.png)
.png)
.png)
Email this article 
Influence of the surface moraine on the state of Djankuat Glacier (Central Caucasus) by 2025
https://doi.org/10.15356/2076-6734-2018-3-307-321
Abstract
Current glaciation of the Central Caucasus is in the regressive stage of evolution. Observed long rising of the air temperature in the ablation seasons (almost 1 °C since 1968 on the Djankuat Glacier) together with insignificant growth of winter precipitation caused a long period of the glacier degradation: since 1871 the mass balance of the glacier, with rare exceptions, remained negative. During this time, the glacier has lost about 60 m w.e. mainly by areas of the smallest ice thickness, i.e. the steep slopes of the rocky framing of the fi n basin which become exposing from ice due to conditions of extreme instability. In parallel with the processes of freezing and thawing in cracks, this leads to a signifi ant increase in the frequency of rockfalls. In 2001–2003, huge rockfalls occurred on the glacier from the slopes, which had recently undergone deglaciation. The last one covered 4% of the glacier surface with about 70 000 m3 of clastic products. The marine cover differs significantly from the open ice surface in its thermal characteristics, which affect the structure of the thermal balance and the absolute values of ablation. The temperature inside the moraine is positive throughout the ablation season, even at a depth of 60 cm, but the absolute values of daily maximum melting are five times lower than those on open ice. The influence of the moraine material layer on the ablation is determined not only by its thickness, but also by the structure. The fi ld experiment conducted in 2011 demonstrated that melting under a layer of coarse-grained material (particle diameter 16–17 cm) is four times faster than under a layer of fi e-grained (7–8 cm) material equal in thickness. The study of the influence of the surface moraine and the account of its further growth in thickness and area made it possible to predict changes in the surface of the glacier by 2025. The climatic forecast was made using the HadCM3 model (A2 climate change scenario). Data on air temperature and precipitation were used to construct a predictive fi ld of the mass balance of the Djankuat Glacier for each year until 2025. Th s became possible by the use of a quantitative parameterized relationship between the mass balance of the entire glacier and each of its points, identifi d in the study of the total mass transfer of the glacier, as well as parameterized linear regression equations. The forecast of hypsometry of the Djankuat Glacier made it possible to determine that by 2025 the depression of the tongue areas covered by the moraine will be 7–15 m (or 42–45%) smaller than areas of the open ice. Th s means that at the present stage of the glaciation development the surface moraine plays a role in the evolution of the glacier, commensurable with the climate factor.
Keywords
About the Authors
A. A. RezepkinRussian Federation
Moscow
V. V. Popovnin
Russian Federation
Moscow
References
1. Caine N. Toppling failures from alpine cliffs on Ben Lomond, Tasmania. Earth Surface Processes and Landforms. 1982, 7: 133–152.
2. Radbruch-Hall D.H. Gravitational creep of rock masses on slopes. Rockslides and Avalanches. V. 1. Natural Phenomena. Ed. B. Voight. Amsterdam: Elsevier, 1978: 607–657.
3. Carlsson A., Olsson T. High rock stresses as a consequence of glaciations. Nature. 1982, 298: 739–742.
4. Ruddiman W. Earth’s Climate: past and future. New York: W.H. Freeman and Company, 2008: 388 p.
5. Wyrwoll K-H. Causes of rock-slope failure in a cold area: Labrador-Ungava. Geological Society of America. Reviews in Engineering Geology. 1977, 3: 59–67.
6. Cruden D.M., Hu X.Q. Exhaustion and steady-state models for predicting landslide hazards in the Canadian Rocky Mountains. Geomorphology. 1993, 8: 279–285.
7. Whalley W.B., Douglas G.R., Jonsson A. The magnitude and frequency of large rock slides in Iceland during the postglacial. Geografiska Annaler. 1983, 65 a: 99–109.
8. Gardner J.S. Alpine mass wasting in contemporary time: some examples from the Canadian Rocky Mountains. Space and Time in Geomorphology. Ed. C.E. Thorn. London: Allen and Unwin, 1982: 171–192.
9. Johnson P.G. Debris transfer and sedimentary environments: alpine glaciated areas. Steepland Geomorphology. Ed. O. Slaymaker. Chichester: Wiley, 1995: 27–44.
10. Muñoz J., Palacios D., de Marcos J. The influence of the geomorphological heritage on present slope dynamics, the Gredos Cirque, Spain. Pirineos, 1995, 145–146: 35–63.
11. Rapp A. Talus slopes and mountain wall at Tempelfjorden, Spitsbergen: a geomorphological study of the denudation of slopes in an Arctic locality. Norsk Polarinstitutt Skrifter. 1960, 119: 96 p.
12. Luckman B.H., Fiske C.J. Holocene development of coarse debris landforms in the Canadian Rocky Mountains. Paläoklimaforschung. 1997, 19: 283–297.
13. Luckman B.H., Fiske C.J. Estimating long-term rockfall accretion rates by lichenometry Steepland Geomorphology. Ed. O. Slaymaker. New York: Wiley, 1995: 233–255.
14. Hinchliffe S., Ballantyne C.K. Talus accumulation and rockwall retreat, Trotternish, Isle of Skye, Scotland. Scottish Geographical Journ. 1999, 115: 53–70.
