Quantifying the Effects of Climate Variability, Land-Use Changes, and Human Activities on Drought Based on the SWAT–PDSI Model

Round 1

Reviewer 1 Report

This manuscript quantifies the impact of climate change, land-use change, and other human activities on drought change based on a constructed SWAT-PDSI model. The manuscript writing is standardized, and the research content is innovative. The results are of guiding significance for drought prevention and control. Therefore, I suggest that the paper be accepted after a minor revision. 

1. Figure 1 is unclear, so the resolution needs improvement.

2. I suggest adding the introduction of climate characteristics related to this article in Section 2.1.

3. Line 260 and 317, Please modify the superscript format of R2 and km2.

4. In Figure 8, please change the abbreviation to the same form.

5. Line 274, Is the reduction rate -0.022/10a or -0.22/a? Please confirm according to Figure 3. I think the current rate is wrong.

Author Response

Dear Reviewer,

Enclosed in this document are our responses to the specific comments from the three reviewers concerning our manuscript entitled “Quantifying the effects of climate variability, land use change, and human activities on drought based on the SWAT-PDSI model” (ID1823083). Those comments are very helpful to our revising and improving the paper. We have studied reviewer’s comments carefully and have made revision which marked in red in the paper. We greatly appreciate your and the reviewers’ help.

Best regards,

Baofu Li

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is well structured and organized and presents a novel work of interest to LULC research communities. The subject of your manuscript is appropriate for the journal. The authors address a very interesting topic regarding the LULC change through on the SWAT model and PDSI. The manuscript is well-written, the objectives are successfully achieved. However, I was wondering about a clear change in LULC between the time periods, which would make readers understand which areas contribute the most. Please see my comments below.

Major comments:

Authors have shown the spatial distribution of LULC and quantified their changes. However, it is not cleared which regions have experienced most of the LULC changes. It would be thus interesting if authors can show a figure by taking differences in the LULC between the periods. e.g. Spatial distribution of the changes in LULC between 1990 and 1995; similarly, between 1990 and 2005; and between 2000-2015.

I am also interested to understand the relationship between the changes in rates of the LULC changes and temperature and/or precipitation. e.g., quantify the LULC changes between 1990 and 1995; similarly, between 1995 and 2005; and between 2005-2015. See the trend between these periods.

Author Response

Dear Reviewer,

Enclosed in this document are our responses to the specific comments from the three reviewers concerning our manuscript entitled “Quantifying the effects of climate variability, land use change, and human activities on drought based on the SWAT-PDSI model” (ID1823083). Those comments are very helpful to our revising and improving the paper. We have studied the comments carefully and have made revision which marked in red in the paper. We greatly appreciate your help.

Best regards,

Baofu Li

Author Response File: Author Response.docx

Reviewer 3 Report

This article especially interesting to hydrologists. In the reviewed manuscript, there are several issues that need to be clarified, including:

 - in the first points, the authors referring to the phenomenon of drought, did not indicate what stage in the development of drought they would be dealing with - whether atmospheric, soil or hydrological drought

 - clearly indicate the purpose of the research,

 - the point "Introduction" requires complementing the information with the results of research by scientists from other regions of the world in terms of changes and variability of droughts

 the homogeneity of the data is a key issue in the analysis, but in the manuscript has not been confirmed in any way - it needs to be complemented

Specific Comments for Authors

Page 3 point 2.1

There is lacks of  assessment of the hydrometeorological conditions in the accepted area. I suggest enriching the manuscript with a short description of the research area in terms of variability, e.g. precipitation, temperature, degree of development

 Page 3 Figure 1

Figure is not legible;

In the drawing, the names of the town (np. Linyi – page 3, page 13) / province that were indicated in the text should be marked,

 Page 3 line 137

"Meteorological data were ..." - what data? From what period?

Page 3 point 2.2

Nothing was mentioned about the homogeneity of the hydrometeorological data.

Are the included hydrometeorological data homogeneous? In what way was their homogeneity verified? - I suggest adding the information

 Page 4 equation 3

What does "S" mean?

 Page 4 line 170

“… Where R is the daily rainfall infiltration depth (mm), and Ia includes surface water storage (mm), interception (mm) and infiltration (mm)” - what method were these values determined by?

 Page 4 equation 4

What does "Ksat" mean?

