The historical Saklei Shuyinj and Chateboi Glacier Dams as triggers for lake outburst cascades in the Karambar Valley, Hindukush

Abstract   Since the mid-nineteenth century, devastating glacier lake outbursts have occurred in the Karambar Valley. The exact source areas of these floods are to date unknown. The present study uses geomorphologic field evidence and interviews of local inhabitants to reconstruct nine potential glacier dams in the Karambar Valley within a horizontal distance of only 40 km. The article focuses on the geomorphologic reconstruction of the highest glacier dams, the Chateboi and Saklei Shuyinj Glaciers. Their lake basins were connected in former times resulting in a complex interfingering of lake sediments, lake terraces and glacial deposits. The outbursts of these lakes could have triggered the drainage of one of the lower ice-dammed lakes (Sokther Rabot, Chillinji, Warghut or Karambar) and therefore initiated an outburst cascade in the upper Karambar Valley. Successive glacier dams are wide spread in the Karakoram, and cascading lakes might have also played a role in other lake outburst scenarios. In the Karambar Valley, even today the Chateboi Glacier blocks the Karambar River over a distance of 4 km and represents a permanent hazard for the villages located downstream.     

Typical debris accumulation forms and formations in High Asia – A glacial-history-based concept of the origin of Postglacial debris accumulation landscapes in subtropical high mountains with selected examples from the Hindu Kush, the Karakoram and the Himalayas

An abridged version of a geomorphological inventory and typology of Postglacial debris accumulations in High Asia is presented, with selected examples from the Hindu Kush, the Karakoram and the Himalayas. The debris accumulations were surveyed in the course of four research expeditions lasting a total of ten months in selected valley systems of High Asia (the eastern Hindu Kush, the northwestern Karakoram, the Nanga Parbat massif (Pakistan), the Ladakh and Zanskar ranges, the Nun Kun massif, the Kumaon and Garhwal Himalayas with the Kamet, Trisul and Nanda Devi massifs (India) and in the central Himalayas with the Kanjiroba, Annapurna, Manaslu and Makalu massifs (Nepal)). The study areas being widely scattered, a supraregional comparison of the debris accumulations proved possible. The debris accumulations are considered in centre-to-periphery sequences from the mountain interior to the mountain fringes, and in vertical sequences, i.e. altitudinal zones, taking into account their topographical relationship to adjoining elements of the landscape. Supraregional and climate-specific types of debris accumulation are distinguished and it is recognized that the debris accumulations of the Karakoram and the Himalayas resemble each other more closely with increasing elevation. The core of the study is the dominant role played by past glaciation in the formation of Postglacial debris accumulations in the high mountains of Asia. This glacial-history-oriented concept of debris accumulation stands in sharp contrast to previous opinions about the genesis of the debris accumulation landscape in the extreme high mountains of Asia. The study shows that at many places morainic deposits mask extensive portions of the valley sides up to several hundred metres above the valley floor. These moraines are the main debris sources and exert a strong influence on, or even suppress, the purely slope-related formation of debris accumulations. Resedimentation of morainic material in combination with additional talus delivery leads to numerous characteristic composite types of debris accumulations, which are here termed transitional glacial debris accumulations. Various stages in the transition from moraine to slope-related debris accumulations were observed, making it necessary to consider the evolutional element in the development of debris accumulations by taking into account both genetic series of debris accumulations and formations of debris accumulations. A significant proportion of debris accumulations are also due to collapse processes which result from pressure release at the valley sides after deglaciation and occur in the course of glacial trough valleys being transformed into more stable fluvial V-shaped valleys. The residual morainic landscape has left debris accumulations that are basically similar in study areas of different climate – i.e. in the Hindu Kush and the Karakoram on the one hand, and the Himalayas on the other. The age classification of the debris accumulations was based on the location of the slope-derived debris accumulations in relation to the corresponding stages of glaciation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Post-sedimentary Transformation of Lateral Moraines-the Tributary Tongue Basins of the Kvíárj(o)kull(Iceland)

