utility for understanding how changes in the relative flux of ice and debris control the morphology of the resulting deposits and for placing rock glacier deposits within alpine glacier chronologies.
The area variations of 48 outlet glaciers of the Southern Patagonia Icefield, South America, were elucidated for a period between 1944/45 and 1985/86, utilizing various remotely-sensed data. All but two of these glaciers are currently calving into a proglacial lake or a fiord. During the 41-yr period, most glaciers retreated, while a few glaciers remained almost stagnant and two glaciers had a net advance. The largest rate of area loss was 1.21 km2 yr-1 (or a distance of 484 m) at O'Higgins Glacier, which is by far the largest loss in Patagonia. On the other hand, Pío XI Glacier, the largest glacier in South America, advanced at a rate of 1.45 km2 yr-1 (or a distance of 288 m) during the same period. Moreno Glacier oscillated frequently, with a net gain of 4.1 km2 in area in 39 yr; however, it is regarded to be currently in equilibrium. Some locational contrasts in the retreating rates can be recognized. For example, those on the northern half and on the east retreated at greater rates than those on the southern half and on the west, respectively. Possible causes for such variation patterns include temperature warming, although weak, in this century in the area south of latitude 46°S. On top of such climatic forcing, glacier dynamics affected by the size of the glacier, surface gradient around the equilibrium line (EL), and calving status and channel geometry exerted influence, causing a wide variety of the changing rates. The volume of ice loss due to snout retreats during the 41-yr period is estimated to be on the order of 40 to 80 km3. The volume loss in the ablation area due to thinning is roughly estimated at about 100 to 300 km3 for the same period.
Results of studies of mountain glaciers undertaken in the USSR for the last 15 years are considered. The data of the glacier inventory of the USSR serve as the primary source of information. Methods of determining the firn line altitude, data for which are contained in the inventory, are discussed. The paper describes a glaciological method of calculating precipitation in the alpine zone, based on the concepts of Ahlmann and developed further by Krenke and Khodakov. Using this method, calculations were carried out at a small scale for the total territory of the USSR and in detail for the Pamirs and Caucasus. It revealed that the amount of precipitation, in particular solid precipitation, is far greater in the mountains than on the abutting plains and piedmonts. In conclusion, the problem of compiling an inventory of surging glaciers is discussed. Problèmes et résultats des recherches sur les glaciers montagnards de l'Union Soviétique Résumé. On présente les résultats des recherches sur les glaciers montagnards qui ont été entreprises durant les 15 dernières années. Les données contenues dans l'inventaire des glaciers de l'URSS sont la principale source d'informations. Les méthodes employées pour la détermination de l'altitude de la ligne de névé, qui fait partie des données recensées, sont discutées. On décrit une méthode glaciologique, basée sur le concept d'Ahlmann et approfondie par Krenke et Khodakov pour la détermination des précipitations en zone alpine. A l'aide de cette méthode, on a effectué des calculs relativement sommaires pour l'ensemble du territoire de l'URSS et des calculs détaillés pour le Pamir et le Caucase. 11 en découle que les précipitations, et en particulier les précipitations solides, sont beaucoup plus abondantes dans les montagnes que dans les plaines adjacentes et qu'au pied des montagnes. Enfin, on discute du problème de l'établissement d'un inventaire des glaciers sujets à des crues catastrophiques.
