Change in the Extent of Glaciers and Glacier Runoff in the Chinese Sector of the Ile River Basin between 1962 and 2012
Round 1
Reviewer 1 Report
General comment:
The article deals with an important problem for the Central Asian States related to the assessment of the current state and dynamics of water resources. This problem is particularly relevant in the context of current degradation of glaciers, which are an important component of the formation of river runoff in mountainous areas. The content of the article is consistent with its title. А large amount of actual data has been processed. The criteria for selecting the initial data of weather stations and materials of space surveys are described in detail and their compliance with the task is assessed. The share of glacial runoff is estimated by comparing the amount of ice losses between repeated glacier inventories and the river runoff measured at the Yamada station on the Ili River. Also, runoff calculations were carried out using the empirical dependence of glacier melting on air temperature, and an assessment of its applicability under the conditions of modern glacier reduction. In a methodical way the work is quite correct. A rather deep analysis of the results obtained, and the conclusions made by the authors do not contradict the existing estimates for other Asian regions. The work contains interesting results and, after taking into account my comments (see below), can be recommended for publication.
Selected comments:
Insufficient resolution of drawings, small letters are not readable, small details look illegible: Figures 1, 3, 4, .... At the review stage, this is still valid, but a higher resolution is required for publication.
The article has four formulas. Three of them need to be edited. When using formulas from other publications, it is desirable to maintain their original appearance, if they do not require adjustment.
It is not clear why in the formula (1) from [8] it was necessary to swap the terms on the right side? In the original, it looks like: H = 53.21S0.3 - 11.32. I propose to correct it.
Formula (3) is incomprehensible. Apparently, in the multiplier of its right side there is no parameter H (thickness), which was discussed in formulas (1) and (2). There is no explanation why all this is divided into 1000?
In formula (4), the value of 2.85 is not a multiplier, but an index of power and should be framed accordingly. Similarly, not ts, but ts. The separator of digits in 1.33 and 2,85 everywhere should be the same - either (.) or (,).
L234-240. “…the ice to snow melt ratio reversed in the structure of the glacial runoff and melting of perennial ice has became a dominant component.” From the above figures it follows that the proportion of melting ice was indeed dominant in the total glacial runoff during the period 2008–2017 for the Tuyuksu glacier. But in order to claim that it was different before, it is necessary to show its value in the previous period for comparison or refer to the source of such information.
L250 “The error of equation (1) given by the author is ± 1.24 °C” - it is not clear which equation is being referred to, since equation (1) mentioned earlier is used to determine the thickness of the glacier. I can assume that we are talking about equation (4) and the authors of the article wanted to say that: “According to A. Krenke, the author of formula (4), the use of this empirical relationship for the regions of Central Asia implies an error in determining the temperature ts equal to ± 1.24 °C [63].” I propose to correct it.
L345 "... the stations are shown in Figure ..." - insert "... Figure 1";
L476 “Figure 6 suggests that the total area of C-IRB for 1963 was underestimated by 40 km2 relatively to the trend line.” It is not clear what is the relationship with Figure 6, which shows the distribution of precipitation and runoff from river basins by months. Need to fix.
L488 "Sosedov [91] ..." - replace with "Sosedov [83];
L503 “Table 9. Average value of glacier runoff components at Northern slope of the Ile Alatau [91]” - replace the link to the publication [83];
L532 “As follows from data in table 8 ...” - correct the table number. Must be “...table 10...”;
L575 «… and by the equation (1), on the other hand, barely exceeds 0.12.»." - replace with equation (4)
As a recommendation - in section 4.2 River Runoff to give more detailed comments on the interannual variability of the river runoff characteristics of the studied area. It is advisable to pay attention to the relationship between the acceleration of glacier degradation, observed in the early 1970s, and its manifestation in the change in the volume of river runoff from the glacial basins. They stand out well in the form of “downturn” in the graphs of Figure 7 (a, c, and d). Additional information on this subject can be found in [29], [30] and [31] from the list of “References”.
Author Response
Response to Reviewer 1 Comments
Selected comments:
Point 1. Insufficient resolution of drawings, small letters are not readable, small details look illegible: Figures 1, 3, 4, .... At the review stage, this is still valid, but a higher resolution is required for publication.
Response 1. Almost all of the figures were corrected.
Point 2. The article has four formulas. Three of them need to be edited. When using formulas from other publications, it is desirable to maintain their original appearance, if they do not require adjustment. It is not clear why in the formula (1) from [8] it was necessary to swap the terms on the right side? In the original, it looks like: H = 53.21S0.3 - 11.32. I propose to correct it.