I suggest checking the explanation of the symbols used throughout the text

 Page 6 line 212

"... Mann Kendall test ..." - I suggest adding citation

 Page 6 line 217

"... and modern statistics were used to analyze the characteristics of land use change in the basin in 1990, 1995, 2005 and 2015" – requires any comment why these years had been chosen.

Why are the other characteristics come from the years: 2009-2019 (page 3 line 134), 1980-1989 (page 7 line 227)

 Page 7 line 227

"In this study, the average SWAT-PDSI value from 1980 to 1989 was used as a benchmark to study drought change and its attribution in the different years" - why was the average from 1980-1989 taken as a reference to the drought change study?

 Page 8 line 259

The title of point 3.1 is the same as point 2.3.1 - I suggest changing the title of point 2.3.1

 Page 8 Figure 2

In Figure, the outer marks of the OX and OY axes should be added - this remark involves to all the figures included in the manuscript

 Page 8 Figure 2

In terms of low flows there is a low compliance of observed and simulated flows, e.g. in 2010, 2013, 2014, 2015, 2017, 2018, 2019 - how was the quality of the model assessed?

Had the model been verified also on independent material?

Page 8 Figure 4

The title of the drawing is not clear

 Page 9 line 287-288

"... experienced a significant increasing trend ..." - is the trend statistically significant?

"... P <0.05 ..." - the notation is not clear, is it a p-value?

 Page 10 line 306

“… Therefore, choosing the land use types in 1990 and 2015…” – the notation is not clear against to page 6 line 217 (“… to analyze the characteristics of land use change in the basin in 1990, 1995, 2005 and 2015 ... ")

 Page 11 Figure 6

"Compared to 1990, changes in the land use types in the Yihe River basin in 1995, 2005 and 2015" - in Figure there is lack of data from 1990 - so the record is not clear

 Page 14 line 446-451

I suggest adding information on the statistical significance / significance level of the detected trend in changes in precipitation and temperature

Author Response

Dear Reviewer,

Enclosed in this document are our responses to the specific comments from the three reviewers concerning our manuscript entitled “Quantifying the effects of climate variability, land use change, and human activities on drought based on the SWAT-PDSI model” (ID1823083). Those comments are very helpful to our revising and improving the paper. We have studied the comments carefully and have made revision which marked in red in the paper. We greatly appreciate your help.

Best regards,

Baofu Li

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Authors have addressed my comments. It good be good if authors could write few sentences in the text about the new figures added in the manuscript. 

Author Response

Reply:

Thanks for the comments! We have written few sentences in the text about the new figures added in the manuscript.

Revised:

From the transfer of land use change in the Yihe River, the transfer quantity of water body, forest and dryland was the most obvious during 1990-1995 and 1995-2005. Among them, the transfer of water to forests is the highest, accounting for 15.33% (636km2) and 15.51% (700km2) of the dominant change directions in the two periods respectively. From 2005 to 2015, the transfer quantity of wetland, unused land and built-up was the most obvious, among which the transfer quantity of wetland to unused land was the most obvious, accounting for 63.46% of the total transfer out area.

Reviewer 3 Report

Comments for Authors

 I thank the authors for their comprehensive answers.

 The article had been greatly improved taking into account comments.

However, I suggest verifying Figure and inserting the outer marks of the OX and OY axes – this suggestion is refers especially to Figure: 1, 2, 3, 5 (a, b), 8, 10.

Page 10 line 310

"P <0.05" – the notation is not clear, I suggest giving  p <0.05

Page 13 Figure 8

I suggest putting the legend common to Fig 8 a, b, c only once

Author Response

Comments:

I thank the authors for their comprehensive answers. The article had been greatly improved taking into account comments.

Reply:

Thanks for your comments! We have made correction according to the comments.

1. However, I suggest verifying Figure and inserting the outer marks of the OX and OY axes – this suggestion is refers especially to Figure: 1, 2, 3, 5 (a, b), 8, 1

Reply:

  Done. Please see the Figures.

2. "P <0.05" – the notation is not clear, I suggest giving p <0.05(page10 line 310)

Reply:

     Done.

Revised:

From 1980 to 2019, the average temperature in the Yihe River basin experienced a significant increasing trend (0.13 °C/10 a, p < 0.05)

3. I suggest putting the legend common to Fig 8 a, b, c only once.(page13 fig 8)

Reply:

Thanks for the comments! We have putting the the legend common to Fig 8 a, b, c only once.