The Austrian glacier inventory is based on vertical aerial photographs made especially in September and October 1969. The inventory is compiled uniformly for 1969 according to TTS instructions from photogrammetrically evaluated large scale maps. In addition, areal losses since 1920 and 1850 are evaluated for 100 m intervals. The work should be complete in late 1979. The total area of the 918 glaciers in the Austrian Alps is estimated to be 540 ±10 km 2 and the volume, assuming a mean thickness of 40 m, is 19 km 3 of water. By September 197 8, 624 glaciers with a total area of 463 km 2 have been inventoried. The areal losses since 1920 have been evaluated for 47 per cent of all glaciers and those since 1850 for 68 per cent. In the Zillertaler Alps (163 glaciers) the total area has decreased by 17 per cent from 1850 to 1920 and 44 per cent from 1850 to 1969. L'inventaire des glaciers autrichiens: état actuel et premiers résultats Résumé. L'inventaire des glaciers autrichiens est élaboré sur la base de photographies aériennes prises essentiellement en septembre et en octobre 1969. L'inventaire est compilé uniformément pour l'année 1969 et conformément aux directives TTS à partir de cartes à grande écheEe obtenues par restitution photogrammétrique. En supplément, on procède à l'évaluation de la diminution des aires englacées intervenue à partir de 1920 et 1850 pour des intervalles hypsométriques de 100 m. L'achèvement des travaux est prévue pour fin 1979. La superficie totale des 918 glaciers dénombrés dans les Alpes autrichiennes est estimée à 540 ±10 km 2 et le volume, en admettant une épaisseur moyenne de 40 m, à 19 km 3 d'eau. Au mois de septembre 1978, 624 glaciers d'une superficie totale de 463 km 2 avaient déjà été inventoriés. La diminution des aires intervenue depuis 1920 a été évaluée pour 47 pour cent, celle intervenue depuis 1850 pour 68 pour cent des glaciers. Dans les Alpes du Zillertal (163 glaciers), la diminution est de 17 pour cent pour la période 1850-1920 et de 44 pour cent pour la période 1850-1969.
IntroductionCharacterisation of the Research AreasModel DescriptionModelling ResultsConclusions
AcknowledgementsReferences
Glaciers are reported to crucially contribute to the water availability for large population numbers around the Himalaya. They are expected to change their water storage capacity under the changing climate conditions with major detrimental consequences for fresh water supply. The potential to modify river runoff of both the storage capacity in glaciers and its variability differs in different climate regimes and decreases downriver. The lack of appropriate data records and model performance leaves us with only vague ideas for most river systems. We present a simple method to assess the contribution potential of glaciers to river runoff from data sets available. Glacier contribution to runoff is shown together with population numbers downriver. Respective results are presented and discussed in simple plots and in a summary map.
Over the past few years there has been an increase in understanding of glacier-impounded or 'ice-dammed' lake behaviour. The spectacular jokulhlaup (catastrophic flood) from Grimsvotn, Iceland in November 1996 has both raised the profile of such events and emphasized the need for awareness of the processes involved. This review summarizes the extent of current knowledge of ice-dammed lakes, highlighting key developments and outlining areas of study still subject to difficulties. Controls on ice-dammed lake formation and persistence are identified, and cycles of jokulhlaup activity are related to glacier fluctuations. Ice-dammed lake drainage trigger mechanisms are reviewed and recent progress in the understanding of such mechanisms is emphasized. Controls on jokulhlaup routing and the development and character of jokulhlaup conduits are discussed and recent advances in jokulhlaup prediction, hydrograph modelling and peak discharge estimation are assessed. A process-based schematic model, drawing on published research, links ice-dammed lake occurrence and drainage to jokulhlaup characteristics. It is demonstrated that ice-dammed lake and ice-dam characteristics ultimately control seven key jokulhlaup attributes which determine the potential impact of jokulhlaups on both landscape and human activity in glaciated regions.
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.
Le glacier de Vernagtferner dans les Alpes Orientales detient le record de temps d'observation. Il a avance quatre fois et bloque la vallee, formant un lac. Il est a l'origine d'inondations. C'est pourquoi le glacier a ete mis sous surveillance il y a 100 ans.