The Kvíárj(o)kull.a southern outlet glacier of the Vatnaj(o)kull,is confined in the mountain foreland by lateral moraines measuring a height of up to 150 m.Each of the lateral moraines shows consjderable breaches with deviations of the main moraine ridges.The paper discusses the possible origins of these modifications of the lateral moraines as result of:1)ice overlappings during glacier advances and subsequent breaches of the lateraltongue triggered by the preglacial relief conditions and the prehistorical moraine landscape leading to affiux conditions,3)drainage of ice-marginal glacier lakes and 4.volcanic activities,such as lava flows and volcanic-induced j(o)kulhlaups. A historic-genetic model of the formation of the lateral moraines is presented considering the breaches in the lateral moraines as result from glacier bifurcations and therefore as former tributary tongue basins.Such breaches in the lateral moraines are also common landscape features at glaciers outside of Iceland and are from wider importance for the paleoreconstruction of former glacier stages.The knowledge of their development is essential for an adequate relative age classification of individual moraine ridges.In regard to the origin of the debris the resedimentation of prehistoric till deposits by younger glacier advances plays a role in the formation of the lateral moraines apart from englacial and supraglacial sediment transfer processes.     

Historical glacier-dammed lakes and outburst floods in the Karambar valley (Hindukush-Karakoram)

At least six devastating glacial floods occurred in the Karambar valley in the 19th and 20th century. Previously mainly the Karambar glacier was considered as the origin of these outburst floods. However, in this project more detailed investigations revealed that up to eight more tributary glaciers could have dammed the Karambar valley in historical and prehistorical times. The ice-dammed lakes reached an approximate length of up to about 5 km and more. The dense concentration of the glacier dams along a horizontal distance of only 40 km results in a complex interfingering of lake basins and flooded valley sections. In the individual flood events were probably involved almost synchronously the drainage of at least two lakes resulting in a lake outburst cascade. The Karambar case study highlights the characteristic geomorphological landforms of the glacier dams, their lake basins and the geomorphological impact of the outburst floods. The abundant occurrence of unconsolidated sediments mantling the valley flanks caused a high sediment load and enhanced the erosion potential of the flood. The erosion cliffs of sediment cones, up to 100 m high, wash limits along the slopes and longitudinal bars in the gravel floors are main characteristics of the flood landscape. Secondary temporary lake formations (back water ponding) during the flood events in consequence of blockages of the ice- and sediment-loaden flood masses occurred at many locations in the narrower valley sections and lasted for several days. Additionally, debris flows in-between the glacier dams have dammed temporarily the Karambar valley. On the basis of losses of settlement area and eye-witness reports, the extent, erosion rates and characteristics of the 1905 flood event could be reconstructed. In order to warn the villagers living downstream, the Karambar people established an early warning fire system (Puberanch) from Sokther Rabot to Gilgit which was operated until 1905. The reconstructed Karambar flood chronology represents one of the longest records for this region and provides also information on historical and recent glacier oscillations, especially on exceptional glacier advances. At present, the Chateboi glacier seals the Karambar valley over a distance of 4 km. An outburst flood would have disastrous impacts to the human infrastructure as the settlement areas expanded to the flood plains in the last decades.     

Post-sedimentary Transformation of Lateral Moraines——the Tributary Tongue Basins of the Kvíárjokull（Iceland）

The Kvíárjokull,a southern outlet glacier of the Vatnajokull,is confined in the mountain foreland by lateral moraines measuring a height of up to 150 m. Each of the lateral moraines shows considerable breaches with deviations of the main moraine ridges. The paper discusses the possible origins of these modifications of the lateral moraines as result of： 1） ice overlappings during glacier advances and subsequent breaches of the lateral moraine,2） bifurcations of the Kvíárjokull glacier tongue triggered by the preglacial relief conditions and the prehistorical moraine landscape leading to afflux conditions,3） drainage of ice-marginal glacier lakes and 4. volcanic activities,such as lava flows and volcanic-induced jokulhlaups. A historic-genetic model of the formation of the lateral moraines is presented considering the breaches in the lateral moraines as result from glacier bifurcations and therefore as former tributary tongue basins. Such breaches in the lateral moraines are also common landscape features at glaciers outside of Iceland and are from wider importance for the paleoreconstruction of former glacier stages. The knowledge of their development is essential for an adequate relative age classification of individual moraine ridges. In regard to the origin of the debris supply areas of the large-sized Kvíárjokull moraines,the resedimentation of prehistoric till deposits by younger glacier advances plays a role in the formation of the lateral moraines apart from englacial and supraglacial sediment transfer processes.     

