|Comments (re-review) by Wilfried Haeberli on|
Development of proglacial lakes and evaluation of related outburst hazard at Adygine complex, Northern Tien Shan
Revised paper submitted to Earth Surface Dynamics
K.Falatkova, M. Šobr, A. Neureiter, W. Schöner, B. Janský, H. Häusler, V. Beneš and Z. Engel
The authors systematically answered the questions/comments in my review and markedly improved the original manuscript, especially by making the text more precise, by providing important additional references and by adding concrete information about radio-echo and resistivity soundings. Some adjustments are still needed to make the paper acceptable for publication. These adjustments concern central aspects of the study as listed below and should therefore be made carefully and with full recognition of the state of science as documented in the corresponding literature. The authors should be able to finalize the paper in their own responsibility but should feel free to contact me directly if they prefer to have my help (especially concerning mountain permafrost which does not appear to be their specialty). The first author has the contact.
Central aspects to be adjusted:
Two terms in the title need attention: “hazard” and “Adygine complex”. The term “hazard” is commonly used in relation to threats with respect to humans and their infrastructure or living conditions. Such aspects are not explicitly treated in the paper. Rather, the “susceptibility” of the lakes in view of potential outbursts is assessed. It may therefore be preferable to replace the term “hazard” in the title and accordingly to use the term “susceptibility” or “outburst susceptibility” in the text as appropriate. The term “Adygine complex” is vague and probably too general. Investigating relations and interactions between glaciers and surrounding permafrost in the Tien Shan, Bolch et al. (2018) used the term “ice-debris complex”. The term “ice” thereby stands for surface ice in glaciers as well as for subsurface ice in perennially frozen ground. The term “Adygine complex” may therefore better be changed into the more precise/comprehensive term “Adygine ice-debris complex”
Permafrost and polythermal glacier ice:
The phenomena of permafrost and polythermal glacier ice should be treated more adequately and with reference to the corresponding scientific literature (an introduction to mountain permafrost could be Haeberli et al. 2013). The fact that the mean annual air temperature (what has it been during the past years at the meteo station near the glacier?) is far below 0°C and the site is at the transition between discontinuous to continuous permafrost should be made clear at the very beginning of the site description (and in the abstract as well). Under such conditions, permafrost is known to reach depths of several tens of meters if not more than hundred meters. The ice content in perennially frozen debris often by far exceeds the pore volume of the material, enables viscous creep to take place resulting in landforms with ages which in many cases are likely to be millennia (Krainer et al. 2014). Creep deformation can accelerate with permafrost warming. Ice-rich perennially frozen ground is virtually impermeable, groundwater flow can take place via the active layer (supra-permafrost groundwater during summer), underneath the permafrost base (sub-permafrost groundwater) or through non-frozen zones within the permafrost (taliks). Buried ice within the permafrost remains stable as long as it is not exposed by surface erosion. All this is essential for the evolution and stability of the described lakes. The electrical resistivity profiles are most informative. The yellow, green and light blue colors in Fig. 3 are indicative of ice-rich frozen ground while the dark blue color – only the values > 1 – 10 MegOhmmeters indeed marks massive glacier ice. The low-resistivity/red color zones could – besides the thin active layer at the surface - be either bedrock or non-frozen materials (taliks near lakes 2 and 3?). The interpretation of the attributed material characteristics to resistivity ranges appears to be plausible. Could a reference be given and compared to the attribution by Haeberli and Vonder Mühll (1996)?
The polythermal structure of the glacier is correctly mentioned in the text but should be documented with measured data or should otherwise at least be discussed in comparison with better-known polythermal glaciers in other parts of the Tien Shan, in Svalbard or in the Alps. Most likely, the ice of the ablation areas is cold and frozen to the bed at the ice margins, while the permeable firn area higher up on the slopes could be temperate due to latent heat input by percolating melt water. This structure of englacial temperature would also explain the warm-based character of higher glacier parts and the formation of fluted/striated moraines under conditions of high (artesian?) water pressure at the warm-cold bed transition near the ice margin.
As already mentioned in relation with the title, the authors treat the aspect of susceptibility to instability and outburst of the lakes rather than related hazards to humans and their infrastructure/living conditions. A differentiated terminology should be used according to modern internationally used concepts.
The English is good over large parts of the text but needs smoothing in some places. Examples of possible improvements have been marked in the abstract of the annotated file. Some specific remarks and suggestions can also be found in the annotated pdf file (uploaded).
I prefer not to be anonymous as a reviewer. The authors should feel free to contact me if they wish to have further comments or assistance.
Bolch, T., Rohrbach, N., Kutuzov, N., Robson, B.A. and Osmonov, A. (2018): Occurrence, evolution and ice content of ice- debris complexes in the Ak-Shiirak, Central Tien Shan revealed by geophysical and remotely-sensed investigations. Earth Surface Processes and Landforms. doi:10.1002/esp.4487
Haeberli, W. (2013): Mountain permafrost — research frontiers and a special long-term challenge. Cold Regions Science and Technology 96, 71-76. doi.org/10.1016/j.coldregions.2013.02.004
Haeberli, W. and Vonder Mühll, D. (1996): On the characteristics and possible origins of ice in rock glacier permafrost. Zeitschrift für Geomorphologie N.F., 104, 43-57.
Krainer, K., Bressan, D., Dietre, B., Haas, J.N., Hajdas, I., Lang, K., Mair, V., Nickus, U., Reidl, D., Thies, H. and Tonidandel, D. (2014): A 10,300-year-old permafrost core from the active rock glacier Lazaun, southern Ötztal Alps (South Tyrol, northern Italy). Quaternary Research 83 (2), 324–335. doi:10.1016/j.yq