Formula (3) is incomprehensible. Apparently, in the multiplier of its right side there is no parameter H (thickness), which was discussed in formulas (1) and (2). There is no explanation why all this is divided into 1000?
In formula (4), the value of 2.85 is not a multiplier, but an index of power and should be framed accordingly. Similarly, not ts, but ts. The separator of digits in 1.33 and 2,85 everywhere should be the same - either (.) or (,).
Response 2. The equation was corrected. The formula contains the division into 1000 due to the different scale of the S (km2) and H (m). The scale is given in the line 256 of the new manuscript.
The (.) and (,) was corrected in the equations, text, tables and the figures.
Point 3. L234-240. “…the ice to snow melt ratio reversed in the structure of the glacial runoff and melting of perennial ice has became a dominant component.” From the above figures it follows that the proportion of melting ice was indeed dominant in the total glacial runoff during the period 2008–2017 for the Tuyuksu glacier. But in order to claim that it was different before, it is necessary to show its value in the previous period for comparison or refer to the source of such information.
Response 3. The comparison and the values of the snow and ice components are given in the line 281-285 of the new manuscript.
Point 4. L250 “The error of equation (1) given by the author is ± 1.24 °C” - it is not clear which equation is being referred to, since equation (1) mentioned earlier is used to determine the thickness of the glacier. I can assume that we are talking about equation (4) and the authors of the article wanted to say that: “According to A. Krenke, the author of formula (4), the use of this empirical relationship for the regions of Central Asia implies an error in determining the temperature ts equal to ± 1.24 °C [63].” I propose to correct it.
Response 4. This part was removed.
Point 5. L345 "... the stations are shown in Figure ..." - insert "... Figure 1";
Response 5. It was corrected
Point 6. L476 “Figure 6 suggests that the total area of C-IRB for 1963 was underestimated by 40 km2 relatively to the trend line.” It is not clear what is the relationship with Figure 6, which shows the distribution of precipitation and runoff from river basins by months. Need to fix.
Response 6. This part was removed.
Point 7. L488 "Sosedov [91] ..." - replace with "Sosedov [83];
L503 “Table 9. Average value of glacier runoff components at Northern slope of the Ile Alatau [91]” - replace the link to the publication [83];
L532 “As follows from data in table 8 ...” - correct the table number. Must be “...table 10...”;
Response 7. It was corrected.
Point 8. L575 «… and by the equation (1), on the other hand, barely exceeds 0.12.»." - replace with equation (4)
Response 8. This part was removed.
Point 9. As a recommendation - in section 4.2 River Runoff to give more detailed comments on the interannual variability of the river runoff characteristics of the studied area. It is advisable to pay attention to the relationship between the acceleration of glacier degradation, observed in the early 1970s, and its manifestation in the change in the volume of river runoff from the glacial basins. They stand out well in the form of “downturn” in the graphs of Figure 7 (a, c, and d). Additional information on this subject can be found in [29], [30] and [31] from the list of “References”.
Response 9. Section 4.2 was modified to “Changes in streamflow” and more detailed analyses of the interannual variabilities were given. Also the relationship between the total river runoff and glacier runoff is provided in the section “Discussion”.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear authors,
I guess you put a lot of effort in your study as you applied several data sets and methods.
Unfortunately, the description of the whole manuscript is absolutly confusing and I got lost quite soon. Therefore, I badly recommend to re-write your paper by
1) structuring the content concerning to your headings
2) consult a professional translater/native speaker
3) re-think your conclusions: what is the outcome of your study/what do you want to say?
Honestly, as I couldn't follow your explanations, I am not sure if the content of your study is scientifically consistent, interesting/new, and correct.
Author Response
Dear reviewer,
Thank you very much for your comments! It was really valuable for us!
The structure of the article was corrected. The “Data and Method” section was divided into separate sections with the description of all of the methods and data which was used in our research. The “Result” section provides the information regarding the changes in glacier area in the study region by different aspects, changes in river streamflow, analyses of the glacier runoff estimated by different methods. The “Discussion” section provides the comparison of our data with other researches and also compare different methods of glacier runoff calculation which was used in the current research with each other. Conclusion section now is presented as the bullet points with the main outcomes of our research. The English language correction was made.
Author Response File: Author Response.docx
Reviewer 3 Report
Overall I think this is an interesting paper. I have just some minor comments on the methodology.
