the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 21 Mar 2024
Predicting the Risk of Glacial Lake Outburst Floods in Karakorum
Abstract. Glacier snouts respond to climate change by forming proglacial meltwater lakes, thereby influencing glacier mass balance and leading to advancements and surges. The positive feedback of climate change results in more frequent ice-dammed glacial lake outburst floods (GLOFs) in the Karakorum and surrounding regions, often facilitated by englacial conduits. However, the complex and multi-factor processes of conduit development are challenging to measure. Determining the lake depths that might trigger GLOFs and the numerical model specifications for breaching are still being determined. Empirical estimates of lake volumes, along with field-based monitoring of lake levels and depths and the assessment of GLOF risks, enable warnings and damage mitigation. Using historical data, remote sensing techniques, high-resolution imagery, cross-correlation feature-tracking, and field-based data, we identified the processes of lake formation, drainage timing, and triggering depth. We developed empirical approaches to determine lake volume and trigger water pressure leading to a GLOF. The correlation of glacier surge and lake volume reveals that glacier surge velocity plays a crucial role in lake formation and controlling the size and volume of the lake. Lake volume estimation involves geometric considerations of the lake basin shape. A GLOF becomes likely when the lake's non-dimensional depth (n’) exceeds 0.60, correlating with a typical water pressure on the dam face of 510 kPa. Additionally, we identified the critical risk zone of lakes, where all lake outburst floods occur, as the point where the lake volume reaches or exceeds 60 % of its capacity. These field-based and empirical findings not only offer valuable insights for early warning procedures in the Karakorum but also suggest that similar approaches can be effectively applied to other mountain environments worldwide where GLOFs pose a hazard.
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CC1: 'Comment on egusphere-2024-565', Taigang Zhang, 25 Mar 2024
Great paper! You proposed a critical lake depth for ice-dammmed GLOF initiation in the Karakoram, which is important for early warning. I noticed Section 2.4, "Geometry of lake basin," where you described two idealized three-dimensional bodies for ice-dammed lake basins. Perhaps you would be interested in checking out our recently published paper in The Cryosphere. It could be beneficial for supporting the principles and applications of these geometry approximation methods.
https://doi.org/10.5194/tc-17-5137-2023
Taigang Zhang
Citation: https://doi.org/10.5194/egusphere-2024-565-CC1 -
AC1: 'Reply on CC1', Nazir Ahmed Bazai, 25 Mar 2024
Dear Dr Taigang Zhang,
Thank you very much for your kind words and positive feedback on our paper. We're delighted to hear that you found our research on the critical lake depth for ice-dammed GLOF initiation in the Karakoram to be of significance, particularly in the context of early warning systems.
Your observation regarding Section 2.4, "Geometry of Lake Basin," is much appreciated. We agree that the idealized three-dimensional bodies described therein play a crucial role in understanding the dynamics of ice-dammed lake basins. Your suggestion to explore your recently published paper in The Cryosphere aligns perfectly with our interests, as it could indeed provide valuable insights into further supporting the principles and applications of these geometry approximation methods.
We will certainly delve into your paper and explore how it complements our research. Collaboration and exchange of ideas are key to advancing scientific understanding, and we are eager to explore opportunities for further collaboration or discussion on this topic.
Once again, thank you for your positive feedback and valuable suggestions. We look forward to delving into your work and contribution to this field in the future.
Best regards,
Dr. Nazir Ahmed Bazai
Citation: https://doi.org/10.5194/egusphere-2024-565-AC1
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AC1: 'Reply on CC1', Nazir Ahmed Bazai, 25 Mar 2024
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RC1: 'Comment on egusphere-2024-565', Wilhelm Furian, 28 Mar 2024
General comments:
The authors of the article "Predicting the Risk of Glacial Lake Outburst Floods in Karakorum" turn to a very important topic, the investigation of the trigger mechanisms of GLOFs. The article contains interesting theories and examines intriguing relations in this context. The article is well written and for the most part logically structured. However, the flow of reading is sometimes impeded because paragraphs do not follow on logically from one another, especially in the methodological chapters 2.2-2.4. But there are also some backtracks later on when methods and contexts are explained instead of just presenting the results of the scientific work.
