Review Reports - Impacts of Climate Change and Human Activity on Lakes around the Depression of Great Lakes in Mongolia

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The western Mongolian regions are particularly responsive to global climate change and is a significant contributor to global dust sources. It is dotted with numerous lakes, and the dynamic shifts in these lakes not only mirror global climate fluctuations but also carry implications for the overall quality of the global ecological environment. This study analyzed impacts of climate changes and human activities on lake fluctuations in these regions. It is an representative study to demonstrate the impacts of the interplay of climate change and human activities. It is suitable for the publication in this journal. However, a moderate revision is recommended before the possible publication. Here are my concerns:

1. The study use various data (soil moisture, grazing and PET datasets) to evaluate the influences; what are the data quality, resolution? How to make the different sources are comparable?

2. Another key issue, why the structural equation modelling was done at a province scale, instead of a watershed scale? For example, although human activities are obvious in the same province but not in the same watershed, human activities should have no obvious impact on the lakes and their watersheds.

Comments on the Quality of English Language

1. The translation of some English terms (e.g., throughput lakes, coccyx lakes, through-type lakes) in the article is not right; the author should check and update accordingly.

Author Response

Thank you for your valuable comments on to this paper, we have revised the paper as required. For specific replies,please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

General Comments:

This manuscript uses Google Earth Engine to produce composites of surface reflectance to observe the area and number of lakes in Mongolia, validated through training sets of lake locations. A structural equation model (SEM) was then used to calculate correlations between socio-economic and physical parameters in administrative regions of Mongolia to investigate their impact on the time series of lake area and number of lakes (while also dividing these lakes into alpine, throughput and coccyx categories). The remote sensing of the lakes was completed effectively and explained well, although could use some more clarification regarding the methodology. My major concern with this paper and I anticipate the authors’ response and clarification, is the research design surrounding the SEM correlation analysis of the social, economic and physical variables. Why were these specific variables chosen? How confident are the authors that these are the variables that can explain the variance in lake area, and have they been informed by other studies? Regarding these variables, there were quite a few statements referring to the trend or outlook of lake area, precipitation, or other weather variables. When referencing a trend, especially in a peer-reviewed manuscript it is important to provide statistics referring to the strength and confidence of the trend, which I suggest that the authors report in a revised version of the paper.

The discussion section is exhaustive, but not in the topics that I would have expected. For instance, I would have expected the authors to address how other studies using SEM would have performed compared to this study, the correlative statistics, or a discussion of how the lakes are shrinking relative to other countries in the region. I have addressed this in the specific comments, but I believe shifting the focus could lead to an improved discussion section.

With these concerns stated, I believe that the objectives of the manuscript are scientifically interesting, and the results a valuable contribution to the literature on lakes in Mongolia. I believe the paper, with major revision is worthy of publication.

Specific Comments:

- At the end of the introduction section the objectives of the paper are quickly introduced. I would suggest specifically defining objectives, of which I believe there are two. 1: “To extract lakes larger than 1 sq km in Watern Mongolia from 1992 to 2021 and analyze the spatial and temporal changes as a result of…”, and “2, to utilize an SEM to quantify the impacts of climate change and human activities on the lake using meteorological, socio-economic and soil moisture data.”

Page 2 Line 93: “524 to 4,323 metres” – I believe you mean above sea level (ASL), so should read “524 to 4,323 metres above sea level”

Figure 1: This figure is very well done it show the relative elevation and location of the provinces that are being considered. Could you please change the colour of the salt water lake to blue? It currently shares a colour in the elevation symbology that may be confusing.

Page 3 Line 110: “GEE” – please define.

Section 3.1. Data Sources: The data source section is quite short. You have identified each of the datasets that you’re using in this analysis, however, little description is provided beyond stating what dataset you’re using is. Please provide further details of the datasets used in the analysis. For instance, how many landsat scenes are used? What seasons? For the Chelsa datasets, what are the precision of the datasets? Available range of data? Please provide more information so that in the future if studies look to replicate your analysis that it is possible.

Page 4 line 129: “eradicate terrain shadows” – what about “mask” instead of eradicate?

Page 4 lines 131 – 137: You discuss that the landsat images are superimposed together or layered together – do you mean that you’re creating an image composite? If so, how are you compositing the images together? You provide references, but there should be a description of the method of compositing. Also, your input dates, are you creating image composites for summer months? Are the composites annual? Please be specific to ensure reproducibility.

Page 5 lines 213 & 217 – Be sure to have equation numbers. And in the line 217 – be sure that all your variables are defined.

Figure 2 – the labels on the axes and the legend are very difficult to read, please increase the size.

Page 6 Lines 230 – 231: “The small, medium and large lakes contributed 4.66%, -9.87% and 105.18%, respectively to the lake area change” – The 105% value is confusing when looking at the area presented in Figure 2. Also, what timeframe is the boave sentence in relation to? 1992 – 1996?

Page 6 Lines 242 – 251: This paragraph simple reported values for the lake area change and rate of change for different administrative regions and could much more simply be understood with a Table summarizing the values. A map or set of choropleth maps could also help.

Figure 4 and 5: Please make reference to a) Alpine Lakes, b) Throughput Lakes, and c) Coccyx lakes in the figure caption, that goes for Figure 5 as well.

Page 8 Line 278: “in Zavkhan, Govi-Altai, and Bayan-Ulgii provinces rapidly decreased from 1995 – 1995” – Based on Figure 5, I only see one location that has rapid decrease in irrigation, I believe it’s Zavkhan – but I’m not sure because the figure size is too small.

Page 8 Line 294: “the most significant decrease in soil moisture was observed in the fourth layer” – What does this mean? The A horizon? B horizon?

Page 9 Line 295: “Correlation analyses were conducted to examine the relationship between environmental factors and lake area in each province” – IT’s a little confusing to me why you’re testing some of the environmental factors without stating a reason. For instance, would there not be factors here that would have the same impact on lake area? For instance, evapotranspiration and summer mean temperature? They appear to have nearly the exact same distribution over time. You state that PET,SMT and four-layer soil moisture have the significant correlations, however I would argue that all of those variables are presenting similar feedbacks to the same environmental conditions (summer tempeartures).

Page 9 – Keep in mind that if you are using acronyms to please define them.

Page 10 Line 333: “-0.719” I don’t see fhits value in figure 7.

Table 1 – Where are all the other values that are not being reported? Are only the significant values being reported?

Page 13 Lines 409 – 458: There are three sections here (Waterfowl, Sandstorm and Water Quality) that could be merged into one. The amount of detail here is exhaustive, and should be reduced because much of the information does not have to do with the topic at hand (lake area/number shrinkage). For instance, the information on the bear species, or the specifics of the concentration of NaCl is too in-depth.

Comments on the Quality of English Language

I have no concerns over the quality of the grammar or writing by the authors.

Author Response

Thank you for your valuable comments on to this paper, we have revised the paper as required. For specific replies,please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article investigates the changing contours of lakes in the western part of Mongolia. Similar studies have earlier been conducted for many regions of the planet. Therefore, there is no scientific novelty from this point of view in the article. The article itself is written correctly. The description of the research methods and the results obtained is presented quite clearly. In general, there are no comments on the article. The article can be published in this form.

Author Response

Thank you for your valuable comments on to this paper, we have revised the paper as required. For specific replies,please see the attachment.