For the positive degree-day (PDD) method you should refer to the review of this approach by Braithwaite 2008 and Braithwaite et al. 2006:
Braithwaite, R.J., 2008: Temperature and precipitation climate at the equilibrium-line altitude of glaciers expressed by the degree-day factor for melting snow. Journal of Glaciology, 54: 437-444.
Braithwaite, R.J., Raper, S.C.B., and Chutko, K., 2006: Accumulation at the equilibrium line altitude of glaciers inferred from a degree-day model and tested against field observations. Annals of Glaciology, 43: 329–334.
Braithwaite (2008) found that degree-day factors for snow on 66 glaciers worldwide had averages of 3.5 ± 1.4 and 4.6 ± 1.4 mm day−1 °C−1 in low- and high-accumulation conditions, respectively, with an overall mean of 4.1 ± 1.5 mm day−1 °C−1, which is consistent with earlier values reported in the literature (e.g. Braithwaite et al., 2006). However, as your study finds, with a DDF is very low at 2.3 mm day−1 °C−1. I am aware that degree-day factors for snow can vary quite significantly between individual sites and degree-day factors for snow have been reported ranging from 2.5 to 11.6 mm day−1 °C−1 (Hock 2003) but your value does seem very low at 2.3 mm day−1 °C−1. You should discuss this a oittle further andprovide an explanation of why this is the case.
For estimations of glacier volume changes from glacier area measurements youuse the Chinese inventory equations. This is fine and appropriate but some mention should be made of other equations such as that of Chen and Ohmura (1990) who derived an equation based on data from 63 mountain glaciers. This has been used to estimate volume on mountain glaciers acrossthe world, such as by Hughes 2009. So, some comparison or mention of how this approach has been used in different settings would be useful in your paper:
Chen, J., and Ohmura, A., 1990: Estimation of Alpine glacier water resources and their change since the 1870s. Hydrology in Mountainous Regions. I – Hydrological Measurements; the Water Cycle. Proceedings of two Lausanne Symposia, August 1990. International Association of Hydrological Sciences, 193: 127-135.
Hughes, P.D. 2009. Twenty-first Century Glaciers in the Prokletije Mountains, Albania. Arctic, Antarctic and Alpine Research 41, 455-459.
Author Response
Dear reviewer,
Thank you very much for your comments. It was really valuable for us.
Point 1. For the positive degree-day (PDD) method you should refer to the review of this approach by Braithwaite 2008 and Braithwaite et al. 2006. Braithwaite (2008) found that degree-day factors for snow on 66 glaciers worldwide had averages of 3.5 ± 1.4 and 4.6 ± 1.4 mm day−1 °C−1 in low- and high-accumulation conditions, respectively, with an overall mean of 4.1 ± 1.5 mm day−1 °C−1, which is consistent with earlier values reported in the literature (e.g. Braithwaite et al., 2006). However, as your study finds, with a DDF is very low at 2.3 mm day−1 °C−1. I am aware that degree-day factors for snow can vary quite significantly between individual sites and degree-day factors for snow have been reported ranging from 2.5 to 11.6 mm day−1 °C−1 (Hock 2003) but your value does seem very low at 2.3 mm day−1 °C−1. You should discuss this a oittle further andprovide an explanation of why this is the case.
Response 1. The references to the Braithwaite (2008) was made in line with the discussion of the small values of the DDF at the Tuyuksu glacier (line 209-216). We think that the main reason of the low DDF at Tyuyksu glacier is the lower humidity.
Point 2. For estimations of glacier volume changes from glacier area measurements you use the Chinese inventory equations. This is fine and appropriate but some mention should be made of other equations such as that of Chen and Ohmura (1990) who derived an equation based on data from 63 mountain glaciers. This has been used to estimate volume on mountain glaciers acrossthe world, such as by Hughes 2009. So, some comparison or mention of how this approach has been used in different settings would be useful in your paper.
Response 2. The reference to the Chen and Ohmura article was made (252-253). But the only reason to use the presented in the article questions was to follow the same procedure as during the first glacier inventory and at the end have the comparable data.
Overall comments. The structure of the manuscript was corrected. The “Data and Method” section was divided into separate sections with the description of all of the methods and data which was used in our research. The “Result” section provides the information regarding the changes in glacier area in the study region by different aspects, changes in river streamflow, analyses of the glacier runoff estimated by different methods. The “Discussion” section provides the comparison of our data with other researches and also compare different methods of glacier runoff calculation which was used in the current research with each other. Conclusion section now is presented as the bullet points with the main outcomes of our research. The English language correction was made.
Author Response File: Author Response.docx