In particular, the focus on determining the lake volume appears somewhat convoluted and, in some cases, does not refer enough to previous research. Hypotheses are put forward and rejected; it is not always clear what the added value is compared to previous methods (e.g. Cook and Quincy (2015) or the paper by Zhang et al. (2023) already mentioned in the comments). Chapter 3.1 on the relationship between water depth and GLOF event is more interesting and also more fluently written, to my mind.
Although the Discussion contains some parts that would have been better placed earlier in the manuscript as they contain new sources and information, it is well written and presents the results of the study, its limitations and achievements well and puts them in context with previous publications.
The illustrations support the article in the right places, but could benefit from a revision of the color schemes and, in some cases, a little more scientific clarity in the statements.
Overall, the results are interesting and contribute to the current state of science, especially with regard to the relationship between lake depth, water pressure and the timing of a GLOF. With the editing of some minor revisions, I see no problems for publication and congratulate the authors on this work.
References:
Cook, S. J. and Quincey, D. J.: Estimating the volume of Alpine glacial lakes, Earth Surf. Dynam., 3, 559–575, https://doi.org/10.5194/esurf-3-559-2015, 2015.
Zhang, T., Wang, W., and An, B.: A conceptual model for glacial lake bathymetric distribution, The Cryosphere, 17, 5137–5154, https://doi.org/10.5194/tc-17-5137-2023, 2023.Specific comments:
- At the beginning of chapter 2, the authors mention three glaciers. At this point, the reader wonders: Why were these glaciers and their lakes selected? It would facilitate the flow of reading if the authors could explain this a bit at this point. Later, in P9L232, the authors mention, that “the three Karakorum [sic!] glaciers can be used as regional exemplars [sic!] of surge behavior controlling GLOF occurrence”. This is too late, this needs to be explained much earlier. Maybe the authors could add a short subchapter about the study area, indicating its location in HMA and the position of the individual glaciers?
- Figure 1 gives a good overview on the two lakes, but some things could be improved.
- Unless I missed a meaning of the color of the year lines, I would suggest using a fixed color scheme for the specific years, so that each year has the same color in each image.
- What is symbolized by the squiggly blue arrows?
- I suspect that “Panel. b” in Fig. 1a delineates the extent of Fig. 1b, but that should be made clearer to the reader.
- In order to make the caption clearer, I would suggest leaving out information on when images were taken of lake elevations identified when this information is also available in the figure itself.
- Chapters 2.2 to 2.4 are very important as they explain the scientific basis of this article. However, all three chapters blur into another as it is not always easy to follow the structure of the article. For example, in 2.2, the eponymous “glacier mapping” is explained with the use of remote sensing and field observations and the lake volume calculation is introduced. Then, chapter 2.3 is called “field observation and lake volume measurement” – even if both have been mentioned before and even though the volume calculation especially is the focus of 2.4. A bit of restructuring and more suitable subtitles would improve the flow of reading.
- At the end of 2.3 (P8L189), you mention another way to compute lake volume – from DEMs. What method did you use here?
- It is difficult for me to understand the reasoning behind chapter 2.4. At the moment, it appears to be a mix between presenting the methodology and results, which does not improve the flow of reading. In the previous chapters you have explained the method of estimating/calculating volume (e.g. using field data, remote sensing, DEMs) – and now the authors present another chapter describing yet another method of estimating the lake volume using the lake basin approximation, even though they have previously stated that they have access to the lake basin once the lake is drained, by plumbing or with the help of DEMs. It would help the reader if the reason for this chapter was made clearer.
As for the content of this subchapter:
Maybe I missed it, but Fig.2a contains the pentahedral lake shape, but only shows the comparison between DEM-based volume and tetrahedral volume in Fig2b. What is the reason for the pentahedral diagram?
Finally, what was the reason for assuming that the vertical cross-section of the lake at the dam is an equilateral triangle? Is this a common geometry for this kind of lakes? Also, if I understand correctly, this approach does not provide useful data because the estimated volumes are far too high (Fig2b). The authors state that lake depth is probably much lower, but do not present alternate estimations. Now of course it is completely acceptably to include an unsuccessful approach, but it should be (a) made clearer to the reader or (b) maybe moved to the Results or Supplements section. - Figure 3 shows the very interesting correlation between surge periods and the occurrence of GLOF. It is a valuable contribution to this article. Unfortunately, it takes too much time to fully understand it. I would encourage the authors to spend more time on making this figure more precise and consistent, as this kind of figure is so important for the reader to fully grasp your work.