Changes of volume anf area of the Pasterze glacier from 1981 to 2000 On the basis of two topographical maps (ÖK 1:50 000 for 1981 and 2000) the loss of ice mass and area of the Pasterze glacier in 19 years was determined with the help of the derivation from surface models. In the course of it a loss of area of 103 ha (5.4%) and a loss of volume of 320.106m3 (16%) were determined of which the latter amounted to a mean loss of 16.82.106m3 per year. With regard to the period from 1964 to 1981 which was more favourable to the glaciers, with a loss of volume of 7.3 .106m3 per year on average this meant an increase to the 2.3-fold. The height of the glacier surface has decreased from ca. 70 m in the area of the glacier snout to 0 m in the area of the highest flanks. This decline of the loss of height and volume with increasing altitude seems to be regular and without any special regional deviations. ©Naturwissenschaftlicher Verein für Kärnten, Austria, download unter www.biologiezentrum.at
About 70 surging glaciers have been registered in the glaciated regions of the Soviet Union (in the Pamirs, the Tien-Shan, the Caucasus, and the Kamchatka peninsula). The Medvezhy Glacier in the Pamirs has a surge period of 12-14 years. The last advance of this glacier occurred in spring of 1963 and was selected as a representative surge. Comprehensive observations with terrestrial resurveys were conducted, and from 1962-70 quantitative information was obtained about the height changes of the glacier tongue, velocities of ice flow, and ablation. This study describes the dynamics of the glacier and the volume of ice mass shift during all stages of the glacier surge. A conclusion is drawn that glacier surges are regular, recurrent phenomena which are caused by dynamic instability of the glacier systems themselves and are unrelated to external factors. The changes of accumulation and ablation conditions may have an influence on the duration of the period and amplitude of surges, but the direct cause of glacier surge is the relaxation of stresses in the body of the glacier. When these stresses exceed the limit of stability of the ice the glacier breaks into blocks. The water-loam emulsion lubricating the glacier bed enables a sharp increase of the speed of flow. The regular character of glacier surges permits the time and scale of the next glacier flood to be forecast. Systematic observations of the surface morphological changes, mass balance, and velocities of ice movement during different stages of a surge may serve as a reliable basis for formulating a theory for surging glacier movements.
The history of catastrophic advances of Vernagtferner (Ötztal Alps, Tyrol) is described briefly. To all appearances these advances were surges. They occurred periodically with a short active advance and a much longer time of retreat; the whole cycle lasted on an average 82 years. The mode of flow of the ice changed typically, i.e. speed during surges increased more than one order of magnitude with heavy crevassing. Dimensions of advance and of retreat were much larger than known from other glaciers in the area.
A carefully homogenized climate dataset is used to interpret glacier behaviour in the Austrian Alps. Periods of glacier advance are generally more maritime and cooler, with reduced sunshine duration and increased precipitation sum during the ablation period. Periods of retreat are associated with a more continental, warmer climate, with increased sunshine duration and reduced precipitation sum. Three recent sub-periods of Austrian glacier behaviour are documented by direct measurement of glacier mass balance (before 1965 more negative; 1965-81 more positive; since 1982 more negative). A long-term mass-balance series in the eastern part of the Austrian Alps parameterized by snow-depth measurements indicates very clearly that periods of more negative mass balance have a higher correlation to summer air temperature and a lower correlation to winter accumulation. Periods of more positive mass balance are highly correlated to winter accumulation and only slightly correlated to summer temperature. The positive mass-balance period 1965-81 is also characterized by negative North Atlantic Oscillation index values which caused an increased meridional circulation mode, resulting in a north-westerly to northerly precipitation regime during winter.
The evolution of surging glaciers of the Pamirs, central Asia, has been studied using repeat remote-sensing surveys in the Institute of Geography, Russian Academy of Sciences, since the early 1970s. We use images obtained from national Resurs-F satellites (1972-91), as well as Landsat 7 and Terra (1999-2006), to provide a basis for monitoring of surging glaciers, aimed at developing their inventory, studying the causes and mechanisms of surges and examining the timing and extent of glacial catastrophes. The inventory from the early 1990s allows identification of 215 glaciers with a dynamically unstable regime. We discovered 51 surging glaciers. Up until 2006, 10 more surges had occurred. We use stereoscopic deciphering and photogrammetric processing of consecutive satellite images to study the morphology and ice-velocity changes of several compound surging glaciers. We analyze the results of monitoring of Bivachny and Oktyabr'sky glaciers from 1972 to 1991 and Sugran glacier from 1972 to 2006. Two surges of Sugran glacier occurred during this time: an internal surge in 1976-80, and a surge with glacier tongue advance as far as 4.5 km in 2000-05. The role of damming in compound glacier systems is examined. Satellite-based monitoring is now the only method for obtaining initial information about the state and fluctuations of such glaciers.
