Analysis of Effects of Sponge City Projects Applying the Geodesign Framework

Round 1

Reviewer 1 Report

The topic presented in this paper is exciting and has a novelty, but the most significant weakness lies in the method used.

-    There must be a justification why only nitrogen was chosen as an indicator for water quality analysis. Phosphate or sediment content is also important as an indicator of water quality.

-    In the results section, the author should include a map of the LULC analysis results along with a map of the soil characteristics at each site. These maps show the existing conditions (scenario 1). In scenarios 2 and 3, the author should present the LULC design map to know where the changes in each land cover type are in each scenario and the extent of the changes.

-    The method used to determine the difference in the effect of the scenarios on the three Sponge City Projects is not quite right. The author should apply a larger scale of observations, not generalize on the whole watershed area. The author should use a higher spatial resolution, for example, 5 x 5 m or 1 x 1 m, as well as the DEM used, should be more detailed.

-    If you continue to use the InVEST model, the boundary study of each site (resulting from DEM extraction) should be at the micro watershed or mini watershed level.

Author Response

The English error is on the process of revision by a professional editor.

The topic presented in this paper is exciting and has a novelty, but the most significant weakness lies in the method used.

-    There must be a justification why only nitrogen was chosen as an indicator for water quality analysis. Phosphate or sediment content is also important as an indicator of water quality.

→ The phosphate analysis is added in 3. Results.

-    In the results section, the author should include a map of the LULC analysis results along with a map of the soil characteristics at each site. These maps show the existing conditions (scenario 1). In scenarios 2 and 3, the author should present the LULC design map to know where the changes in each land cover type are in each scenario and the extent of the changes.

→ The LULC scenario maps are added in Figure. 3. The tables showing changes in LULC according to different scenarios (Table 2. 3. 4.) are added.

-    The method used to determine the difference in the effect of the scenarios on the three Sponge City Projects is not quite right. The author should apply a larger scale of observations, not generalize on the whole watershed area. The author should use a higher spatial resolution, for example, 5 x 5 m or 1 x 1 m, as well as the DEM used, should be more detailed.

→ In order to run the NDR analysis and the urban flood risk mitigation analysis in InVEST model, the watershed should be set as the basic analysis unit. The watershed scale selected for the analysis is level 2 according to Strahler’s order, which is generally used in the watershed classification in China. If the scale gets large than level 2, the analysis area was not proper for the InVEST model yielding distorted results. The level 2 watershed was the largest scale we can apply in the given condition. A detailed explanation about the scale issue is added in 2.1. In terms of the watershed scale, level 7 is the smallest and level 2 is the largest.  

-    If you continue to use the InVEST model, the boundary study of each site (resulting from DEM extraction) should be at the micro watershed or mini watershed level.

→ In order to run the NDR analysis and the urban flood risk mitigation analysis in InVEST model, the watershed should be set as the basic analysis unit. The watershed scale selected for the analysis is level 2 according to Strahler’s order, which is generally used in the watershed classification in China. If the scale gets large than level 2, the analysis area was not proper for the InVEST model yielding distorted results. The level 2 watershed was the largest scale we can apply in the given condition. A detailed explanation about the scale issue is added in 2.1. In terms of the watershed scale, level 7 is the smallest and level 2 is the largest.  

City issues related to emerging flooding within large cities, especially regions with rapid development become an increasingly important topic. The concept of Sponge City to mitigate such urban issues is no doubt a great topic, and analysis of its effects should be attractive to the readers.

However, a lot of aspects of sponge city aren’t well described. For instance, what is considered the general protocol of sponge city, what components are required for each protocol? The three scenarios are just design abstract that is very superficially touched on this topic, but the authors do need to further dig into it.

Author Response File: Author Response.docx

Reviewer 2 Report

City issues related to emerging flooding within large cities, especially regions with rapid development become an increasingly important topic. The concept of Sponge City to mitigate such urban issues is no doubt a great topic, and analysis of its effects should be attractive to the readers.

However, a lot of aspects of sponge city aren’t well described. For instance, what is considered the general protocol of sponge city, what components are required for each protocol? The three scenarios are just design abstract that is very superficially touched on this topic, but the authors do need to further dig into it.

For the nutrient modeling, why select nitrogen only? Need justification for that. For the pollutant in the watershed as well as the flood risk mitigation model, the results need to be refined to make a convincing analysis of its effect.