The valley of Shimshal – a geographical portrait of a remote high mountain settlement and its pastures with reference to environmental habitat conditions in the North-West Karakorum (Pakistan)

This article presents observations on the natural hazard potential for permanent and seasonal mountain settlements and infrastructure such as routeways and irrigation canals in the North-West Karakorum. The remote high mountain settlement Shimshal (3080 m), located in the upper Shimshal valley and surrounded by three potential natural glacier dams, is of particular interest. The permanent settlement of Shimshal and its seasonal pasture settlements in the Shimshal Pamir at heights of 3200 and 4600 m respectively, reach the upper limits for permanent and temporary settlement. The choice of location for settlement and agricultural activities is already dictated by relief conditions. Primary settlement areas are the sediment accumulations in the valley floors. The wide distribution of unconsolidated screes in particular prevents settlement expansion upwards along the valley slopes. Glacial outburst floods as well as seasonal flooding events further reduce the scanty settlement area, as well as being among the most devastating sources of danger. The production of debris and the supply of loose material deposits induced in connection with the glaciation history of the area becomes a permanent source of danger for human settlement through resedimentation in the form of rockfall or mudflow. Furthermore, canal systems essential for the survival of oasis settlements suffer annual destruction through mass movements on the slopes, induced by the glacially pre-formed relief. Thus the adaptation of settlement locations to a glacially formed mountain relief will be examined in this study, with particular reference to the geomorphological landscape situation. What makes the Shimshal settlement particularly interesting is its very isolated location at a distance of 80 km from the Hunza valley which contains the main settlement concentration of the North-West Karakorum. Traditional ways of life can be expected to be well protected from outside influences. In the North-West Karakorum we find a debris landscape which differs greatly in its development and distribution from that of the Himalayas, influenced particularly in the lower valley locations between 1000 and 3000 m by the different climatic situation, and where therefore in comparison with the Himalayas a completely different pattern of natural hazards arises.     

Lateroglacial valleys and landforms in the Karakoram Mountains (Pakistan)

Lateroglacial landforms play a major role in the geomorphological landscape assemblage of the Karakoram Mountains. Nevertheless, in the past they have received only little attention in the glacial-geomorphological literature. In this article, the lateroglacial landscape will be presented as a geomorphological landscape unit. The Karakoram glaciers with lengths of up to 60 km are accompanied by lateroglacial sediment complexes over tens of kilometers. Besides their large horizontal distribution, they are spread over a considerable vertical range and occur between 2500 m–5000 m.The traditional view is that primary processes of rock disintegration such as ice avalanches and freeze-thaw processes as well as glaciofluvial sediments are the main debris suppliers for the formation of lateroglacial sediment complexes. However, the investigation of the lateroglacial sediment landscape of the Karakoram glaciers showed, that firstly the secondary debris supply in form of reworking of older glacigenic deposits (Late glacial slope moraines) represents a major debris source. Secondly, the lateroglacial sediments are composed to a major part of debris supplies from the tributary valleys. In this regard, the sediment input by mudflow events accords a prominent role. Therefore a considerable proportion of the lateroglacial sediments is of non-glacial origin. This fact has to be taken into consideration regarding glacier reconstruction in recent unglaciated mountain valleys. Further on, resedimented mudflow deposits could be identified as important parent material for recent lateral moraine formation. The distribution of lateroglacial valleys (`lateral moraine valleys') was traditionally closely linked to differences in insolation, which are in the subtropical latitude very high (`ablation valleys'). Therefore the S-faced valley flank was seen as the favourable location for lateroglacial valleys. However, field observations on more than 20 glaciers in the Karakoram Mountains proved that lateroglacial valleys occur in all exposures, and can be even absent in S-exposure. Topographical factors seem to be more important than insolation differences for the distribution pattern. Only the distribution of `true ablation valleys' can be regarded as a result of insolation differences. In fact, they can act as initial form for the formation of lateral moraine valleys.     

Historical beacon fire lines as early warning systems for glacier lake outbursts in the Hindu Kush–Karakoram Mountains

Natural Hazards - The paper presents a historical long-distance communication system based on beacon fires in one of the most dynamic and rugged mountain ranges of the world, the Hindu...