Review Reports - Effects of Urbanization on Changes in Precipitation Extremes in Guangdong-Hong Kong-Macao Greater Bay Area, China

Round 1

Reviewer 1 Report

This is a very interesting research on the role of urbanized areas in precipitation in the Guangdong-Hong Kong-Macao Greater Bay Area, China. The combination of the space and time dimensions supported by statistical analysis contributes to a better understanding of these effects in large urban areas.

Broad comments

- I suggest that the authors can discuss and/or address in more detail the role of the extent of urbanization/urban areas in high-intensity rainfall events. From what dimension can urban areas influence spatial patterns and precipitation intensity?

- Is it possible to assume, in a broader perspective, that the effects of climate change on the increase in precipitation in a given area can be quantified or understood as the value of the increase in an urban area minus the value of the increase in a rural area? Perhaps the authors could further elaborate on this point in the manuscript.

- In my opinion, the subsections 4.1 and 4.2 should be included in the results section. Eventually, the authors can change the name of the section 3 to results and discussion.

- Does not the sentence written on page 19, lines 547-550 (“Third, in the stage III (Stable stage), except for NW (Fig.10 (c)) and CWD (Fig.10 (f)), the UFk curves of other EPIs rise further and all greater than that in the stage I (Slow urbanization) and stage II (Rapid urbanization), it means that in the third stage, extreme precipitation has further intensified)”, contradict the sentence written on page 12, lines 379-381 (“The findings reveal that the average extreme precipitation during Stage II exceeds that of Stage III, which in turn exceeds that of Stage I (except for NW and CWD)”)?

Specific comments

The following are minor errors that should be corrected:

- Figure 2: there is a missing “v” in the word “impervious” (vertical axis).

- Page 18, line 519: there is a repetition in the word “secondly”.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study explores the relationship between extreme precipitation and urbanization in the Guangdong Hong Kong Macao Greater Bay Area. The main problem is that statistical methods themselves can only indicate mathematical correlation and cannot prove the impact of urbanization on precipitation from a mechanistic perspective. One conclusion is that cities with rapid urbanization (Guangzhou, Foshan, Zhongshan, and Dongguan) have a more significant increase in extreme precipitation, which is a very suspicious viewpoint. At least from the current analysis, the author cannot convince me to accept this.

Other issues:

Land cover data was usually unreliable in the early years. Since you have no land cover data during 1986~1989, the interpolation from 1985 to 1990 (Figure 2) is not reliable. In your analysis of urbanization, the analysis before 1990 should be removed. This will affect your main conclusion (the three stages of urbanization).

Figure 1a: What is the difference between gray-shaded provinces and white provinces?

Figure 1b: Why are there no data in Foshan, Dongguan, Zhongshan and Shenzhen? There should be no missing data on altitude.

Table 1: CWD, wet days, not dry days.

Tabel 2: I don't think this is a good way to express the speed of urbanization. The proportion of urban land cover in different years of each city should be listed. As for GBA, the analysis of Hong Kong and Macau should not be excluded.

Why are there no data for Shenzhen, Dongguan, and Zhongshan in Figures 3 and 5-8, and there is no explanation in the main text?

Table 3: The number in the table is difficult to compare. A box plot or bar chart should be used to demonstrate these results.