Why did the authors end up choosing three parks for a sponge “city” study? It would make more sense if you have selected the urban area. The authors definitely need to expand their introduction and discussion of the scope of “Sponge city”, apparently, “urban water management called Sponge City” as you defined in the second paragraph does not well represent the scope of this paper.

Discussions need to focus more on the sponge city topic. rather than the model that you used to implement the sponge city concept.

What spatial scale is considered in this study? Regarding “city”, the results shown from figure 5 and 6 are kind of narrowed down. You need discuss the limit in terms of spatial scale coverage.

Given these concerns, I still suggest an acceptance for publication, but major revisions are required to address the above comments.

Specific comments:

Line 28: the frequency of heavy?

Line 61 to 63, please expand your literature review, and discuss how other researchers have been done on this topic.

Line 82: please add his last name.

Line 170, why select nitrogen only? Need justification.

Line 233: Figure 5: not quite intuitive to understand. Please change a different color scheme.

Line 303: those statistics are kind of black box to the readers.

Line 321: I would like to see the authors discuss more on the sponge city topic.

Author Response

The English error is ㅑn the process of revision by a professional editor.

City issues related to emerging flooding within large cities, especially regions with rapid development become an increasingly important topic. The concept of Sponge City to mitigate such urban issues is no doubt a great topic, and analysis of its effects should be attractive to the readers.

However, a lot of aspects of sponge city aren’t well described. For instance, what is considered the general protocol of sponge city, what components are required for each protocol? The three scenarios are just design abstract that is very superficially touched on this topic, but the authors do need to further dig into it.

→ The details of the sponge city solution and protocols are added in 1.2. More detailed interpretations of the result related to sponge city issues are added in 4. Discussion.

For the nutrient modeling, why select nitrogen only? Need justification for that. For the pollutant in the watershed as well as the flood risk mitigation model, the results need to be refined to make a convincing analysis of its effect.

→ The phosphate analysis is added.

Why did the authors end up choosing three parks for a sponge “city” study? It would make more sense if you have selected the urban area. The authors definitely need to expand their introduction and discussion of the scope of “Sponge city”, apparently, “urban water management called Sponge City” as you defined in the second paragraph does not well represent the scope of this paper.

→ The explanation why we chose the three sites for the sponge city study is described in detail 2.1.

→ The details of the sponge city solution and protocols are added in 1.2

Discussions need to focus more on the sponge city topic. rather than the model that you used to implement the sponge city concept.

→ More detailed interpretations of the result related to sponge city issues are added in 4. Discussion.

What spatial scale is considered in this study? Regarding “city”, the results shown from figure 5 and 6 are kind of narrowed down. You need discuss the limit in terms of spatial scale coverage.

→ In order to run the NDR analysis and the urban flood risk mitigation analysis in InVEST model, the watershed should be set as the basic analysis boundary. The watershed scale selected for the analysis is level 2 according to Strahler’s order, which is generally used in watershed classification in China. If the scale gets large than level 2, the analysis boundary was not proper for the InVEST model yielding distorted results. The level 2 watershed was the largest scale we can apply in the given condition. The detailed explanation about the scale issue is added in 2.1. In terms of the watershed scale, level 7 is the smallest and level 2 is the largest.  

Given these concerns, I still suggest an acceptance for publication, but major revisions are required to address the above comments.

Specific comments:

Line 28: the frequency of heavy?

→ The error is revised

.

Line 61 to 63, please expand your literature review, and discuss how other researchers have been done on this topic.

→ A more in-depth literature review is added in 1.3

.

Line 82: please add his last name.

→ The error is revised.

Line 170, why select nitrogen only? Need justification.

→ The phosphate analysis is added.

Line 233: Figure 5: not quite intuitive to understand. Please change a different color scheme.

→ The LULC scenario maps are added in Figure. X. The table showing changes in LULC according to different scenarios (Table X.) is added.

Line 303: those statistics are kind of black box to the readers.

→ The more detail interpretation of the result is added.

→ The added LUCL scenario maps and the table showing changes in LULC according to different scenarios may give a more clear explanation of the statistics.

Line 321: I would like to see the authors discuss more on the sponge city topic.

→ The details of the sponge city solution and protocols are added in 1.2. More detailed interpretations of the result related to sponge city issues are added in 4. Discussion.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have taken into account my comments and suggestions on the review. I recommend the manuscript can be continued for the next process in Land, while waiting for the results of the English correction.

Author Response

Thank you for your comments. The English revision is done by the professional editor and reflected in the revision version of the manuscript.