“The 20 July 2021 Major Flood Event” in Greater Zhengzhou, China: A Case Study of Flooding Severity and Landscape Characteristics

Round 1

Reviewer 1 Report

Please see attached PDF file for my comments.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Overall, this is an interesting topic. The methods are reasonable and the results are presented well. Figures look good. However, the paper reads in some parts like a technical note than a research article. I have the following questions/suggestions to improve the quality:

1. Line 124, how did you divide the study area into three sections? Was it based on specific physical characteristics? Explain this here clearly.

2. Line 175, how did you ensure that the selection of permanent/seasonal water bodies had not been affected by potentially unusual precipitation prior to the flood event? In other words, have you checked the regular extent of water bodies whose regular boundaries may have shifted due to extreme precipitation?

3. Line 189, How did you measure the river width? What tool was used? I understand the authors refer to the RivWidthCloud tool, but it’s not clear how it was used to fit in this study’s context. Did you make any modifications to the original code? 

4. “ENVI5.3” is capitalized in line 193, not capitalized in line 203

5. Line 208, what is the justification for this specific definition of GI? The most common definition of GI in literature is that it is at least a “planned” and “interconnected network of green and blue spaces” for a green space to be classified as green infrastructure. Your definition might therefore be too broad and potentially involve green spaces that are not placed as part of GI initiatives. Consider adding citations and/or a brief explanation to support the broad inclusion. 

6.  While this study acknowledges it could have applied GWR or a similar method, it doesn’t explain why it was not applied. (Lines 570 – 574)

7. Discussion section 4.1, while interesting, is too broad, try to connect it to your results and study area rather than focusing on a global context.

8. This is a minor suggestion: If the p-Value is significant, an asterisk may be used next to Moran's I value and described in the table description (e.g., * indicates p <0.05), rather than in a separate column. 

Author Response

1.The review’s comment: Line 124, how did you divide the study area into three sections? Was it based on specific physical characteristics? Explain this here clearly.

[Authors]: Our study divided the 137 km stretch into upper, middle, and lower regions along the Jialu River system based several criteria The starting point of Jialu River system is labeled as A and is traditionally regarded as its origin. The dividing point between the upper the middle regions is labelled as B, is where a major water diversion duct system meets Jialu River, and a major change in elevation occurs. The dividing point between the MJLR and LJLR is labelled as C and is the where the eastern administrative boundary of Zhengzhou City. D is the eastern edge of Greater Zhengzhou. 

2.The review’s comment: Line 175, how did you ensure that the selection of permanent/seasonal water bodies had not been affected by potentially unusual precipitation prior to the flood event? In other words, have you checked the regular extent of water bodies whose regular boundaries may have shifted due to extreme precipitation?

[Authors]: we have added the related description in Section 2.3 224-231. The daily rainfall data from June 1 to July 15 in 2018-2021 based on seven national meteorological stations throughout Greater Zhengzhou were collected and analyzed. No extreme rainfall events were observed from June 1 to July 15 in 2021. Hence, the satellite images collected on July 15, 2022 was an accurate representation of permanent/seasonal water bodies. Second, boundaries of permanent/seasonal water bodies were verified visually on computer by comparing our images to those obtained through Gaofen-6 on May 13, 2020 (a spatial resolution of 2m).

3.The review’s comment: Line 189, How did you measure the river width? What tool was used? I understand the authors refer to the RivWidthCloud tool, but it’s not clear how it was used to fit in this study’s context. Did you make any modifications to the original code? 

[Authors]: Our additions were listed at the Section 2.3 Lines 245-250. They are “The widths of the river were measured using ArcGIS in edit mode. The centerline was identified using a function Collapse Dual Lines to Centerline in ArcGIS. The entire center line was then divided into 1 km segments using the Equidistance Segmentation Tool. The widths of the river were calculated by creating a cross-sectional line perpendicular to the river centerline at the end points using the Construction Tool in ArcGIS.” We did not use “the RivWidthCloud tool” and deleted the reference to this tool in our manuscript to eliminate confusion.

4.The review’s comment: “ENVI5.3” is capitalized in line 193, not capitalized in line 203

[Authors]: Done.

5.The review’s comment: Line 208, what is the justification for this specific definition of GI? The most common definition of GI in literature is that it is at least a “planned” and “interconnected network of green and blue spaces” for a green space to be classified as green infrastructure. Your definition might therefore be too broad and potentially involve green spaces that are not placed as part of GI initiatives. Consider adding citations and/or a brief explanation to support the broad inclusion. 

[Authors]: We have made the correction based on this suggestion. Please refer to the Section 2.4.1, lines 273-274 for more information.

6.The review’s comment: While this study acknowledges it could have applied GWR or a similar method, it doesn’t explain why it was not applied. (Lines 570 – 574)

[Authors]: We revised our manuscript based on your comment (Section 4.3 lines 775-785) They are “The objective of our study was to reveal the spatial binary correlation of each factor along the Jialu River. The results of local bivariate Moran's I were used to visualize local spatial correlations by generating cluster maps (bivariate LISA map). We are hoping that our results can help city planners develop site specific recommendations. The reason that we did not use the GWR model is because it is better suited for exploring spatial heterogeneity so that users can estimate parameters at any place in the study area when the spatial coordinates are available. The GWR model is an extension of the general linear regression model and is typically used to build a linear relationship between a given dependent variable and a set of independent variables. We may try this modeling tool in our future studies.”

7.The review’s comment:  Discussion Section 4.1, while interesting, is too broad, try to connect it to your results and study area rather than focusing on a global context

[Authors]: We agree. We moved the Section 4.1 to the introduction section. Hope this will suffice.