One example: the labeling of the x-axis is very strange in 3a-c, as the same interval sometimes means one year and sometimes three years. The vertical labeling is also difficult to read. A different type of labeling that, for example, only shows every five years (but written horizontally) and has constant axis ticks for the years between the labels would be much more appropriate and would clean up the picture a lot.
Also, the font sizes are not consistent. Fig3b and Fig3c are missing a legend (comparable to Fig3a) which would explain the differently colored dots.
And even after some consideration, I am not sure I understand Fig3d. The date seems to be 01/01/1990, but also some kind of timeline is indicated by the rising numbers below the bars. If this panel is only a combination of 3a-c, the authors should explain it more. - In Fig.4 and the preceding paragraph, the authors mention the exclusion of outliers from their data. In Fig.4, only two of the four excluded outliers are shown, but at least one of them appears to be relatively close to the main data spread. I would encourage the authors to include the reasoning behind the detection and treatment of the outliers – e.g., are they errors in the measurements, are they not representative etc.
- In general, Fig.4 is a valid support for the interesting investigation in the connection between surge velocity and lake size. However, it could be improved by a clearer legend and a more distinctive color mapping. At the moment, one color (light blue) is used for a trendline, glacier points, and the background shading (which should have a legend entry). Also, the triangles are explained two contradictory ways: In the caption, the authors describe the triangle lakes to have residual volume. In the legend, the triangles indicate drained lakes.
- In Chapter 3 (P11-12 from L265-L290), the authors repeat the contents of chapter 2.4. They again mention the theory of the lake cross section resembling either an equilateral three-sided triangle or a square at the dam face. However, this approach was already described as unsuccessful in 2.4. due to the resulting volume estimations being much too high. As this section explains some methods more concise than before, these parts should be merged with its already existing counterparts in the Methodology, while the parts of the Methodology in 2.4 dealing with actual results should be moved here.
- Figure 6 appears very full, but it conveys interesting results, especially in 6d. However, I would encourage the authors to spend some more time to “clean up” the figure. Some fonts are extremely small – maybe some information can be put into a separate table (like the L, E, and V data between c and d). I also wonder why there is no inset card for 6c.
Technical corrections:
P1L1ff: The mountain range is called Karakoram, to distinguish it from the city of Karakorum, if I’m not mistaken. Please change it throughout the text.
P2L40: Why is “Moraine Lake” capitalized?
P3L92: “The current research focuses of Bazai and colleagues aims to leverage…” The plural of focus should be foci. à “The current research foci/priorities of Bazai and colleagues aim to leverage…”
P3L98: A very nitpicky comment: In this sentence, the authors claim to have used “all available open and commercial satellite imagery sources”, and they list a lot of sources, but surely not all. Please clarify if you indeed used the others, or rephrase the sentence.
P4L124: Maybe a translation issue: The authors explain that lake extent and surface level can be used to “measure” the lake’s volume. To my mind, “estimate” or “approximate” would be more accurate, because to really measure a lake’s depth one would need to study its bathymetry.
P5L132: Probably will be fixed during editing, but “Gilgit-Baltistan Disaster Management Authority” has a smaller font size than the rest.
P5L136: I would suggest swapping this paragraph with the next paragraph. With a little rewording, the reader would then first learn that all three glaciers are surging glaciers, and then learn about the method of measuring velocity. See also specific comment 1.
P6L156: There is a colon in this line, the meaning of which I do not understand.
P6L157: Maybe it's just me, but I still don't understand how you estimate the lake depth. If the lake is empty and you measure from the bottom to the shoreline, I understand the method. But what role does the ice dam play in this calculation? It is explained better in Chapter 2.3, but here the explanation is somewhat fuzzy.
P8L198: Before the reference (Dillencourt et al. 1992) there is a “to” too much.
P9L232: “regional exemplars” à “regional examples”
P10L246: “resultant” à “resulting”
P10L248: “for ease of trend comparison” could be better rephrased as “to facilitate the understanding of the trends”
P10L251: The authors mention four excluded outliers, however, in Fig.4, there are only two outliers plotted. I would suggest adding the two remaining outliers.