The general features of alpine permafrost such as spatial distribution, temperatures, ice content, permafrost and active-layer thickness within the Tien Shan Mountains, Central Asia are described. The modern thermal state of permafrost reflects climatic processes during the twentieth century when the average rise in mean annual air temperature was 0.006–0.032 °C/yr for the different parts of the Tien Shan. Geothermal observations during the last 30 yr indicate an increase in permafrost temperatures from 0.3 °C up to 0.6 °C. At the same time, the average active-layer thickness increased by 23% in comparison to the early 1970s. The long-term records of air temperature and snow cover from the Tien Shan's high-mountain weather stations allow reconstruction of the thermal state of permafrost dynamics during the last century. The modeling estimation shows that the altitudinal lower boundary of permafrost distribution has shifted by about 150–200 m upward during the twentieth century. During the same period, the area of permafrost distribution within two river basins in the Northern Tien Shan decreased approximately by 18%. Both geothermal observations and modeling indicate more favorable conditions for permafrost occurrences and preservation in the coarse blocky material, where the ice-rich permafrost could still be stable even when the mean annual air temperatures exceeds 0 °C.
This paper summarizes the methods applied to determine the mass balance of Hintereisferner and several other glaciers in the Tyrolean Alps since 1952. On an annual basis the direct glaciological method was applied with fixed date measurements on 10–15 accumulation pits and 30–90 ablation stakes on 9 km2.
Indirect mass balance determination from equilibrium line altitude, accumulation area ratios or representative stakes, yield fair results and some exceptions could be related to anomalous meteorological conditions.
Monthly or more frequent stake readings supplied time series of ablation at various altitudes and slope aspects that served as basis for the calibration of energy and mass balance models. Of various models developed, two are presented in this paper. Both are based on degree days, one using daily values from a valley station to predict the mean annual balance of the entire glacier, while the other calculates day-to-day changes at 50-m grid points on the glacier.
The geodetic method has been applied for longer periods and yields results consistent with those of the glaciological method. The balance velocity calculated from recent ice thickness soundings and accumulation measurements is significantly less than observed velocity.
At Galena Creek, the ice/debris system has alternated between rock glacier and debris-covered glacier modes due to changes in the size of the accumulation area. In the rock glacier mode, coarse debris is concentrated at the base of couloirs along the lower edge of a small, steep accumulation area where it becomes part of the surface debris mantle of the rock glacier. In the debris-covered glacier mode, debris is primarily incorporated englacially within an expanded accumulation area. Englacial debris originating on the sides of the cirque is concentrated at the margins of the glacier; debris originating from the cirque headwall is concentrated where it emerges in the ablation area and forms a debris cover. As the equilibrium line rises during warm periods, the debris-covered glacier is transformed into a rock glacier. The marginal englacial debris is exposed progressively up-glacier resulting in ice-cored debris ridges which extend into the cirque and are analogous to the ice-cored lateral moraines of many subpolar alpine glaciers. The debris-covered terminus continues to flow as a rock glacier lobe. The debris ridges/lateral moraines record previous positions of a debris-covered glacier margin and can be used to map past accumulation areas and to infer the position of the associated glacier terminus. At least three of these features are cross-cut by the rock glacier. Age estimates for three glacial advances are made using reasonable surface velocities and the distance between a rock glacier lobe and the inferred position of its associated glacier terminus. The estimated ages correlate with regional alpine glacier chronologies. These observations, which are not unique to the Absaroka Range, have general utility for understanding how changes in the relative flux of ice and debris control the morphology of the resulting deposits and for placing rock glacier deposits within alpine glacier chronologies.
This paper describes the HISTALP database, consisting of monthly homogenised records of temperature, pressure, precipitation, sunshine and cloudiness for the ‘Greater Alpine Region’ (GAR, 4–19°E, 43–49°N, 0–3500m asl). The longest temperature and air pressure series extend back to 1760, precipitation to 1800, cloudiness to the 1840s and sunshine to the 1880s. A systematic QC procedure has been applied to the series and a high number of inhomogeneities (more than 2500) and outliers (more than 5000) have been detected and removed. The 557 HISTALP series are kept in different data modes: original and homogenised, gap-filled and outlier corrected station mode series, grid-1 series (anomaly fields at 1° × 1°, lat × long) and Coarse Resolution Subregional (CRS) mean series according to an EOF-based regionalisation. The leading climate variability features within the GAR are discussed through selected examples and a concluding linear trend analysis for 100, 50 and 25-year subperiods for the four horizontal and two altitudinal CRSs. Among the key findings of the trend analysis is the parallel centennial decrease/increase of both temperature and air pressure in the 19th/20th century. The 20th century increase (+1.2 °C/+ 1.1 hPa for annual GAR-means) evolved stepwise with a first peak near 1950 and the second increase (1.3 °C/0.6hPa per 25 years) starting in the 1970s. Centennial and decadal scale temperature trends were identical for all subregions. Air pressure, sunshine and cloudiness show significant differences between low versus high elevations. A long-term increase of the high-elevation series relative to the low-elevation series is given for sunshine and air pressure. Of special interest is the exceptional high correlation near 0.9 between the series on mean temperature and air pressure difference (high-minus low-elevation). This, further developed via some atmospheric statics and thermodynamics, allows the creation of ‘barometric temperature series’ without use of the measures of temperature. They support the measured temperature trends in the region. Precipitation shows the most significant regional and seasonal differences with, e.g., remarkable opposite 20th century evolution for NW (9% increase) versus SE (9% decrease). Other long- and short-term features are discussed and indicate the promising potential of the new database for further analyses and applications. Copyright © 2006 Royal Meteorological Society.
The application PERMAKART of the glaciological information system KRYO on ARC/INFO plots supposed mountain permafrost distribution on any topographical map. Results of fieldwork since 1970 and surface analyses based on a digital terrain model (DTM) are used. In Switzerland PERMAKART could become a planning tool for decisions about possible occurrence of mountain permafrost because the DTM RIMINI is available for the entire country.
Le module PERMAKART du système d'information glaciologique KRYO, développé sur ARC/INFO, trace la distribution potentielle du permafrost de montagne sur une carte topographique. Des données de terrain collectées depuis 1970, ainsi que des analyses basées sur un modèle numérique d'altitudes (MNA) sont utilisées. En Suisse, le MNA RIMINI couvrant l'ensemble du territoire, PERMAKART est susceptible de devenir un outil de planification et d'aide à la décision pour tous les travaux effectués.
Norway and New Zealand both experienced recent glacial advances, commencing in the early 1980s and ceasing around 2000, which were more extensive than any other since the end of the Little Ice Age. Common to both countries, the positive glacier balances are associated with an increase in the strength of westerly atmospheric circulation which brought increased precipitation. In Norway, the changes are also associated with lower ablation season temperatures. In New Zealand, where the positive balances were distributed uniformly throughout the Southern Alps, the period of increased mass balance was coincident with a change in the Interdecadal Pacific Oscillation and an associated increase in El Niño/Southern Oscillation events. In Norway, the positive balances occurred across a strong west-east gradient with no balance increases to the continental glaciers of Scandinavia. The Norwegian advances are linked to strongly positive North Atlantic Oscillation events which caused an overall increase of precipitation in the winter accumulation season and a general shift of maximum precipitation from autumn towards winter. These cases both show the influence of atmospheric circulation on maritime glaciers.
After a long period of general retreat, the Franz Josef Glacier on the western flanks of the Southern Alps of New Zealand has undergone a major advance, beginning about 1982. Key climatic variables, atmospheric circulation patterns over the Southwest Pacific, and the Southern Oscillation Index (SOI), are compared for two 20-year periods that represent advance and retreat phases of the Franz Josef Glacier. The results show strong links between atmospheric circulation changes, climate variables and glacier behaviour. The retreat phase is characterised by slightly warmer temperatures and markedly lower precipitation in the ablation season, a high pressure anomaly over New Zealand, and a southward shift in the subtropical high pressure zone. In contrast, the advance phase is characterised by anomalous southwest airflow, especially during the ablation season, and higher precipitation. The high pressure anomaly is shifted westward by about 55° of longitude so as to lie south of Australia. The advance phase is also related to a higher frequency of El Niño events.