15. Levinson-Lessing F.Yu. Petrographic research in Central Caucasus (Higher Osetiya, Digoriya, Balkariya). Izvestiya Peterburgskogo Politekhnicheskogo instituta. Bulletin of Saint-Petersburg Polytechnic Institute. 1904, II (12): 97–136. [In Russian].
16. Serebryannyy L.R., Orlov A.V., Medvedev A.S. Study of form and character of fragments in the moraines of Caucasian glaciers. Izvestiya AN SSSR. Seriya geograficheskaya. Bulletin of the USSR Academy of Sciences. Geography series. 1981, 6: 117–124. [In Russian].
17. Serebryannyy L.R., Orlov A.V. Surface debris of glaciers: laws of the structure and formation. Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 1984, 51: 74–80. [In Russian].
18. Medvedev A.S., Barykov A.A. Mechanisms of formation of surface debris on alpine glaciers. Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 1983, 53: 47–53. [In Russian].
19. Serebryannyy L.R., Orlov A.V. Ledniki v gorakh. Glaciers in the mountains. Moscow: Nauka, 1985: 160 p. [In Russian].
20. Bayly M.B. The Lower Hecla Hock Rocks of Ny Priesland, Spitsbergen. Geological Magazine. 1957, 94 (5): 377–392.
21. Gee E.R., Harland W.B., McWhae J.R.H. Geology of central Vest Spitsbergen. Pt. l. Review of the geology of Spitsbergen, with special reference to central Vestspitsbergen. Pt. 2. Carboniferous to Lower Permian of Billefjorden. Transactions of the Royal Society of Edinburgh. 1951–1952. 62, 2 (9). Edinburgh: 1953: 299–321.
22. Popovnin V.V., Rozova A.V. Influnce of sub-debris thawing on ablation and runoff of the Djankuat glacier in the Cacucasus. Nordic Hydrology. 2002, 33 (1): 75–94.
23. Dyurgerov M.B., Popovnin V.V. Reconstruction of mass balance, spatial location and liquid runoff from the Djankuat Glacier from the second half of XIX century. Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 1981, 40: 73–82. [In Russian].
24. Popovnin V.V., Rezepkin A.A., Tielidze L.G. Expansion of supraglacial debris on Djankuat glacier snout over the period of direct monitoring. Kriosfera Zemli. Cryosphere of the Earth. 2015, XIX (1): 89–98. [In Russian].
25. Bozhinskiy A.N., Krass M.S., Popovnin V.V. Role of debris cover in the thermal physics of glaciers. Journ. of Glaciology. 1986, 32 (111): 255–266.
26. Khodakov V.G. Calculation of ice ablation under the debris layer. Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 1972, 20: 105–108. [In Russian].
27. Lambrecht A., Mayer C., Hagg W., Popovnin V., Rezepkin A., Lomidze N., Svanadze D. A comparison of glacier melt on debris–covered glaciers in the northern and southern Caucasus. The Cryosphere. 2011, 5: 525–538.
28. Østrem G. Ice melting under thin layer of moraine and existence of ice cores in moraine ridges. Geografiska Annaler. 1959, 41 (4): 228–230.
29. Nakicenovic N., Alcamo J., Davis G., de Vries B., Fenhann J., Gaffin S., Gregory K., Grübler A., Jung T.Y., Kram T., La Rovere E.L., Michaelis L., Mori S., Morita T., Pepper W., Pitcher H., Price L., Riahi K., Roehrl A., Rogner H.-H., Sankovski A., Schlesinger M., Shukla P., Smith S., Swart R., van Rooijen R., Victor N., Dadi Z. IPCC Special Report on Emission Scenarios. Cambridge: Cambridge University Press, 2000: 570 p.
30. Hagg W., Shahgedanova M., Mayer C., Lambrecht A., Popovnin V. A sensitivity study for water availability in the Northern Caucasus based on climate projections. Global and Planetary Change. 2010, 73 (3–4): 161–171.
31. Popovnin V.V. Accumulation field of an alpine glacier. Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 2000, 88: 16–29. [In Russian].
32. Kunakhovich M.G. Annual mass balance formation on a flat summit glacier. Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 1989, 67: 163–169. [In Russian].
33. Pastukhov V.G. Polnyi massoobmen lednika Djankuat. Full mass exchange of the Djankuat Glacier. Moscow: MSU, 2011: 185 p. [In Russian].
34. Petrakov D.A. Stability of the fields of external mass exchange of the Djankuat Glacier. Ustoychivost poley vneshnevo massoobmena gornovo lednika. PhD. Moscow: MSU, 2000: 218 p. [In Russian].
35. Dyurgerov M.B., Freydlin V.S. Calculation of surface ablation of the glacier (on the example of Djankuat mountain basin). Materialy Glyatsiologicheskikh Issledovaniy. Data of Glaciological Studies. 1972, 20: 151–156. [In Russian].
Supplementary files
For citation: Rezepkin A.A., Popovnin V.V. Influence of the surface moraine on the state of Djankuat Glacier (Central Caucasus) by 2025 Ice and Snow. 2018;58(3):307-321. https://doi.org/10.15356/2076-6734-2018-3-307-321
Refbacks
- There are currently no refbacks.
ISSN 2076-6734 (Print)
ISSN 2412-3765 (Online)