P13L291: In Fig.5, the x-axis label contradicts the caption. Are the values the volumes of tetrahedrons or pentahedrons? In any case, the axis label should indicate that the volume values have been divided by 10 to match the measurements.
P13L297: “improving” à “improved”
P16L357: The abbreviation GLOFs has already been explained in L45.
P17L359: Am I correct in the assumption, that the values in 6c are divided by 10 to match the measurements? Because this time, it is not mentioned in the figure or the caption.
P17L372: “Values of values n’ < were associated…” à There appears to be a missing value (probably “0.60”) after the “<”. Also, the beginning of the sentence should be rephrased. In the same line, there is a space too much before the new sentence beginning with “Therefore, in...”
P17L378-380: While the discussion in general does very well in summarizing the article, this part does not belong here. It introduces information better suited for the Methodology as it justifies the reason behind this geometric approach. In the next paragraph, there are a few more sentences with the same problem.
Citation: https://doi.org/10.5194/egusphere-2024-565-RC1 -
RC2: 'Comment on egusphere-2024-565', Anonymous Referee #2, 15 Apr 2024
Review: Predicting the Risk of Glacial Lake Outburst Floods in Karakorum
Based on remote sensing as well as field data the authors aim to support their hypothesis that GLOFs can be anticipated from remotely sensed surge velocities as well as knowledge of lake geometries and lake expansion. They find a link between glacier velocity and lake volumes, and subsequently a relation between lake volume (or depth) and the risk of disastrous drainage. They do this based on 3 well known case studies in the Karakoram and in the end expand this to the global scale for the Discussion. The manuscript is in general well written and language is clear. Literature has to be revised at times and is not always completely appropriate with respect to basic conclusions in the Introduction, that are at the basis of the arguments then later followed. More problematic is that the hypothesis isn’t clearly laid out at the start and hence the presentation of Results becomes a bit confusing, which would require some restructuring. Additionally, there is also a general lack of scrutiny on error margins especially for field measurements, which has implications on interpretation of results as I outline below, as these uncertainties propagate into your results. As I describe further down as well (and as the authors themselves admit throughout the text), ‘prediction’ itself isn’t possible with this approach (if it will ever be) and hence the title is in my view misleading, and I would strongly consider to revise that.
Most importantly however, I think that there remains lack of clarity on why surge velocities need to be part of the predictive mechanism and even the initial hypothesis that links them to the thickness of the ice dam. This oversimplifies a complex problem and the physical reasoning escapes me. This then also leads to strong interpretation of results, that are not as clear cut as the text makes them seem. All this in mind I think the manuscript needs a careful major rehaul before it is suitable for The Cryosphere (while the importance of the topic itself and the general approach I do think merit consideration for this Journal). I explain this in more detail with a number of major concerns below, followed by quite a short list of minor issues encountered throughout the text.
Major comments including conceptual/methodological issues:
Title: I am concerned that ‘predicting the risk’ is a very strong term as this will unlikely ever work to a degree that people understand what ‘predicting’ means and we shouldn’t suggest we can predict it (you say that yourself in the Discussion). You could change it to what you use later to ‘Enhance the predictive capabilities for Glacial lake outburst risk in the Karakoram’
L14: Not all glacier snouts produce lakes and there is no evidence that proglacial lakes lead to advancements or surges! Please amend.
L15: Recent research is conflicted on this topic and maybe actually showing the opposite - that ice dammed lakes drain less frequently (Veh et al., 2023). I would therefore remain very cautious with such kind of assertions to set the scene for your research.
L32: While mass gain has indeed been observed this trend is already over since approximately a decade – see (Jackson et al., 2023) for a number of studies referring to this. It would be prudent to note here that by now we consider this anomalous process to be over.
L34: The statement that there is a link between the anomalous mass balance and surges is spurious – what do you base this on (or which study specifically)? Also there has to my knowledge been no evidence for an increase in surge frequency (but only our ability to detect them).
L40: All three studies cited here for ‘glacier avalanche increase’ are based on few specific events, not trends (since so far we do not have long records). Hence you can not speak of an increase of these events based on this evidence or need to adapt language to caution our lack of records so far.