In the upper Shimshal valley three glacier dams are present along a horizontal distance of only 25 km: the Khurdopin/Yukshin Gardan, Yazghil and Malungutti glaciers. Only a few decameters separate the glacier tongues from the opposite valley flanks. At some localities the drainage of the main river already takes place subglacially. About 20 glacial floods occurred in the last century in the Shimshal valley, some of them with devastating consequences. The erosion potential is clearly visible by the high loss of settlement areas of the villages Shimshal (3080 m) and Pasu (2450 m). In the past, the lake formation was mainly attributed to the Khurdopin dam. New field observations in summer 2001 revealed that advances of the Yukshin Gardan glacier can also contribute to a blockade of the Shimshal river.Slightest snow line depressions already would lead to numerous stable glacier dams and therefore to long-lasting ice-dammed lakes. Such a situation occurred during Neoglacial times, if not even during the Little Ice Age. Huge sequences of lake sediments, several decameters in height, evidence the prehistorical glacial lake ponding in the Karakoram valleys.
Glaciers and snowfields can form potential hazards in the Himalayas, and in similarly glacierised regions of the world. Some glaciological phenomena can have significant impacts upon society over a short time scale (minutes–days), such as ice/snow avalanches and glacial floods. Other related hazards can be equally serious but less obvious when considered on a much longer time scale (months–years–decades), such as glacier volume fluctuations leading to water resource problems. Only when humans and their activities become vulnerable to glacier-related processes is there considered to be a hazard risk.As glaciers recede in response to climatic warming, the number and volume of potentially hazardous moraine-dammed lakes in the Himalayas is increasing. These lakes develop behind unstable ice-cored moraines, and have the potential to burst catastrophically, producing devastating Glacial Lake Outburst Floods (GLOFs). Discharge rates of 30,000 m3 s−1 and run-out distances in excess of 200 km have been recorded. Despite the scale of the risk, it is possible to assess and mitigate hazardous lakes successfully. Hazard assessment using satellite images has been effective for remote areas of Bhutan, and remediation techniques successfully developed in the Peruvian Andes are now being deployed for the first time in Nepal.
The tropical climate is characterized by a homogeneous atmosphere without frontal activity, a lack of thermal seasonality, and by one to two differently pronounced precipitation seasons. Consequently, tropical climate has a characteristic impact on tropical glaciers, with glacier–climate interactions different from those of the mid- and high-latitudes.The glaciers of tropical South America, Africa and New Guinea had a general maximum extent during the Little Ice Age (LIA) and have receded since the second half of the 19th century. Since then the fluctuations have been differently pronounced in different regions, but their general behaviour has been largely synchronous. The retreat from the LIA extent slowed on many glaciers at the beginning of the 20th century, some of them even readvanced almost to the LIA extent. The 1930s and 1940s brought a marked loss of ice masses and were followed by a moderate retreat. Around 1970 the recession generally slowed. Some glaciers even advanced. The last decade was again characterized by a pronounced glacier recession on all tropical mountains which are under observation. The modern fluctuations of tropical glaciers are also quite synchronous to those of the glaciers in the mid-latitudes.A reduction in air humidity with all the consequent changes in energy and mass balance is suggested to be a major reason for the general recession of tropical glaciers since the end of LIA. The rise in air temperature explains only part of the glacier recession. The accelerated recession since the 1980s is most probably caused by increased air temperature and increased air humidity. Nevertheless, the knowledge of tropical glaciers is still scarce compared to those of the mid and high latitudes. This contribution reviews present knowledge of the fluctuations of tropical glaciers.
