Exploring the Drivers for Changes in Lake Area in a Typical Arid Region during Past Decades

Round 1

Reviewer 1 Report

The authors investigated the spatiotemporal changes in the surface area of four lakes in a typical dry region in Northwest China, and they also illustrated the key drivers for these changes by integrating multiple sources of data and combining statistical and modeling methods. The topic falls into the scope of the journal, substantial analyses have been conducted, and interesting conclusions to peers have been drawn in the manuscript. Some minor revisions are needed before publication.

a) Plentiful results are presented in the study, but some descriptions, especially the results section, need to be revised and improved. For example, the sentence in lines 209-211 is unclear; the relationship between latitude and river inflow amount (lines 212-214) could not be supported by data at four lakes only; the reasons for the correlation between “lake surface precipitation” and “river inflow” (lines 231-232) needs to be deeply analyzed.

b) It’s a long manuscript that includes substantial calculations/analyses, but some detailed descriptions could be deleted or moved to the supporting materials. For instance, the specific numbers in lines 296-309 did not provide strong supports for the presentation of results, and relevant info could be found in corresponding figures, so I do suggest the authors deleted these numbers and descriptions. The specific descriptions of ice sublimation calculation and section 5.3 et al. could be moved to the supporting file.

c) Some important info should be added and clarified, including the specific temporal resolution of data in section 2.2, the methods of dividing different phases in section 4.3.1 (e.g., manual or quantitative methods), and the specific years (or periods) for the lake areas in Table 1, et al.

Detailed comments:

Line 13: ‘estimating different driver’s contribution ….’

Line 15: It should be ‘statistical’ methods.

Line 25: ‘arid zone’ should be changed to ‘arid region’ throughout the ms.

Lines 33-34: ‘expanding’ trend; ‘decreasing’ trend.

Line 80: dry ‘regions’ instead of ‘areas’.

Line 188: ‘results are shown…’

Line 228: ‘Relationships between …’

Line 310: River inflow, ‘as’ …

Line 538: ‘an increasing trend’…

The English is ok.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

- -the explanation of the abbreviation of units 10a^-1 is missing

- A sediment supply factor  should not be taken into account in the possible reduction of the storage volume of the lakes during the evaluated years ?

- How was the wind factor taken into account during evaporation and sublimation processes?

- Seepage through the bottom of the lakes did not affect the water balance

- In Figure 1, I recommend marking the divides of the watersheds

- A more extensive discussion and comparison with relevant research results of other authors would contribute to increase the scientific level of the article

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Water balance elements of lakes, such as inflow and outflow from the lake (river - here), atmospheric precipitation, evaporation from the water surface and sublimation, are well-researched and described in scientific literature. The literature also provides examples of the impact of water supply on the lake's surface area. In recent years, research has also focused on the influence of climate change on lake surface changes. In the presented work, the authors aim to confirm this knowledge pertaining to a selected geographic region in a dry area using modern mathematical analyses.

Abstract

Please briefly write which lakes were selected for study and what was found (from line 19)

Introduction

Please describe the effects of climate change on lake surface changes coherently, so that it is clear from the content whether the authors are referring to the 84 lakes mentioned and whether this applies to the further mentioned lakes discussed in this manuscript. Perhaps this is a translation issue?

Similarly, lines 40 - 43 - unclear. Please describe it differently

Lines 67 - 73 - please move to Methodology chapter

I think that the threads of anthropopression and groundwater recharge should be introduced into the Introduction chapter. To which the authors refer in the Discussion of results

2.1 Study sites

Please describe the location of the lakes and terrain in more detail. This is of great interest to readers from a different geographical area. What "elevations" in this context means? Please give the depth of these lakes (maximum, average), this is very important information.

Line 84: The low winter temperature (range?)

Table 1: why do the authors put Salinity in the table, when nowhere in the text do they comment on it? What is the relevance of water salinity to the topic at hand? Salinity varies widely, perhaps this should be commented on in the discussion or when characterising the lakes?

Is the duration of ice cover on the lakes (given in the table) an estimate or based on observational data?

2.2 Study materials. Please organise the data (maybe add a diagram?) for the lakes analysed. Perhaps a table should be added in the supplement? For each lake, describe which data were taken from which source. In fact it is described, but it is difficult to read, please simplify it.

The abbreviations used in the manuscript should be explained in the Methodology chapter.

Please describe the phases of the lake. What is it and what years does it cover? The authors refer to this in the table

3.1 Calculation of TWVF and sublimation

In our previous study [19] , we evaluated .... (reference site)

Results.

Open and closed lakes. The authors list open lakes, namely Bosten Lake, Ulungur Lake, and Ebinur Lake, and the outflow is only given for Bosten Lake. Why?

Table 2. Can the data for individual lakes be separated by a horizontal line?

Discussion

The first paragraph is not a discussion, it does not refer to the results obtained by the Authors, but adds other, different research results. Please describe it in a different way

478 While the CLM method has been considered one of the more 497 accurate approaches for modelling and calculating TWVF in lakes (add references)

496 - 501 in my opinion this is a conclusion, not part of the discussion

504 - 514 this is a methodology, not an element of discussion

6. Conclusions - in fact it is not conclusions but summary.  Please write what conclusions come out of your research. However, if this chapter is to remain a summary, please try to refer to the entire study area coherently and point out similarities and differences , rather than describing each lake separately again.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Review of Manuscript ID: water-2576916

The evaluated manuscript’s main subject is an estimation of the main components of the water balance of four lakes in the arid region of China and an analysis of long-term changes in the area of analyzed lakes. Limnology of drylands is a less recognized part of limnological research. Hence such type of analysis is important for better recognition of lake functioning in dry regions.

I think the paper is relatively well written, but the presented analysis seems to be incomplete. For the water balance of lakes, very important information is also vertical water exchange. The Authors analyzed not every component of water balance – the exchange between lake and ground is incomplete. They mention that in SWAT model the hydrogeological data are included. However, we have no information about the basic limnological characteristics of investigated lakes, such as lake water volume, maximum depth, mean depth, and water retention time. Also, information about the lake’s total and direct catchment areas should be presented They are very important, considering the water exchange processes in the lake and the water balance. They should be analyzed as well, together with other parameters. Therefore I think that the evaluated manuscript should give the information I mentioned above, for a complete explanation and understanding of the water balance for analyzed lakes, and all factors should be discussed together. Also trends of air temperature and precipitation shoud be more discussed, if Authors would like to obtain proper conclusions about climate change influence on long term lake water balance changes. Also I could not open the supplementary file of the evaluated paper, hence I did not take this part in my evaluation.

Author Response

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Round 2

Reviewer 4 Report

Dear Authors,

You manuscript was improved and I have no further comments.