L41: I am not sure what you refer to when you speak of ‘positive variation in regional climate feedback’ with respect to lakes. You mean ‘more lakes leading to more mass loss leading to yet more lakes’? Then spell this out and you’d need to cite studies that show an increase in lakes leading to more mass loss (e.g. (Zhang et al., 2023))
L54ff: While (Carrivick & Tweed, 2016) is of course a global compilation, there is since a more recent overview globally (Veh et al., 2022) as well as for HMA specifically (Shrestha et al., 2023), both showing a much larger number of events and providing more accurate statistics for the numbers you are quoting here. Since we need to be mindful of the advancement of research, it would be prudent to refer to these updated studies here.
L96: ‘Data’ is generally not a subsection of Methodology but at least on equal footing. I would hence rename this section 2 to ‘Data and Methods’. Also, you lack an introduction of your specific field locations and why you chose those but rather jump directly on the three lakes in L98ff. It doesn’t require much, but an introduction of your field sites here briefly is required, possibly with an overview map as Figure 1 or an inset elsewhere. L146f actually is a kind of introduction in this regard that should be placed earlier.
L167: Please explain how you ‘estimated’ this length.
L199: What are ‘other’ dimensions you get to with this method, please explain.
L193ff and Figure 2: I am a bit confused by this section leading into results. You introduce the tetrahedral and pentrahedral shape of the dam, but never refer to the second but just the first. Why? You then also present results already in Figure 2b, even though we are still in Methods (especially your very last part on the issue of overestimated h). It is important to keep this apart and not mix the two sections. Finally, I think it would be important to rather use the space in methods how you were able to determine the D, E and Z (and Y, which is wrongly denoted twice as Y1 in the figure but should be Y1 and Y2!) in the field. How accurate are your GPS measurements? How accurately are you able to determine the position of the dam crest and base? The errors that are quite normal from such field measurements will then propagate into your volume estimates, which in a complex equation like equation 1 you show here, can become complex themselves. It is important to note them however to judge your comparisons you then make against volume estimates from the DEMs. In turn, you also need to specify the uncertainty of your UAV derived DEM, which in turn translates into an error range for your volume estimate.
L256f: You here come up with the physical hypothesis you try to prove after you present the results. That is confusing and should be the other way around, the hypothesis should be introduced in the Introduction already, when you set out to argue why you look at the datasets you choose. I then however do not quite follow your hypothesis. You argue that ice thickness at the lake dam decreases as velocities of the surge peak. But lake dams are in the receiving zone of the surging glacier (mostly, definitely in all the three cases here), where velocity peaks coincide with thickening of the tongue. Ice thins in the quiescent phase after the surge (where again we see many GLOFs of course in all three cases, for many years to come). This leads me then to the main concern I have with the prediction plan based on just velocity here – I would argue that lakes fill following closure of the subglacial drainage, from crevassing (as you argue) but also with changing lake water temperatures (depending on inflow temperatures and atmospheric temperatures and snow melt and glacier melt forcing. These variables are of course very hard to constrain, but with your approach you are packing these complex processes into glacier velocity alone – which is sometimes changing without any perceptible effect on lake properties as well. This way you gloss over other potential drivers, which could become a problem when wanting to be truly predictive. I think this is finally all reflected in your results. Naturally there are GLOFs always after surges (Figure 3), but that just follows from the damming. I can’t see any clear relation between speed up and occurrence just from these results. In Figure 4 you finally of course have a very large spread. For Shisper alone there seems to be no change of volume with velocity (I suspect here it is simply constrained by topography also since around later drainage events the surge had stopped completely), at Kyagar the volumes varies widely with very similar velocities and I see no geometric relationship at all. It finally is a deficiency here that you do not show the uncertainty bars around velocities (especially since these mean values spread quite a lot during the surge itself on top of the error introduced from the SfM approach) or the volumes, which would further put your relations into context (and put the geometric relationship in question).