8.The review’s comment: This is a minor suggestion: If the p-Value is significant, an asterisk may be used next to Moran's I value and described in the table description (e.g., * indicates p <0.05), rather than in a separate column. 

[Authors]: We added symbol “*” to describe the significant p-Value in the table and removed the separate column.

Reviewer 3 Report

The papers requires a thorough revision in order to start review process

Author Response

[Authors]: We have made major revisions to our manuscript and hope our changes met reviewer 3’s expectations.

Reviewer 4 Report

The following recommendations are suggested to improve the quality of the research paper:

1. Enlarge Fig. 1(a) to present the relative location of the province of the study area with China; texts are too small/illegible

2. Mention how the stretch of Jialu River was divided into three regions; what was/were the criteria?

3. In Section 2.2, Line 147, you mentioned that the rainfall data used were from July 19 to July 21, 2021. Is this the whole duration of that particular rainfall event or this duration was chosen because it was the day before and after the flood event? Elaborate the rationale for using this duration.

4. Check punctuation for the whole manuscript; Ex: Line 187; "...Yang et al. [51]..."

5. Most figures showing the results have very small texts/illegible; 

6. Check spacing for the whole manuscript; Ex:  In Lines 583 - 584, ".. model [103]and a scenario simulation method with different rainfall return periods [104]were applied to supports decision-making for GI planning. 

7. In Lines  595 - 596, did you mean "...flood mitigation planning and implementation..."?

8. Achievement of objective (4) provide a “real-world-tested” blueprint and effective resilience strategies of GI planning to achieve the dual goals of reducing flood vulnerability and increasing landscape connectivity is not strongly justified within the manuscript.

Author Response

Dear  Reviewers:

We would like to extend our sincere appreciation to all the reviewers for their valuable suggestions and comments regarding our manuscript entitled “The July 20 2021 Major Flood Event” in Greater Zhengzhou, China: A Case Study of Flooding Severity and Landscape Characteristics” (Manuscript ID: land-1938262). Since one of our co-authors is a regular reviewer for MDPI, our team can sense the high degree of professionalism of your selected peer reviewers. We have made major revisions to our manuscript based on their comments. Below are our responses to their specific points. Hope our changes are satisfactory to them.

 1.Enlarge Fig. 1(a) to present the relative location of the province of the study area with China; texts are too small/illegible

[Authors]: Done.

2.The review’s comment: Mention how the stretch of Jialu River was divided into three regions; what was/were the criteria?

[Authors]: We have added the detailed description in Section 21 lines 155-160. Here is what we added “Our study divided the 137 km stretch into upper, middle, and lower regions along the Jialu River system based several criteria The starting point of Jialu River system is labeled as A and is traditionally regarded as its origin. The dividing point between the upper the middle regions is labelled as B， is where a major water diversion duct system meets Jialu River, and a major change in elevation occurs. The dividing point between the MJLR and LJLR is labelled as C and is the where the eastern administrative boundary of Zhengzhou City. D is the eastern edge of Greater Zhengzhou.”

3.The review’s comment: In Section 2.2, Line 147, you mentioned that the rainfall data used were from July 19 to July 21, 2021. Is this the whole duration of that particular rainfall event or this duration was chosen because it was the day before and after the flood event? Elaborate the rationale for using this duration.

[Authors]: We added more details our manuscript in Section 2.2 lines 183-190. Here is what we added “The major rainfall event started on 0500 UTC on 18 July 2021, reached the highest perception rate at 1700 UTC on 20 July 2021, dropped to a very low rate at 0600 UTC on 21 July 2021, and completely stopped at 0900 UTC on 22 July 2021. Hence, 88.34% of the total rainfall amounts was captured between 0600 UTC on 19 July 2021 and 0600 UTC 21 July 2021.”

4.The review’s comment: Check punctuation for the whole manuscript; Ex: Line 187; "...Yang et al. [51]..."

[Authors]: Done.

5.Most figures showing the results have very small texts/illegible; 

[Authors]: We have enlarged the texts and reconfigured the figures to make them more legible.

6.The review’s comment: Check spacing for the whole manuscript; Ex:  In Lines 583 - 584, ".. model [103]and a scenario simulation method with different rainfall return periods [104] were applied to supports decision-making for GI planning. 

[Authors]: We have made the corrections throughout our manuscript.

7.The review’s comment: In Lines 595 - 596, did you mean "...flood mitigation planning and implementation..."?

[Authors]: It was a great catch! We replaced the word “planting” with “planning.”

8.The review’s comment: Achievement of objective (4) provide a “real-world-tested” blueprint and effective resilience strategies of GI planning to achieve the dual goals of reducing flood vulnerability and increasing landscape connectivity is not strongly justified within the manuscript.

[Authors]: We have made the change. Here is our revised objective (4) “develop an effective tool to help city planners in drafting flood mitigation strategies (Lines 146-147).”

Round 2

Reviewer 1 Report

The article has extensive improvements after the edits. Although many scientific or engineering questions are left for future works, the logic is now critical, and the presentation is clear. Thus, I consider this article appropriate to publish.

A few minor editing issues:

1. Line 135-136, replace the second "possible" with "potential."

2. Some of the numerical presentation formats are not consistent in the manuscript. For example, line 269 uses the English number "Seventy percent," while line 270 uses the Arabic number "30%". The same issues exist in section 3.4.

3. Please be consistent with the capitalized and non-capitalized words in section 2.5. For example, the "Local Bivariate" is always capitalized in the manuscript except for line 310, "Global and Local bivariate."

4. Line 534, "were observed in six pairs," should be "eight pairs."

Reviewer 3 Report

The revisions has been done