The Miage Glacier is the biggest in the Italian side of the Mont Blanc and is located a few km west of Courmayeur. The Miage lake is a typical periglacial lake that is found on the right hydrographical side of the glacier. The glacier high dynamics produces frequent falls of huge ice blocks into the lake representing an important tourist draw. On August 9, 1996, after a long period of heavy rain, a big ice block, with estimated volume in the range 7,000–16,000 cubic meters, fell into the lake provoking an anomalous water wave that involved many tourists, causing some persons to be seriously wounded.The main goal of this work is to stress that for alpine glaciers a correct policy of natural hazard mitigation must be founded both on a good scientific understanding of the glacier dynamics and on rigorous measures of prevention, that in case of conflict must have anyhow priorities on touristic activities.
The historical record of in situ measurements of the terminus positions of the Pasterze and Kleines Fleißkees glaciers in the eastern Alps of Austria is used to assess uncertainties in the measurement of decadal scale changes using satellite data. Topographic maps beginning in 1893, and satellite data from 1976 to 2001, were studied in concert with ground measurements to measure glacier changes. Ground measurements show that the tongue of the Pasterze Glacier receded ∼1150 m from 1893 to 2001, while satellite-derived measurements, using August 2001 Landsat Enhanced Thematic Mapper Plus (ETM+) data registered to an 1893 topographic map, show a recession of 1300–1800 m, with an unknown error. The measurement accuracy depends on the registration technique and the pixel resolution of the sensor when two satellite images are used. When using topographic maps, an additional source of error is the accuracy of the glacier position shown on the map. Between 1976 and 2001, Landsat-derived measurements show a recession of the terminus of the Pasterze Glacier of 479±136 m (at an average rate of 19.1 m a−1) while measurements from the ground showed a recession of 428 m (at an average rate of 17.1 m a−1). Four-meter resolution Ikonos satellite images from 2000 and 2001 reveal a shrinkage of 22,096±46 m2 in the Pasterze tongue. The nearby Kleines Fleißkees glacier lost 30% of its area between 1984 and 2001, and the area of exposed ice increased by 0.44±0.0023 km2, according to Landsat satellite measurements. As more recent satellite images are utilized, especially data that are geocoded, the uncertainty associated with measuring glacier changes has decreased. It is not possible to assess the uncertainty when an old topographic map and a satellite image are coregistered.
The Global Land Ice Measurements from Space (GLIMS) project has built a geospatial and temporal database of glacier data, composed of glacier outlines and various scalar attributes. These data are being derived primarily from satellite imagery, such as from ASTER and Landsat. Each "snapshot" of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. We have implemented two web-based interfaces to the database; one enables exploration of the data via interactive maps (web map server), while the other allows searches based on text-field constraints. The web map server is an Open Geospatial Consortium (OGC) compliant Web Map Server (WMS) and Web Feature Server (WFS). This means that other web sites can display glacier layers from our site over the Internet, or retrieve glacier features in vector format. All components of the system are implemented using Open Source software: Linux, PostgreSQL, PostGIS (geospatial extensions to the database), MapServer (WMS and WFS), and several supporting components such as Proj.4 (a geographic projection library) and PHP. These tools are robust and provide a flexible and powerful framework for web mapping applications. As a service to the GLIMS community, the database contains metadata on all ASTER imagery acquired over glacierized terrain. Reduced-resolution of the images (browse imagery) can be viewed either as a layer in the MapServer application, or overlaid on the virtual globe within Google Earth. The interactive map application allows the user to constrain by time what data appear on the map. For example, ASTER or glacier outlines from 2002 only, or from Autumn in any year, can be displayed. The system allows users to download their selected glacier data in a choice of formats. The results of a query based on spatial selection (using a mouse) or text-field constraints can be downloaded in any of these formats: ESRI shapefiles, KML (Google Earth), MapInfo, GML (Geography Markup Language) and GMT (Generic Mapping Tools). This "clip-and-ship" function allows users to download only the data they are interested in. Our flexible web interfaces to the database, which includes various support layers (e.g. a layer to help collaborators identify satellite imagery over their region of expertise) will facilitate enhanced analysis to be undertaken on glacier systems, their distribution, and their impacts on other Earth systems.