L265ff: Maybe this is just me, but I would find it more easy to follow if you first present results on your ability to represent volumes of lakes with trigonometric considerations and then follow this by the much more complex relation with surge velocities. As it stands now you jump between one and the other, which leaves it quite hard for the reader to follow the final reasoning. When it comes to volume estimates you furthermore now have results spread between Figure 2 and Figure 5, with a completely different story in between. It would be advisable to bring this together to then come to a clear conclusion simply on your ability to estimate volumes accurately. Once that is done, it will also be more reliable to interprete your results from Figure 4. Relating to your volume estimates I am finally surprised that you do not refer to earlier considerations in this direction, e.g. taken in (Cook & Quincey, 2015), who summarize multiple attempts in literature in this direction.
L316ff and Figure 6: You have used multiple data to assess volumes/lake dimensions but do not specify what your lake geometries are based here now. They look very detailed, is this all taken from UAV generated DEMs and field measurements (for depth)? It needs to be absolutely clear what data finally leads you to what conclusion, especially when you draw up ranges that may be used later for breach assessments but whose accuracy change widely depending on what data you base them on. I am also not entirely sure, how to interprete the red lines in Figure 6 – are these the actual depths/volumes at the respective GLOF events as presented in Table 1? Make that clear in the caption to Figure 6. Also you then show relations for times when ice thickness wasn’t well known right (e.g. older Kyagar events)? Doesn’t you assumption of a constantly same geometry become weaker away from your UAV-DEM date? You have deposition, sediment drainage as well as different dam heights every time. This will affect the final calculation of n/pressure and hence I suspect give you much more spread in 6d, which to me now seems surprisingly well lined up for Khurdopin and Kyagar.
L328: Following from above to your conclusion that 500kPa is the threshold – this is simply 50 m of water table equivalent. Isn’t that simply confirming that ‘a lot of water is needed to cause a splash’? Below 50 m in most cases we will have small GLOFs (which have occurred often unrecorded in all lakes and one could argue aren’t really GLOFs but simply high flow drainage events) while when you get to 50 m you slowly get to volumes that cause considerable flow. But why would that be specific to surging glaciers or the region? Again this will then depend on ice dam properties (temperature, thickness) which bring in a number of other unknowns and can’t just be summarized with a single value. Even your results show that for Shsiper it may be >1000 kPA, while for Khurdopin 700 kPA, quite big differences.
L340f: It is nice that at this stage you manage to pull in examples from elsewhere to support your volume/threshold theory. This of course gives your approach some strength. This leads however to two observations:
- Maybe it would be prudent to leave away the surge aspect from your study altogether, to me the velocity story doesn’t quite hold up and also does not have a clear connection to the critical threshold. It even further weakens your prediction capabilities as making the step from ‘surge velocity u’ to ‘critical threshold n’ becomes spurious and doesn’t hold as a clear indication (i.e. you can’t say ‘if Shisper exceeds a velocity of x m/d a GLOF may be more likely’).
- As you note yourself in L391f, you can’t ‘predict’ above a certain threshold (hence also my concern with the title), you can just indicate higher likelihood of catastrophic drainage. This itself is useful but the recommendation to always report that as imminent threat has its drawbacks, as people will become less sensitive to warnings if they are reported often without any resulting events. Hence I rather suggest to use this as a general support in risk assessment procedures (paired with other means).
- In L380 you get back to the volume estimation – I agree that for a first order measure this is useful, but to make this a considerable improvement over simply seeing lake area from space (much easier), the reader requires much more scrutiny on your volume estimates. How accurate are the depth/dam dimension variables you have to come to good volume estimates here and how does that propagate to your n computation to make it robust? This is currently missing from the text and with the data you show from lakes elsewhere could be expanded upon for a thorough Discussion.
L410f: The Conclusion as it stands is too short. It also hinges much weight on the linear regression against one means to estimate volume, while I do not think that was the initial aim of the paper (prediction and GLOFs rather than lake volumes). This suggests that the general aim needs sharpening and the conclusion should also converge on that. From your Conclusions I would also like to see to what degree your field data was essential in this process as this clearly impacts the potential to upscale. For this a more thorough descriptions of said field data including their uncertainties is however required (even if parts of this has been presented in other publications).
