Review Reports - Impact of Flooding on Shallow Groundwater Chemistry in the Taklamakan Desert Hinterland: Remote Sensing Inversion and Geochemical Methods

Round 1

Reviewer 1 Report

The manuscript and the topic of study fit well with Water's scope and aims. The paper has good structure and content. The results are presented in an appropriate manner and support the conclusions. However, the following must be addressed before the paper can be considered for publication.

Abstract

does PF stands for 'post flood'? if so instead of after flood mention post-flood... it might be better to use POF and PRF...

the results described in the abstract are just reporting the measured data rather than describing the meaning of this in terms of groundwater quality. for example, what is the meaning of these results in terms of local ecological environment development?? how the results can be applied for groundwater management, planning, etc.

Introduction

The intro section provides good discussions on the necessity of the research and the case-study area research efforts. The introduction content can be further enhanced by a more up-to-date review of the knowledge gap. Given that your manuscript investigates the effects of flooding events on the groundwater characteristics, I think some short discussions on the necessity of the study and understanding of the long-term effects of climate change can be beneficial (doi.10.3390/su11010213), e.g. climate resilience and ecology angle for discussions (doi.org/10.3389/fmars.2021.674630). I noticed you mentioned climate change, i.e. Ref 7, but didnt add any further info.

L52 - are you using the correct format for referencing? Bayanzul et al. (2019) or Bayanzul et al. [11]?

I think one of the relevant missing discussions in your literature is about the hyporheic exchange induced by flood events, and the potential for influencing the hydrochemical composition of groundwater (doi/10.1016/j.scitotenv.2020.141397).

L85-L94 - you are proposing 'This study provides a scientific basis for the utilization of water resources and the protection of vegetation in arid areas by combining traditional methods such as statistics, correlation analysis, Piper's trilinear diagram, Gibbs model, and ion ratio with new methods such as random forest modeling', I think the idea of using data-driven models for the problem addressed in the manuscript is excellent. However, your literature doesnt really reflect on the recent data-driven models for hydrological problems (e.g. doi./10.3390/hydrology9020036; doi/10.1038/s41598-022-08417-4; doi/10.2166/wst.2020.220). I think the brief discussion on the range of data-driven models adopted in solving hydrological problems can better engage the readers and provide information on the available methodological approaches for getting the most out of monitoring/remote sensing data.

Materials and Methods

Fig. 1 - I am not sure if I understood the picture of the trees? what is the significance of the trees? if you are referring to 'leafy coccyx oasis' then it can be useful to provide a more detailed caption for the Figure.

Section 2.1 and 2.2 have sufficient information. However, Section 2.3 requires more detailed info about the Random Forest Model. There is no in-depth definition of the model and governing equations, there is no discussion on the appropriateness of the proposed model for the problem studied, i.e. why this model and not other data-driven models? Section 2.3 needs significant enhancement in the revision to provide sufficient information about the model, equations, and the process that the model applied for the case study data.

Results and discussion

Overall, good results but I think the discussions lack depth and doesn't go further than just describing the values presented in the figures and tables. I think a comparison of the results with the existing data can be very useful, i.e. are you finding anything which is aligned or different from the existing knowledge in the field?

3.2. Correlation of individual ions - you describe the correlations but not much discussion? can you relate these correlations to the 'local ecological environment development' as promised in the abstract?

Fig. 3 is not acceptable in the current form - you will need to replot the figure as the axis, legend and the content is not really clear (too small) and cannot be read by the readers.

'3.4. Water chemistry type analysis based on piper trilinear diagram' - should read as 'water chemistry analysis' the text of the subsection can describe the method of data analysis and visualization (i.e. piper trilinear diagram).

Fig. 4 needs to be re-drawn and get enlarged so readers can understand the details

You dont have consistency in the formatting of your figures - e.g. font style and size changes. All your figures are drawn too small which dont allow the readers to easily interpret the data.

Conclusions

The conclusions are not providing information on the significance of the findings and the overall message of the paper. The manuscript states 'The results show that the environmental variables have a good relationship with the groundwater parameters, providing a reliable method for estimating groundwater ions and other parameters in other regions using environmental covariates.' what is this supposed to mean? the environmental variables have a good relationship with the groundwater parameters? what about the case-specific climate-specific considerations? I don't think this conclusion is very reliable.

The manuscript should reflect on the abovementioned detailed comments and revise the manuscript accordingly before it can be reconsidered for publication.

Author Response

Dear Sir/Madam,

Thank you so much for your kind encouragement on our manuscript entitled “Impact of flooding on shallow groundwater chemistry in the Taklamakan Desert hinterland: Remote sensing inversion and geochemical methods” (water-1718132) and sending us the review on our manuscript.

We greatly appreciate reviewer for your valuable comments and constructive suggestions. We have carefully addressed these points in our revised manuscript and a point-to-point response to the comments has been detailed in our Cover Letter, in which the comments are written in italics followed by our responses in regular text. In addition, the changes or revision were marked with red text in new version of the manuscript.

Now, we are resubmitting the latest vision of our manuscript to you.

Best wishes,

Lei Peng

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

I found manuscript water-1718132 by Lei Peng et al interesting and well organized. I think it should be soon published after some minor revisions as follows.

1) Authors utilize the words "remote sensing" in various places of text. Usually "remote sensing" is intended as a method which utilize satellites. I didn't find satellite or space techniques described so I think some changes in the English language should be done.

2) Authors consider chemical reactions but never tell something about the time of reactions which depends from water velocity. I think better to add some sentences about water velocity and to permeability of considered aquifers.

Author Response

Dear Sir/Madam,

Now, we are resubmitting the latest vision of our manuscript to you.

Best wishes,

Lei Peng

Responds to the reviewers' comments:

[1] Authors utilize the words "remote sensing" in various places of text. Usually "remote sensing" is intended as a method which utilize satellites. I didn't find satellite or space techniques described so I think some changes in the English language should be done.

[Response] Thank you for your suggestion. The main mention in remote sensing in the paper is in the method column, and the remote sensing data are mainly on the references of environmental variables for the inversion of groundwater parameters, such as digital elevation model (DEM), climatic factors, soil types, and other remote sensing images.

[2] Authors consider chemical reactions but never tell something about the time of reactions which depends from water velocity. I think better to add some sentences about water velocity and to permeability of considered aquifers.

[Response] Thank you for your suggestion. In this study, groundwater water samples were mainly obtained at two time points in October 2018 and May 2019, and the response time should be between the two time periods, while the groundwater water velocity was not measured because of the instrumentation (HOBO), and the permeability of the aquifer did some permeability experiments, which have been added in the paper. We have added the following:

In this paper, soil property characteristics and hydrogeological information of the study area were obtained through field survey and field infiltration experiment. Among them, the double-loop method was used to determine the soil infiltration coefficient K. The survey and experimental results showed that the soil and hydrogeological conditions in the study area were basically homogeneous and the soil structure was single, and the infiltration coefficients were almost similar, with values ranging from 8.84 to 9.36 m/d.

Round 2

Reviewer 1 Report

The manuscript is improved significantly. I could spot few minor formatting issues as below:

P2 - L70 it should read Cook et al. [16]...

P2 - L95 it should read Noori et al. [23]

p3 - L100 '...Sina Borzooei et al.[25]' should read Borzooei et al. [25]..

Author Response

I have revised the citation format as requested by the reviewer.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.