Review Reports

Round 1

Reviewer 1 Report

The paper is well structured, minor revisions are required before publication.
In detail:
- more information are needed on the data used for the SWMM modeling, especially regarding the DEM (for example, the resolution must be indicated and it must be specified if it has been coupled to a topographic survey) and about the road-pipe network-water system. These data are only mentioned in lines 129 and 130
- more information is needed on the 12 rainfall events mentioned in paragraph 2.3.2 and on the 4 rainfall events analyzed in paragraph 3.3 (for example, the cumulative rainfall, the duration, the maximum rainfall intensity, etc.)

Author Response

Response to Reviewer 1.

Point 1. More information are needed on the data used for the SWMM modeling, especially regarding the DEM (for example, the resolution must be indicated and it must be specified if it has been coupled to a topographic survey) and about the road-pipe network-water system. These data are only mentioned in lines 129 and 130.

Response 1. We explained the DEM resolution and other basic data in more detail in lines 129-135. This is very necessary. Thank you for your suggestions.

The basic data obtained from the urban construction management department are used for the construction of the SWMM model. Among them, tertiary highways and rivers are used as the boundary of the subcatchments, DEM with resolution of 30 m, land use and pipe networks data are used for the model runoff generation calculation, involving the setting of basic parameters and the subcatchments and the nodes hydraulic connection. The model is calibrated on the basis of reflecting the actual situation as much as possible to simulate the process of urban rainfall and waterlogging.

Point 2. More information is needed on the 12 rainfall events mentioned in paragraph 2.3.2 and on the 4 rainfall events analyzed in paragraph 3.3 (for example, the cumulative rainfall, the duration, the maximum rainfall intensity, etc.)

Response 2. We have supplemented the information of the 12 rainfall events in Table 2, including the cumulative rainfall, the rainfall duration and the maximum rainfall intensity. This is helpful for explaining the rainfall threshold. Thank you for your suggestions.

Table 2. Information and classification results of the 12 rainstorms.

Rainfall events	Cumulative rainfall (mm)	Duration (min)	Maximum rainfall intensity（mm/min）	Return periods (a)
				0.5	1	2	5
20140729	58.0	70	2.20	CW	CW	CW	CW
20160805	53.5	80	1.75	CW	CW	CW	IW
20170812	63.5	110	1.70	CW	CW	CW	AW
20130807	78.5	110	1.60	CW	CW	CW	AW
20120827	50.0	130	1.50	CW	CW	CW	NW
20130811	52.0	90	1.15	CW	CW	AW	NW
20150722	35.0	90	1.05	CW	NW	NW	NW
20160719	24.5	130	1.10	NW	NW	NW	NW
20160605	37.5	140	0.95	CW	NW	NW	NW
20180727	38.0	150	0.75	AW	NW	NW	NW
20170729	43.0	180	0.60	AW	NW	NW	NW
20150501	19.5	180	0.15	NW	NW	NW	NW

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments:

This study has proposed a method for identifying criteria of urban waterlogging rainstorms and rainfall thresholds through the application of web crawlers. In particular, it is interesting to use Internet data resources to obtain and apply urban waterlogging information without extensive flood observation. However, for a better understanding, the paper needs to be supplemented as follows:

(1) I think the reliability of internet information, collected by web crawlers to supplement the lack of flood-related data, can greatly influence the accuracy of the results. From this point of view, eliminating wrong information is considered an important step in collecting reliable data. Especially in areas where information is scarce, information screening will be a more important process. Therefore, a more detailed description of this process is needed.

(2) Although full names of IW, AW, CW, and NW have been mentioned in the abstract, it is necessary to mention them again in the introduction.

(3) Authors mentioned in the Introduction that the rainfall intensity-duration (ID) curve has been used to improve the method of dividing thresholds of waterlogging. However, many studies have already analyzed and applied the IDF curves to investigate extreme rainfall, thresholds, and so on. Further literature research is needed in relation to it.

(4) It is necessary to explain exactly what the unit ‘a’ of the return period means.

(5) Check the units of duration shown on the x-axis of figure 6(a).

 

Author Response

Response to Reviewer 2 Comments.

Point 1. I think the reliability of internet information, collected by web crawlers to supplement the lack of flood-related data, can greatly influence the accuracy of the results. From this point of view, eliminating wrong information is considered an important step in collecting reliable data. Especially in areas where information is scarce, information screening will be a more important process. Therefore, a more detailed description of this process is needed.

Response 1. Data cleaning is an effective means to eliminate redundant and false information to improve the authenticity of the results, and we elaborate in lines 168-177. Thank you for your suggestion, it is very crucial for this research.

The reliability of internet information, collected by web crawlers to supplement the lack of flood-related data can greatly influence the accuracy of the results. From this point of view, data cleaning is considered an important step in collecting reliable data. The research achieves the purpose of data cleaning by eliminating redundancy and wrong information. Redundant information is mainly due to the same news reprinted by different news media, the wrong information mainly comes from news media's reports on flooding news in other regions or other times. For example, on July 21, 2012, Beijing, China suffered the worst rainfall event in the past 70 years, which caused widespread concern. The Weibo media in the research area also reported and reprinted this news in large numbers. These data are invalid for the research and need to be eliminated.

Point 2. Although full names of IW, AW, CW, and NW have been mentioned in the abstract, it is necessary to mention them again in the introduction.

Response 2. Thank you very much for correcting us in the details, we have modified it in the introduction, see lines 87-88.

This study is based on the urban waterlogging news obtained by web crawlers, combined with the rainfall ID curves to define and classify waterlogging rainstorms into 4 types, Rainfall intensity waterlogging (IW), Rainfall amount waterlogging (AW), Combined waterlogging (CW) and No waterlogging (NW).

Point 3. Authors mentioned in the Introduction that the rainfall intensity-duration (ID) curve has been used to improve the method of dividing thresholds of waterlogging. However, many studies have already analyzed and applied the IDF curves to investigate extreme rainfall, thresholds, and so on. Further literature research is needed in relation to it.

Response 3. Thank you for your comments. Since the ID curve covers rainfall intensity information, compared to the RD curve, it has improved significance for this study. We have further explained this part in lines 80-85.

       Compared with the RD curve, the ID curve can highlight the impact of rainfall intensity on waterlogging. Therefore, it has obvious improvement significance in the division of rainfall thresholds. This has been confirmed in the research fields of hydrogeological disasters such as mountain floods, landslides and debris flows. This study applies it to the study of urban waterlogging to comprehensively analyze the effects of rainfall intensity and accumulated rainfall in waterlogging.

Point 4. It is necessary to explain exactly what the unit ‘a’ of the return period means.

Response 4. Thanks for your suggestion, we explained the return period and its units in lines 185-187.

The return period of rainfall is an important basis for the construction of urban flood control facilities, in unit of year (a), it represents the average interval time between the occurrence of rainfall greater than or equal to a certain intensity, and the value is equal to the reciprocal of the frequency of heavy rainfall.

Point 5. Check the units of duration shown on the x-axis of figure 6(a).

Response 5. Thank you for correcting the details. The unit of the x-axis in Figure 6(a) is min, and we have modified it.

 

 

Author Response File: Author Response.pdf