Minor:
L1: While ‘Karakorum’ spelling is of course possible, I would consider going with the standard in English in literature by now and go for ‘Karakoram’
L40: ‘has increased’
L92: ‘…research foci described in this study aims to leverage …’
L142: ‘measured’
L147: ‘have occurred’
L150: ‘Sentinel 2’, capitalized
L165: ‘the empty lake’
L197: ‘outlines’
L198: remove first ‘to’
L205: ‘a value which can be …’
L240/Figure 3: typo in the figure – ‘Kayager’. Also what are the numbers in 3d? I assume days after 1/1/1990? You would need to say that but it is also a very hard way of reading your data. Dates would be much more useful.
References:
Carrivick, J. L., & Tweed, F. S. (2016). A global assessment of the societal impacts of glacier outburst floods. Global and Planetary Change, 144, 1–16. https://doi.org/10.1016/j.gloplacha.2016.07.001
Cook, S. J., & Quincey, D. J. (2015). Estimating the volume of Alpine glacial lakes. Earth Surface Dynamics, 3(4), 559–575. https://doi.org/10.5194/esurf-3-559-2015
Jackson, M., Azam, M. F., Baral, P., Benestad, R., Brun, F., Muhammad, S., Pradhananga, S., Shrestha, F., Steiner, J. F., & Thapa, A. (2023). Chapter 2: Consequences of climate change for the cryosphere in the Hindu Kush Himalaya. https://doi.org/10.53055/ICIMOD.1030
Shrestha, F., Steiner, J. F., Shrestha, R., Dhungel, Y., Joshi, S. P., Inglis, S., Ashraf, A., Wali, S., Walizada, K. M., & Zhang, T. (2023). A comprehensive and version-controlled database of glacial lake outburst floods in High Mountain Asia. Earth System Science Data, 15(9), 3941–3961. https://doi.org/10.5194/essd-15-3941-2023
Veh, G., Lützow, N., Kharlamova, V., Petrakov, D., Hugonnet, R., & Korup, O. (2022). Trends, Breaks, and Biases in the Frequency of Reported Glacier Lake Outburst Floods. Earth’s Future, 10(3), e2021EF002426. https://doi.org/10.1029/2021EF002426
Veh, G., Lützow, N., Tamm, J., Luna, L. V., Hugonnet, R., Vogel, K., Geertsema, M., Clague, J. J., & Korup, O. (2023). Less extreme and earlier outbursts of ice-dammed lakes since 1900. Nature, 614(7949), 701–707. https://doi.org/10.1038/s41586-022-05642-9
Citation: https://doi.org/10.5194/egusphere-2024-565-RC2 -
RC3: 'Comment on egusphere-2024-565', Anonymous Referee #3, 16 May 2024
Dear Editors,
Dear Authors,
Thank you for the opportunity to review the manuscript "Predicting the Risk of Glacial Lake Outburst Floods in Karakorum" by Bazai and co-authors.
In their study, Bazai et al. ask the important question of when an ice-dammed lake reaches a critical depth, requiring further investigation and possibly warning of impending flooding. This is a timely question, as many ice-dammed lakes form and drain each year in this and other regions. However, the text lacks structural clarity and motivation as to why we need both geometric models and DEMs to better understand the volumes and depths of ice-dammed lakes. Parts of the results should be better placed in the methods to motivate the two geometric approximations developed to estimate volumes and depths of ice-dammed lakes. The idea that surge velocity controls lake depth is interesting, but the underlying analysis falls a bit short, using mostly visually guided drawing of exponential curves. Another good point is the comparison of ice-dammed lakes and their depths at failure in other regions, but there is no information on how this data was obtained and processed. The discussion is largely focused on a single paper (Carrivick et al., 2020), but could benefit from a more thorough reflection on previous work on the geometry and processes involved in the drainage of ice-dammed lakes.
Please see the attached PDF for more specific comments.
The editor has asked for a third opinion on this manuscript. Admittedly, I can only add a few points to the comments of the other two reviewers, who have done a very good job in suggesting ways to improve this manuscript. If their comments are fully taken into account, I expect that this manuscript can be a suitable one for the community focusing on ice-dammed lake outburst floods.
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| 339 | 124 | 27 | 490 | 35 | 15 | 13 |
- HTML: 339
- PDF: 124
- XML: 27
- Total: 490
- Supplement: 35
- BibTeX: 15
- EndNote: 13
Viewed (geographical distribution)
| Country | # | Views | % |
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| Total: | 0 |
| HTML: | 0 |
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