Three-Dimensional Surface Deformation Characteristics Based on Time Series InSAR and GPS Technologies in Beijing, China

Round 1

Reviewer 1 Report

The article presents a broad analysis of the impact of the exploitation of underground water resources on the land surface, based on the example of Beijing. In addition to the analysis of land surface displacements based on the PSInSAR, reference measurements were carried out using classical measurement techniques, i.e. leveling and GPS measurements. The comparison of three measurement techniques deserves recognition, because the authors often limit their research only to satellite interferometry techniques. In this way, a spatial field of displacements was obtained.

I am asking the authors to take into account their remarks and comments.

1. A) A few small editing errors:

1) line 255, correct vertial

2) lines 281, 296, 301, why authors use settlement rate instead of subsidence rate?

3) lines 285-286, please correct power exponent (10 ^ 4),

4) lines 322 and 326, please correct power exponent (R ^ 2),

5) line 524, please correct 300mwasn't,

1. B) Notes to figures and tables:

1) Fig.4, the drawing is not legible, please consider show a few points on the scatterplot and compile the displacements for: PSI, GPS and leveling,

2) Fig. 6, what is the reason for the visible annual trend for PSI displacement?

3) Table 3, please explain for which period the data are presented in the table: 2013-2018, annual (which one) or others? what is the difference between mm / y and mm / a? The most important thing, how was the accuracy determined? Is it position accuracy or displacement accuracy?

1. C) Remarks on the methodology:

1) Please describe the methodology of measuring altitude, what are the tie points? How long was the measurement session with GPS receivers? It determines accuracy of vertical and horizontal coordinates components. Did authors only use the GPS system? 

2) section 3.2.1, how was LOS to vertical displacement decomposition done using only one descending orbit?

3) Table 2 specifies the accuracy of the PSI vertical displacements, did the authors consider comparing the subsidence differences for adjacent points for individual measurement techniques?

4) in Fig. 9 some of points show random directions of displacements in successive periods, e.g. 3 points near Nankou fault. Are the observed values ​​of displacements greater than the accuracy? What could be the reason for this behavior of displacement vectors? How to explain the behavior, i.e. the value and direction of the displacements south and east of the Daxing district?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

Dear Editors,

The study is well organized and presented. The research design is appropriate. The methods are adequately described. The results are clearly presented and the conclusions are supported by the results.

The most important issue that you should be address has been detected in the "Discussion" section and in particular to the "5.1.1 The control effect of basement structure on vertical deformation" subsection, where there is a misunderstanding of the thickness of the Quaternary beds and the fault offset. Please see the comments for details.

Furthermore, it is recommended to add in the Discussion section a comparison of your results with previous and recent published studies concerning the subsidence of the Beijing Plain area detected by using similar methodology or synergies of methodologies. Do you detect agreement or differences? Which methodology is better and more accurate?

I have added more comments in the attached pdf file. 

With best regards

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf