Identification of Preferential Runoff Belts in Jinan Spring Basin Based on Hydrological Time-Series Correlation

Round 1

Reviewer 1 Report

Thanks for taking care of the revised manuscript. I have decided to accept it. Just polish another time the English language and look with the editors for improving the figures.

Author Response

Dear Reviewers and Editors,

Thank for your comments concerning our paper. We have made careful corrections that we hope to meet your approval. The detailed responses to your comments are as following:

 

Responses to Reviewer 1 Comments

 

Point 1: English language and style are fine/minor spell check required.

Response 1: Thanks for your approval and suggestions. We have carefully scrutinized the manuscript, and made corresponding revisions including some typos, grammatical errors and long sentences, etc.

We look forward to hearing from you regarding our submission. We would be glad to respond to any further questions and comments that you may have.

                               Yours sincerely,

                               Author: Niu Shuyao

 

Author Response File: Author Response.doc

Reviewer 2 Report

Wavelet analysis for time and frequency domain is a particular kind of Time Series Analysis.

This method has been applied to a Chinese karst system with the aim to define the relation and time lag between precipitation (input) and respectively springs flow rate and groundwater level.

Moreover, the Pearson correlation coefficient has been used to describe possible correlations between the same parameters. 

The paper is well constructed and written.

However, in my opinion, is really strange a too small correlation between precipitation and springs flow rate. It is acceptable for groundwater but not for springs. 

Are there other external factors that control the aquifer? Your statement about the deficiency of Pearson coefficient is not convincing.

Finally, why did you use the wavelet and not the simple time series analysis indicated by Mangin which would have given you more information on the karst system?

 

 

Author Response

Dear Reviewers and Editors,,

Thank for your comments concerning our paper. We have made careful corrections that we hope to meet your approval. The detailed responses to your comments are as following:

 

Responses to Reviewer 2 Comments

 

Point 1: However, in my opinion, is really strange a too small correlation between precipitation and springs flow rate. It is acceptable for groundwater but not for springs. Response 1: Line 251-254：Thanks for your constructive comments and suggestions. We agree and have updated. In this part, we explained the reason why the correlation coefficient is small in more detail. We have calculated that the correlation coefficient will be larger if we remove the time-lag of precipitation and spring water level artificially, and the correlation coefficient is about 0.3-0.4. However, there is a time-lag of 3-4 months between precipitation and spring water level, and the time-lag will affect the correlation coefficient between the two, so the correlation coefficient is small.

Point 2: Are there other external factors that control the aquifer? Your statement about the deficiency of Pearson coefficient is not convincing.

Response 2: Line 47-52: Thanks for your constructive comments and suggestions. Jinan karst system is mainly affected by natural factors and human factors. Natural factors include precipitation, and human factors include groundwater exploitation and urbanization. But precipitation is the primary factor affecting spring dynamics since 2003. We supplemented these contents in introduction.

Line 156-157(Figure 3): Thanks for your constructive comments and suggestions. In Figure 3, the variation of spring water level lags behind precipitation. In some periods, the changes of precipitation and spring water are even opposite.

Line 251-254: Thanks for your constructive comments and suggestions. We explained the reasons for the correlation coefficient is small in these sentences. This part has been introduced in Response 1.

Point 3: Finally, why did you use the wavelet and not the simple time series analysis indicated by Mangin which would have given you more information on the karst system?

Response 3: Line 87-92: Thanks for your constructive comments and suggestions. Considering the reviewer’s suggestion, we have further illustrated the functions and advantages of the XWT. The XWT can examine relationships in time frequency space between two time-series, and can calculate cross wavelet phase angle, the cross wavelet phase angle can be used to analyze the time-lag of two time-series.

We look forward to hearing from you regarding our submission. We would be glad to respond to any further questions and comments that you may have.

                               Yours sincerely,

                               Author: Niu Shuyao

Author Response File: Author Response.doc

Reviewer 3 Report

The authors suggest that their use of time series is unique: even if it the first use for preferential runoff belts.  However, that is not a correct statement.  Time series analysis has been utilized for studying water properties for decades.

Time series has four components: (1) trend; (2) seasonality; (4) cycles; and (4) variation and possibly (5) irregular points in the data.  It is utilized for the following two items:  (1) to obtain an understanding of the underlying forces and structure that produced the observed data; and (2) to fit a model and proceed to forecasting, monitoring or even feedback and feedforward control.   Moreover, time series provides a preliminary or initial tool for detecting data that allows one to see what factors influence certain variables from time to time or period to period.  That was not done in this study.  Using time series: it is utilized for forecasting.  That too was not done in this study, i.e., there is no future or past forecasting for the preferential runoff belts .  How does the water or the preferential runoff belts change over time?  That also is not clear.

Additionally, it was not clear to me why assessing or studying preferential runoff belts is relevant or important.  Also, would damming the preferential runoff belts aid in keeping more water for use by people, farming, etc.?  This is not addressed.  It should be.

If the authors insist on using time series to analyze their data, they ought to sit down and decide why they seek to use it as opposed to a regression or other statistical tool.  The authors state that this "study was conducted in Jinan Spring Basin to identify preferential runoff belts based on hydrological time series correlation."  But, unfortunately, I did not discern an explanation why this was done and towards what end this study was undertaken.

  

Author Response

Dear Reviewers and Editors,,

Thank for your comments concerning our paper. We have made careful corrections that we hope to meet your approval. The detailed responses to your comments are as following:

Responses to Reviewer 3 Comments

 

Point 1: The authors suggest that their use of time series is unique: even if it the first use for preferential runoff belts. However, that is not a correct statement. Time series analysis has been utilized for studying water properties for decades.

Response 1: Thanks for your constructive comments and suggestions. We have deleted these incorrect statements of this paper.

Point 2: Time series has four components: (1) trend; (2) seasonality; (4) cycles; and (4) variation and possibly (5) irregular points in the data. It is utilized for the following two items: (1) to obtain an understanding of the underlying forces and structure that produced the observed data; and (2) to fit a model and proceed to forecasting, monitoring or even feedback and feedforward control. Moreover, time series provides a preliminary or initial tool for detecting data that allows one to see what factors influence certain variables from time to time or period to period. That was not done in this study.

Response 2: Line 41-52: Thanks for your constructive comments and suggestions. We have tried our best to revise the manuscript according to your kind and construction comments and suggestions. There have been many research on the characteristics of hydrological time-series in Jinan Spring Basin and the factors affecting spring water, and the analysis results of hydrological time-series show that Jinan spring is mainly affected by natural factors and human factors. The primary factor affecting spring dynamics since 2003 is atmospheric precipitation. We supplemented these contents in introduction.

Point 3: Using time series: it is utilized for forecasting. That too was not done in this study, i.e., there is no future or past forecasting for the preferential runoff belts. How does the water or the preferential runoff belts change over time? That also is not clear. 

Response 3: Line 60-69: Thanks for your constructive comments and suggestions. Preferential runoff belts are channels of karst aquifers where fractures and conduits are well-developed and serves as the main pathways for groundwater movement and solute transport. Preferential runoff belt is a hydrogeological concept, and it should not change over time, so we did not forecast the runoff belt. 

Thanks for your constructive comments and suggestions. Predicting and analyzing the changes of karst water over time is essential for the protection of karst water systems. However, we do not have enough data to predict the changes of karst water in the study area over time. Line 56-58: In this paper, precipitation and spring water level are also considered as the input and output signals of karst spring catchment, respectively.

The goal of this paper is to apply XWT and Pearson correlation coefficient to analyze the relationship between spring water level and precipitation. In the following papers with similar research content, there is no forecasting for the preferential runoff belts or hydrological time-series.

Line 384-385: An, L.X.; Ren, X.Y.; Hao, Y.H.; Yen, T.Q.; Zhang, B.J. Utilizing Precipitation and Spring Discharge Data to Identify Groundwater Quick Flow Belts in a Karst Spring Catchment. J Hydrometeorolo 2019, 20(10).

Line 412-413: Miao, J.J.; Liu, G.L.; Cao, B.B.; Hao, Y.H.; Yen, T.Q. Identification of Strong Karst Groundwater Runoff Belt by Cross Wavelet Transform. Water Resour Manag 2014,28(10),2903-2916.

Point 4: Additionally, it was not clear to me why assessing or studying preferential runoff belts is relevant or important. Also, would damming the preferential runoff belts aid in keeping more water for use by people, farming, etc.? This is not addressed.

Response 4: Line 60-69: Thanks for your constructive comments and suggestions. We explained the reasons for studying preferential runoff belts in the introduction. The main meaning of these sentences is that preferential runoff belts serves as the main pathways for groundwater movement and solute transport, so it is the main recharge pathways of springs. These runoff belts are critical for recharging the spring. In addition, building a correct hydrogeological model also needs to understand the distribution position of preferential runoff belts, and a correct hydrogeological model is the basis of establishing the numerical model of the study area.

Point 5: If the authors insist on using time series to analyze their data, they ought to sit down and decide why they seek to use it as opposed to a regression or other statistical tool. The authors state that this "study was conducted in Jinan Spring Basin to identify preferential runoff belts based on hydrological time series correlation." But, unfortunately, I did not discern an explanation why this was done and towards what end this study was undertaken.

Response 5: Line 33-46: Thanks for your constructive comments and suggestions. We explained the reasons for choosing the study area in introduction. The main meaning of these sentences is that Jinan karst system is one of the typical karst systems in North China, the research on Jinan Spring Basin has important reference value for the protection of karst water system. 

Line 66-76: Thanks for your constructive comments and suggestions. Considering the reviewer’s suggestion, we added the reasons for using hydrological time-series. The importance of preferential runoff belts has been introduced in Response 4. The traditional method to find preferential runoff belt is analyzing a considerable amount of hydrogeological data, however, these hydrogeological data are usually difficult to obtain. The cost of obtaining hydrological time-series data is low and time-saving. Using hydrological time-series to identify the most likely location of preferential runoff belt preliminarily can carry out hydrogeological survey more pertinently. In addition, the combination of hydrological sequence analysis method and geological survey method makes the results more reliable. In addition, the combination of hydrological time-series analysis and hydrogeological survey makes the results more reliable.

Thanks for your approval and suggestion. We have carefully scrutinized the manuscript, and made corresponding revisions including some typos, grammatical errors and long sentences, etc. We look forward to hearing from you regarding our submission. We would be glad to respond to any further questions and comments that you may have.

                               Yours sincerely,

                               Author: Niu Shuyao

Author Response File: Author Response.doc

Round 2

Reviewer 2 Report

The authors improved the paper following the suggestions. Not all the responses to my answers are convincing. However, in my opinion, the paper can be accepted in its current form.

 

Author Response

Dear Reviewers and Editors,

         Thanks for your approval and suggestions. We have carefully scrutinized and modified the manuscript. We would be glad to respond to any further questions and comments that you may have.

 

                               Yours sincerely,

                              First Author: Niu Shuyao

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The paper deals with identification of runoff belts in Jinan Spring basin. the study could be potentially interesting. However, I believe that the emphasis is not on the right elements in this article. a/ For example, both the introduction and the method section focuses on XWT and CWT. These algorithms are known for a long time (last 15 years at least). Therefore, you do not need to go in details on that. Good references and concise introduction should be preferred. b/How did you choose the locations for this study (place to collect the observations)?

My second issue is that the results show strong correlations, but all the places. Figure 4 and 5 show identical XWT/CWT figures.  Thus, you need to build a case and show places where there is no strong correlation. In Table 2, what shall I conclude?  there is a strong correlation between the two springs,  and for all the places looking at the phase angle? Thus, you need to take an additional spring at the border of the region and show the decorrelation.

 

Minor point: Avoid to discuss your method and future results in the introduction. Please, make the conclusions short and concise. Only the overall results should be mentioned.

Reviewer 2 Report

Please see my comments in the attached file. 

Comments for author File: Comments.pdf